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Ganeshkumar A, Muthuselvam M, de Lima PMN, Rajaram R, Junqueira JC. Current Perspectives of Antifungal Therapy: A Special Focus on Candida auris. J Fungi (Basel) 2024; 10:408. [PMID: 38921394 PMCID: PMC11205254 DOI: 10.3390/jof10060408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2024] [Revised: 05/29/2024] [Accepted: 06/03/2024] [Indexed: 06/27/2024] Open
Abstract
Candida auris is an emerging Candida sp. that has rapidly spread all over the world. The evidence regarding its origin and emerging resistance is still unclear. The severe infection caused by this species results in significant mortality and morbidity among the elderly and immunocompromised individuals. The development of drug resistance is the major factor associated with the therapeutic failure of existing antifungal agents. Previous studies have addressed the antifungal resistance profile and drug discovery for C. auris. However, complete coverage of this information in a single investigation is not yet available. In this review, we have mainly focused on recent developments in therapeutic strategies against C. auris. Based on the available information, several different approaches were discussed, including existing antifungal drugs, chemical compounds, essential oils, natural products, antifungal peptides, immunotherapy, antimicrobial photodynamic therapy, drug repurposing, and drug delivery systems. Among them, synthetic chemicals, natural products, and antifungal peptides are the prime contributors. However, a limited number of resources are available to prove the efficiency of these potential therapies in clinical usage. Therefore, we anticipate that the findings gathered in this review will encourage further in vivo studies and clinical trials.
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Affiliation(s)
- Arumugam Ganeshkumar
- Department of Biosciences and Oral Diagnosis, Institute of Science and Technology, São Paulo State University (UNESP), São José dos Campos 12245-000, SP, Brazil;
- Department of Materials Physics, Saveetha School of Engineering, Saveetha Institute of Medical and Technical Sciences (SIMTS), Chennai 602105, Tamil Nadu, India
| | - Manickam Muthuselvam
- Department of Biotechnology, Bharathidasan University, Tiruchirappalli 620024, Tamil Nadu, India;
| | - Patricia Michelle Nagai de Lima
- Department of Biosciences and Oral Diagnosis, Institute of Science and Technology, São Paulo State University (UNESP), São José dos Campos 12245-000, SP, Brazil;
| | - Rajendren Rajaram
- Department of Marine Science, Bharathidasan University, Tiruchirappalli 620024, Tamil Nadu, India;
| | - Juliana Campos Junqueira
- Department of Biosciences and Oral Diagnosis, Institute of Science and Technology, São Paulo State University (UNESP), São José dos Campos 12245-000, SP, Brazil;
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Singh R, Shukla J, Ali M, Dubey AK. A novel diterpenic derivative produced by Streptomyces chrestomyceticus ADP4 is a potent inhibitor of biofilm and virulence factors in Candida albicans and C. auris. J Appl Microbiol 2024; 135:lxae139. [PMID: 38866718 DOI: 10.1093/jambio/lxae139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 05/29/2024] [Accepted: 06/11/2024] [Indexed: 06/14/2024]
Abstract
AIM Isolation, identification, structural and functional characterization of potent anti-Candida compound with specific antagonistic activities against significant human pathogens, Candida albicans and C. auris. METHODS AND RESULTS The compound (55B3) was purified from the metabolites produced by Streptomyces chrestomyceticus ADP4 by employing column chromatography. The structure of 55B3 was determined from the analyses of spectral data that included LCMS, nuclear magnetic resonance, FTIR, and UV spectroscopies. It was identified as a novel derivative of diterpenic aromatic acid, 3-(dictyotin-11'-oate-15'α, 19'β-olide)-4-(dictyotin-11'-oate-15″α, 19″β-olide)-protocatechoic acid. The compound displayed potent antifungal and anti-biofilm activities against C. albicans ATCC 10231 (Minimum Inhibitory Concentration, MIC90:14.94 ± 0.17 μgmL-1 and MBIC90: 16.03 ± 1.1 μgmL-1) and against C. auris CBS 12372 (MIC90: 21.75 ± 1.5 μgmL-1 and Minimum Biofilm Inhibitory Concentration, MBIC90: 18.38 ± 1.78 μgmL-1). Further, pronounced inhibition of important virulence attributes of Candida spp., e.g. yeast-to-hyphae transition, secretory aspartyl proteinase and phospholipase B by 55B3 was noted at subinhibitory concentrations. A plausible mechanism of anti-Candida action of the compound appeared to be the inhibition of ergosterol biosynthesis, which was inhibited by 64 ± 3% at the MIC90 value. The non-cytotoxic attribute of the compound was noted in the liver cell line (HepG2 cells). CONCLUSION The present work led to the discovery of a novel diterpenic derivative produced by S. chrestomyceticus ADP4. The compound displayed potent anti-Candida activity, particularly against the two most significant human pathogens, C. albicans and C. auris, which underlined its significance as a potential drug candidate for infections involving these pathogens.
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Affiliation(s)
- Radha Singh
- Department of Biological Sciences and Engineering, Netaji Subhas University of Technology, New Delhi 110078, India
| | - Jyoti Shukla
- Department of Biological Sciences and Engineering, Netaji Subhas University of Technology, New Delhi 110078, India
| | - Mohd Ali
- Faculty of Pharmacy, Hamdard University, New Delhi 110062, India
| | - Ashok K Dubey
- Department of Biological Sciences and Engineering, Netaji Subhas University of Technology, New Delhi 110078, India
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Kraut-Cohen J, Frenkel O, Covo S, Marcos-Hadad E, Carmeli S, Belausov E, Minz D, Cytryn E. A pipeline for rapidly evaluating activity and inferring mechanisms of action of prospective antifungal compounds. PEST MANAGEMENT SCIENCE 2024; 80:2804-2816. [PMID: 38323791 DOI: 10.1002/ps.7989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 01/22/2024] [Accepted: 01/23/2024] [Indexed: 02/08/2024]
Abstract
BACKGROUND Fungal phytopathogens are a significant threat to crops and food security, and there is a constant need to develop safe and effective compounds that antagonize them. In-planta assays are complex and tedious and are thus not suitable for initial high-throughput screening of new candidate antifungal compounds. We propose an in vitro screening pipeline that integrates five rapid quantitative and qualitative methods to estimate the efficacy and mode of action of prospective antifungal compounds. RESULTS The pipeline was evaluated using five documented antifungal compounds (benomyl, catechol, cycloheximide, 2,4-diacetylphloroglucinol, and phenylacetic acid) that have different modes of action and efficacy, against the model soilborne fungal pathogen Fusarium oxysporum f. sp. radicis cucumerinum. We initially evaluated the five compounds' ability to inhibit fungal growth and metabolic activity using green fluorescent protein (GFP)-labeled F. oxysporum and PrestoBlue staining, respectively, in multiwell plate assays. We tested the compounds' inhibition of both conidial germination and hyphal elongation. We then employed FUN-1 and SYTO9/propidium iodide staining, coupled to confocal microscopy, to differentiate between fungal growth inhibition and death at the cellular level. Finally, using a reactive oxygen species (ROS)-detection assay, we were able to quantify ROS production in response to compound application. CONCLUSIONS Collectively, the proposed pipeline provides a wide array of quantitative and qualitative data on the tested compounds that can help pinpoint promising novel compounds; these can then be evaluated more vigorously using in planta screening assays. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
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Affiliation(s)
- Judith Kraut-Cohen
- Institute of Soil, Water and Environmental Sciences, Agricultural Research Organization, Volcani Center, Rishon LeZion, Israel
| | - Omer Frenkel
- Department of Plant Pathology and Weed Research, Institute of Plant Protection, Agricultural Research Organization, Volcani Center, Rishon LeZion, Israel
| | - Shay Covo
- Department of Plant Pathology and Microbiology, Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University, Rehovot, Israel
| | - Evgeniya Marcos-Hadad
- Department of Plant Pathology and Microbiology, Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University, Rehovot, Israel
| | - Shmuel Carmeli
- Raymond and Beverly Sackler School of Chemistry, Faculty of Exact Sciences, Tel Aviv University, Ramat Aviv, Israel
| | - Eduard Belausov
- Confocal Microscopy Unit, Agricultural Research Organization, Volcani Center, Rishon LeZion, Israel
| | - Dror Minz
- Institute of Soil, Water and Environmental Sciences, Agricultural Research Organization, Volcani Center, Rishon LeZion, Israel
| | - Eddie Cytryn
- Institute of Soil, Water and Environmental Sciences, Agricultural Research Organization, Volcani Center, Rishon LeZion, Israel
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Madhuri M, Rudramurthy SM, Roy U. Two promising Bacillus-derived antifungal lipopeptide leads AF 4 and AF 5 and their combined effect with fluconazole on the in vitro Candida glabrata biofilms. Front Pharmacol 2024; 15:1334419. [PMID: 38708082 PMCID: PMC11066293 DOI: 10.3389/fphar.2024.1334419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Accepted: 01/29/2024] [Indexed: 05/07/2024] Open
Abstract
Introduction: Candida species are endowed with the ability to produce biofilms, which is one of the causes of pathogenicity, as biofilms protect yeasts from antifungal drugs. Candida glabrata (Nakaseomyces glabrata) is one of the most prevalent pathogenic yeasts in humans and a biofilm producer. Methods: The study was aimed at evaluating the combined effects of two highly promising antifungal biomolecules (AF4 and AF5) lipopeptide in nature, chromatographically purified to homogeneity from Bacillus subtilis (B. subtilis) and the standard antifungal fluconazole (at different concentrations) to demonstrate C. glabrata biofilm formation inhibition. Biofilm production and inhibition were evaluated by quantification of the biofilm biomass and metabolic activity using crystal violet (CV) staining and XTT reduction assays, respectively. Microscopic techniques such as confocal scanning laser microscopy (CSLM) and scanning electron microscopy (SEM) were employed to visualize biofilm formation and inhibition. Results and Discussion: Compared to untreated and fluconazole-treated biofilms, an enhanced in vitro anti-biofilm effect of the antifungal lipopeptides AF4/AF5 alone and their combinations with fluconazole was established. The lipopeptides AF4/AF5 alone at 8 and 16 μg/mL exhibited significant biomass and metabolic activity reductions. SEM and CSLM images provided evidence that the lipopeptide exposure results in architectural alterations and a significant reduction of C. glabrata biofilms, whereas (2', 7'-dichlorofluorescin diacetate (DCFDA) and propidium iodide (PI) analyses showed reactive oxygen species (ROS) generation along with membrane permeabilization. The estimation of exopolysaccharides (EPS) in AF4/AF5-treated biofilms indicated EPS reduction. The combinations of fluconazole (64/128 μg/mL) and AF4/AF5 lipopeptide (16 μg/mL) were found to significantly disrupt the mature (24 h) biofilms as revealed by CSLM and SEM studies. The CSLM images of biofilms were validated using COMSTAT. The FTIR-analyses indicate the antibiofilm effects of both lipopeptides on 24 h biofilms to support CSLM and SEM observations. The combinations of fluconazole (64/128 μg/mL) and AF4/AF5 lipopeptide were found to disrupt the mature biofilms; the study also showed that the lipopeptides alone have the potentials to combat C. glabrata biofilms. Taken together, it may be suggested that these lipopeptide leads can be optimized to potentially apply on various surfaces to either reduce or nearly eradicate yeast biofilms.
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Affiliation(s)
- Madduri Madhuri
- Department of Biological Sciences, BITS Pilani, Sancoale, Goa, India
| | - Shivaprakash M Rudramurthy
- Department of Medical Microbiology, Medical Mycology Division, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
| | - Utpal Roy
- Department of Biological Sciences, BITS Pilani, Sancoale, Goa, India
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Jakab Á, Kovács F, Balla N, Nagy-Köteles C, Ragyák Á, Nagy F, Borman AM, Majoros L, Kovács R. Comparative transcriptional analysis of Candida auris biofilms following farnesol and tyrosol treatment. Microbiol Spectr 2024; 12:e0227823. [PMID: 38440972 PMCID: PMC10986546 DOI: 10.1128/spectrum.02278-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 02/11/2024] [Indexed: 03/06/2024] Open
Abstract
Candida auris is frequently associated with biofilm-related invasive infections. The resistant profile of these biofilms necessitates innovative therapeutic options, where quorum sensing may be a potential target. Farnesol and tyrosol are two fungal quorum-sensing molecules with antifungal effects at supraphysiological concentrations. Here, we performed genome-wide transcript profiling with C. auris biofilms following farnesol or tyrosol exposure using transcriptome sequencing (RNA-Seq). Since transition metals play a central role in fungal virulence and biofilm formation, levels of intracellular calcium, magnesium, and iron were determined following farnesol or tyrosol treatment using inductively coupled plasma optical emission spectrometry. Farnesol caused an 89.9% and 73.8% significant reduction in the calcium and magnesium content, respectively, whereas tyrosol resulted in 82.6%, 76.6%, and 81.2% decrease in the calcium, magnesium, and iron content, respectively, compared to the control. Genes involved in biofilm events, glycolysis, ergosterol biosynthesis, fatty acid oxidation, iron metabolism, and autophagy were primarily affected in treated cells. To prove ergosterol quorum-sensing molecule interactions, microdilution-based susceptibility testing was performed, where the complexation of farnesol, but not tyrosol, with ergosterol was impeded in the presence of exogenous ergosterol, resulting in a minimum inhibitory concentration increase in the quorum-sensing molecules. This study revealed several farnesol- and tyrosol-specific responses, which will contribute to the development of alternative therapies against C. auris biofilms. IMPORTANCE Candida auris is a multidrug-resistant fungal pathogen, which is frequently associated with biofilm-related infections. Candida-derived quorum-sensing molecules (farnesol and tyrosol) play a pivotal role in the regulation of fungal morphogenesis and biofilm development. Furthermore, they may have remarkable anti-biofilm effects, especially at supraphysiological concentrations. Innovative therapeutic approaches interfering with quorum sensing may be a promising future strategy against C. auris biofilms; however, limited data are currently available concerning farnesol-induced and tyrosol-related molecular effects in C. auris. Here, we detected several genes involved in biofilm events, glycolysis, ergosterol biosynthesis, fatty acid oxidation, iron metabolism, and autophagy, which were primarily influenced following farnesol or tyrosol exposure. Moreover, calcium, magnesium, and iron homeostasis were also significantly affected. These results reveal those molecular and physiological events, which may support the development of novel therapeutic approaches against C. auris biofilms.
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Affiliation(s)
- Ágnes Jakab
- Department of Medical Microbiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Fruzsina Kovács
- Department of Medical Microbiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Doctoral School of Pharmaceutical Sciences, University of Debrecen, Debrecen, Hungary
| | - Noémi Balla
- Department of Medical Microbiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Doctoral School of Pharmaceutical Sciences, University of Debrecen, Debrecen, Hungary
| | - Csaba Nagy-Köteles
- Department of Molecular Biotechnology and Microbiology, Institute of Biotechnology, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary
| | - Ágota Ragyák
- Department of Inorganic and Analytical Chemistry, Agilent Atomic Spectroscopy Partner Laboratory, University of Debrecen, Debrecen, Hungary
| | - Fruzsina Nagy
- Department of Medical Microbiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Andrew M. Borman
- UK National Mycology Reference Laboratory, UK Health Security Agency, Science Quarter, Southmead Hospital, Bristol, United Kingdom
- Medical Research Council Centre for Medical Mycology (MRCCMM), University of Exeter, Exeter, United Kingdom
| | - László Majoros
- Department of Medical Microbiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Renátó Kovács
- Department of Medical Microbiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
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Sreelakshmi KP, Madhuri M, Swetha R, Rangarajan V, Roy U. Microbial lipopeptides: their pharmaceutical and biotechnological potential, applications, and way forward. World J Microbiol Biotechnol 2024; 40:135. [PMID: 38489053 DOI: 10.1007/s11274-024-03908-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Accepted: 01/24/2024] [Indexed: 03/17/2024]
Abstract
As lead molecules, cyclic lipopeptides with antibacterial, antifungal, and antiviral properties have garnered a lot of attention in recent years. Because of their potential, cyclic lipopeptides have earned recognition as a significant class of antimicrobial compounds with applications in pharmacology and biotechnology. These lipopeptides, often with biosurfactant properties, are amphiphilic, consisting of a hydrophilic moiety, like a carboxyl group, peptide backbone, or carbohydrates, and a hydrophobic moiety, mostly a fatty acid. Besides, several lipopeptides also have cationic groups that play an important role in biological activities. Antimicrobial lipopeptides can be considered as possible substitutes for antibiotics that are conventional to address the current drug-resistant issues as pharmaceutical industries modify the parent antibiotic molecules to render them more effective against antibiotic-resistant bacteria and fungi, leading to the development of more resistant microbial strains. Bacillus species produce lipopeptides, which are secondary metabolites that are amphiphilic and are typically synthesized by non-ribosomal peptide synthetases (NRPSs). They have been identified as potential biocontrol agents as they exhibit a broad spectrum of antimicrobial activity. A further benefit of lipopeptides is that they can be produced and purified biotechnologically or biochemically in a sustainable manner using readily available, affordable, renewable sources without harming the environment. In this review, we discuss the biochemical and functional characterization of antifungal lipopeptides, as well as their various modes of action, method of production and purification (in brief), and potential applications as novel antibiotic agents.
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Affiliation(s)
- K P Sreelakshmi
- Department of Biological Sciences, Birla Institute of Technology and Science-KK Birla Goa Campus Goa, NH 17 B Bypass Rd., Goa, 403726, India
| | - M Madhuri
- Department of Biological Sciences, Birla Institute of Technology and Science-KK Birla Goa Campus Goa, NH 17 B Bypass Rd., Goa, 403726, India
| | - R Swetha
- Department of Biological Sciences, Birla Institute of Technology and Science-KK Birla Goa Campus Goa, NH 17 B Bypass Rd., Goa, 403726, India
| | - Vivek Rangarajan
- Department of Chemical Engineering, Birla Institute of Technology and Science-KK Birla Goa Campus Goa, NH 17 B Bypass Rd., Goa, 403726, India
| | - Utpal Roy
- Department of Biological Sciences, Birla Institute of Technology and Science-KK Birla Goa Campus Goa, NH 17 B Bypass Rd., Goa, 403726, India.
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Karle SB, Kumar K. Rice tonoplast intrinsic protein member OsTIP1;2 confers tolerance to arsenite stress. JOURNAL OF HAZARDOUS MATERIALS 2024; 465:133078. [PMID: 38056278 DOI: 10.1016/j.jhazmat.2023.133078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 10/23/2023] [Accepted: 11/22/2023] [Indexed: 12/08/2023]
Abstract
The International Agency for Research on Cancer categorizes arsenic (As) as a group I carcinogen. Arsenic exposure significantly reduces growth, development, metabolism, and crop yield. Tonoplast intrinsic proteins (TIPs) belong to the major intrinsic protein (MIP) superfamily and transport various substrates, including metals/metalloids. Our study aimed to characterize rice OsTIP1;2 in As[III] stress response. The gene expression analysis showed that the OsTIP1;2 expression was enhanced in roots on exposure to As[III] treatment. The heterologous expression of OsTIP1;2 in S. cerevisiae mutant lacking YCF1 (ycf1∆) complemented the As[III] transport function of the YCF1 transporter but not for boron (B) and arsenate As[V], indicating its substrate selective nature. The ycf1∆ mutant expressing OsTIP1;2 accumulated more As than the wild type (W303-1A) and ycf1∆ mutant strain carrying the pYES2.1 vector. OsTIP1;2 activity was partially inhibited in the presence of the aquaporin (AQP) inhibitors. The subcellular localization studies confirmed that OsTIP1;2 is localized to the tonoplast. The transient overexpression of OsTIP1;2 in Nicotiana benthamiana leaves resulted in increased activities of enzymatic and non-enzymatic antioxidants, suggesting a potential role in mitigating oxidative stress induced by As[III]. The transgenic N. tabacum overexpressing OsTIP1;2 displayed an As[III]-tolerant phenotype, with increased fresh weight and root length than the wild-type (WT) and empty vector (EV line). The As translocation factor (TF) for WT and EV was around 0.8, while that of OE lines was around 0.4. Moreover, the OE line bioconcentration factor (BCF) was more than 1. Notably, the reduced TF and increased BCF in the OE line imply the potential of OsTIP1;2 for phytostabilization.
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Affiliation(s)
- Suhas Balasaheb Karle
- Birla Institute of Technology and Science, Pilani, K K Birla Goa Campus, Goa 403726, India
| | - Kundan Kumar
- Birla Institute of Technology and Science, Pilani, K K Birla Goa Campus, Goa 403726, India.
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Ramesh S, Roy U, Roy S, Rudramurthy SM. A promising antifungal lipopeptide from Bacillus subtilis: its characterization and insight into the mode of action. Appl Microbiol Biotechnol 2024; 108:161. [PMID: 38252130 DOI: 10.1007/s00253-023-12976-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 11/20/2023] [Accepted: 11/27/2023] [Indexed: 01/23/2024]
Abstract
Emerging resistance of fungal pathogens and challenges faced in drug development have prompted renewed investigations into novel antifungal lipopeptides. The antifungal lipopeptide AF3 reported here is a natural lipopeptide isolated and purified from Bacillus subtilis. The AF3 lipopeptide's secondary structure, functional groups, and the presence of amino acid residues typical of lipopeptides were determined by circular dichroism, Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy. The lipopeptide's low minimum inhibitory concentrations (MICs) of 4-8 mg/L against several fungal strains demonstrate its strong antifungal activity. Biocompatibility assays showed that ~ 80% of mammalian cells remained viable at a 2 × MIC concentration of AF3. The treated Candida albicans cells examined by scanning electron microscopy, transmission electron microscopy, and atomic force microscopy clearly showed ultrastructural alterations such as the loss of the cell shape and cell membrane integrity. The antifungal effect of AF3 resulted in membrane permeabilization facilitating the uptake of the fluorescent dyes-acridine orange (AO)/propidium iodide (PI) and FUN-1. Using 1,6-diphenyl-1,3,5-hexatriene (DPH) and 4-(2-[6-(dioctylamino)-2-naphthalenyl] ethenyl)-1-(3-sulfopropyl) pyridinium inner salt (di-8-ANEPPS), we observed that the binding of AF3 to the membrane bilayer results in membrane disruption and depolarization. Flow cytometry analyses revealed a direct correlation between lipopeptide activity, membrane permeabilization (~ 75% PI uptake), and reduced cell viability. An increase in 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) fluorescence demonstrates endogenous reactive oxygen species production. Lipopeptide treatment appears to induce late-stage apoptosis and alterations to nuclear morphology, suggesting that AF3-induced membrane damage may lead to a cellular stress response. Taken together, this study illustrates antifungal lipopeptide's potential as an antifungal drug candidate. KEY POINTS: • The studied lipopeptide variant AF3 displayed potent antifungal activity against C. albicans • Its biological activity was stable to proteolysis • Analytical studies demonstrated that the lipopeptide is essentially membranotropic and able to cause membrane dysfunction, elevated ROS levels, apoptosis, and DNA damage.
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Affiliation(s)
- Swetha Ramesh
- Department of Biological Sciences, BITS Pilani K.K. Birla Goa Campus, NH 17B Bypass Road, Sancoale, Goa, 403726, India
| | - Utpal Roy
- Department of Biological Sciences, BITS Pilani K.K. Birla Goa Campus, NH 17B Bypass Road, Sancoale, Goa, 403726, India.
| | - Subhasish Roy
- Department of Chemistry, BITS Pilani K.K. Birla Goa Campus, NH 17B Bypass Road, Sancoale, Goa, 403726, India
| | - Shivaprakash M Rudramurthy
- Department of Medical Microbiology, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, 160012, India
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Ramesh S, Roy U, Roy S. The elucidation of the multimodal action of the investigational anti- Candida lipopeptide (AF 4) lead from Bacillus subtilis. Front Mol Biosci 2023; 10:1248444. [PMID: 38131013 PMCID: PMC10736182 DOI: 10.3389/fmolb.2023.1248444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 09/11/2023] [Indexed: 12/23/2023] Open
Abstract
Background: Candida species are the main etiological agents for candidiasis, and Candida albicans are the most common infectious species. Candida species' growing resistance to conventional therapies necessitates more research into novel antifungal agents. Antifungal peptides isolated from microorganisms have potential applications as novel therapeutics. AF4 a Bacillus-derived lipopeptide demonstrating broad-spectrum antifungal activity has been investigated for its ability to cause cell death in Candida species via membrane damage and oxidative stress. Methods: Using biophysical techniques, the secondary structure of the AF4 lipopeptide was identified. Scanning electron microscopy and confocal microscopy with fluorescent dyes were performed to visualise the effect of the lipopeptide. The membrane disruption and permeabilization were assessed using the 1,6-diphenyl hexatriene (DPH) fluorescence assay and flow cytometric (FC) assessment of propidium iodide (PI) uptake, respectively. The reactive oxygen species levels were estimated using the FC assessment. The induction of apoptosis and DNA damage were studied using Annexin V-FITC/PI and DAPI. Results: Bacillus-derived antifungal variant AF4 was found to have structural features typical of lipopeptides. Microscopy imaging revealed that AF4 damages the surface of treated cells and results in membrane permeabilization, facilitating the uptake of the fluorescent dyes. A loss of membrane integrity was observed in cells treated with AF4 due to a decrease in DPH fluorescence and a dose-dependent increase in PI uptake. Cell damage was also determined from the log reduction of viable cells treated with AF4. AF4 treatment also caused elevated ROS levels, induced phosphatidylserine externalisation, late-stage apoptosis, and alterations to nuclear morphology revealed by DAPI fluorescence. Conclusion: Collectively, the mode of action studies revealed that AF4 acts primarily on the cell membrane of C. albicans and has the potential to act as an antifungal drug candidate.
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Affiliation(s)
- Swetha Ramesh
- Department of Biological Sciences, Birla Institute of Technology and Science, K.K. Birla Goa Campus, Goa, India
| | - Utpal Roy
- Department of Chemistry, Birla Institute of Technology and Science, K.K. Birla Goa Campus, Goa, India
| | - Subhashis Roy
- Department of Chemistry, Birla Institute of Technology and Science, K.K. Birla Goa Campus, Goa, India
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