In vitro evaluation of the efficacy of 8-hydroxyquinoline derivatives for the control of Phaeomoniella chlamydospora, the causative agent of Petri disease in grapevines.

AIM: This study evaluates the in vitro efficacy of 8-hydroxyquinoline (8HQ) derivatives in controlling the phytopathogenic fungus Phaeomoniella chlamydospora. METHODS AND RESULTS: The in vitro tests assessed the susceptibility to the minimum inhibitory concentration (MIC), checkerboard assay, mycelial growth (MG) inhibition, and EC50 determination. Among the seven agricultural fungicides tested, tebuconazole (TEB) displayed the lowest MIC, 1.01 µg mL-1, followed by captan (CAP), thiophanate methyl (TM), and mancozeb with MICs of 4.06, 5.46, and 10.62 µg mL-1, respectively. The 8HQ derivatives used in this study were clioquinol and PH 151 (PH) with MICs of 1.09 and 2.02 µg mL-1, respectively. PH associated with TEB and CAP showed synergism and inhibited 95.8% of MG at the highest dose. TEB inhibited 100% of MG at the three highest doses, while associated with PH exhibited the lowest EC50 (0.863 + 0.0381 µg mL-1). CONCLUSIONS: We concluded that the 8HQ derivatives tested controlled effectively the P. chlamydospora in vitro. PH associated with CAP and TEB exhibited a synergistic effect. The association between PH and TM was considered indifferent. IMPACT STATEMENT: This study expands the list of active ingredients tested against P. chlamydospora, with the PH 151 and clioquinol derivatives being tested for the first time. The in vitro efficacy and synergistic action with other fungicides suggest a potential use as a grapevine wound protectant. This association makes it possible to reduce doses and increase the potency of both drugs, reducing the risk of resistance development and harm to humans and the environment.

Drosophila melanogaster as a model of systemic dermatophytosis.

BACKGROUND: Dermatophytosis is one of the most common fungal infections worldwide. The distribution of dermatophytes varies across continents, but the genera Trichophyton and Microsporum have emerged as the main isolated agents in humans and animals. OBJECTIVES: To validate Drosophila melanogaster flies as a fast and feasible model to study dermatophytic infections. METHODS: Wild-type (WT) and Toll-deficient D. melanogaster flies were infected by Trichophyton rubrum, T. mentagrophytes, Microsporum canis and Nannizzia gypsea by pricking with a needle previously dipped in inoculum concentrations ranging from 103 to 108 colony-forming units/mL. Establishment of infection was confirmed by survival curves, histopathological analysis and fungal burden. Thereafter, flies were treated with terbinafine, itraconazole and clioquinol. RESULTS: WT flies were predominantly resistant to the infection, whereas Toll-deficient flies succumbed to the four dermatophyte genera tested. The antifungal drugs protected flies from the infection, except for N. gypsea whose survival curves did not differ from the untreated group. CONCLUSIONS: This pilot study confirms that D. melanogaster is a suitable model to study the virulence and antifungal drug efficacy in dermatophyte species.

Clioquinol and 8-hydroxyquinoline-5-sulfonamide derivatives damage the cell wall of Pythium insidiosum.

AIMS: To evaluate the antimicrobial activity and to determine the pharmacodynamic characteristics of three 8-hydroxyquinoline derivatives (8-HQs) against Pythium insidiosum, the causative agent of pythiosis. METHODS AND RESULTS: Antimicrobial activity was tested by broth microdilution and MTT assays. The antimicrobial mode of action was investigated using sorbitol protection assay, ergosterol binding assay, and scanning electron microscopy. Clioquinol, PH151, and PH153 were active against all isolates, with MIC values ranging from 0.25 to 2 µg ml-1. They also showed a time- and dose-dependent antimicrobial effect, damaging the P. insidiosum cell wall. CONCLUSIONS: Together, these results reinforce the potential of 8-HQs for developing new drugs to treat pythiosis.

The influence of the microwave oven on the production of solid culture medium and quality of microbial growth.

Numerous cultivation media currently exist, whether selective, non-selective, enrichment or identification. However, they all have a common goal, which is the growth of microorganisms; the constitution and quality of the culture medium must favor it. For this reason, an important factor that directly affects the quality of a culture medium is its production. Thus, this article investigated the use of a microwave oven in the production of Sabouraud dextrose agar (SDA), and the microbial inactivation compared to the autoclave in a microbiology laboratory. The quality of the medium, time exposure, and sterilization potential were performed using fungal strains of Candida spp., Cryptococcus spp., Microsporum spp., and Aspergillus spp. The results showed that the advantages of the use of a microwave oven for the preparation of SDA are practicality, speed, lower energy expense, pH, and constituents preservation of the culture medium, resulting in a richer growth compared to autoclaved SDA. The multivariate analysis of digital images allowed the detection of melanoidins (brownish tone of medium), which are responsible for the negative influence on the microorganisms growth. This research shows the use of the microwave oven as an efficient alternative for the production of the culture medium and maintaining their best quality.

In vitro antidermatophytic synergism of double and triple combination of clioquinol with ciclopirox and terbinafine.

BACKGROUND: Dermatophytoses are the most frequent fungal infections worldwide and there have been described clinical resistance to the commonly used antifungals. Clioquinol is an antimicrobial that had the oral formulations withdrawn from the market in the 70s due to the report of neurotoxicity and recently has been considered as an effective alternative for the treatment of dermatophytosis. OBJECTIVES: To evaluate the effect of the double and triple association between clioquinol with terbinafine and ciclopirox on clinical isolates of dermatophytes. The cytotoxicity of these associations on human leukocytes was also verified. METHODS: Checkerboard method was used to evaluate the interaction between antifungal agents. Time-kill assay was used to verify fungicidal action and evaluate the combination with greater effect for TRU47 isolate. Cell viability was assessed by loss of integrity of the leukocyte membrane in order to verify the toxicity. RESULTS: Synergistic interaction was observed in 42% of isolates when terbinafine was associated with clioquinol and in 50% of isolates when ciclopirox was associated with clioquinol. The triple association resulted in synergistic interaction for 75% of the isolates. Clioquinol + terbinafine and triple combination were more effective for TRU47 isolate, and the combinations exhibited a time-dependent fungicidal effect. Furthermore, the results of cell viability demonstrated that clioquinol and terbinafine combination is not cytotoxic to human leukocytes. CONCLUSIONS: Clioquinol in combination with antifungals in the treatment of dermatophytosis can be a therapeutic strategy to overcome problems related to resistance, action spectrum and toxicity of the antifungal drugs used in the clinic.

Influence of detergents and sodium hypochlorite on Yarrowia lipolytica biofilms in utensils used in industrial production of colonial cheese.

The formation of microbial biofilms in materials used in the industrial production of dairy may lead to deterioration of these foods. Yarrowia lipolytica biofilms are widely found in dairy products and can modify the final characteristics of these products. Thus, this study investigated the effectiveness of hygienization by detergents and sodium hypochlorite on the formation of Y. lipolytica biofilms in different utensils usually employed during industrial cheese production, like polypropylene, hoses, and nylon/polyethylene. The utensils were sanitized using solutions of mild and alkaline detergents, and sodium hypochlorite, according to the cheese industry Standard Operation Procedure. Results showed that in all coupons there was biofilm formation with Y. lipolytica isolates. The contact angle measurements were favored to promote the adhesion of the biofilm in the evaluated surfaces. Even after treatment with sanitizers, a significant survival rate of planktonic cells was observed in all coupons tested. These results indicate that Y. lipolytica biofilms show a significant ability to adhere to polypropylene, presenting an important impact on the quality of colonial cheese.

Microbial transformation of ambrisentan to its glycosides by Cunninghamella elegans.

The purpose of this paper is to describe the glycosylation of ambrisentan (AMB) by cultures of Cunninghamella elegans ATCC 9245. AMB is an endothelin receptor antagonist, which is used to treat pulmonary arterial hypertension. Filamentous fungi are morphologically complex and may exhibit different forms depending on the species and the nature of the culture medium. A biotransformation study was conducted to investigate the ability of C. elegans to metabolize AMB. Parameters were optimized by testing on different culture media and concentrations, pH, drug concentration, static and shaking conditions. Ambrisentan's metabolite, obtained after 240 h of incubation as a result of glycosylation pathway, was separated by HPLC and determined by high-resolution mass spectrometry. The method showed linearity over 300-1000 µg mL-1 (r = 0.998). Accuracy, precision, robustness and stability studies agree with international guidelines. Results are consistent in accordance with the principles of green chemistry as the experimental conditions had a low environmental impact, and used little solvent.

Antichemotactic and Antifungal Action of the Essential Oils from Cryptocarya aschersoniana, Schinus terebinthifolia, and Cinnamomum amoenum.

The purpose of this work was to determine the chemical composition and evaluate the antichemotactic, antioxidant, and antifungal activities of the essential oil obtained from the species Cryptocarya aschersoniana Mez, Cinnamomum amoenum (Ness & Mart.) Kosterm., and Schinus terebinthifolia Raddi, as well as the combination of C. aschersoniana essential oil and terbinafine against isolates of dermatophytes. Allo-aromadendrene, bicyclogermacrene, and germacrene B were identified as major compounds in essential oils. The essential oil of C. aschersoniana shown 100 % inhibitory effect on leukocyte migration at the concentration of 10 µg/mL while S. terebinthifolia oil presented 80.1 % inhibitory effect at the same concentration. Only S. terebinthifolia oil possessed free-radical-scavenging activity which indicates its antioxidant capacity. The essential oils were also tested against fungal isolates of dermatophyte species (Trichophyton rubrum, Trichophyton mentagrophytes, Microsporum canis and Microsporum gypseum), resulting in MIC ranging from 125 µg/mL to over 500 µg/mL. C. aschersoniana oil combined with terbinafine resulted in an additive interaction effect. In this case, the essential oil may act as a complement to conventional therapy for the topical treatment of superficial fungal infections, mainly because it is associated with an anti-inflammatory effect.

Genetic diversity and antifungal susceptibility of Fusarium isolates in onychomycosis.

Fusarium species have emerged as an important human pathogen in skin disease, onychomycosis, keratitis and invasive disease. Onychomycosis caused by Fusarium spp. The infection has been increasingly described in the immunocompetent and immunosuppressed hosts. Considering onychomycosis is a difficult to treat infection, and little is known about the genetic variability and susceptibility pattern of Fusarium spp., further studies are necessary to understand the pathogenesis and better to define the appropriate antifungal treatment for this infection. Accordingly, the objective of this study was to describe the in vitro susceptibility to different antifungal agents and the genetic diversity of 35 Fusarium isolated from patients with onychomycosis. Fusarium spp. were isolated predominantly from female Caucasians, and the most frequent anatomical location was the nail of the hallux. Results revealed that 25 (71.4%) of isolates belonged to the Fusarium solani species complex, followed by 10 (28.5%) isolates from the Fusarium oxysporum species complex. Noteworthy, the authors report the first case of Neocosmospora rubicola isolated from a patient with onychomycosis. Amphotericin B was the most effective antifungal agent against the majority of isolates (60%, MIC ≤4 µg/mL), followed by voriconazole (34.2%, MIC ≤4 µg/mL). In general, Fusarium species presented MIC values >64 µg/mL for fluconazole, itraconazole and terbinafine. Accurate pathogen identification, characterisation and susceptibility testing provide a better understanding of pathogenesis of Fusarium in onychomycosis.

Reversal of fluconazole resistance induced by a synergistic effect with Acca sellowiana in Candida glabrata strains.

CONTEXT: The increased incidence of non-albicans Candida (NAC) resistant to fluconazole (FLZ) makes it necessary to use new therapeutic alternatives. Acca sellowiana (O.berg) Burret (Myrtaceae) is a guava with several proven biological activities. The interaction with fluconazole can be a feasible alternative to overcome this resistance. OBJECTIVE: This study evaluates the in vitro antifungal activity of fractions obtained from the lyophilized aqueous extract of the leaves of A. sellowiana against resistant strains of NAC. MATERIALS AND METHODS: The antifungal activity of the fractions was evaluated at 500 µg/mL by microdilution method. Checkerboard assay was performed to determine the effect of the combination of the F2 fraction and antifungal at concentrations: MIC/4, MIC/2, MIC, MIC × 2 and MIC × 4. RESULTS: Candida glabrata showed the lowest MIC values (500-3.90 µg/mL) and the F2 active fraction was the most effective. The association of F2 with FLZ showed a strong synergistic effect (FICI ≤ 0.5) against 100% of C. glabrata resistant isolates. Moreover, the F2 active fraction has demonstrated that probably acts in the cell wall of these yeasts. There was no observed acute dermal toxicity of lyophilized aqueous extract of leaves of A. sellowiana on pig ear skin cells. DISCUSSION AND CONCLUSION: The interaction between substances present in the F2 active fraction is possibly responsible for the antifungal activity presented by this fraction. This study is unprecedented and suggests that the combination of F2 active fraction and FLZ might be used as an alternative treatment for mucocutaneus infections caused by C. glabrata resistant.

Synthesis and biological evaluation of hydrazone derivatives as antifungal agents.

Emerging yeasts are among the most prevalent causes of systemic infections with high mortality rates and there is an urgent need to develop specific, effective and non-toxic antifungal agents to respond to this issue. In this study 35 aldehydes, hydrazones and hydrazines were obtained and their antifungal activity was evaluated against Candida species (C. parapsilosis, C. tropicalis, C. krusei, C. albicans, C. glabrata and C. lusitaneae) and Trichosporon asahii, in an in vitro screening. The minimum inhibitory concentrations (MICs) of the active compounds in the screening was determined against 10 clinical isolates of C. parapsilosis and 10 of T. asahii. The compounds 4-pyridin-2-ylbenzaldehyde] (13a) and tert-butyl-(2Z)-2-(3,4,5-trihydroxybenzylidine)hydrazine carboxylate (7b) showed the most promising MIC values in the range of 16-32 µg/mL and 8-16 µg/mL, respectively. The compounds' action on the stability of the cell membrane and cell wall was evaluated, which suggested the action of the compounds on the fungal cell membrane. Cell viability of leukocytes and an alkaline comet assay were performed to evaluate the cytotoxicity. Compound 13a was not cytotoxic at the active concentrations. These results support the discovery of promising candidates for the development of new antifungal agents.

Chemical analysis and in vitro antiviral and antifungal activities of essential oils from Glechon spathulata and Glechon marifolia.

CONTEXT: Glechon spathulata Benth. and Glechon marifolia Benth. (Lamiaceae, Mentheae) are aromatic plants used in traditional medicine for the treatment of viral infections. OBJECTIVE: The chemical composition and antiviral and antifungal activities of Glechon spathulata and Glechon marifolia essential oils were investigated. MATERIALS AND METHODS: The oils were obtained by hydrodistillation and analyzed by GC-FID and GC-MS. Anti-herpes virus (HSV-1) activity was examined in Vero cells by yield reduction assay, in doses of 0.0095% v/v and 0.039% v/v, for G. spathulata and G. marifolia oil, respectively. Antifungal activity was carried by the broth microdilution method, in oil concentrations that ranged from 5.2 to 500 µg/mL. RESULTS: ß-Caryophyllene (14.2% and 32.2% for G. spathulata and G. marifolia, respectively) and bicyclogermacrene (17.1% and 16.5%, respectively) were the major components of both oils. At noncytotoxic concentrations of the essential oils, the viral titer was reduced by up to 2 log10 for KOS and VR-733 strains. The antifungal activity was observed against Trichophyton rubrum (MIC 10-83 µg/mL) and Epidermophyton floccosum (MIC 83-500 µg/mL). The oil of G. spathulata exhibited activity against the three strains tested (KOS, VR733, and 29-R), whereas G. marifolia oil was active against two strains, KOS and VR733. DISCUSSION AND CONCLUSION: The chemical composition for G. spathulata and G. marifolia essential oils is very similar. The oil of G. spathulata can be promising as a new antifungal agent against dermatophytes. The findings add important information to the biological activity of Glechon species essential oils, specifically its antiviral and antidermatophytic properties.

Antifungal activity of azoles, allylamines, and 8-hidroxiquinolines, alone and in combination, against Malassezia pachydermatis in vitro and in vivo.

Malassezia pachydermatis is often reported as the causative agent of dermatitis in dogs. This study aims to evaluate the in vitro and in vivo antifungal activity of azoles and terbinafine (TRB), alone and in combination with the 8-hydroxyquinoline derivatives (8-HQs) clioquinol (CQL), 8-hydroxyquinoline-5-(n-4-chlorophenyl)sulfonamide (PH151), and 8-hydroxyquinoline-5-(n-4-methoxyphenyl)sulfonamide (PH153), against 16 M. pachydermatis isolates. Susceptibility to the drugs was evaluated by in vitro broth microdilution and time-kill assays. The Toll-deficient Drosophila melanogaster fly model was used to assess the efficacy of drugs in vivo. In vitro tests showed that ketoconazole (KTZ) was the most active drug, followed by TRB and CQL. The combinations itraconazole (ITZ)+CQL and ITZ+PH151 resulted in the highest percentages of synergism and none of the combinations resulted in antagonism. TRB showed the highest survival rates after seven days of treatment of the flies, followed by CQL and ITZ, whereas the evaluation of fungal burden of dead flies showed a greater fungicidal effect of azoles when compared to the other drugs. Here we showed for the first time that CQL is effective against M. pachydermatis and potentially interesting for the treatment of malasseziosis.

Which amphetamine-type stimulants can be detected by oral fluid immunoassays?

INTRODUCTION: The use of oral fluid for monitoring drug consumption on roads has many advantages over conventional biological fluids; therefore, several immunoassays have been developed for this purpose. In this work, the ability of 3 commercial immunoassays to detect amphetamine-type stimulants (ATSs) in oral fluid was assessed. In addition, it was reviewed the main controlled ATSs available worldwide, as well as the oral fluid immunological screening tests that have been used for identifying ATSs in drivers. MATERIALS AND METHODS: The analytical specificity of amphetamine direct enzyme-linked immunosorbent assay (ELISA), methamphetamine direct ELISA (Immunalysis Corporation), and Oral-View saliva multidrug of abuse test (Alfa Scientific Designs) was evaluated using ATS-spiked oral fluid. Legislation and published articles that report the use of immunological screening tests to detect ATS consumption in conductors were reviewed, including the kit's technical information, project reports, police and drug databases. RESULTS AND DISCUSSION: Even at high concentrations, the tested assays were not able to detect methylphenidate, fenproporex, or diethylpropion, controlled ATSs legally marketed in many countries. CONCLUSIONS: This evidences the need to develop new kits that enable one to control the misuse of prescription ATSs on roads through oral fluid immunoassays.

Antifungal Activity and Stability of Fluconazole Emulsion Containing Ionic Liquids Explained by Intermolecular Interactions.

This research reports accelerated stability experiments, the evaluation of intermolecular interactions, and antifungal assays for fluconazole emulsions prepared using ultrasound (US) and magnetic stirring (MS) in the presence of ionic liquids derived from 1,n-(3-methylimidazolium-1-yl)alkane bromide ([CnMIM]Br; n = 12 or 16). The goals of the investigation are to quantify the stability, identify the forces that drive the formation and stability, and determine the antifungal activity of fluconazole-containing emulsions, and corroborate the data from our previous results that indicated that the emulsion based on [C16MIM]Br seemed to be more stable. In this study, accelerated stability experiments evidenced a considerable stability for the [C16MIM]Br emulsions at two temperatures (25 and 37 °C)­the instability index increased in the following order: US40% < US20% < MS. The 1H NMR data showed that the ILs interacts differently with medium-chain triglycerides (MCT). Two distinct interaction mechanisms were also observed for [C12MIM]Br and [C16MIM]Br with fluconazole, in which the latter formed more compact mixed aggregates than the former. The result was corroborated by diffusion data, which showed that ILs suffered a decrease in diffusion in the presence of fluconazole. The antifungal assay showed that emulsions containing ILs displayed superior activity compared with fluconazole alone. The emulsions also showed potent activity in inhibiting a resistant species (C. glabrata­CG34) to FLZ. All emulsions showed weak irritant potential in HET-CAM assay.

Antibacterial and synergistic activity of a new 8-hydroxyquinoline derivative against methicillin-resistant Staphylococcus aureus.

Aim: To evaluate the antibacterial and synergistic effect of a new 8-hydroxyquinoline derivative (PH176) against MRSA. Materials & methods: PH176 activity was determined by broth microdilution against 38 Staphylococcus aureus clinical isolates. The antibacterial and synergistic effects with oxacillin and nitroxoline were evaluated by time-kill assays to five MRSA isolates. Toxicity was evaluated by in vitro and ex vivo models. Results: The MIC50 and MIC90 of PH176 were 16 and 32 µg/ml, respectively. The PH176 and nitroxoline led to a reduction in colony count for four isolates and the combination of PH176 and oxacillin acted synergically for three isolates. Furthermore, PH176 was determined to be noncytotoxic/nonirritant. Conclusion: These results demonstrate that PH176 has revealed promising results to be a potential candidate to treat MRSA infections.

Antimicrobial and Toxicity Evaluation of Imidazolium-Based Dicationic Ionic Liquids with Dicarboxylate Anions.

Imidazolium-based dicationic ILs (DILs) presenting antimicrobial activity and relatively low toxicity are highly desirable and are envisioned for use in live tissue to prevent bacterial or fungal infections. In this context, we present here DILs with dicarboxylate anions [Cn(MIM)2[Cn(MIM)2][CO2-(CH2)mCO2], in which n = 4, 6, 8, and 10, and m = 0, 1, 2, 3, 4, and 5. The results showed that DILs with an alkyl chain spacer of ten carbons were active against yeasts and the bacterial strains tested. However, most of the DILs were cytotoxic and toxic at 1 mM. By contrast, DILs with alkyl chains possessing less than ten carbons were active against some specific Candidas and bacteria (mainly S. aureus), and they showed moderate cytotoxicity. The best activity against Gram-positive bacteria was observed for [C4(MIM)2][Pim] toward MRSA. For the DILs described herein, their level of toxicity against C. elegans was lower than that of most of the mono- and dicationic IL analogs with other anions. Our results showed that the presence of carboxylate anions reduces the toxicity of DILs compared to DILs containing halide anions, which is particularly significant to the means of designing biologically active compounds in antimicrobial formulations.

Human metabolite-derived alkylsuccinate/dilinoleate copolymers: from synthesis to application.

The advances in polymer chemistry have allowed the preparation of biomedical polymers using human metabolites as monomers that can hold unique properties beyond the required biodegradability and biocompatibility. Herein, we demonstrate the use of endogenous human metabolites (succinic and dilinoleic acids) as monomeric building blocks to develop a new series of renewable resource-based biodegradable and biocompatible copolyesters. The novel copolyesters were characterized in detail employing several standard techniques, namely 1H NMR, 13C NMR, and FTIR spectroscopy and SEC, followed by an in-depth thermomechanical and surface characterization of their resulting thin films (DSC, TGA, DMTA, tensile tests, AFM, and contact angle measurements). Also, their anti-fungal biofilm properties were assessed via an anti-fungal biofilm assay and the biological properties were evaluated in vitro using relevant human-derived cells (human mesenchymal stem cells and normal human dermal fibroblasts). These novel highly biocompatible polymers are simple and cheap to prepare, and their synthesis can be easily scaled-up. They presented good mechanical, thermal and anti-fungal biofilm properties while also promoting cell attachment and proliferation, outperforming well-known polymers used for biomedical applications (e.g. PVC, PLGA, and PCL). Moreover, they induced morphological changes in the cells, which were dependent on the structural characteristics of the polymers. In addition, the obtained physicochemical and biological properties can be design-tuned by the synthesis of homo- and -copolymers through the selection of the diol moiety (ES, PS, or BS) and by the addition of a co-monomer, DLA. Consequently, the copolyesters presented herein have high application potential as renewable and cost-effective biopolymers for various biomedical applications.

Influence of Monoterpenes in Biological Activities of Nectandra megapotamica (Spreng.) Mez Essential Oils.

Investigating the influence of seasonal variations on biological activities is important for pharmacological studies and metabolic engineering. Therefore, this study was conducted to determine the variation of the chemical composition of essential oils obtained from Nectandra megapotamica leaves, collected at different stages of plant development, as well as its influence on the biological activities. A total of 38 compounds were identified that accounted for 97⁻99.2% of the chemical composition of the oils. Major differences were observed in the monoterpenic fraction, representing 5.1% of the compounds identified in the productive rest phase to 37.1% in the blooming phase. Bicyclogermacrene and germacrene D were the predominant compounds identified in the oil of all collections. Furthermore, limonene, ß-pinene, and spathulenol were identified predominantly in the samples of blooming and fruiting phases. The oils exhibited significant antichemotactic activity and different effects in scavenging the radical 2,2-diphenyl-1-picrylhydrazyl. Variations were also observed in the antifungal activity, with the minimum inhibitory concentrations ranging from 125 to 500 µg/mL. These results demonstrate the influence of monoterpenes, primarily limonene, α-pinene, and ß-pinene, on the bioactivities of the oil. Studies investigating the variations in the chemical composition of essential oil may offer a strategy to produce a compound or a group of compounds of interest to industries with a specific pharmacological focus.

Structure-based design of δ-lactones for new antifungal drug development: susceptibility, mechanism of action, and toxicity.

Dermatophytes are the etiological agents of cutaneous mycoses, including the prevalent nail infections and athlete's foot. Candida spp. are opportunistic and emerging pathogens, causing superficial to deeper infections related to high mortality rates. As a consequence of prolonged application of antifungal drugs, the treatment failures combined with multidrug-resistance have become a serious problem in clinical practice. Therefore, novel alternative antifungals are required urgently. δ-Lactones have attracted great interest owing to their wide range of biological activity. This article describes the antifungal activity of synthetic δ-lactones against yeasts of the genus Candida spp. and dermatophytes (through the broth microdilution method), discusses the pathways by which the compounds exert this action (toward the fungal cell wall and/or membrane), and evaluates the toxicity to human leukocytes and chorioallantoic membrane (by the hen's egg test-chorioallantoic membrane). Two of the compounds in the series presented broader spectrum of antifungal activity, including against resistant fungal species. The mechanism of action was related to damage in the fungal cell wall and membrane, with specific target action dependent on the type of substituent present in the δ-lactone structure. The damage in the fungal cell was corroborated by electron microscopy images, which evidenced lysed and completely altered cells after in vitro treatment with δ-lactones. Toxicity was dose dependent for the viability of human leukocytes, but none of the compounds was mutagenic, genotoxic, or membrane irritant when evaluated at higher concentrations than MIC. In this way, δ-lactones constitute a class with excellent perspectives regarding their potential applications as antifungals.