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Zhang P, Li C, Huo L, Xiang B, Rahim K, Hao X, Zhu X. Role of the fungus-specific flavin carrier Flc1 in antifungal resistance in the fungal pathogen Cryptococcus neoformans. Med Mycol 2019; 57:468-477. [PMID: 30010978 DOI: 10.1093/mmy/myy050] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 04/27/2018] [Accepted: 07/09/2018] [Indexed: 01/13/2023] Open
Abstract
FLC family, a conserved fungus-specific family of integral membrane proteins, has been demonstrated to play important roles in flavin transport, growth, and virulence in several fungi but not yet in Cryptococcus neoformans. In this study, we have identified the single homologue of flavin adenine dinucleotide transporter in the opportunistic pathogen C. neoformans. The computational and phylogenetic analysis confirmed the fungal specificity of cryptococcal Flc1 protein, thus providing a promising drug target for clinical treatment of cryptococcosis. Disruption of FLC1 conferred sensitivity to 1% Congo red and 0.02% SDS, as well as leading to impaired chitin distribution in cell wall as observed with Calcofluor White staining, which collectively indicated the roles of FLC1 in maintenance of cell wall integrity. Further investigations revealed the defects of flc1Δ mutant in resistance to poor nutrition and elevated temperatures, and the ability to undergo invasive growth under nutrient-depleted conditions was reduced as well in flc1Δ mutant, suggesting the roles of Flc1 in response to environmental stresses. More importantly, our results showed that flc1Δ mutant exhibited severe susceptibility to antifungal aminoglycosides (hygromycin B and geneticin) and amphotericin B, but developed multidrug resistance to flucytosine and rapamycin, which provided great hints for therapeutic failure of cryptococcosis in clinic with the standard combination therapy. Finally, typical virulence factors including melanin biosynthesis and capsule formation in flc1Δ mutant were reduced as well, indicating the possible involvement of Flc1 in virulence.
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Affiliation(s)
- Ping Zhang
- Beijing Key Laboratory of Genetic Engineering Drug and Biotechnology, Institute of Biochemistry and Biotechnology, College of Life Sciences, Beijing Normal University (CLS-BNU), Beijing 100875, China
| | - Chenxi Li
- Beijing Key Laboratory of Genetic Engineering Drug and Biotechnology, Institute of Biochemistry and Biotechnology, College of Life Sciences, Beijing Normal University (CLS-BNU), Beijing 100875, China
| | - Liang Huo
- Beijing Key Laboratory of Genetic Engineering Drug and Biotechnology, Institute of Biochemistry and Biotechnology, College of Life Sciences, Beijing Normal University (CLS-BNU), Beijing 100875, China
| | - Biyun Xiang
- Beijing Key Laboratory of Genetic Engineering Drug and Biotechnology, Institute of Biochemistry and Biotechnology, College of Life Sciences, Beijing Normal University (CLS-BNU), Beijing 100875, China
| | - Kashif Rahim
- Beijing Key Laboratory of Genetic Engineering Drug and Biotechnology, Institute of Biochemistry and Biotechnology, College of Life Sciences, Beijing Normal University (CLS-BNU), Beijing 100875, China
| | - Xiaoran Hao
- Beijing Key Laboratory of Genetic Engineering Drug and Biotechnology, Institute of Biochemistry and Biotechnology, College of Life Sciences, Beijing Normal University (CLS-BNU), Beijing 100875, China
| | - Xudong Zhu
- Beijing Key Laboratory of Genetic Engineering Drug and Biotechnology, Institute of Biochemistry and Biotechnology, College of Life Sciences, Beijing Normal University (CLS-BNU), Beijing 100875, China
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52
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Lei S, Zhao H, Pang B, Qu R, Lian Z, Jiang C, Shao D, Huang Q, Jin M, Shi J. Capability of iturin from Bacillus subtilis to inhibit Candida albicans in vitro and in vivo. Appl Microbiol Biotechnol 2019; 103:4377-4392. [PMID: 30997554 DOI: 10.1007/s00253-019-09805-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 03/25/2019] [Accepted: 03/29/2019] [Indexed: 01/23/2023]
Abstract
Candida albicans is a fungal pathogen that is difficult to cure clinically. The current clinic C. albicans-inhibiting drugs are very harmful to humans. This study revealed the potential of iturin fractions from Bacillus subtilis to inhibit C. albicans in free status (MIC = 32 μg/mL) and natural biofilm in vitro. The inhibition mechanism was identified as an apoptosis pathway via the decrease of mitochondrial membrane potential, the increase of the reactive oxygen species (ROS) accumulation, and the induction of nuclear condensation. For in vivo experiments, the C. albicans infection model was constructed via intraperitoneal injection of 1 × 108C. albicans cells into mice. One day after the infection, iturin was used to treat infected mice at different concentrations alone and in combination with amphotericin B (AmB) by intraperitoneal injection. The treatment with AmB alone could cause the death of infected mice, whereas treatment with 15 mg/kg iturin per day alone led to the survival of all infected mice throughout the study. After continuously treated for 6 days, all mice were sacrificed and analyzed. As results, the combination of 15 mg/kg iturin and AmB at a ratio of 2:1 had the most efficient effect to remove the fungal burden in the kidney and cure the infected mice by reversing the symptoms caused by C. albicans infection, such as the loss of body weight, change of immunology cells in blood and cytokines in serum, and damage of organ structure and functions. Overall, iturin had potential in the development of efficient and safe drugs to cure C. albicans infection.
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Affiliation(s)
- Shuzhen Lei
- Key Laboratory for Space Bioscience and Space Biotechnology, School of Life Sciences, Northwestern Polytechnical University, 127 Youyi West Road, Xi'an, 710072, Shaanxi Province, China
| | - Haobin Zhao
- Key Laboratory for Space Bioscience and Space Biotechnology, School of Life Sciences, Northwestern Polytechnical University, 127 Youyi West Road, Xi'an, 710072, Shaanxi Province, China
| | - Bing Pang
- Key Laboratory for Space Bioscience and Space Biotechnology, School of Life Sciences, Northwestern Polytechnical University, 127 Youyi West Road, Xi'an, 710072, Shaanxi Province, China
| | - Rui Qu
- Key Laboratory for Space Bioscience and Space Biotechnology, School of Life Sciences, Northwestern Polytechnical University, 127 Youyi West Road, Xi'an, 710072, Shaanxi Province, China
| | - Ziyang Lian
- Key Laboratory for Space Bioscience and Space Biotechnology, School of Life Sciences, Northwestern Polytechnical University, 127 Youyi West Road, Xi'an, 710072, Shaanxi Province, China
| | - Chunmei Jiang
- Key Laboratory for Space Bioscience and Space Biotechnology, School of Life Sciences, Northwestern Polytechnical University, 127 Youyi West Road, Xi'an, 710072, Shaanxi Province, China
| | - Dongyan Shao
- Key Laboratory for Space Bioscience and Space Biotechnology, School of Life Sciences, Northwestern Polytechnical University, 127 Youyi West Road, Xi'an, 710072, Shaanxi Province, China
| | - Qingsheng Huang
- Key Laboratory for Space Bioscience and Space Biotechnology, School of Life Sciences, Northwestern Polytechnical University, 127 Youyi West Road, Xi'an, 710072, Shaanxi Province, China
| | - Mingliang Jin
- Key Laboratory for Space Bioscience and Space Biotechnology, School of Life Sciences, Northwestern Polytechnical University, 127 Youyi West Road, Xi'an, 710072, Shaanxi Province, China
| | - Junling Shi
- Key Laboratory for Space Bioscience and Space Biotechnology, School of Life Sciences, Northwestern Polytechnical University, 127 Youyi West Road, Xi'an, 710072, Shaanxi Province, China.
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53
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Gonzalez-Lara MF, Sifuentes-Osornio J, Ostrosky-Zeichner L. Drugs in Clinical Development for Fungal Infections. Drugs 2019; 77:1505-1518. [PMID: 28840541 DOI: 10.1007/s40265-017-0805-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Despite increasing rates of invasive fungal infections being reported globally, only a single antifungal drug has been approved during the last decade. Resistance, toxicity, drug interactions and restricted routes of administration remain unresolved issues. This review focuses on new antifungal compounds which are currently in various clinical phases of development. We discuss two azoles with a tetrazole moiety that allows selective activity against the fungal CYP: VT-1161 for Candida infections and VT-1129 for cryptococcal meningoencephalitis. We also discuss two glucan synthesis inhibitors: CD101, an echinocandin with an increased half-life, and SCY-078 with oral bioavailability and increased activity against echinocandin-resistant isolates. Among the polyenes, we discuss MAT023, an encochleated amphotericin B formulation that allows oral administration. Two novel classes of antifungal drugs are also described: glycosylphosphatidylinositol inhibitors, and the leading drug APX001, which disrupt the integrity of the fungal wall; and the orotomides, inhibitors of pyrimidine synthesis with the leading drug F901318. Finally, a chitin synthesis inhibitor and progress on human monoclonal antifungal antibodies are discussed.
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Affiliation(s)
- Maria F Gonzalez-Lara
- Department of Infectious Diseases, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Vasco de Quiroga 15, Belisario Domínguez Sección XVI, Tlalpan, Zip Code 14080, Mexico City, Mexico.
| | - Jose Sifuentes-Osornio
- Department of Medicine, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Vasco de Quiroga 15, Belisario Domínguez Sección XVI, Tlalpan, Zip Code 14080, Mexico City, Mexico
| | - Luis Ostrosky-Zeichner
- Division of Infectious Diseases, McGovern Medical School, Medical Director of Epidemiology, Memorial Hermann Texas Medical Center, 6431 Fanning MSB 2.112, Houston, TX, USA
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Giacobbe DR, Corcione S, Salsano A, Del Puente F, Mornese Pinna S, De Rosa FG, Mikulska M, Santini F, Viscoli C. Current and emerging pharmacotherapy for the treatment of infections following open-heart surgery. Expert Opin Pharmacother 2019; 20:751-772. [PMID: 30785333 DOI: 10.1080/14656566.2019.1574753] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
INTRODUCTION Patients undergoing open-heart surgery may suffer from postoperative complications, including severe infections. Antimicrobials to treat infectious complications in this population should be selected thoughtfully, taking into account three different and fundamental issues: (i) the site of infection; (ii) the suspected or proven causative agent and its susceptibility pattern; and (iii) the risk of suboptimal pharmacokinetic characteristics and potential toxicity of the chosen drug/s. AREAS COVERED The present narrative review summarizes the current and future antimicrobial options for the treatment of infections developing after open-heart surgery. EXPERT OPINION The pharmacological treatment of infections developing in cardiac surgery patients poses peculiar challenges, including the need for an active empirical therapy for severe events such as bloodstream infections, deep sternal wound infections, or early-onset postoperative prosthetic endocarditis. In addition, the risk for multidrug-resistant pathogens should also be taken into account in endemic areas. A multidisciplinary evaluation on a patient-by-patient basis, deeply involving infectious diseases specialists and cardiothoracic surgeons, remains essential for appropriately balancing both short-term and long-term risks and benefits of any possible surgical reintervention in combination with adequate pharmacotherapy.
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Affiliation(s)
| | - Silvia Corcione
- b Department of Medical Sciences, Infectious Diseases , University of Turin , Turin , Italy
| | - Antonio Salsano
- c Division of Cardiac Surgery, Dipartimento di Scienze Chirurgiche e Diagnostiche Integrate (DISC) , University of Genoa , Genoa , Italy.,d Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Ospedale Policlinico San Martino , Genoa , Italy
| | - Filippo Del Puente
- a Dipartimento di Scienze della Salute (DISSAL) , University of Genoa , Genoa , Italy
| | - Simone Mornese Pinna
- b Department of Medical Sciences, Infectious Diseases , University of Turin , Turin , Italy
| | | | - Malgorzata Mikulska
- a Dipartimento di Scienze della Salute (DISSAL) , University of Genoa , Genoa , Italy.,d Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Ospedale Policlinico San Martino , Genoa , Italy
| | - Francesco Santini
- c Division of Cardiac Surgery, Dipartimento di Scienze Chirurgiche e Diagnostiche Integrate (DISC) , University of Genoa , Genoa , Italy.,d Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Ospedale Policlinico San Martino , Genoa , Italy
| | - Claudio Viscoli
- a Dipartimento di Scienze della Salute (DISSAL) , University of Genoa , Genoa , Italy.,d Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Ospedale Policlinico San Martino , Genoa , Italy
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55
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Genetically Compromising Phospholipid Metabolism Limits Candida albicans' Virulence. Mycopathologia 2019; 184:213-226. [PMID: 30693413 DOI: 10.1007/s11046-019-00320-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 01/19/2019] [Indexed: 01/06/2023]
Abstract
Perturbing ergosterol synthesis has been previously shown to reduce the virulence of Candida albicans. We tested the hypothesis that further altering cell membrane composition by limiting phospholipid synthesis or remodeling will have the same effect. To model partial inhibition, C. albicans strains independently harboring heterozygous deletion of four genes that encode for enzymes that mediate phospholipid synthesis or modification were generated. Quantitative PCR determined that heterozygous deletion routinely caused a nearly 50% reduction in the respective gene's transcript abundance. Compensatory increased transcript abundance was only found with the deletion of LRO1, a homolog of phospholipid diacylglycerol acyltransferases. Virulence of the mutants was assayed in a Caenorhabditis elegans host model. Even modestly reduced expression of LRO1, phosphatidylserine synthase (CHO1), and lysophospholipid acyltransferase (LPT1) significantly reduced virulence by 23-38%. Reintroducing a second functional allele, respectively, to all three mutants restored virulence. Heterozygous deletion of SLC1, a homolog of 1-acylglycerol-3-phosphate O-acyltransferases, did not significantly reduce virulence. Electrospray ionization tandem mass spectrometry analysis of phospholipid composition followed by principal component analysis identified comprehensive changes in the LRO1 and CHO1 deletion heterozygotes. Strikingly (p < 0.001), univariate comparisons found that both deletion heterozygotes had 20% more phosphatidylinositol, 75% less lysophosphatidylcholine, and 35% less lysophosphatidylethanolamine compared to wild type. Heterozygous deletion of LPT1 also significantly increased phosphatidylinositol abundance. No growth phenotype, including filamentation, was affected by any mutation. Together, these data predict that even partial pharmacological inhibition of Lro1p, Cho1p, and Lpt1p will limit C. albicans virulence through altering phospholipid composition.
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56
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Arockianathan PM, Mishra M, Niranjan R. Recent Status and Advancements in the Development of Antifungal Agents: Highlights on Plant and Marine Based Antifungals. Curr Top Med Chem 2019; 19:812-830. [PMID: 30977454 DOI: 10.2174/1568026619666190412102037] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 03/13/2019] [Accepted: 03/13/2019] [Indexed: 11/22/2022]
Abstract
The developing resistance in fungi has become a key challenge, which is being faced nowadays with the available antifungal agents in the market. Further search for novel compounds from different sources has been explored to meet this problem. The current review describes and highlights recent advancement in the antifungal drug aspects from plant and marine based sources. The current available antifungal agents act on specific targets on the fungal cell wall, like ergosterol synthesis, chitin biosynthesis, sphingolipid synthesis, glucan synthesis etc. We discuss some of the important anti-fungal agents like azole, polyene and allylamine classes that inhibit the ergosterol biosynthesis. Echinocandins inhibit β-1, 3 glucan synthesis in the fungal cell wall. The antifungals poloxins and nikkomycins inhibit fungal cell wall component chitin. Apart from these classes of drugs, several combinatorial therapies have been carried out to treat diseases due to fungal resistance. Recently, many antifungal agents derived from plant and marine sources showed potent activity. The renewed interest in plant and marine derived compounds for the fungal diseases created a new way to treat these resistant strains which are evident from the numerous literature publications in the recent years. Moreover, the compounds derived from both plant and marine sources showed promising results against fungal diseases. Altogether, this review article discusses the current antifungal agents and highlights the plant and marine based compounds as a potential promising antifungal agents.
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Affiliation(s)
- P Marie Arockianathan
- PG & Research Department of Biochemistry, St. Joseph's College of Arts & Science (Autonomous), Cuddalore-607001, Tamil Nadu, India
| | - Monika Mishra
- Neurobiology laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Rituraj Niranjan
- Unit of Microbiology and Molecular Biology, ICMR-Vector Control Research Center, Puducherry 605006, India
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57
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Nicola AM, Albuquerque P, Paes HC, Fernandes L, Costa FF, Kioshima ES, Abadio AKR, Bocca AL, Felipe MS. Antifungal drugs: New insights in research & development. Pharmacol Ther 2018; 195:21-38. [PMID: 30347212 DOI: 10.1016/j.pharmthera.2018.10.008] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The need for better antifungal therapy is commonly accepted in view of the high mortality rates associated with systemic infections, the low number of available antifungal classes, their associated toxicity and the increasing number of infections caused by strains with natural or acquired resistance. The urgency to expand the range of therapeutic options for the treatment of fungal infections has led researchers in recent decades to seek alternative antifungal targets when compared to the conventional ones currently used. Although new potential targets are reported, translating the discoveries from bench to bedside is a long process and most of these drugs fail to reach the patients. In this review, we discuss the development of antifungal drugs focusing on the approach of drug repurposing and the search for novel drugs for classical targets, the most recently described gene targets for drug development, the possibilities of immunotherapy using antibodies, cytokines, therapeutic vaccines and antimicrobial peptides.
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Affiliation(s)
| | - Patrícia Albuquerque
- Faculty of Ceilândia, University of Brasília, Brazil; Graduate Programme in Microbial Biology, University of Brasília, Brazil
| | - Hugo Costa Paes
- Division of Clinical Medicine, University of Brasília Medical School, Brazil
| | - Larissa Fernandes
- Faculty of Ceilândia, University of Brasília, Brazil; Graduate Programme in Microbial Biology, University of Brasília, Brazil
| | - Fabricio F Costa
- Graduate Programme in Genomic Science and Biotechnology, Catholic University of Brasília, Brazil; MATTER, Chicago, IL, USA; Cancer Biology and Epigenomics Program, Ann & Robert Lurie Children's Hospital of Chicago Research Center, Northwestern University's Feinberg School of Medicine, Chicago, Illinois, USA
| | - Erika Seki Kioshima
- Department of Clinical Analysis and Biomedicine, State University of Maringá, Paraná, Brazil
| | - Ana Karina Rodrigues Abadio
- School for Applied Social and Agricultural Sciences, State University of Mato Grosso, Nova Mutum Campus, Mato Grosso, Brazil
| | | | - Maria Sueli Felipe
- Graduate Programme in Genomic Science and Biotechnology, Catholic University of Brasília, Brazil; Department of Cell Biology, Institute of Biological Sciences, University of Brasília, Brazil.
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58
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Fizil Á, Sonderegger C, Czajlik A, Fekete A, Komáromi I, Hajdu D, Marx F, Batta G. Calcium binding of the antifungal protein PAF: Structure, dynamics and function aspects by NMR and MD simulations. PLoS One 2018; 13:e0204825. [PMID: 30321182 PMCID: PMC6188699 DOI: 10.1371/journal.pone.0204825] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 09/14/2018] [Indexed: 11/19/2022] Open
Abstract
Calcium ions (Ca2+) play an important role in the toxicity of the cysteine-rich and cationic antifungal protein PAF from Penicillium chrysogenum: high extracellular Ca2+ levels reduce the toxicity of PAF in the sensitive model fungus Neurospora crassa in a concentration dependent way. However, little is known about the mechanistic details of the Ca2+ ion impact and the Ca2+ binding capabilities of PAF outside the fungal cell, which might be the reason for the activity loss. Using nuclear magnetic resonance (NMR), isothermal titration calorimetry and molecular dynamics (MD) simulations we demonstrated that PAF weakly, but specifically binds Ca2+ ions. MD simulations of PAF predicted one major Ca2+ binding site at the C-terminus involving Asp53 and Asp55, while Asp19 was considered as putative Ca2+ binding site. The exchange of Asp19 to serine had little impact on the Ca2+ binding, however caused the loss of antifungal activity, as was shown in our recent study. Now we replaced the C-terminal aspartates and expressed the serine variant PAFD53S/D55S. The specific Ca2+ binding affinity of PAFD53S/D55S decreased significantly if compared to PAF, whereas the antifungal activity was retained. To understand more details of Ca2+ interactions, we investigated the NMR and MD structure/dynamics of the free and Ca2+-bound PAF and PAFD53S/D55S. Though we found some differences between these protein variants and the Ca2+ complexes, these effects cannot explain the observed Ca2+ influence. In conclusion, PAF binds Ca2+ ions selectively at the C-terminus; however, this Ca2+ binding does not seem to play a direct role in the previously documented modulation of the antifungal activity of PAF.
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Affiliation(s)
- Ádám Fizil
- Department of Organic Chemistry, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary
| | - Christoph Sonderegger
- Division of Molecular Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - András Czajlik
- Department of Organic Chemistry, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary
| | - Attila Fekete
- Department of Organic Chemistry, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary
| | - István Komáromi
- Division of Clinical Laboratory Science, Department of Laboratory Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Dorottya Hajdu
- Department of Organic Chemistry, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary
| | - Florentine Marx
- Division of Molecular Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
- * E-mail: (GB); (FM)
| | - Gyula Batta
- Department of Organic Chemistry, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary
- * E-mail: (GB); (FM)
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59
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Kuhnert E, Li Y, Lan N, Yue Q, Chen L, Cox RJ, An Z, Yokoyama K, Bills GF. Enfumafungin synthase represents a novel lineage of fungal triterpene cyclases. Environ Microbiol 2018; 20:3325-3342. [PMID: 30051576 DOI: 10.1111/1462-2920.14333] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 06/18/2018] [Accepted: 06/19/2018] [Indexed: 01/12/2023]
Abstract
Enfumafungin is a glycosylated fernene-type triterpenoid produced by the fungus Hormonema carpetanum. Its potent antifungal activity, mediated by its interaction with β-1,3-glucan synthase and the fungal cell wall, has led to its development into the semi-synthetic clinical candidate, ibrexafungerp (=SCY-078). We report on the preliminary identification of the enfumafungin biosynthetic gene cluster (BGC) based on genome sequencing, phylogenetic reconstruction, gene disruption, and cDNA sequencing studies. Enfumafungin synthase (efuA) consists of a terpene cyclase domain (TC) fused to a glycosyltransferase (GT) domain and thus represents a novel multifunctional enzyme. Moreover, the TC domain bears a phylogenetic relationship to bacterial squalene-hopene cyclases (SHC) and includes a typical DXDD motif within the active centre suggesting that efuA evolved from SHCs. Phylogenetic reconstruction of the GT domain indicated that this portion of the fusion gene originated from fungal sterol GTs. Eleven genes flanking efuA are putatively involved in the biosynthesis, regulation, transport and self-resistance of enfumafungin and include an acetyltransferase, three P450 monooxygenases, a dehydrogenase, a desaturase and a reductase. A hypothetical scheme for enfumafungin assembly is proposed in which the E-ring is oxidatively cleaved to yield the four-ring system of enfumafungin. EfuA represents the first member of a widespread lineage of fungal SHCs.
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Affiliation(s)
- Eric Kuhnert
- Texas Therapeutics Institute, the Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX, USA.,Leibniz University Hannover, Institute for Organic Chemistry and BMWZ, Hannover, Germany
| | - Yan Li
- Texas Therapeutics Institute, the Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX, USA.,Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Nan Lan
- Texas Therapeutics Institute, the Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Qun Yue
- Texas Therapeutics Institute, the Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX, USA.,Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Li Chen
- Texas Therapeutics Institute, the Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Russell J Cox
- Leibniz University Hannover, Institute for Organic Chemistry and BMWZ, Hannover, Germany
| | - Zhiqiang An
- Texas Therapeutics Institute, the Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Kenichi Yokoyama
- Duke University School of Medicine, Department of Biochemistry, Durham, NC, USA
| | - Gerald F Bills
- Texas Therapeutics Institute, the Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX, USA
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60
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Weissman Z, Pinsky M, Wolfgeher DJ, Kron SJ, Truman AW, Kornitzer D. Genetic analysis of Hsp70 phosphorylation sites reveals a role in Candida albicans cell and colony morphogenesis. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2018; 1868:140135. [PMID: 31964485 DOI: 10.1016/j.bbapap.2018.09.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 08/20/2018] [Accepted: 09/06/2018] [Indexed: 11/30/2022]
Abstract
Heat shock proteins are best known for their role as chaperonins involved in general proteostasis, but they can also participate in specific cellular regulatory pathways, e.g. via their post-translational modification. Hsp70/Ssa1 is a central cytoplasmic chaperonin in eukaryotes, which also participates in cell cycle regulation via its phosphorylation at a specific residue. Here we analyze the role of Ssa1 phosphorylation in the morphogenesis of the fungus Candida albicans, a common human opportunistic pathogen. C. albicans can assume alternative yeast and hyphal (mold) morphologies, an ability that contributes to its virulence. We identified 11 phosphorylation sites on C. albicans Ssa1, of which 8 were only detected in the hyphal cells. Genetic analysis of these sites revealed allele-specific effects on growth or hyphae formation at 42 °C. Colony morphology, which is normally wrinkled or crenellated at 37 °C, reverted to smooth in several mutants, but this colony morphology phenotype was unrelated to cellular morphology. Two mutants exhibited a mild increase in sensitivity to the cell wall-active compounds caspofungin and calcofluor white. We suggest that this analysis could help direct screens for Ssa1-specific drugs to combat C. albicans virulence. The pleiotropic effects of many Ssa1 mutations are consistent with the large number of Ssa1 client proteins, whereas the lack of concordance between the phenotypes of the different alleles suggests that different sites on Ssa1 can affect interaction with specific classes of client proteins, and that modification of these sites can play cellular regulatory roles, consistent with the "chaperone code" hypothesis.
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Affiliation(s)
- Ziva Weissman
- Department of Molecular Microbiology, B. Rappaport Faculty of Medicine, Technion - I.I.T. and the Rappaport Institute for Research in the Medical Sciences, Haifa 31096, Israel
| | - Mariel Pinsky
- Department of Molecular Microbiology, B. Rappaport Faculty of Medicine, Technion - I.I.T. and the Rappaport Institute for Research in the Medical Sciences, Haifa 31096, Israel
| | - Donald J Wolfgeher
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
| | - Stephen J Kron
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
| | - Andrew W Truman
- Department of Biological Sciences, University of North Carolina, Charlotte, NC 28223, USA.
| | - Daniel Kornitzer
- Department of Molecular Microbiology, B. Rappaport Faculty of Medicine, Technion - I.I.T. and the Rappaport Institute for Research in the Medical Sciences, Haifa 31096, Israel.
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61
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Cortés Hidalgo AP, Roa Dueñas OH, Méndez Fandiño YR, Álvarez Moreno CA. Opciones terapéuticas frente a especies de Candida resistentes a las equinocandinas. UNIVERSITAS MÉDICA 2018. [DOI: 10.11144/javeriana.umed59-2.cand] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
<p><strong>Introducción</strong>: La infección por levaduras del género <em>Candida</em> representa la causa más común de infecciones fúngicas invasivas. Su alta incidencia y la creciente resistencia frente a los azoles y, recientemente, a las equinocandinas ha generado la necesidad de buscar nuevas alternativas farmacológicas. Esta revisión presenta las principales alternativas farmacológicas en estudio frente a <em>Candida</em> resistente a equinocandinas. <strong>Métodos</strong>: Se buscó literatura referente al tema en las bases de datos Bireme, Clinical Key, Embase, Cochrane, Lilacs, Pubmed y Scopus. Se incluyeron 15 artículos en esta revisión. <strong>Resultados</strong>: Se exploran diferentes alternativas, incluyendo el aumento de dosis de las equinocandinas, su combinación con otros medicamentos y nuevos compuestos en estudio. <strong>Conclusión</strong>: A pesar de que las infecciones por <em>Candida</em> resistente a equinocandinas aún representan un desafío, dos alternativas farmacológicas se presentan como promisorias: la combinación con medicamentos existentes como el diclofenaco y nuevos compuestos que se encuentran actualmente en fase II de estudios clínicos.</p><p> </p>
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Thombare VJ, Holden JA, Pal S, Reynolds EC, Chattopadhyay A, O'Brien-Simpson NM, Hutton CA. Antimicrobial activity of simplified mimics of celogentin C. Tetrahedron 2018. [DOI: 10.1016/j.tet.2017.12.032] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Liu N, Tu J, Dong G, Wang Y, Sheng C. Emerging New Targets for the Treatment of Resistant Fungal Infections. J Med Chem 2018; 61:5484-5511. [DOI: 10.1021/acs.jmedchem.7b01413] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Na Liu
- School of Pharmacy, Second Military Medical University, 325 Guohe Road, Shanghai 200433, People’s Republic of China
| | - Jie Tu
- School of Pharmacy, Second Military Medical University, 325 Guohe Road, Shanghai 200433, People’s Republic of China
| | - Guoqiang Dong
- School of Pharmacy, Second Military Medical University, 325 Guohe Road, Shanghai 200433, People’s Republic of China
| | - Yan Wang
- School of Pharmacy, Second Military Medical University, 325 Guohe Road, Shanghai 200433, People’s Republic of China
| | - Chunquan Sheng
- School of Pharmacy, Second Military Medical University, 325 Guohe Road, Shanghai 200433, People’s Republic of China
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Perlin DS, Rautemaa-Richardson R, Alastruey-Izquierdo A. The global problem of antifungal resistance: prevalence, mechanisms, and management. THE LANCET. INFECTIOUS DISEASES 2017; 17:e383-e392. [DOI: 10.1016/s1473-3099(17)30316-x] [Citation(s) in RCA: 458] [Impact Index Per Article: 65.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 04/09/2017] [Accepted: 04/10/2017] [Indexed: 01/05/2023]
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Pyrpasopoulou A, Iosifidis E, Roilides E. Current and potential treatment options for invasiveCandidainfections. Expert Opin Orphan Drugs 2017. [DOI: 10.1080/21678707.2017.1379392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- A. Pyrpasopoulou
- Infectious Diseases Unit, 3rd Department of Paediatrics, Aristotle University School of Health Sciences, Thessaloniki, Greece
- 2nd Department of Propedeutic Internal Medicine, Faculty of Medicine, Aristotle University School of Health Sciences, Thessaloniki, Greece
| | - E. Iosifidis
- Infectious Diseases Unit, 3rd Department of Paediatrics, Aristotle University School of Health Sciences, Thessaloniki, Greece
| | - E. Roilides
- Infectious Diseases Unit, 3rd Department of Paediatrics, Aristotle University School of Health Sciences, Thessaloniki, Greece
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De Novo Acquisition of Resistance to SCY-078 in Candida glabrata Involves FKS Mutations That both Overlap and Are Distinct from Those Conferring Echinocandin Resistance. Antimicrob Agents Chemother 2017. [PMID: 28630180 DOI: 10.1128/aac.00833-17] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
SCY-078 is an orally active antifungal whose target is the β-(1,3)-d-glucan synthase (GS). We evaluated the spontaneous emergence of SCY-078-resistant Candida glabrata isolates following drug exposure in vitro Resistant isolates were analyzed using broth microdilution methodology and FKS sequencing. The kinetic inhibition parameter IC50 (50% inhibitory concentration) was also determined from GS complexes. The spectrum of resistance mutations found suggested a partially overlapping but independent binding site for SCY-078 relative to echinocandins on GS.
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Pfaller MA, Messer SA, Rhomberg PR, Borroto-Esoda K, Castanheira M. Differential Activity of the Oral Glucan Synthase Inhibitor SCY-078 against Wild-Type and Echinocandin-Resistant Strains of Candida Species. Antimicrob Agents Chemother 2017; 61:e00161-17. [PMID: 28533234 PMCID: PMC5527608 DOI: 10.1128/aac.00161-17] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 05/11/2017] [Indexed: 01/05/2023] Open
Abstract
SCY-078 (formerly MK-3118) is a novel orally active inhibitor of fungal β-(1,3)-glucan synthase (GS). SCY-078 is a derivative of enfumafungin and is structurally distinct from the echinocandin class of antifungal agents. We evaluated the in vitro activity of this compound against wild-type (WT) and echinocandin-resistant isolates containing mutations in the FKS genes of Candida spp. Against 36 Candida spp. FKS mutants tested, 30 (83.3%) were non-WT to 1 or more echinocandins, and only 9 (25.0%) were non-WT (MIC, >WT-upper limit) to SCY-078. Among C. glabrata isolates carrying FKS alterations, 84.0% were non-WT to the echinocandins versus only 24.0% for SCY-078. In contrast to the echinocandin comparators, the activity of SCY-078 was minimally affected by the presence of FKS mutations, suggesting that this agent is useful in the treatment of Candida infections due to echinocandin-resistant strains.
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Pfaller MA, Messer SA, Rhomberg PR, Castanheira M. CD101, a long-acting echinocandin, and comparator antifungal agents tested against a global collection of invasive fungal isolates in the SENTRY 2015 Antifungal Surveillance Program. Int J Antimicrob Agents 2017; 50:352-358. [PMID: 28689871 DOI: 10.1016/j.ijantimicag.2017.03.028] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 03/16/2017] [Accepted: 03/18/2017] [Indexed: 12/29/2022]
Abstract
CD101 is a novel echinocandin with exceptional chemical stability and long-acting pharmacokinetics. The activity of CD101 and comparators was evaluated using CLSI broth microdilution methods against 713 invasive fungal isolates, including 589 Candida spp. (6 species), 14 C. neoformans, 97 A. fumigatus and 13 A. flavus species complex collected worldwide during 2015. All C. tropicalis, C. krusei and C. dubliniensis, 99.7% of C. albicans and 98.3% of C. glabrata were inhibited by ≤0.12 µg/mL of CD101, and these isolates were susceptible/wild type to other echinocandins using CLSI clinical breakpoint and epidemiological cutoff value (ECV) interpretive criteria. C. parapsilosis displayed higher MIC values (range 0.25-2 µg/mL), but similar results were observed for other echinocandins. One C. glabrata and one C. albicans with CD101 MIC value at 1 and 0.25 µg/mL possessed F625S and S645P alterations on FKS1, respectively. These isolates also displayed elevated MIC values for at least one clinically available echinocandin. Fluconazole resistance was noted for 6.6% of C. glabrata and 3.6% C. parapsilosis. Echinocandins had limited activity against C. neoformans. CD101 activity against A. fumigatus and A. flavus (MEC ≤0.03 µg/mL) was comparable to other echinocandins (MEC ≤0.03 µg/mL). These moulds had MIC values below ECVs for the mould-active azoles. CD101 was as active as other echinocandins against common fungal organisms recovered from invasive fungal infections. The extended half-life profile is very desirable as less frequent dosing of this agent should facilitate shorter and more cost-effective hospital stays, improve compliance for outpatients, and provide more convenient outpatient prophylaxis.
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Affiliation(s)
- Michael A Pfaller
- JMI Laboratories, North Liberty, Iowa, USA; University of Iowa, Iowa City, Iowa, USA
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Alcázar M, Kind T, Gschaedler A, Silveria M, Arrizon J, Fiehn O, Vallejo A, Higuera I, Lugo E. Effect of steroidal saponins from Agave on the polysaccharide cell wall composition of Saccharomyces cerevisiae and Kluyveromyces marxianus. Lebensm Wiss Technol 2017. [DOI: 10.1016/j.lwt.2016.11.048] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Belewa V, Baijnath H, Frost C, Somai BM. Tulbaghia violacea Harv. plant extract affects cell wall synthesis in Aspergillus flavus. J Appl Microbiol 2017; 122:921-931. [PMID: 28132403 DOI: 10.1111/jam.13405] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 12/14/2016] [Accepted: 01/16/2017] [Indexed: 11/26/2022]
Abstract
AIMS This study investigates the effect that aqueous extracts of Tulbaghia violacea Harv. harbouring plant saponins, phenolics and tannins have on Aspergillus flavus β-(1,3) glucan and chitin synthesis. METHODS AND RESULTS Aspergillus flavus was treated with various subinhibitory concentrations of an aqueous T. violacea plant extract and the β-(1,3) glucan and chitin content was determined together with glucan synthase and chitin synthase production respectively. CONCLUSIONS The aqueous extract caused a significant decline (P < 0·05) in β-glucan production in A. flavus in a dose-dependent manner when compared to the untreated sample. Further investigations showed a decrease in β-glucan synthase production as the concentration of the plant extract was increased. A significant reduction in total chitin content corresponding to a decrease in chitin synthase production in the presence of the plant extract was also found. SIGNIFICANCE AND IMPACT OF THE STUDY The broad spectrum activity and the efficacy of aqueous T. violacea plant extract on both β-glucan and chitin synthesis may limit the potential of the fungus developing resistance towards it and therefore the extract is an ideal candidate for use as a potential antifungal agent.
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Affiliation(s)
- V Belewa
- Department of Biochemistry and Microbiology, Nelson Mandela Metropolitan University, Port Elizabeth, Eastern Cape, South Africa
| | - H Baijnath
- Ward Herbarium, School of Life Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - C Frost
- Department of Biochemistry and Microbiology, Nelson Mandela Metropolitan University, Port Elizabeth, Eastern Cape, South Africa
| | - B M Somai
- Department of Biochemistry and Microbiology, Nelson Mandela Metropolitan University, Port Elizabeth, Eastern Cape, South Africa
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Victoria Castelli M, Gabriel Derita M, Noelí López S. Novel antifungal agents: a patent review (2013 - present). Expert Opin Ther Pat 2016; 27:415-426. [DOI: 10.1080/13543776.2017.1261113] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- María Victoria Castelli
- Universidad Nacional de Rosario, CONICET, Farmacognosia, Facultad de Ciencias Bioquímicas y Farmacéuticas, Rosario, Santa Fe, Argentina
| | - Marcos Gabriel Derita
- Universidad Nacional de Rosario, CONICET, Farmacognosia, Facultad de Ciencias Bioquímicas y Farmacéuticas, Rosario, Santa Fe, Argentina
- Universidad Nacional del Litoral, CONICET, Cátedra de Cultivos Intensivos, Facultad de Ciencias Agrarias, Esperanza, Santa Fe, Argentina
| | - Silvia Noelí López
- Universidad Nacional de Rosario, CONICET, Farmacognosia, Facultad de Ciencias Bioquímicas y Farmacéuticas, Rosario, Santa Fe, Argentina
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Abstract
ABSTRACT
Invasive fungal infections are becoming an increasingly important cause of human mortality and morbidity, particularly for immunocompromised populations. The fungal pathogens
Candida albicans
,
Cryptococcus neoformans
, and
Aspergillus fumigatus
collectively contribute to over 1 million human deaths annually. Hence, the importance of safe and effective antifungal therapeutics for the practice of modern medicine has never been greater. Given that fungi are eukaryotes like their human host, the number of unique molecular targets that can be exploited for drug development remains limited. Only three classes of molecules are currently approved for the treatment of invasive mycoses. The efficacy of these agents is compromised by host toxicity, fungistatic activity, or the emergence of drug resistance in pathogen populations. Here we describe our current arsenal of antifungals and highlight current strategies that are being employed to improve the therapeutic safety and efficacy of these drugs. We discuss state-of-the-art approaches to discover novel chemical matter with antifungal activity and highlight some of the most promising new targets for antifungal drug development. We feature the benefits of combination therapy as a strategy to expand our current repertoire of antifungals and discuss the antifungal combinations that have shown the greatest potential for clinical development. Despite the paucity of new classes of antifungals that have come to market in recent years, it is clear that by leveraging innovative approaches to drug discovery and cultivating collaborations between academia and industry, there is great potential to bolster the antifungal armamentarium.
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Fujitani M, Tanino K. Synthetic studies on enfumafungin: stereoselective synthesis of the CD ring segment. Tetrahedron Lett 2016. [DOI: 10.1016/j.tetlet.2016.09.057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Design and Synthesis of Analogues of Marine Natural Product Galaxamide, an N-methylated Cyclic Pentapeptide, as Potential Anti-Tumor Agent in Vitro. Mar Drugs 2016; 14:md14090161. [PMID: 27598177 PMCID: PMC5039532 DOI: 10.3390/md14090161] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 08/26/2016] [Accepted: 08/26/2016] [Indexed: 12/14/2022] Open
Abstract
Herein, we report design and synthesis of novel 26 galaxamide analogues with N-methylated cyclo-pentapeptide, and their in vitro anti-tumor activity towards the panel of human tumor cell line, such as, A549, A549/DPP, HepG2 and SMMC-7721 using MTT assay. We have also investigated the effect of galaxamide and its representative analogues on growth, cell-cycle phases, and induction of apoptosis in SMMC-7721 cells in vitro. Reckon with the significance of conformational space and N-Me aminoacid (aa) comprising this compound template, we designed the analogues with modification in N-Me-aa position, change in aa configuration from l to d aa and substitute one Leu-aa to d/l Phe-aa residue with respective to the parent structure. The efficient solid phase parallel synthesis approach is employed for the linear pentapeptide residue containing N-Me aa, followed by solution phase macrocyclisation to afford target cyclo pentapeptide compounds. In the present study, all galaxamide analogues exhibited growth inhibition in A549, A549/DPP, SMMC-7721 and HepG2 cell lines. Compounds 6, 18, and 22 exhibited interesting activities towards all cell line tested, while Compounds 1, 4, 15, and 22 showed strong activity towards SMMC-7221 cell line in the range of 1–2 μg/mL IC50. Flow cytometry experiment revealed that galaxamide analogues namely Compounds 6, 18, and 22 induced concentration dependent SMMC-7721 cell apoptosis after 48 h. These compounds induced G0/G1 phase cell-cycle arrest and morphological changes indicating induction of apoptosis. Thus, findings of our study suggest that the galaxamide and its analogues 6, 18 and 22 exerted growth inhibitory effect on SMMC-7721 cells by arresting the cell cycle in the G0/G1 phase and inducing apoptosis. Compound 1 showed promising anti-tumor activity towards SMMC-7721 cancer cell line, which is 9 and 10 fold higher than galaxamide and reference DPP (cisplatin), respectively.
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Gumbo T. Single or 2-Dose Micafungin Regimen for Treatment of Invasive Candidiasis: Therapia Sterilisans Magna! Clin Infect Dis 2016; 61 Suppl 6:S635-42. [PMID: 26567282 DOI: 10.1093/cid/civ715] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The time the earth takes to rotate its axis (the day) has dictated how often pharmaceutical compounds are dosed. The scientific link between the 2 events is materia medica arcana. As an example, in the treatment of invasive candidiasis, antifungal therapy with intravenous micafungin is dosed daily. A literature review revealed population pharmacokinetic analyses, in vivo pharmacokinetics/pharmacodynamics studies, and maximum-tolerated-dose studies of micafungin that examined optimal micafungin dosing strategies. The half-life of micafungin in patient blood was 14 hours in several studies, but was even longer in different organs, so that the concentration will persist above minimum inhibitory concentrations of Candida species for several days. Studies in mice and rabbits with persistent neutropenia and disseminated candidiasis, otherwise fatal, demonstrated that a single large dose of micafungin could clear disseminated candidiasis, even though the micafungin half-life in such animals is shorter than in humans. Human pharmacokinetics/pharmacodynamics studies confirmed this link between micafungin efficacy and the ratio of the area under the concentration-time curve, and the optimal exposures initially identified in neutropenic animals. Maximum tolerated dose studies have demonstrated safety of 900 mg administered daily for several weeks, whereas case reports demonstrate efficacy and safety of single 1400-mg doses. Thus, a single dose of micafungin, or 2 such doses within a few days of each other, is not only logical, but might even lead to faster clearance of Candida.
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Affiliation(s)
- Tawanda Gumbo
- Center for Infectious Diseases Research and Experimental Therapeutics, Baylor Research Institute, Baylor University Medical Center, Dallas, Texas
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Jacob K S, Ganguly S, Kumar P, Poddar R, Kumar A. Homology model, molecular dynamics simulation and novel pyrazole analogs design of Candida albicans CYP450 lanosterol 14 α-demethylase, a target enzyme for antifungal therapy. J Biomol Struct Dyn 2016; 35:1446-1463. [PMID: 27142238 DOI: 10.1080/07391102.2016.1185380] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Candida albicans infections and their resistance to clinically approved azole drugs are major concerns for human. The azole antifungal drugs inhibit the ergosterol synthesis by targeting lanosterol 14α-demethylase of cytochrome P450 family. The lack of high-resolution structural information of fungal pathogens has been a barrier for the design of modified azole drugs. Thus, a preliminary theoretical molecular dynamic study is carried out to develop and validate a simple homologous model using crystallographic structure of the lanosterol 14α-demethylase of Mycobacterium tuberculosis (PDB ID-1EA1) in which the active site residues are substituted with that of C. albicans (taxid 5476). Further, novel designed pyrazole analogs (SGS1-16) docked on chimeric 1EA1 and revealed that SGS-16 show good binding affinity through non-bonding interaction with the heme, which is different from the leading azole antifungals. The ADME-T results showed these analogs can be further explored in design of more safe and effective antifungal agents.
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Affiliation(s)
- Sony Jacob K
- a Department of Pharmaceutical Sciences and Technology , Birla Institute of Technology, Mesra , Ranchi , Jharkhand 835215 , India
| | - Swastika Ganguly
- a Department of Pharmaceutical Sciences and Technology , Birla Institute of Technology, Mesra , Ranchi , Jharkhand 835215 , India
| | - Pravin Kumar
- b Department of Bio-Engineering , Birla Institute of Technology, Mesra , Ranchi , Jharkhand 835215 , India
| | - Raju Poddar
- b Department of Bio-Engineering , Birla Institute of Technology, Mesra , Ranchi , Jharkhand 835215 , India
| | - Anoop Kumar
- a Department of Pharmaceutical Sciences and Technology , Birla Institute of Technology, Mesra , Ranchi , Jharkhand 835215 , India
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Zhao Y, Perez WB, Jiménez-Ortigosa C, Hough G, Locke JB, Ong V, Bartizal K, Perlin DS. CD101: a novel long-acting echinocandin. Cell Microbiol 2016; 18:1308-16. [PMID: 27354115 PMCID: PMC5096055 DOI: 10.1111/cmi.12640] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 06/22/2016] [Accepted: 06/25/2016] [Indexed: 01/05/2023]
Abstract
CD101 is a novel echinocandin drug being developed to treat severe fungal infections including invasive candidiasis. We have performed a series of studies to evaluate the antifungal properties of CD101 against both echinocandin‐susceptible and ‐resistant Candida strains. Antifungal susceptibility testing performed on a collection of 95 Candida strains including 30 caspofungin‐resistant isolates containing fks mutations demonstrated comparable antifungal potency of CD101 relative to micafungin (MCF) across different Candida species. Comparable kinetic inhibition of glucan synthase activity was also observed for CD101 and MCF on both wild‐type (WT) and resistant fks mutant Candida strains. Similarly, both drugs yielded nearly identical values for a mutant prevention concentration. In a murine model of invasive candidiasis, CD101 displayed better or at least comparable efficacy relative to MCF in treating WT or fks mutant Candida albicans. An exceptional long‐lived pharmacokinetic profile was observed in mice following a single dose of CD101. Collectively, CD101 has great potential not only in treating invasive Candida infections but also in preventing emergence of resistance to currently approved echinocandin drugs.
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Affiliation(s)
- Yanan Zhao
- Public Health Research Institute, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Newark, NJ, USA
| | - Winder B Perez
- Public Health Research Institute, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Newark, NJ, USA
| | - Cristina Jiménez-Ortigosa
- Public Health Research Institute, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Newark, NJ, USA
| | | | | | - Voon Ong
- Cidara Therapeutics, Inc., San Diego, CA, USA
| | | | - David S Perlin
- Public Health Research Institute, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Newark, NJ, USA
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Meetei PA, Rathore RS, Prabhu NP, Vindal V. In silico screening for identification of novel β-1,3-glucan synthase inhibitors using pharmacophore and 3D-QSAR methodologies. SPRINGERPLUS 2016; 5:965. [PMID: 27429875 PMCID: PMC4932017 DOI: 10.1186/s40064-016-2589-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 06/15/2016] [Indexed: 12/31/2022]
Abstract
The enzyme β-1,3-glucan synthase, which catalyzes the synthesis of β-1,3-glucan, an essential and unique structural component of the fungal cell wall, has been considered as a promising target for the development of less toxic anti-fungal agents. In this study, a robust pharmacophore model was developed and structure activity relationship analysis of 42 pyridazinone derivatives as β-1,3-glucan synthase inhibitors were carried out. A five-point pharmacophore model, consisting of two aromatic rings (R) and three hydrogen bond acceptors (A) was generated. Pharmacophore based 3D-QSAR model was developed for the same reported data sets. The generated 3D-QSAR model yielded a significant correlation coefficient value (R2 = 0.954) along with good predictive power confirmed by the high value of cross-validated correlation coefficient (Q2 = 0.827). Further, the pharmacophore model was employed as a 3D search query to screen small molecules database retrieved from ZINC to select new scaffolds. Finally, ADME studies revealed the pharmacokinetic efficiency of these compounds.
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Affiliation(s)
- Potshangbam Angamba Meetei
- Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad, 500046 India
| | - R S Rathore
- Bioinformatics Infrastructure Facility, School of Life Sciences, University of Hyderabad, Hyderabad, 500046 India ; Centre for Biological Sciences, School of Earth, Biological and Environmental Sciences, Central University of South Bihar, Patna, 800014 India
| | - N Prakash Prabhu
- Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad, 500046 India
| | - Vaibhav Vindal
- Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad, 500046 India ; Bioinformatics Infrastructure Facility, School of Life Sciences, University of Hyderabad, Hyderabad, 500046 India
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Wang NN, Yan X, Gao XN, Niu HJ, Kang ZS, Huang LL. Purification and characterization of a potential antifungal protein from Bacillus subtilis E1R-J against Valsa mali. World J Microbiol Biotechnol 2016; 32:63. [PMID: 26925625 DOI: 10.1007/s11274-016-2024-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 02/03/2016] [Indexed: 01/29/2023]
Abstract
In order to identify the antagonistic substances produced by Bacillus subtilis E1R-J as candidate of biocontrol agents for controlling Apple Valsa Canker, hydrochloric acid precipitation, reverse phase chromatography, gel filtration, and ion exchange chromatography were used. The purified fraction EP-2 showed a single band in native-polyacrylamide gel electrophoresis (native-PAGE) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Fraction EP-2 was eluted from native-PAGE and showed a clear inhibition zone against V. mali 03-8. These results prove that EP-2 is one of the most important antifungal substances produced by B. subtilis E1R-J in fermentation broth. SDS-PAGE and Nano-LC-ESI-MS/MS analysis results demonstrated that EP-2 was likely an antifungal peptide (trA0A086WXP9), with a relative molecular mass of 12.44 kDa and isoelectric point of 9.94. The examination of antagonistic mechanism under SEM and TEM showed that EP-2 appeared to inhibit Valsa mali 03-8 by causing hyphal swelling, distortion, abnormality and protoplasts extravasation. Inhibition spectrum results showed that antifungal protein EP-2 had significantly inhibition on sixteen kinds of plant pathogenic fungi. The stability test results showed that protein EP-2 was stable with antifungal activity at temperatures as high as 100 °C for 30 min and in pH values ranging from 1.0 to 8.0, or incubated with each 5 mM Cu(2+), Zn(2+), Mg(2+), or K(+). However, the antifungal activity was negatively affected by Proteinase K treatment.
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Affiliation(s)
- N N Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, 712100, Shaanxi, People's Republic of China
| | - X Yan
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, 712100, Shaanxi, People's Republic of China
| | - X N Gao
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, 712100, Shaanxi, People's Republic of China
| | - H J Niu
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, 712100, Shaanxi, People's Republic of China
| | - Z S Kang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, 712100, Shaanxi, People's Republic of China
| | - L L Huang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, 712100, Shaanxi, People's Republic of China.
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81
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Ramakrishnan J, Rathore SS, Raman T. Review on fungal enzyme inhibitors – potential drug targets to manage human fungal infections. RSC Adv 2016. [DOI: 10.1039/c6ra01577h] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The potential applications of enzyme inhibitors for the management of invasive fungal infections are explored.
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Affiliation(s)
- Jayapradha Ramakrishnan
- Centre for Research in Infectious Diseases (CRID)
- School of Chemical and Biotechnology
- SASTRA University
- Thanjavur
- India-613401
| | - Sudarshan Singh Rathore
- Centre for Research in Infectious Diseases (CRID)
- School of Chemical and Biotechnology
- SASTRA University
- Thanjavur
- India-613401
| | - Thiagarajan Raman
- Centre for Research in Infectious Diseases (CRID)
- School of Chemical and Biotechnology
- SASTRA University
- Thanjavur
- India-613401
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82
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Novel orally active inhibitors of β-1,3-glucan synthesis derived from enfumafungin. Bioorg Med Chem Lett 2015; 25:5813-8. [DOI: 10.1016/j.bmcl.2015.10.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 10/01/2015] [Accepted: 10/05/2015] [Indexed: 12/11/2022]
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83
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Jacob TR, Peres NTA, Martins MP, Lang EAS, Sanches PR, Rossi A, Martinez-Rossi NM. Heat Shock Protein 90 (Hsp90) as a Molecular Target for the Development of Novel Drugs Against the Dermatophyte Trichophyton rubrum. Front Microbiol 2015; 6:1241. [PMID: 26617583 PMCID: PMC4639609 DOI: 10.3389/fmicb.2015.01241] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 10/26/2015] [Indexed: 01/14/2023] Open
Abstract
Treatment of fungal infections is difficult due to several reasons, such as side effects of drugs, emergence of resistant strains, and limited number of molecular targets for the drug compounds. In fungi, heat shock proteins (Hsps) have been implicated in several processes with the conserved molecular chaperone Hsp90 emerging as a potential target for antifungal therapy. It plays key cellular roles by eliciting molecular response to environmental changes, morphogenesis, antifungal resistance, and fungal pathogenicity. Here, we evaluated the transcription profiles of hsp genes of the most prevalent dermatophyte Trichophyton rubrum in response to different environmental challenges including nutrient availability, interaction with cells and molecules of the host tissue, and drug exposure. The results suggest that each Hsp responds to a specific stress condition and that the cohort of Hsps facilitates fungal survival under various environmental challenges. Chemical inhibition of Hsp90 resulted in increased susceptibility of the fungus to itraconazole and micafungin, and decreased its growth in human nails in vitro. Moreover, some hsp and related genes were modulated by Hsp90 at the transcriptional level. We are suggesting a role of Hsp90 in the pathogenicity and drug susceptibility of T. rubrum as well as the regulation of other Hsps. The synergism observed between the inhibition of Hsp90 and the effect of itraconazole or micafungin in reducing the fungal growth is of great interest as a novel and potential strategy to treat dermatophytoses.
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Affiliation(s)
- Tiago R Jacob
- Department of Genetics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto São Paulo, Brazil
| | - Nalu T A Peres
- Department of Morphology, Federal University of Sergipe Aracaju, Brazil
| | - Maíra P Martins
- Department of Genetics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto São Paulo, Brazil
| | - Elza A S Lang
- Department of Genetics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto São Paulo, Brazil
| | - Pablo R Sanches
- Department of Genetics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto São Paulo, Brazil
| | - Antonio Rossi
- Department of Genetics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto São Paulo, Brazil
| | - Nilce M Martinez-Rossi
- Department of Genetics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto São Paulo, Brazil
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84
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Balibar CJ, Roemer T. Yeast: a microbe with macro-implications to antimicrobial drug discovery. Brief Funct Genomics 2015; 15:147-54. [PMID: 26443612 DOI: 10.1093/bfgp/elv038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Paramount to any rational discovery of new antibiotics displaying novel mechanisms of action is a deep knowledge of the genetic basis of microbial growth, division and virulence. The bakers' yeast,Saccharomyces cerevisiae, illustrates the highest understanding of the genetic underpinnings of microbial life, and from this framework, a systems biology paradigm has evolved, begging to be emulated in antibacterial discovery. Here, we review landmark events in the history of yeast genomics that provide this new foundation for antibacterial drug discovery.
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85
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Stierle AA, Stierle DB. Bioactive Secondary Metabolites Produced by the Fungal Endophytes of Conifers. Nat Prod Commun 2015. [DOI: 10.1177/1934578x1501001012] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
This is a review of bioactive secondary metabolites isolated from conifer-associated endophytic fungi from 1990-2014. This includes compounds with antimicrobial, anti-inflammatory, anti-proliferative and cytotoxic activity towards human cancer cell lines, and activity against either plant pathogens or plant insect pests. Compounds that were originally reported without associated activity were included if other studies ascribed activity to these compounds. Compounds were not included if they were exclusively phytotoxic or if they were isolated from active extracts but were not determined to be the active component of that extract.
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Affiliation(s)
- Andrea A. Stierle
- Department of Biomedical and Pharmaceutical Sciences, The University of Montana, Missoula, Montana 59812, USA
| | - Donald B. Stierle
- Department of Biomedical and Pharmaceutical Sciences, The University of Montana, Missoula, Montana 59812, USA
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86
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Stierle AA, Stierle DB. Bioactive Secondary Metabolites Produced by the Fungal Endophytes of Conifers. Nat Prod Commun 2015; 10:1671-1682. [PMID: 26669101 PMCID: PMC5156325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023] Open
Abstract
This is a review of bioactive secondary metabolites isolated from conifer-associated endophytic fungi from 1990-2014. This includes compounds with antimicrobial, anti-inflammatory, anti-proliferative and cytotoxic activity towards human cancer cell lines, and activity against either plant pathogens or plant insect pests. Compounds that were originally reported without associated activity were included if other studies ascribed activity to these compounds. Compounds were not included if they were exclusively phytotoxic or if they were isolated from active extracts but were not determined to be the active component of that extract.
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87
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Abstract
Fungal infections due to Candida and Aspergillus species cause extensive morbidity and mortality, especially among immunosuppressed patients, and antifungal therapy is critical to patient management. Yet only a few drug classes are available to treat invasive fungal diseases, and this problem is compounded by the emergence of antifungal resistance. Echinocandin drugs are the preferred choice to treat candidiasis. They are the first cell wall-active agents and target the fungal-specific enzyme glucan synthase, which catalyzes the biosynthesis of β-1,3-glucan, a key cell wall polymer. Therapeutic failures occur rarely among common Candida species, with the exception of Candida glabrata, which is frequently multidrug resistant. Echinocandin resistance in susceptible species is always acquired during therapy. The mechanism of resistance involves amino acid changes in hot-spot regions of Fks subunits of glucan synthase, which decrease the sensitivity of the enzyme to drug. Cellular stress response pathways lead to drug adaptation, which promotes the formation of resistant fks strains. Clinical factors promoting echinocandin resistance include empiric therapy, prophylaxis, gastrointestinal reservoirs, and intra-abdominal infections. A better understanding of the echinocandin-resistance mechanism, along with cellular and clinical factors promoting resistance, will facilitate more effective strategies to overcome and prevent echinocandin resistance.
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Affiliation(s)
- David S Perlin
- New Jersey Medical School, Rutgers Biomedical and Health Sciences, Public Health Research Institute, Newark, New Jersey
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88
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Jiang H, Wang X, Xiao C, Wang W, Zhao X, Sui J, Sa R, Guo TL, Liu X. Antifungal activity of Brevibacillus laterosporus JX-5 and characterization of its antifungal components. World J Microbiol Biotechnol 2015; 31:1605-18. [PMID: 26265360 DOI: 10.1007/s11274-015-1912-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 07/20/2015] [Indexed: 10/23/2022]
Abstract
The establishment of safe and effective methods for controlling fungal disease is an urgent issue in agriculture and forestry. Microbiological control of plant disease is expected to achieve better results than use of chemically derived fungicides. This study aimed to establish Brevibacillus laterosporus JX-5 as a potential microbiological control agent of poplar canker. The bacterium was isolated from the poplar rhizosphere and demonstrated significant growth inhibition of several pathogenic fungi in vitro. The antifungal components of Br. laterosporus JX-5 were isolated and identified. The fermentation broth of Br. laterosporus JX-5 and its main antifungal component, designated as component B, reduced Botryosphaeria dothidea associated canker of the excised poplar branch by 70 and 90%, respectively. Component B is considerably heat-stable, adaptable to a broad pH range, and UV-resistant. It could inhibit Bo. dothidea by permeating the fungal membrane, fracturing the nuclei, damaging the cell wall, and eventually killing the pathogenic fungus. The antifungal activity exhibited by Br. laterosporus JX-5 and its bioactive metabolic products indicate its feasibility as a potential biocontrol agent for plant diseases.
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Affiliation(s)
- Hongxia Jiang
- College of Life Science, Shandong Agricultural University, Taian, 271018, China. .,School of Life Science, Taishan Medical University, Taian, 271018, China.
| | - Xiaohui Wang
- College of Life Science, Shandong Agricultural University, Taian, 271018, China
| | - Chengze Xiao
- College of Forestry, Shandong Agricultural University, Taian, 271018, China
| | - Weiyan Wang
- College of Forestry, Shandong Agricultural University, Taian, 271018, China
| | - Xu Zhao
- College of Forestry, Shandong Agricultural University, Taian, 271018, China
| | - Junkang Sui
- College of Life Science, Shandong Agricultural University, Taian, 271018, China
| | - Rongbo Sa
- College of Life Science, Shandong Agricultural University, Taian, 271018, China.,School of Life Science, Taishan Medical University, Taian, 271018, China
| | - Tai L Guo
- Department of Veterinary Biosciences and Diagnostic Imaging, College of Veterinary Medicine, University of Georgia, Athens, GA, 30602-7382, USA.
| | - Xunli Liu
- College of Forestry, Shandong Agricultural University, Taian, 271018, China.
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89
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Lamoth F, Alexander BD. Antifungal activities of SCY-078 (MK-3118) and standard antifungal agents against clinical non-Aspergillus mold isolates. Antimicrob Agents Chemother 2015; 59:4308-11. [PMID: 25896696 PMCID: PMC4468689 DOI: 10.1128/aac.00234-15] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 04/12/2015] [Indexed: 11/20/2022] Open
Abstract
The limited armamentarium of active and oral antifungal drugs against emerging non-Aspergillus molds is of particular concern. Current antifungal agents and the new orally available beta-1,3-d-glucan synthase inhibitor SCY-078 were tested in vitro against 135 clinical non-Aspergillus mold isolates. Akin to echinocandins, SCY-078 showed no or poor activity against Mucoromycotina and Fusarium spp. However, SCY-078 was highly active against Paecilomyces variotii and was the only compound displaying some activity against notoriously panresistant Scedosporium prolificans.
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Affiliation(s)
- Frédéric Lamoth
- Division of Infectious Diseases and International Health, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA Clinical Microbiology Laboratory, Department of Pathology, Duke University Medical Center, Durham, North Carolina, USA Infectious Diseases Service, Department of Medicine, Lausanne University Hospital, Lausanne, Switzerland Institute of Microbiology, Lausanne University Hospital, Lausanne, Switzerland
| | - Barbara D Alexander
- Division of Infectious Diseases and International Health, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA Clinical Microbiology Laboratory, Department of Pathology, Duke University Medical Center, Durham, North Carolina, USA
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90
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Cheung RCF, Ng TB, Wong JH. Marine Peptides: Bioactivities and Applications. Mar Drugs 2015; 13:4006-43. [PMID: 26132844 PMCID: PMC4515606 DOI: 10.3390/md13074006] [Citation(s) in RCA: 190] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 06/15/2015] [Accepted: 06/18/2015] [Indexed: 12/11/2022] Open
Abstract
Peptides are important bioactive natural products which are present in many marine species. These marine peptides have high potential nutraceutical and medicinal values because of their broad spectra of bioactivities. Their antimicrobial, antiviral, antitumor, antioxidative, cardioprotective (antihypertensive, antiatherosclerotic and anticoagulant), immunomodulatory, analgesic, anxiolytic anti-diabetic, appetite suppressing and neuroprotective activities have attracted the attention of the pharmaceutical industry, which attempts to design them for use in the treatment or prevention of various diseases. Some marine peptides or their derivatives have high commercial values and had reached the pharmaceutical and nutraceutical markets. A large number of them are already in different phases of the clinical and preclinical pipeline. This review highlights the recent research in marine peptides and the trends and prospects for the future, with special emphasis on nutraceutical and pharmaceutical development into marketed products.
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Affiliation(s)
- Randy Chi Fai Cheung
- School of Biomedical Sciences, Faculty of Medicine, the Chinese University of Hong Kong, Hong Kong, China.
| | - Tzi Bun Ng
- School of Biomedical Sciences, Faculty of Medicine, the Chinese University of Hong Kong, Hong Kong, China.
| | - Jack Ho Wong
- School of Biomedical Sciences, Faculty of Medicine, the Chinese University of Hong Kong, Hong Kong, China.
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91
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Evolution of Chemical Diversity in Echinocandin Lipopeptide Antifungal Metabolites. EUKARYOTIC CELL 2015; 14:698-718. [PMID: 26024901 DOI: 10.1128/ec.00076-15] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2015] [Accepted: 05/19/2015] [Indexed: 11/20/2022]
Abstract
The echinocandins are a class of antifungal drugs that includes caspofungin, micafungin, and anidulafungin. Gene clusters encoding most of the structural complexity of the echinocandins provided a framework for hypotheses about the evolutionary history and chemical logic of echinocandin biosynthesis. Gene orthologs among echinocandin-producing fungi were identified. Pathway genes, including the nonribosomal peptide synthetases (NRPSs), were analyzed phylogenetically to address the hypothesis that these pathways represent descent from a common ancestor. The clusters share cooperative gene contents and linkages among the different strains. Individual pathway genes analyzed in the context of similar genes formed unique echinocandin-exclusive phylogenetic lineages. The echinocandin NRPSs, along with the NRPS from the inp gene cluster in Aspergillus nidulans and its orthologs, comprise a novel lineage among fungal NRPSs. NRPS adenylation domains from different species exhibited a one-to-one correspondence between modules and amino acid specificity that is consistent with models of tandem duplication and subfunctionalization. Pathway gene trees and Ascomycota phylogenies are congruent and consistent with the hypothesis that the echinocandin gene clusters have a common origin. The disjunct Eurotiomycete-Leotiomycete distribution appears to be consistent with a scenario of vertical descent accompanied by incomplete lineage sorting and loss of the clusters from most lineages of the Ascomycota. We present evidence for a single evolutionary origin of the echinocandin family of gene clusters and a progression of structural diversification in two fungal classes that diverged approximately 290 to 390 million years ago. Lineage-specific gene cluster evolution driven by selection of new chemotypes contributed to diversification of the molecular functionalities.
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92
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Kang HK, Seo CH, Park Y. Marine peptides and their anti-infective activities. Mar Drugs 2015; 13:618-54. [PMID: 25603351 PMCID: PMC4306955 DOI: 10.3390/md13010618] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 01/01/2015] [Indexed: 12/29/2022] Open
Abstract
Marine bioresources are a valuable source of bioactive compounds with industrial and nutraceutical potential. Numerous clinical trials evaluating novel chemotherapeutic agents derived from marine sources have revealed novel mechanisms of action. Recently, marine-derived bioactive peptides have attracted attention owing to their numerous beneficial effects. Moreover, several studies have reported that marine peptides exhibit various anti-infective activities, such as antimicrobial, antifungal, antimalarial, antiprotozoal, anti-tuberculosis, and antiviral activities. In the last several decades, studies of marine plants, animals, and microbes have revealed tremendous number of structurally diverse and bioactive secondary metabolites. However, the treatments available for many infectious diseases caused by bacteria, fungi, and viruses are limited. Thus, the identification of novel antimicrobial peptides should be continued, and all possible strategies should be explored. In this review, we will present the structures and anti-infective activity of peptides isolated from marine sources (sponges, algae, bacteria, fungi and fish) from 2006 to the present.
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Affiliation(s)
- Hee Kyoung Kang
- Department of Biomedical Science, Chosun University, Gwangju 501-759, Korea.
| | - Chang Ho Seo
- Department of Bioinformatics, Kongju National University, Kongju 314-701, Korea.
| | - Yoonkyung Park
- Department of Biomedical Science, Chosun University, Gwangju 501-759, Korea.
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93
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Sivashanmugam M, Nagarajan H, Vetrivel U, Ramasubban G, Therese KL, Narahari MH. In silico analysis and prioritization of drug targets in Fusarium solani. Med Hypotheses 2014; 84:81-4. [PMID: 25555413 DOI: 10.1016/j.mehy.2014.12.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Revised: 12/12/2014] [Accepted: 12/16/2014] [Indexed: 02/08/2023]
Abstract
Mycotic keratitis has emerged as a major ophthalmic problem and a leading cause of blindness, since its recognition in 1879. Filamentous fungi are major causative of mycotic keratitis. In India, the main etiological organism responsible for mycotic keratitis is Aspergillus species followed by Fusarium species. In South India, Fusarium based keratitis scales up to 43%. Nearly one-third of mycotic keratitis treatment results in failure, as fungal infections are highly resistant to antibiotic therapies. Therefore, there is need to determine novel and specific targets to constrain Fusarium infections in human eye. In this study, we implemented subtractive proteomics coupled with in silico functional annotation to prioritize potential and specific drug targets which can be used to modulate the virulence of Fusarium solani subsp.pisi (Nectria haematococca MPVI). The results infer that Thiamine thiazole synthase (Thi4), an intracellular membrane bound protein as the potential target, which is a core protein in biological and metabolic process of this pathogen. Moreover, this protein occurs in the thiamine thiazole biosynthesis pathway which is unique to F.solani and devoid in human. Hence, we predicted a plausible structure for this protein and also performed ligand-binding cavity analysis which can be for a strong base for drug designing studies. This study will pave way in better understanding of potential drug targets in F.solani and also leading to therapeutic interventions of fungal keratitis.
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Affiliation(s)
| | | | | | - Gayathri Ramasubban
- L&T Microbiology Research Centre, Vision Research Foundation, Chennai, India
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94
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Rodrigues ME, Silva S, Azeredo J, Henriques M. Novel strategies to fight Candida species infection. Crit Rev Microbiol 2014; 42:594-606. [PMID: 25383647 DOI: 10.3109/1040841x.2014.974500] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
In recent years, there has been a significant increase in the incidence of human fungal infections. The increase in cases of infection caused by Candida species, and the consequent excessive use of antimicrobials, has favored the emergence of resistance to conventional antifungal agents over the past decades. Consequently, Candida infections morbidity and mortality are also increasing. Therefore, new approaches are needed to improve the outcome of patients suffering from Candida infections, because it seems unlikely that the established standard treatments will drastically lower the morbidity of mucocutaneous Candida infections and the high mortality associated with invasive candidiasis. This review aims to present the last advances in the traditional antifungal therapy, and present an overview of novel strategies that are being explored for the treatment of Candida infections, with a special focus on combined antifungal agents, antifungal therapies with alternative compounds (plant extracts and essential oils), adjuvant immunotherapy, photodynamic therapy and laser therapy.
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Affiliation(s)
- Maria Elisa Rodrigues
- a CEB -- Centre of Biological Engineering, LIBRO -- Laboratório de Investigação em Biofilmes Rosário Oliveira, University of Minho , Braga , Portugal
| | - Sónia Silva
- a CEB -- Centre of Biological Engineering, LIBRO -- Laboratório de Investigação em Biofilmes Rosário Oliveira, University of Minho , Braga , Portugal
| | - Joana Azeredo
- a CEB -- Centre of Biological Engineering, LIBRO -- Laboratório de Investigação em Biofilmes Rosário Oliveira, University of Minho , Braga , Portugal
| | - Mariana Henriques
- a CEB -- Centre of Biological Engineering, LIBRO -- Laboratório de Investigação em Biofilmes Rosário Oliveira, University of Minho , Braga , Portugal
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95
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Moriyama B, Gordon LA, McCarthy M, Henning SA, Walsh TJ, Penzak SR. Emerging drugs and vaccines for candidemia. Mycoses 2014; 57:718-33. [PMID: 25294098 DOI: 10.1111/myc.12265] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2014] [Revised: 08/26/2014] [Accepted: 09/01/2014] [Indexed: 11/27/2022]
Abstract
Candidemia and other forms of invasive candidiasis are important causes of morbidity and mortality. The evolving challenge of antimicrobial resistance among fungal pathogens continues to highlight the need for potent, new antifungal agents. MEDLINE, EMBASE, Scopus and Web of Science searches (up to January 2014) of the English-language literature were performed with the keywords 'Candida' or 'Candidemia' or 'Candidiasis' and terms describing investigational drugs with activity against Candida spp. Conference abstracts and the bibliographies of pertinent articles were also reviewed for relevant reports. ClinicalTrials.gov was searched for relevant clinical trials. Currently available antifungal agents for the treatment of candidemia are summarised. Investigational antifungal agents with potential activity against Candida bloodstream infections and other forms of invasive candidiasis and vaccines for prevention of Candida infections are also reviewed as are selected antifungal agents no longer in development. Antifungal agents currently in clinical trials include isavuconazole, albaconazole, SCY-078, VT-1161 and T-2307. Further data are needed to determine the role of these compounds in the treatment of candidemia and other forms of invasive candidiasis. The progressive reduction in antimicrobial drug development may result in a decline in antifungal drug discovery. Still, there remains a critical need for new antifungal agents to treat and prevent invasive candidiasis and other life-threatening mycoses.
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Affiliation(s)
- Brad Moriyama
- Pharmacy Department, NIH Clinical Center, Bethesda, MD, USA
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96
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Zhang C, Cheng J, Jiang Y, Liu J. Application of caspofungin in China compared with amphotericin B and fluconazole. Ther Clin Risk Manag 2014; 10:737-41. [PMID: 25228811 PMCID: PMC4164385 DOI: 10.2147/tcrm.s47146] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Fungal infection has increased in the past 2 decades in China. There are three classes of antifungal drugs, polyenes, azoles, and echinocandins, that are applied frequently in China. Caspofungin, which disrupts the fungal cell wall glucan formation through inhibiting the enzyme 1,3-β-glucan synthase, is one of the echinocandins. According to the results of clinical practices applied in China, caspofungin has shown to be superior to the other two classes of antifungal drugs, due to its efficacy in treating fungal infection (15% superior to fluconazole); fewer adverse events such as infusion-related reaction, hepatic dysfunction, and vomiting (25%-50% lower incidence rate); rapid resolution of symptoms (about 3 days quicker than amphotericin B); and absence of antagonism in combination with other antifungal drugs. However, caspofungin will remain as a second-line antifungal drug in the near future because of its high price and the policy of health insurance reimbursement in China.
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Affiliation(s)
- Chunyu Zhang
- Department of Health Reform and Development, China-Japan Friendship Hospital, Beijing, People's Republic of China
| | - Jiaoying Cheng
- Department of Obstetrics and Gynecology, China-Japan Friendship Hospital, Beijing, People's Republic of China
| | - Yan Jiang
- National Management Center of 12320 Health Hotline, Chinese Center for Disease Control and Prevention, Beijing, People's Republic of China
| | - Junyang Liu
- Department of Pharmacy, China-Japan Friendship Hospital, Beijing, People's Republic of China
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97
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Perlin DS. Echinocandin resistance, susceptibility testing and prophylaxis: implications for patient management. Drugs 2014; 74:1573-85. [PMID: 25255923 PMCID: PMC4201113 DOI: 10.1007/s40265-014-0286-5] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
This article addresses the emergence of echinocandin resistance among Candida species, mechanisms of resistance, factors that promote resistance and confounding issues surrounding standard susceptibility testing. Fungal infections remain a significant cause of global morbidity and mortality, especially among patients with underlying immunosupression. Antifungal therapy is a critical component of patient management for acute and chronic diseases. Yet, therapeutic choices are limited due to only a few drug classes available to treat systemic disease. Moreover, the problem is exacerbated by the emergence of antifungal resistance, which has resulted in difficult to manage multidrug resistant strains. Echinocandin drugs are now the preferred choice to treat a range of candidiasis. These drugs target and inhibit the fungal-specific enzyme glucan synthase, which is responsible for the biosynthesis of a key cell wall polymer. Therapeutic failures involving acquisition of resistance among susceptible organisms like Candida albicans is largely a rare event. However, in recent years, there is an alarming trend of increased resistance among strains of Candida glabrata, which in many cases are also resistant to azole drugs. Echinocandin resistance is always acquired during therapy and the mechanism of resistance is well established to involve amino acid changes in "hot-spot" regions of the Fks subunits carrying the catalytic portion of glucan synthase. These changes significantly decrease the sensitivity of the enzyme to drug resulting in higher MIC values. A range of drug responses, from complete to partial refractory response, is observed depending on the nature of the amino acid substitution, and clinical responses are recapitulated in pharmacodynamic models of infection. The cellular processes promoting the formation of resistant Fks strains involve complex stress response pathways, which yield a variety of adaptive compensatory genetic responses. Stress-adapted cells become drug tolerant and can form stable drug resistant FKS mutations with continued drug exposure. A major concern for resistance detection is that classical broth microdilution techniques show significant variability among clinical microbiology laboratories for certain echinocandin drugs and Candida species. The consequence is that susceptible strains are misclassified according to established clinical breakpoints, and this has led to confusion in the field. Clinical factors that appear to promote echinocandin resistance include the expanding use of antifungal agents for empiric therapy and prophylaxis. Furthermore, host reservoirs such as biofilms in the gastrointestinal tract or intra-abdominal infections can seed development of resistant organisms during therapy. A fundamental understanding of the primary molecular resistance mechanism, along with cellular and clinical factors that promote resistance emergence, is critical to develop better diagnostic tools and therapeutic strategies to overcome and prevent echinocandin resistance.
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Affiliation(s)
- David S Perlin
- Public Health Research Institute, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, 07103, USA,
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Wang J, Wu XP, Song XM, Han CR, Chen Z, Chen GY. F-01A, an antibiotic, inhibits lung cancer cells proliferation. Chin J Nat Med 2014; 12:284-9. [PMID: 24863353 DOI: 10.1016/s1875-5364(14)60055-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Indexed: 11/24/2022]
Abstract
AIM In an effort to identify novel, small molecules which can affect the proliferation of lung cancer cells, F-01A, a polyether antibiotic isolated from the fermentation broth of Streptomyces was tested. METHOD F-01A was tested for its antitumor properties on the lung cancer cell line SPC-A-1, at six doses (0.1, 0.5, 1, 2.5, and 5 μmol·L(-1)), using various cellular assays. Cell viability was measured by the MTT assay, Hochest 33258 was used to study nuclear morphology; DNA ladder and the loss of mitochondrial membrane potential were also evaluated. RESULTS F-01A induces apoptosis against SPC-A-1 cells in a dose-dependent manner. The IC50 is 0.65 μmol·L(-1), and the inhibition at 5 μmol·L(-1) is 87.89%. Further, JC-1 staining indicates F-01A could induce the loss of mitochondrial membrane potential, and the DNA fragment is evident. CONCLUSION Mechanistic analysis showed that F-01A induced apoptosis of cancer cells probably in the mitochondrial pathway. The antitumor actions of F-01A involve activation of the apoptotic pathway against SPC-A-1 cells, and it may be valuable for further drug development.
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Affiliation(s)
- Jing Wang
- Key Laboratory of Tropical Medicinal Plant Chemistry of Ministry of Education, Hainan Normal University, Haikou 571158, China; College of Life Sciences, Hainan Normal University, Haikou 571158, China
| | - Xiao-Peng Wu
- Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
| | - Xin-Ming Song
- Key Laboratory of Tropical Medicinal Plant Chemistry of Ministry of Education, Hainan Normal University, Haikou 571158, China
| | - Chang-Ri Han
- Key Laboratory of Tropical Medicinal Plant Chemistry of Ministry of Education, Hainan Normal University, Haikou 571158, China
| | - Zhong Chen
- College of Life Sciences, Hainan Normal University, Haikou 571158, China.
| | - Guang-Ying Chen
- Key Laboratory of Tropical Medicinal Plant Chemistry of Ministry of Education, Hainan Normal University, Haikou 571158, China.
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99
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Roemer T, Krysan DJ. Antifungal drug development: challenges, unmet clinical needs, and new approaches. Cold Spring Harb Perspect Med 2014; 4:a019703. [PMID: 24789878 PMCID: PMC3996373 DOI: 10.1101/cshperspect.a019703] [Citation(s) in RCA: 336] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Invasive, life-threatening fungal infections are an important cause of morbidity and mortality, particularly for patients with compromised immune function. The number of therapeutic options for the treatment of invasive fungal infections is quite limited when compared with those available to treat bacterial infections. Indeed, only three classes of molecules are currently used in clinical practice and only one new class of antifungal drugs has been developed in the last 30 years. Here we summarize the unmet clinical needs of current antifungal therapy, discuss challenges inherent to antifungal drug discovery and development, and review recent developments aimed at addressing some of these challenges.
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Affiliation(s)
- Terry Roemer
- Infectious Disease Research, Merck Research Laboratories, Kenilworth, New Jersey 07033
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100
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Cruz I, Cheetham JJ, Arnason JT, Yack JE, Smith ML. Alkamides from Echinacea disrupt the fungal cell wall-membrane complex. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2014; 21:435-442. [PMID: 24252333 DOI: 10.1016/j.phymed.2013.10.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 08/15/2013] [Accepted: 10/17/2013] [Indexed: 06/02/2023]
Abstract
We tested the hypothesis that alkamides from Echinacea exert antifungal activity by disrupting the fungal cell wall/membrane complex. Saccharomyces cerevisiae cells were treated separately with each of seven synthetic alkamides found in Echinacea extracts. The resulting cell wall damage and cell viability were assessed by fluorescence microscopy after mild sonication. Membrane disrupting properties of test compounds were studied using liposomes encapsulating carboxyfluorescein. Negative controls included hygromycin and nourseothricin (aminoglycosides that inhibit protein synthesis), and the positive control used was caspofungin (an echinocandin that disrupts fungal cell walls). The results show that yeast cells exposed to sub-inhibitory concentrations of each of the seven alkamides and Echinacea extract exhibit increased frequencies of cell wall damage and death that were comparable to caspofungin and significantly greater than negative controls. Consistent with effects of cell wall damaging agents, the growth inhibition by three representative alkamides tested and caspofungin, but not hygromycin B, were partially reversed in sorbitol protection assays. Membrane disruption assays showed that the Echinacea extract and alkamides have pronounced membrane disruption activity, in contrast to caspofungin and other controls that all had little effect on membrane stability. A Quantitative Structure-Activity Relationship (QSAR) analysis was performed to study the effect of structural substituents on the antifungal activity of the alkamides. Among the set studied, diynoic alkamides showed the greatest antifungal and cell wall disruption activities while an opposite trend was observed in the membrane disruption assay where the dienoic group was more effective. We propose that alkamides found in Echinacea act synergistically to disrupt the fungal cell wall/membrane complex, an excellent target for specific inhibition of fungal pathogens. Structure-function relationships provide opportunities for synthesis of alkamide analogs with improved antifungal activities.
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Affiliation(s)
- I Cruz
- Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada
| | - J J Cheetham
- Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada
| | - J T Arnason
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, Ontario K1N 6N5, Canada
| | - J E Yack
- Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada
| | - M L Smith
- Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada.
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