Background/Objectives: Leishmaniasis remains a major neglected tropical disease, and current chemotherapeutic options are limited by toxicity and resistance in Leishmania species, including L. amazonensis. Prenylated coumarins have emerged as promising bioactive scaffolds. Altissimacoumarin D and its analogues inhibit fungal efflux pumps associated with resistance. However, their antileishmanial potential and mechanisms of action remain unclear. Here, we evaluated the in vitro, in vivo, and in silico effects of altissimacoumarin D and seven analogues against L. amazonensis. Methods: In vitro assays were performed to identify active compounds and assess toxicity in keratinocytes. In vivo experiments in hamsters evaluated antileishmanial activity and renal and hepatic toxicity. In silico analyses were conducted to investigate the mechanism of action of the substances. Results: In vitro assays showed that ACS47, ACS48, and ACS51 were the most active and safe compounds. In a hamster infection model, daily administration of ACS47 and ACS48 (2.5 mg/kg) significantly reduced parasite burden and lesion size, while maintaining normal renal and hepatic biochemical parameters. Histological analysis correlated reduced lesion size with marked decreases in amastigote density. Based on in silico analysis, spermidine synthase was supported as a plausible molecular target. Conclusions: Collectively, these findings identify ACS47 and ACS48 as promising lead compounds for future antileishmanial drug development.

Quinones have been strategically combined with various heterocyclic scaffolds to enhance their biological properties. In this study, two new series of hybrid derivatives of 4-amino-1,2-naphthoquinones bearing a triazole ring were synthesized via a three-step procedure. These compounds were evaluated for antifungal activity and for their ability to generate reactive oxygen species (ROS). The compounds were active against both yeast and filamentous fungi. Notably, their antifungal effect was not linked to ROS generation or to interaction with lanosterol 14α-demethylase, the main accepted mechanisms of action for naphthoquinones and triazoles, respectively. The structural diversity of these 1,2-naphthoquinones enables a range of molecular interactions with fungal targets, making them promising candidates for developing novel antifungal agents, particularly given the high prevalence of fungal infections in human colonization and their clinical significance.

Candida spp. can be found in the human microbiome. However, immunocompromised patients are likely to develop invasive Candida infections, with mortality rates higher than 50

Oral candidiasis can be presented in different ways due to the virulence factors of its etiology such as Candida albicans that have developed an effective set of these factors that are able to improve its pathogenesis. The role of salivary immunological components in the development of candidiasis can provide insights for the development of new methodologies aiming to control this disease. The aim of this study was to evaluate the antifungal activity of two salivary components, histatin 5 and lactoferrin on C. albicans viability and virulence using a fluconazole resistant C. albicans clinical strain. Results showed that histatin 5 and lactoferrin decreased cell viability, and the cell surface hydrophobicity was increased by 18

Multidrug resistance in fungi is a growing challenge to global public health, resulting in ineffective treatments and thus high mortality rates [...]

Candida species are one of the most concerning causative agents of fungal infections in humans. The treatment of invasive Candida infections is based on the use of fluconazole, but the emergence of resistant isolates has been an increasing concern which has led to the study of alternative drugs with antifungal activity. Sphingolipids have been considered a promising target due to their roles in fungal growth and virulence. Inhibitors of the sphingolipid biosynthetic pathway have been described to display antifungal properties, such as myriocin and aureobasidin A, which are active against resistant Candida isolates. In the present study, aureobasidin A did not display antibiofilm activity nor synergism with amphotericin B, but its combination with fluconazole was effective against Candida biofilms and protected the host in an in vivo infection model. Alterations in treated cells revealed increased oxidative stress, reduced mitochondrial membrane potential and chitin content, as well as altered morphology, enhanced DNA leakage and a greater susceptibility to sodium dodecyl sulphate (SDS). In addition, it seems to inhibit the efflux pump CaCdr2p. All these data contribute to elucidating the role of aureobasidin A on fungal cells, especially evidencing its promising use in clinical resistant isolates of Candida species.

We evaluated the effects of dentine biomodification after pre-treatment with two sulphonamide carbonic anhydrase inhibitors (CAIs) of the N-[4-sulphamoylphenethylcarbamoyl]benzenesulphonamide type, investigating matrix metalloproteases activity, resin-dentine micro tensile bond strength, dentine surface wettability, and antimicrobial activities. Ninety-five sound-extracted human molars were selected for the study. Inhibitory effects were evaluated by gelatinase and collagenase activity tests and collagen degradation FT-IR spectroscopic analysis. Pre-treatment with the two CAIs kept the micro tensile values after 12 months of storage (32.23 +/- 5.95) and cariogenic challenge (34.13 +/- 2.71) similar to the initial, pre-treatment values (33.56 +/- 4.34). A decreased Streptococcus mutans biofilm formation on dentine surfaces and antibacterial activity against planktonic bacteria were observed after CAI treatment. Dentine pre-treatment with sulphonamide CAIs maintained adhesion strength stability, allowed better dentine wettability, maintained matrix collagen, and showed anti-S. mutans activity.

Azoles are the main antifungal agents employed in clinical practice to treat invasive candidiasis. Nonetheless, their efficacy is limited by fungal resistance mechanisms, mainly the overexpression of efflux pumps. Consequently, candidiasis has a worrisome death rate of 75%. One potential strategy to overcome efflux-mediated resistance is to inhibit this process. Ailanthus altissima is a Chinese tree that produces several active substances, including altissimacoumarin D. Due to the low yield of its extraction and the need to search for new drugs to treat candidiasis, this study aimed to synthesize altissimacoumarin D and its analogues, as well as evaluating their ability to reverse the resistance phenotype of Candida albicans. Coumarin isofraxidin was prepared via total synthesis through a solvent-free Knoevenagel condensation as the key step. Isofraxidin and other commercially available coumarins were alkylated with prenyl or geranyl groups to yield the natural product altissimacoumarin D and seven analogues. The antifungal activity of the coumarins and their ability to reverse the fungal resistance phenotype were assessed using microbroth methodologies. Toxicity was evaluated using erythrocytes and an in silico prediction. All compounds improved the antifungal activity of fluconazole by inhibiting efflux pumps, and ACS47 and ACS50 were the most active. None of the coumarins were toxic to erythrocytes. In silico predictions indicate that ACS47 and ACS50 may be safe for human use. ACS47 and ACS50 are promising candidates when used as adjuvants in the antifungal therapy against C. albicans-resistant strains.

The poor outcome of treatments for fungal infections is a consequence of the increasing incidence of resistance to antifungal agents, mainly due to the overexpression of efflux pumps. To surpass this mechanism of resistance, a substance able to inhibit these pumps could be administered in association with antifungals. Saccharomyces cerevisiae possesses an efflux pump (Pdr5p) homologue to those found in pathogenic yeast. Digoxin is a natural product that inhibits Na+, K+-ATPase. The aim of this study was to evaluate whether digoxin and its derivatives (i.e., DGB, digoxin benzylidene) can inhibit Pdr5p, reversing the resistance to fluconazole in yeasts. An S. cerevisiae mutant strain that overexpresses Pdr5p was used in the assays. The effects of the compounds on yeast growth, efflux activity, and Pdr5p ATPase activity were measured. All derivatives enhanced the antifungal activity of fluconazole against S. cerevisiae, in comparison to fluconazole alone, with FICI values ranging from 0.031 to 0.500. DGB 1 and DGB 3 presented combined effects with fluconazole against a Candida albicans strain, with fractional inhibitory concentration index (FICI) values of 0.625 and 0.281, respectively The compounds also inhibited the efflux of rhodamine 6G and Pdr5p ATPase activity, with IC50 values ranging from 0.41 μM to 3.72 μM. The results suggest that digoxin derivatives impair Pdr5p activity. Considering the homology between Pdr5p and efflux pumps from pathogenic fungi, these compounds are potential candidates to be used in association with fluconazole to treat resistant fungal infections.

Candida auris emerges as an important causative agent of fungal infections, with worrisome mortality rates, mainly in immunocompromised individuals. This scenario is worsened by the limited availability of antifungal drugs and the increasing development of resistance to them. Due to the relevance of C. auris infections to public health, several studies aimed to discover new antifungal compounds capable of overcoming this fungus. Nonetheless, these information are decentralized, precluding the understandment of the current status of the search for new anti-C. auris compounds. Thus, this integrative review aimed to summarize information regarding anti-C. auris compounds reported in literature. After using predefined selection criteria, 71 articles were included in this review, and data from a total of 101 substances were extracted. Most of the studies tested synthetic substances, including several azoles. Moreover, drug repurposing emerges as a suitable strategy to discover new anti-C. auris agents. Few studies, however, assessed the mechanism of action and the in vivo antifungal activity of the compounds. Therefore, more studies must be performed to evaluate the usefulness of these substances as anti-C. auris therapies.

Infections caused particularly by Candida glabrata are hard to treat due to the development of antifungal resistance that occurs mainly through the production of efflux pumps and biofilm. Thus, a promising strategy to overcome infections caused by C. glabrata could be to use a substance able to inhibit efflux pumps and eradicate biofilms. Lapachones are natural naphthoquinones that possess a variety of pharmacological properties. Previous studies show that these substances inhibit the growth, virulence factors and efflux pumps of C. albicans. The aim of the present study was to evaluate whether lapachones are able to inhibit efflux pumps related to antifungal resistance in C. glabrata and either prevent biofilm formation or affect mature biofilms. Assays were performed with Saccharomyces cerevisiae strains that overexpress C. glabrata transporters (CgCdr1p and CgCdr2p). One C. glabrata clinical isolate that overexpresses CgCdr1p was also used. Both β-lapachone and β-nor-lapachone affected the growth of S. cerevisiae and C. glabrata when combined to fluconazole, and this action was inhibited by ascorbic acid. Both lapachones stimulated ROS production, inhibited efflux activity, adhesion, biofilm formation and the metabolism of mature biofilms of C. glabrata. Data obtained on the present study point to the potential use of β-lapachone and β-nor-lapachone as antibiofilm agents and adjuvants on the antifungal therapy related to resistant infections caused by C. glabrata.

The aim of this study was to evaluate the ability of lapachones in disrupting the fungal multidrug resistance (MDR) phenotype, using a model of study which an azole-resistant Saccharomyces cerevisiae mutant strain that overexpresses the ATP-binding cassette (ABC) transporter Pdr5p. The evaluation of the antifungal activity of lapachones and their possible synergism with fluconazole against the mutant S. cerevisiae strain was performed through broth microdilution and spot assays. Reactive oxygen species (ROS) and efflux pump activity were assessed by fluorometry. ATPase activity was evaluated by the Fiske and Subbarow method. The effect of β-lapachone on PDR5 mRNA expression was assessed by RT-PCR. The release of hemoglobin was measured to evaluate the hemolytic activity of β-lapachone. α-nor-Lapachone and β-lapachone inhibited S. cerevisiae growth at 100 μg/ml. Only β-lapachone enhanced the antifungal activity of fluconazole, and this combined action was inhibited by ascorbic acid. β-Lapachone induced the production of ROS, inhibited Pdr5p-mediated efflux, and impaired Pdr5p ATPase activity. Also, β-lapachone neither affected the expression of PDR5 nor exerted hemolytic activity. Data obtained indicate that β-lapachone is able to inhibit the S. cerevisiae efflux pump Pdr5p. Since this transporter is homologous to fungal ABC transporters, further studies employing clinical isolates that overexpress these proteins will be conducted to evaluate the effect of β-lapachone on pathogenic fungi.

Objectives The aim of this study was to evaluate the ability of lapachones in disrupting the fungal multidrug resistance (MDR) phenotype, using a model of study which an azole-resistantSaccharomyces cerevisiaemutant strain that overexpresses the ATP-binding cassette (ABC) transporter Pdr5p. Methods The evaluation of the antifungal activity of lapachones and their possible synergism with fluconazole against the mutantS. cerevisiaestrain was performed through broth microdilution and spot assays. Reactive oxygen species (ROS) and efflux pump activity were assessed by fluorometry. ATPase activity was evaluated by the Fiske and Subbarow method. The effect of beta-lapachone onPDR5mRNA expression was assessed by RT-PCR. The release of hemoglobin was measured to evaluate the hemolytic activity of beta-lapachone. Results alpha-nor-Lapachone and beta-lapachone inhibitedS. cerevisiaegrowth at 100 mu g/ml. Only beta-lapachone enhanced the antifungal activity of fluconazole, and this combined action was inhibited by ascorbic acid. beta-Lapachone induced the production of ROS, inhibited Pdr5p-mediated efflux, and impaired Pdr5p ATPase activity. Also, beta-lapachone neither affected the expression ofPDR5nor exerted hemolytic activity. Conclusions Data obtained indicate that beta-lapachone is able to inhibit theS. cerevisiaeefflux pump Pdr5p. Since this transporter is homologous to fungal ABC transporters, further studies employing clinical isolates that overexpress these proteins will be conducted to evaluate the effect of beta-lapachone on pathogenic fungi.

Abstract ABC transporters constitute a superfamily of transmembrane proteins that act mediating the translocation of several substrates across the membrane, using the energy of ATP hydrolysis. This mechanism of unrelated substrates efflux (multidrug resistance) has been associated with several diseases and it is a problem in chemotherapy efficacy. Nowadays, approximately 25% of the prescription drugs in the world are derived from plants. Casearia sylvestris is commonly found in the Americas and different parts of this plant are popularly used to treat several diseases. Previous studies have also confirmed the biological activities of C. sylvestris, such as anti-tumor, anti-leishmania, and antifungal properties. Then, the propose of this study was demonstrate that fraction 1-6 of C. sylvestris, essential oil, was able to reverse the fluconazole resistance phenotype in the Saccharomyces cerevisiae model mediated by the heterologous protein CaCdr2p from Candida albicans. The MIC value of fraction 1-6 combined with fluconazole in the checkerboard assay decreased approximately 4-fold, suggesting a synergistic effect. In addition, fraction 1-6 increased intracellular rhodamine 6G accumulation from 17% to 49% in the presence of glucose. Data indicate that C. sylvestris fraction 1-6 is a potential reverser of the fluconazole resistance phenotype.

The search for new antifungal strategies to overcome Candida infections is essential and a matter of public health, due to the high mortality associated to candidiasis, the increasing incidence of resistance to antifungals and the limited number of drugs available for treatment. Several approaches have been exploited in order to develop new antifungal strategies, e.g. the use of natural products, vaccines, and the combination of an antifungal drug to a non-antifungal substance. Nonetheless, issues related to pharmacokinetic parameters, toxicity and costs have been jeopardizing the discovery of new antifungal drugs. An alternative that could overcome these problems would be treating candidiasis with drugs that have been originally developed to treat other diseases. This strategy, known as drug repositioning or drug repurposing, could diminish the incidence of adverse effects and lower the cost of production, since several steps involved in drug discovery and development have already been accomplished. This review presents a set of known drugs that have been exploited as anticandidal agents, such as antidepressant agents, antiepileptic drugs, statins, among others. These substances affect the growth of Candida spp. in vitro, as well as virulence factors such as morphogenesis and biofilm formation. Moreover, some drugs are able to potentiate the anticandidal activity of known antifungal drugs. Drug repositioning appears as a remarkable alternative to increase the pharmacological arsenal against candidiasis, but further studies must be conducted in order to evaluate the real applicability of known drugs in the treatment of these infections.

The search for new antifungal strategies to overcome Candida infections is essential and a matter of public health, due to the high mortality associated to candidiasis, the increasing incidence of resistance to antifungals and the limited number of drugs available for treatment. Several approaches have been exploited in order to develop new antifungal strategies, e.g. the use of natural products, vaccines, and the combination of an antifungal drug to a non-antifungal substance. Nonetheless, issues related to pharmacokinetic parameters, toxicity and costs have been jeopardizing the discovery of new antifungal drugs. An alternative that could overcome these problems would be treating candidiasis with drugs that have been originally developed to treat other diseases. This strategy, known as drug repositioning or drug repurposing, could diminish the incidence of adverse effects and lower the cost of production, since several steps involved in drug discovery and development have already been accomplished. This review presents a set of known drugs that have been exploited as anticandidal agents, such as antidepressant agents, antiepileptic drugs, statins, among others. These substances affect the growth of Candida spp. in vitro, as well as virulence factors such as morphogenesis and biofilm formation. Moreover, some drugs are able to potentiate the anticandidal activity of known antifungal drugs. Drug repositioning appears as a remarkable alternative to increase the pharmacological arsenal against candidiasis, but further studies must be conducted in order to evaluate the real applicability of known drugs in the treatment of these infections.

BACKGROUND:Fungal infections are a serious problem among haemodialysis patients.AIM:The aims of this study were to estimate the frequency of oral Candida species among children and adolescents undergoing haemodialysis (HD), to identify the isolated species, and to study the relationship between haemodialysis duration, amounts of colony-forming units, and salivary pH.DESIGN:A matched sample of 52 patients undergoing HD and 52 healthy individuals were selected. The samples were obtained from the dorsum of the tongue, and the colonies were identified through a substrate assimilation test. Stimulated whole saliva was collected from each patient for evaluation of salivary pH.RESULTS:The frequency of oral Candida species was 34.6% (18/52) and 46.20% (24/52) in the HD and control groups (P = 0.23), respectively. Candida parapsilosis complex was the most frequently isolated fungi species in the HD group (P = 0.03). A HD therapy duration of more than 1 year was statistically correlated with a higher number of colony-forming units (P = 0.03) but was not statistically related to salivary pH.CONCLUSIONS:Candida parapsilosis complex was the most frequently isolated fungal species in the young HD patients, and the duration therapy was associated with higher oral colonization.

Background. - Candida albicans is the most important fungal pathogen that causes infections in humans, and the search for new therapeutic strategies for its treatment is essential. Objective. - The aim of this study was to evaluate the activity of seven naphthoquinones (beta-lapachone, beta-nor-lapachone, bromide-beta-lapachone, hydroxy-beta-lapachone, alpha-lapachone, alpha-nor-lapachone and axyloidone) on the growth of a fluconazole-resistant C. albicans oral clinical isolate and the effects of these compounds on the viability of mammalian cells, on yeast's morphogenesis, biofilm formation and cell wall mannoproteins availability. Results. - All the compounds were able to completely inhibit the yeast growth. beta-lapachone and alpha-norlapachone were the less cytotoxic compounds against L929 and RAW 264.7 cells. At IC50, beta-lapachone inhibited morphogenesis in 92%, while the treatment of yeast cells with alpha-nor-lapachone decreased yeast-to-hyphae transition in 42%. At 50 mu g/ml, beta-lapachone inhibited biofilm formation by 84%, whereas alpha-nor-lapachone reduced biofilm formation by 64%. The treatment of yeast cells with beta-lapachone decreased cell wall mannoproteins availability in 28.5%, while alpha-nor-lapachone was not able to interfere on this virulence factor. Taken together, data show that beta-lapachone and alpha-nor-lapachone exhibited in vitro cytotoxicity against a fluconazole-resistant C. albicans strain, thus demonstrating to be promising candidates to be used in the treatment of infections caused by this fungus. (C) 2018 Elsevier Masson SAS. All rights reserved.

BACKGROUND:Candidiasis is a major opportunistic fungal infection in humans. The low number of antifungal drugs available to treat Candida infections and the increasing incidence of multidrug resistant (MDR) strains point to an urgent need of identifying new therapeutic options. The role of salivary components can provide insights for the development of new methodologies of control. OBJECTIVE:The aim of this study was to evaluate the ability of histatin-5, a constitutive immunological peptide present in saliva, in reversing fungal MDR phenotype, using a resistant Saccharomyces cerevisiae strain as model of study. RESULTS:A total of 2.5μg and 5μg of histatin-5 revealed to be able to chemosensitize (to revert antifungal resistance) a MDR strain to fluconazole impairing its intrinsic resistance. The presence of histatin-5 decreased the strain growth when associated to fluconazole, and also assisted in the retention of rhodamine 6G within cell cytoplasm. The ATPase activity of Pdr5p, an ABC efflux transporter, was significantly reduced up to 65% within physiological concentration of the peptide. CONCLUSION:Results revealed that histatin-5 is able to revert MDR phenotype and may be considered a potential alternative MDR inhibitor. Since Pdr5p is homologous to Candida albicans CaCdr1p and CaCdr2p, data obtained might be extrapolated to these transporters, inferring that associating fluconazole and histatin-5 may be a useful tool to circumvent failure treatments of infections caused by Candida MDR strains.