An Overview on Conventional and Non-Conventional Therapeutic Approaches for the Treatment of Candidiasis and Underlying Resistance Mechanisms in Clinical Strains

Association of mucoadhesive polymeric matrices and liposomes for local delivery of miconazole: A new approach for the treatment of oral candidiasis

Since the local treatment of oral candidiasis usually requires long-term administration of the antifungal drug, an ideal dosage form should be able to maintain the drug release over an extended period, assuring an adequate concentration at the infection site. In this context, we have considered the possibility of a buccal delivery of miconazole nitrate (MN) by mucoadhesive polymeric matrices. The loading of the antifungal drug in a hydrophilic matrix was made possible by taking advantage of the amphiphilic nature of liposomes (LP). The MN-loaded LP were prepared by a thin film evaporation method followed by extrusion, while solid matrices were obtained by freeze-drying a suspension of the LP in a polymeric solution based on chitosan (CH), sodium hyaluronate (HYA), or hydroxypropyl methylcellulose (HPMC). MN-loaded LP measured 284.7 ± 20.1 nm with homogeneous size distribution, adequate drug encapsulation efficiency (86.0 ± 3.3 %) and positive zeta potential (+47.4 ± 3.3). CH and HYA-based formulations almost completely inhibited C. albicans growth after 24 h, even if the HYA-based one released a higher amount of the drug. The CH-based matrix also provided the best mucoadhesive capacity and therefore represents the most promising candidate for the local treatment of oral candidiasis.

Advancements in nanoparticle-based therapies for multidrug-resistant candidiasis infections: a comprehensive review

Candida auris, a rapidly emerging multidrug-resistant fungal pathogen, poses a global health threat, with cases reported in over 47 countries. Conventional detection methods struggle, and the increasing resistance ofC. auristo antifungal agents has limited treatment options. Nanoparticle-based therapies, utilizing materials like silver, carbon, zinc oxide, titanium dioxide, polymer, and gold, show promise in effectively treating cutaneous candidiasis. This review explores recent advancements in nanoparticle-based therapies, emphasizing their potential to revolutionize antifungal therapy, particularly in combatingC. aurisinfections. The discussion delves into mechanisms of action, combinations of nanomaterials, and their application against multidrug-resistant fungal pathogens, offering exciting prospects for improved clinical outcomes and reduced mortality rates. The aim is to inspire further research, ushering in a new era in the fight against multidrug-resistant fungal infections, paving the way for more effective and targeted therapeutic interventions.

A first-in-class inhibitor of Hsp110 molecular chaperones of pathogenic fungi

Proteins of the Hsp110 family are molecular chaperones that play important roles in protein homeostasis in eukaryotes. The pathogenic fungus Candida albicans, which causes infections in humans, has a single Hsp110, termed Msi3. Here, we provide proof-of-principle evidence supporting fungal Hsp110s as targets for the development of new antifungal drugs. We identify a pyrazolo[3,4-b] pyridine derivative, termed HLQ2H (or 2H), that inhibits the biochemical and chaperone activities of Msi3, as well as the growth and viability of C. albicans. Moreover, the fungicidal activity of 2H correlates with its inhibition of in vivo protein folding. We propose 2H and related compounds as promising leads for development of new antifungals and as pharmacological tools for the study of the molecular mechanisms and functions of Hsp110s.

Acetate modulates the inhibitory effect of Lactobacillus gasseri against the pathogenic yeasts Candida albicans and Candida glabrata

The exploration of the interference prompted by commensal bacteria over fungal pathogens is an interesting alternative to develop new therapies. In this work we scrutinized how the presence of the poorly studied vaginal species Lactobacillus gasseri affects relevant pathophysiological traits of Candida albicans and Candida glabrata. L. gasseri was found to form mixed biofilms with C. albicans and C. glabrata resulting in pronounced death of the yeast cells, while bacterial viability was not affected. Reduced viability of the two yeasts was also observed upon co-cultivation with L. gasseri under planktonic conditions. Either in planktonic cultures or in biofilms, the anti-Candida effect of L. gasseri was augmented by acetate in a concentration-dependent manner. During planktonic co-cultivation the two Candida species counteracted the acidification prompted by L. gasseri thus impacting the balance between dissociated and undissociated organic acids. This feature couldn't be phenocopied in single-cultures of L. gasseri resulting in a broth enriched in acetic acid, while in the co-culture the non-toxic acetate prevailed. Altogether the results herein described advance the design of new anti-Candida therapies based on probiotics, in particular, those based on vaginal lactobacilli species, helping to reduce the significant burden that infections caused by Candida have today in human health.

Curcumin nanoparticles: the topical antimycotic suspension treating oral candidiasis

Phytotherapeutics is widely used nowadays as an alternative to the current antifungal drugs to reduce their side effects. Curcumin, with its wide therapeutic array as antioxidant and anti-inflammatory agent, is one of the natural compounds that ha..s an antifungal effect, especially when being used at nanoscale to increase its bioavailability. Our research aimed to evaluate clinically and microbiologically the effect of using topical nanocurcumin suspension to treat oral candidiasis. After 4 days from induction of oral candidiasis (baseline), we randomly divided 39 female BALB/c mice into three groups of 13 animals; nanocurcumin, nystatin, and sham groups. All animals in nanocurcumin and nystatin groups received topical treatment twice daily for 10 days. Then, we performed clinical and microbiological evaluations at baseline, day 5, and day 10. By the end of treatment, our results revealed that nanocurcumin promoted a significant reduction in the number of candida colonies. There was no statistically significant difference neither clinically nor microbiologically between nanocurcumin and nystatin groups. In conclusion, nanocurcumin has a good antifungal effect as nystatin, however, its therapeutic efficacy takes a longer time to appear than nystatin. The enhanced bioavailability of curcumin at the nanoscale qualifies this nano-herb as a promising alternative therapy for oral candidiasis, evading nystatin-associated morbidity.

Anti-Biofilm Activity of Phenyllactic Acid against Clinical Isolates of Fluconazole-Resistant Candida albicans

Commonly found colonizing the human microbiota, Candida albicans is a microorganism known for its ability to cause infections, mainly in the vulvovaginal region, and is responsible for 85% to 90% of vulvovaginal candidiasis (VVC) cases. The development of drug resistance in C. albicans isolates after long-term therapy with fluconazole is an important complication to solve and new therapeutic strategies are required to target this organism and its pathogenicity. In the present study, phenyllactic acid (PLA) an important broad-spectrum antimicrobial compound was investigated for its antifungal and antivirulence activities against clinical isolates of C. albicans. Previously characterized strains of C. albicans isolates from women with VVC and C. albicans ATCC90028 were used to evaluate the antimicrobial and time dependent killing assay activity of PLA showing a MIC 7.5 mg mL−1 and a complete reduction of viable Candida cells detected by killing kinetics after 4 h of treatment with PLA. Additionally, PLA significantly reduced the biomass and the metabolic activity of C. albicans biofilms and impaired biofilm formation also with changes in ERG11, ALS3, and HWP1 genes expression as detected by qPCR. PLA eradicated pre-formed biofilms as showed also with confocal laser scanning microscopy (CLSM) observations. Furthermore, the compound prolonged the survival rate of Galleria mellonella infected by C. albicans isolates. These results indicate that PLA is a promising candidate as novel and safe antifungal agents for the treatment of vulvovaginal candidiasis.

Effects of Hst3p inhibition in Candida albicans: a genome-wide H3K56 acetylation analysis

Candida spp. represent the third most frequent worldwide cause of infection in Intensive Care Units with a mortality rate of almost 40%. The classes of antifungals currently available include azoles, polyenes, echinocandins, pyrimidine derivatives, and allylamines. However, the therapeutical options for the treatment of candidiasis are drastically reduced by the increasing antifungal resistance. The growing need for a more targeted antifungal therapy is limited by the concern of finding molecules that specifically recognize the microbial cell without damaging the host. Epigenetic writers and erasers have emerged as promising targets in different contexts, including the treatment of fungal infections. In C. albicans, Hst3p, a sirtuin that deacetylates H3K56ac, represents an attractive antifungal target as it is essential for the fungus viability and virulence. Although the relevance of such epigenetic regulator is documented for the development of new antifungal therapies, the molecular mechanism behind Hst3p-mediated epigenetic regulation remains unrevealed. Here, we provide the first genome-wide profiling of H3K56ac in C. albicans resulting in H3K56ac enriched regions associated with Candida sp. pathogenicity. Upon Hst3p inhibition, 447 regions gain H3K56ac. Importantly, these genomic areas contain genes encoding for adhesin proteins, degradative enzymes, and white-opaque switching. Moreover, our RNA-seq analysis revealed 1330 upregulated and 1081 downregulated transcripts upon Hst3p inhibition, and among them, we identified 87 genes whose transcriptional increase well correlates with the enrichment of H3K56 acetylation on their promoters, including some well-known regulators of phenotypic switching and virulence. Based on our evidence, Hst3p is an appealing target for the development of new potential antifungal drugs.

Bioactive compounds with antifungal activity against pathogens isolated from pregnant woman: Gallesia integrifolia (garlic wood) is a promising treatment for vulvovaginal candidiasis

ETHNOPHARMACOLOGICAL RELEVANCE

The leaves, bark, and roots of Gallesia integrifolia are consumed in folk medicine through infusion, decoction, and topical preparation by crushing because of its pharmacological properties in several peripheral system disorders, including microbial infections. The presence of various molecules in different parts of the plant likely confers this species' fungicidal action, but scientific evidence is lacking. Vulvovaginal candidiasis mainly affects women of reproductive age. When left untreated, it can cause pregnancy complications. Currently available antifungals often cause undesirable side effects. New alternative therapeutic strategies based on medicinal plants have been proposed.

AIM

To investigate the antifungal activity of G. integrifolia against vulvovaginal candidiasis secretion in pregnant women.

MATERIALS AND METHODS

Antifungal activity was determined by the minimum inhibitory concentration (MIC), determined by broth microdilution method using Candida spp (NEWP1210), C. albicans (CCCD-CC001), C. tropicalis (CCCD-CC002) standard and clinical isolates from pregnant women with vulvovaginal candidiasis. Nystatin and fluconazole were used as positive controls. The chemical composition of essential oils that were extracted from leaves, flowers, and fruits of G. integrifolia was determined by gas chromatography coupled to mass spectrometry. Reverse docking was used to suggest a possible target in Candida. Conventional docking was used to identify the most probable compound that inhibits fungal growth.

RESULTS

A total of 24 compounds were identified, accounting for ∼99% of volatile constituents in the essential oils. Leaves of G. integrifolia contained 3,5-dithiahexanol-5,5-dioxide (40.93%), flowers contained methionine ethyl ester (46.78%), and fruits contained 2,8-dithianonane (54.01%) as the most abundant compounds. The MICs of essential oils of leaves, flowers, and fruits of G. integrifolia against standard strains of Candida spp, C. albicans, and C. tropicalis ranged from 13.01 to 625.00 μg/mL. The essential oil of flowers more effectively inhibited Candida spp. Essential oils of leaves and flowers were similar to fluconazole against C. albicans. Essential oils of flowers and fruits were similar to fluconazole against C. tropocalis. In Candida yeast species that were isolated from vaginal secretion samples from pregnant patients, the MICs of leaves and flowers ranged from 52.08 to 5000.00 μg/mL. The essential oil of leaves (277.77 μg/mL) was the most active against C. albicans. No significant differences were found between the essential oils of leaves and flowers against C. glabrata. Docking simulations suggested that phytol in leaves and flowers was responsible for the antimicrobial effect.

CONCLUSION

The present results suggest the potential therapeutic use of G. integrifolia, especially its leaves and flowers, against Candida and vulvovaginal candidiasis.

Disclosing azole resistance mechanisms in resistant Candida glabrata strains encoding wild-type or gain-of-function CgPDR1 alleles through comparative genomics and transcriptomics

The pathogenic yeast Candida glabrata is intrinsically resilient to azoles and rapidly acquires resistance to these antifungals, in vitro and in vivo. In most cases azole-resistant C. glabrata clinical strains encode hyperactive CgPdr1 variants, however, resistant strains encoding wild-type CgPDR1 alleles have also been isolated, although remaining to be disclosed the underlying resistance mechanism. In this study, we scrutinized the mechanisms underlying resistance to azoles of 8 resistant clinical C. glabrata strains, identified along the course of epidemiological surveys undertaken in Portugal. Seven of the strains were found to encode CgPdr1 gain-of-function variants (I392M, E555K, G558C, and I803T) with the substitutions I392M and I803T being herein characterized as hyper-activating mutations for the first time. While cells expressing the wild-type CgPDR1 allele required the mediator subunit Gal11A to enhance tolerance to fluconazole, this was dispensable for cells expressing the I803T variant indicating that the CgPdr1 interactome is shaped by different gain-of-function substitutions. Genomic and transcriptomic profiling of the sole azole-resistant C. glabrata isolate encoding a wild-type CgPDR1 allele (ISTB218) revealed that under fluconazole stress this strain over-expresses various genes described to provide protection against this antifungal, while also showing reduced expression of genes described to increase sensitivity to these drugs. The overall role in driving the azole-resistance phenotype of the ISTB218 C. glabrata isolate played by these changes in the transcriptome and genome of the ISTB218 isolate are discussed shedding light into mechanisms of resistance that go beyond the CgPdr1-signalling pathway and that may alone, or in combination, pave the way for the acquisition of resistance to azoles in vivo.

Evaluation of the anticandidal activity of clotrimazole using Lactobacillus caseie ghosts as biological drug carrier

BACKGROUND

Candida albicans cause oral and vaginal mucosa infections as well as bloodstream and deep-tissue infections. Commonly, clotrimazole as a broad-spectrum antimitotic drug applied for treatment of Candida albicans infections. Bacterial ghosts are dead cells that have the broad potential to target the various body tissues and cells as drug vector.

OBJECTIVES

We hope to conquest this resistance by using clotrimazole loaded on bacterial ghosts.

METHODS

Lactobacillus ghosts were produced by using tween 80 and lactic acid according to the protocol and the amount of the DNA and protein in supernatant was measured by Nano-drop spectrophotometry. Ghost's morphological characteristics were detected by using light microscopy, SEM and AFM. Antifungal activities of the synthesized ghosts were measured by plate methods. Three independent vertical Franz cells were used to evaluate drug release profile. BG-clotrimazole was added into cream base and was examined for dispensability as well as uniformity of the formulation on the skin.

RESULTS

Results of the Nano-drop analysis showed that protein and DNA was seen in supernatant of treatment compared to control groups. AFM results showed well-dispersed and rod-shaped L. casei ghost cells. Lysis pores formation in the L. casei ghosts was indicated by SEM micrographs. BGs represent an excellent drug delivery system because of the high loading capability. Nearly, 50% of clotrimazole was released from BGs during 90 min. Highest anticandidal activity occurred using 100 mg/l clotrimazole-BG, while toxic effects were also seen with 10 mg/l clotrimazole. IC₅₀ clotrimazole-BG was found at 0.001 mg/l. Chemical stability results showed that about 90% of clotrimazole remained in the formulation.

CONCLUSION

It could be concluded that the bacterial ghosts are very talented to high loading capability, keeping and releasing drug during six months, therefore these could act as an excellent drug delivery system.

Exploring the Antifungal Activity and Action of Saussurea costus Root Extracts against Candida albicans and Non-albicans Species

The isolation and assessment of the active constituents in polar and non-polar crude extracts of Saussurea costus roots as antifungal agents, against Candida albicans and non-C. albicans (NAC) species, was the aim of this current investigation. The SEM “Scanning electron microscopy” imaging provided potential action modes of n-hexane extract (nhhE) toward Candida spp., whereas the TLC-DB “Thin layer chromatography-direct bioautography” was employed for detecting the anticandidal compounds. nhhE had the greatest biocidal activity against all strains and clinical isolates of Candida spp. with maximum zones of inhibition. SEM revealed the occurrence of irregular, dense inclusions of C. albicans cell walls after treatment with nhhE for 12 h. Complete morphological distortions with lysed membranes and deterioration signs appeared in most treated cells of C. parapsilosis. The most effectual compound with anticandidal activity was isolated using TLC-BD and identified as sesquiterpene by GC/MS analysis. The infra-red analysis revealed the presence of lactone ring stretching vibrations at 1766.72 cm−1. The anticandidal activity of nhhE of S. costus roots was confirmed from the results, and the treated cotton fabrics with nhhE of S. costus possessed observable activity against C. albicans. Data could recommend the practical usage of S. costus extracts, particularly nhhE, as influential natural bioactive sources for combating pathogenic Candida spp.

DectiSomes: Glycan Targeting of Liposomal Drugs Improves the Treatment of Disseminated Candidiasis

Candida albicans causes life-threatening disseminated candidiasis. Individuals at greatest risk have weakened immune systems. An outer cell wall, exopolysaccharide matrix, and biofilm rich in oligoglucans and oligomannans help Candida spp. evade host defenses. Even after antifungal treatment, the 1-year mortality rate exceeds 25%. Undoubtedly, there is room to improve drug performance. The mammalian C-type lectin pathogen receptors Dectin-1 and Dectin-2 bind to fungal oligoglucans and oligomannans, respectively. We previously coated amphotericin B-loaded liposomes, AmB-LLs, pegylated analogs of AmBisome, with the ligand binding domains of these two Dectins. DectiSomes, DEC1-AmB-LLs and DEC2-AmB-LLs, showed two distinct patterns of binding to the exopolysaccharide matrix surrounding C. albicans hyphae grown in vitro. Here we showed that DectiSomes were preferentially associated with fungal colonies in the kidneys. In a neutropenic mouse model of candidiasis, DEC1-AmB-LLs and DEC2-AmB-LLs delivering only one dose of 0.2 mg/kg AmB reduced the kidney fungal burden several fold relative to AmB-LLs. DEC1-AmB-LLs and DEC2-AmB-LLs increased the percent of surviving mice 2.5-fold and 8.3-fold, respectively, relative to AmB-LLs. Dectin-2 targeting of anidulafungin loaded liposomes, DEC2-AFG-LLs, and of commercial AmBisome, DEC2-AmBisome, reduced fungal burden in the kidneys several fold over their untargeted counterparts. The data herein suggest that targeting of a variety of antifungal drugs to fungal glycans may achieve lower safer effective doses and improve drug efficacy against a variety of invasive fungal infections.

Zinc Oxide Nanoparticles Prime a Protective Immune Response in Galleria mellonella to Defend Against Candida albicans

Purpose: Zinc oxide nanoparticles (ZnO-NPs) have exerted antimicrobial properties. However, there is insufficient evaluation regarding the in vivo antifungal activity of ZnO-NPs. This study aimed to investigate the efficacy and mechanism of ZnO-NPs in controlling Candida albicans in the invertebrate Galleria mellonella. Methods: Galleria mellonella larvae were injected with different doses of ZnO-NPs to determine their in vivo toxicity. Non-toxic doses of ZnO-NPs were chosen for prophylactic injection in G. mellonella followed by C. albicans infection. Then the direct in vitro antifungal effect of ZnO-NPs against C. albicans was evaluated. In addition, the mode of action of ZnO-NPs was assessed in larvae through different assays: quantification of hemocyte density, morphology observation of hemocytes, characterization of hemocyte aggregation and phagocytosis, and measurement of hemolymph phenoloxidase (PO) activity. Results: Zinc oxide nanoparticles were non-toxic to the larvae at relatively low concentrations (≤20 mg/kg). ZnO-NP pretreatment significantly prolonged the survival of C. albicans-infected larvae and decreased the fungal dissemination and burden in the C. albicans-infected larvae. This observation was more related to the activation of host defense rather than their fungicidal capacities. Specifically, ZnO-NP treatment increased hemocyte density, promoted hemocyte aggregation, enhanced hemocyte phagocytosis, and activated PO activity in larvae. Conclusion: Prophylactic treatment with lower concentrations of ZnO-NPs protects G. mellonella from C. albicans infection. The innate immune response primed by ZnO-NPs may be part of the reason for the protective effects. This study provides new evidence of the capacity of ZnO-NPs in enhancing host immunity and predicts that ZnO-NPs will be attractive for further anti-infection applications.

A new humanized antibody is effective against pathogenic fungi in vitro

Invasive fungal infections mainly affect patients undergoing transplantation, surgery, neoplastic disease, immunocompromised subjects and premature infants, and cause over 1.5 million deaths every year. The most common fungi isolated in invasive diseases are Candida spp., Cryptococcus spp., and Aspergillus spp. and even if four classes of antifungals are available (Azoles, Echinocandins, Polyenes and Pyrimidine analogues), the side effects of drugs and fungal acquired and innate resistance represent the major hurdles to be overcome. Monoclonal antibodies are powerful tools currently used as diagnostic and therapeutic agents in different clinical contexts but not yet developed for the treatment of invasive fungal infections. In this paper we report the development of the first humanized monoclonal antibody specific for β-1,3 glucans, a vital component of several pathogenic fungi. H5K1 has been tested on C. auris, one of the most urgent threats and resulted efficient both alone and in combination with Caspofungin and Amphotericin B showing an enhancement effect. Our results support further preclinical and clinical developments for the use of H5K1 in the treatment of patients in need.

Purification and biochemical characterization of Msi3, an essential Hsp110 molecular chaperone in Candida albicans

Hsp110s are unique and essential molecular chaperones in the eukaryotic cytosol. They play important roles in maintaining cellular protein homeostasis. Candida albicans is the most prevalent yeast opportunistic pathogen that causes fungal infections in humans. As the only Hsp110 in Candida albicans, Msi3 is essential for the growth and infection of Candida albicans. In this study, we have expressed and purified Msi3 in nucleotide-free state and carried out biochemical analyses. Sse1 is the major Hsp110 in budding yeast S. cerevisiae and the best characterized Hsp110. Msi3 can substitute Sse1 in complementing the temperature-sensitive phenotype of S. cerevisiae carrying a deletion of SSE1 gene although Msi3 shares only 63.4% sequence identity with Sse1. Consistent with this functional similarity, the purified Msi3 protein shares many similar biochemical activities with Sse1 including binding ATP with high affinity, changing conformation upon ATP binding, stimulating the nucleotide-exchange for Hsp70, preventing protein aggregation, and assisting Hsp70 in refolding denatured luciferase. These biochemical characterizations suggested that Msi3 can be used as a model for studying the molecular mechanisms of Hsp110s.

Herbal Products and Their Active Constituents Used Alone and in Combination with Antifungal Drugs against Drug-Resistant Candida sp

Clinical isolates of Candida yeast are the most common cause of opportunistic fungal infections resistant to certain antifungal drugs. Therefore, it is necessary to detect more effective antifungal agents that would be successful in overcoming such infections. Among them are some herbal products and their active constituents.The purpose of this review is to summarize the current state of knowledge onherbal products and their active constituents havingantifungal activity against drug-resistant Candida sp. used alone and in combination with antifungal drugs.The possible mechanisms of their action on drug-resistant Candida sp. including (1) inhibition of budding yeast transformation into hyphae; (2) inhibition of biofilm formation; (3) inhibition of cell wall or cytoplasmic membrane biosynthesis; (4) ROS production; and (5) over-expression of membrane transporters will be also described.

Bioactive Coatings with Ag-Camphorimine Complexes to Prevent Surface Colonization by the Pathogenic Yeast Candida albicans

Currently there is a gap between the rate of new antifungal development and the emergence of resistance among Candida clinical strains, particularly threatened by the extreme adhesiveness of C. albicans to indwelling medical devices. Two silver camphorimine complexes, [Ag(OH){OC₁₀H₁₄N(C₆H₄)₂NC₁₀H₁₄O}] (compound P) and [{Ag(OC₁₀H₁₄NC₆H₄CH₃-p)}₂(μ-O)] (compound Q), are herein demonstrated as having high inhibiting activity towards the growth of Candida albicans and Candida glabrata clinical strains resistant to azoles, the frontline antifungals used in clinical practice. Compounds P and Q were also explored as bioactive coatings to prevent colonization by C. albicans and colonize the surface of indwelling medical devices, resulting in persistent infections. Functionalization of stainless steel with polycaprolactone (PCL) matrix embedded with compounds P or Q was reported for the first time to inhibit the colonization of C. albicans by 82% and 75%, respectively. The coating of PCL loaded with Q or P did not cause cytotoxic effects in mammalian cells, demonstrating the biocompatibility of the explored approach. The identification and further exploration of new approaches for surface engineering based on new molecules that can sensitize resistant strains, as herein demonstrated for complexes P and Q, is a significant step forward to improve the successful treatment of candidiasis.

Design, synthesis and biological evaluation of a series of iron and copper chelating deferiprone derivatives as new agents active against Candida albicans

Candida albicans, in specific conditions, is responsible of severe invasive systemic candidiasis that are related to its ability to produce biofilm on biological and artificial surfaces. Many studies reported the role of iron in fungal growth and virulence and the ability of metal chelating agents to interfere with C. albicans metabolism, virulence and biofilm formation. Here we report the activity of 3-hydroxy-1,2-dimethyl-4(1H)-pyridinone (deferiprone) derivatives against C. albicans planktonic cells and biofilm. Some of the studied compounds (2b and 3b) were able to chelate Fe(III) and Cu(II), and showed an interesting activity on planktonic cells (MIC₅₀ of 32 μg/mL and 16 μg/mL respectively) and on biofilm formation (BMIC₅₀ of 32 μg/mL and 16 μg/mL respectively) in cultured ATCC 10,231C. albicans; this activity was reduced, in a concentration dependent way, by the addition of Fe(III) and Cu(II) to the culture media. Furthermore, the most active compound 3b showed a low toxicity on Galleria mellonella larvae.

New perspectives on the topical management of recurrent candidiasis

Candidiasis is a common opportunistic infection caused by fungi of the Candida genus that affects mainly mucocutaneous tissues (e.g., vaginal, oral, and mammary). This condition has been known for a long time; thus, innumerous topical and systemic treatments are already available on the market worldwide. Yet, recurrent superficial candidiasis (RSC) is an expected outcome, still lacking effective and convenient treatments. Although several individual conditions may contribute to disease recurrence, biofilms' presence seems to be the main etiological factor contributing to antifungal resistance. More than proposing novel antifungal agents, current research seems to be focusing on improving the pharmaceutical technology aspects of formulations to address such a challenge. These include extending and improving intimate contact of drug delivery systems with the mucocutaneous tissues, increasing drug loading dose, and enhancing topical drug permeation. This review discusses the current understanding of the RSC and the use of pharmaceutical technology tools in obtaining better results. Even though several drawbacks of conventional formulations have been circumvented with the help of nano- or microencapsulation techniques and with the use of mucoadhesive formulation excipients, many challenges remain. In particular, the need to mask the unpalatable taste of formulations for the treatment of oral candidiasis, and the necessity of formulations with a "dryer" sensorial feeling and improved performances in providing higher bioavailability for the treatment of mammary and vaginal candidiasis.

Coronary Vasculitis Induced in Mice by Cell Wall Mannoprotein Fractions of Clinically Isolated Candida Species

Kawasaki disease (KD) is an inflammatory disease that was identified by Professor Tomisaku Kawasaki in 1961. Candida albicans-derived substances (CADS) such as the hot water extract of C. albicans and Candida water-soluble fractions (CAWS) induce coronary vasculitis similar to KD in mice. An increasing proportion of deep-seated candidiasis cases are caused by non-albicans Candida and are often resistant to antifungal drugs. We herein investigated whether the mannoprotein fractions (MN fractions) of clinically isolated Candida species induce vasculitis in mice. We prepared MN fractions from 26 strains of Candida species by conventional hot water extraction and compared vasculitis in DBA/2 mice. The results obtained revealed that the induction of vasculitis and resulting heart failure were significantly dependent on the species; namely, death rates on day 200 were as follows: Candida krusei (100%), Candida albicans (84%), Candida dubliniensis (47%), Candida parapsilosis (44%), Candida glabrata (32%), Candida guilliermondii (20%), and Candida tropicalis (20%). Even for C. albicans, some strains did not induce vasculitis. The present results suggest that MN-induced vasculitis is strongly dependent on the species and strains of Candida, and also that the MN fractions of some non-albicans Candida induce similar toxicity to those of C. albicans.

Plant-Derived Substances in the Fight Against Infections Caused by Candida Species

Yeast-like fungi from the Candida genus are predominantly harmless commensals that colonize human skin and mucosal surfaces, but under conditions of impaired host immune system change into dangerous pathogens. The pathogenicity of these fungi is typically accompanied by increased adhesion and formation of complex biofilms, making candidal infections challenging to treat. Although a variety of antifungal drugs have been developed that preferably attack the fungal cell wall and plasma membrane, these pathogens have acquired novel defense mechanisms that make them resistant to standard treatment. This causes an increase in the incidence of candidiasis and enforces the urgent need for an intensified search for new specifics that could be helpful, alone or synergistically with traditional drugs, for controlling Candida pathogenicity. Currently, numerous reports have indicated the effectiveness of plant metabolites as potent antifungal agents. These substances have been shown to inhibit growth and to alter the virulence of different Candida species in both the planktonic and hyphal form and during the biofilm formation. This review focuses on the most recent findings that provide evidence of decreasing candidal pathogenicity by different substances of plant origin, with a special emphasis on the mechanisms of their action. This is a particularly important issue in the light of the currently increasing frequency of emerging Candida strains and species resistant to standard antifungal treatment.

Green Synthesis of Antileishmanial and Antifungal Silver Nanoparticles Using Corn Cob Xylan as a Reducing and Stabilizing Agent

Corn cob is an agricultural byproduct that produces an estimated waste burden in the thousands of tons annually, but it is also a good source of xylan, an important bioactive polysaccharide. Silver nanoparticles containing xylan (nanoxylan) were produced using an environmentally friendly synthesis method. To do this, we extracted xylan from corn cobs using an ultrasound technique, which was confirmed by both chemical and NMR analyses. This xylan contained xylose, glucose, arabinose, galactose, mannose, and glucuronic acid in a molar ratio of 50:21:14:9:2.5:2.5, respectively. Nanoxylan synthesis was analyzed using UV-vis spectroscopy at kmax = 469 nm and Fourier transform infrared spectroscopy (FT-IR), which confirmed the presence of both silver and xylan in the nanoxylan product. Dynamic light scattering (DLS) and atomic force microscopy (AFM) revealed that the nanoxylan particles were ~102.0 nm in size and spherical in shape, respectively. DLS also demonstrated that nanoxylan was stable for 12 months and coupled plasma optical emission spectrometry (ICP-OES) showed that the nanoxylan particles were 19% silver. Nanoxylan reduced Leishmania amazonensis promastigote viability with a half maximal inhibitory concentration (IC50) value of 25 μg/mL, while xylan alone showed no effective. Additionally, nanoxylan exhibited antifungal activity against Candida albicans (MIC = 7.5 μg/mL), C. parapsilosis (MIC = 7.5 μg/mL), and Cryptococcus neoformans (MIC = 7.5 μg/mL). Taken together, these data suggest that it is possible to synthesize silver nanoparticles using xylan and that these nanoxylan exert improved antileishmanial and antifungal activities when compared to the untreated polysaccharide or silver nitrate used for their synthesis. Thus, nanoxylan may represent a promising new class of antiparasitic agents for use in the treatment of these microorganisms.