Evaluation of Antifungal Efficacy in an Optimized Animal Model ofTrichophytonmentagrophytes-Dermatophytosis

Allosteric inhibition of tRNA synthetase Gln4 by N-pyrimidinyl-β-thiophenylacrylamides exerts highly selective antifungal activity

Candida species are among the most prevalent causes of systemic fungal infections, which account for ∼1.5 million annual fatalities. Here, we build on a compound screen that identified the molecule N-pyrimidinyl-β-thiophenylacrylamide (NP-BTA), which strongly inhibits Candida albicans growth. NP-BTA was hypothesized to target C. albicans glutaminyl-tRNA synthetase, Gln4. Here, we confirmed through in vitro amino-acylation assays NP-BTA is a potent inhibitor of Gln4, and we defined how NP-BTA arrests Gln4's transferase activity using co-crystallography. This analysis also uncovered Met496 as a critical residue for the compound's species-selective target engagement and potency. Structure-activity relationship (SAR) studies demonstrated the NP-BTA scaffold is subject to oxidative and non-oxidative metabolism, making it unsuitable for systemic administration. In a mouse dermatomycosis model, however, topical application of the compound provided significant therapeutic benefit. This work expands the repertoire of antifungal protein synthesis target mechanisms and provides a path to develop Gln4 inhibitors.

In vitro and In vivo study targeting the development of Unani Antidermatophytic Cream: Implication of Herbal Formulations in Treatment of Dermatophytosis

Panwad (Cassia tora L.), Sarshaf (Brassica nigra L.) and Kunjad (Sesamum indicum L.) have been used in the treatment of ringworm infection since ancient times and are documented in classical literature of Unani Medicine. These plant drugs give promising results when used topically in the form of paste (zimad). Hence, the development and evaluation of a cream containing extracts of Tukhm-e-Panwad (Cassia tora L.), Sarshaf (Brassica nigra L.), and Kunjad (Sesamum indicum L.) was carried out to get better efficacy of the drugs. A total of 16 batches (F1-F16) of cream were prepared by adding varying concentrations of hydro-alcoholic extract of the drugs (20%, 40% and 50%) in water removable bases, and three batches were selected as final batches (F4-20%, F6-40% and F16-50%). In vitro antidermatophytic activity was conducted to optimize MIC against dermatophytosis-causing fungi. Dermal irritation of the prepared cream was determined in New Zealand Albino Rabbits. In vivo testing of the different concentrations of the prepared cream (20%, 40%, and 50%) was also carried out using Wistar rats to assess the antidermatophytic activity. Final batches showed good results in all the tested parameters and significant in vitro and in vivo antifungal activity in a dose-dependent manner. No microbial growth was seen in the prepared formulation. The study revealed significant antidermatophytic activity of the prepared cream against dermatophytosis-causing fungi. Hence, it can be concluded that the prepared cream can be an alternative topical agent with safe and effective antifungal activity for treating dermatophytosis.

Development, Optimization, and In Vitro/In Vivo Evaluation of Azelaic Acid Transethosomal Gel for Antidermatophyte Activity

Treatment of dermatophytosis is quite challenging. This work aims to investigate the antidermatophyte action of Azelaic acid (AzA) and evaluate its efficacy upon entrapment into transethosomes (TEs) and incorporation into a gel to enhance its application. Optimization of formulation variables of TEs was carried out after preparation using the thin film hydration technique. The antidermatophyte activity of AzA-TEs was first evaluated in vitro. In addition, two guinea pig infection models with Trichophyton (T.) mentagrophytes and Microsporum (M.) canis were established for the in vivo assessment. The optimized formula showed a mean particle size of 219.8 ± 4.7 nm and a zeta potential of -36.5 ± 0.73 mV, while the entrapment efficiency value was 81.9 ± 1.4%. Moreover, the ex vivo permeation study showed enhanced skin penetration for the AzA-TEs (3056 µg/cm²) compared to the free AzA (590 µg/cm²) after 48 h. AzA-TEs induced a greater inhibition in vitro on the tested dermatophyte species than free AzA (MIC₉₀ was 0.01% vs. 0.32% for T. rubrum and 0.032% for T. mentagrophytes and M. canis vs. 0.56%). The mycological cure rate was improved in all treated groups, specially for our optimized AzA-TEs formula in the T. mentagrophytes model, in which it reached 83% in this treated group, while it was 66.76% in the itraconazole and free AzA treated groups. Significant (p < 0.05) lower scores of erythema, scales, and alopecia were observed in the treated groups in comparison with the untreated control and plain groups. In essence, the TEs could be a promising carrier for AzA delivery into deeper skin layers with enhanced antidermatophyte activity.

Antifungal activity of alexidine dihydrochloride in a novel diabetic mouse model of dermatophytosis

Dermatophytosis is one of the most prevalent fungal infections and a major public health problem worldwide. Recent years have seen a change in the epidemiological patterns of infecting fungi, corresponding to an alarming rise in the prevalence of drug-recalcitrant dermatophyte infections. In patients with diabetes mellitus, dermatophytosis is more severe and recurrent. The potency of promising new antifungal drugs in the pipeline must be expanded to include dermatophytosis. To facilitate this effort, we established a clinically pertinent mouse model of dermatophyte infections, in which diabetic mice were infected with Trichophyton mentagrophytes on abraded skin. The diabetic mouse model was optimized as a simple and robust system for simulating dermatophytoses in diabetic patients. The outcome of infection was measured using clinical and mycological parameters. Infected mice with fungal lesions were treated with oral and topical formulations of terbinafine or topical administration of the FDA-approved and repurposed pan-antifungal drug alexidine dihydrochloride (AXD). In this model, AXD was found to be highly effective, with outcomes comparable to those of the standard of care drug terbinafine.

Olorofim Effectively Eradicates Dermatophytes In Vitro and In Vivo

Superficial fungal infections are prevalent worldwide, with dermatophytes as the most common cause. Various antifungal agents including azoles and allylamines are commonly used to treat dermatophytosis. However, their overuse has yielded drug-resistant strains, calling for the development of novel antimycotic compounds. Olorofim is a newly developed antifungal compound that targets pyrimidine biosynthesis in molds. The purpose of this study was to determine the in vitro and in vivo antifungal effects of olorofim against common dermatophytes. The in vitro activity of olorofim against dermatophytes was assessed by microtiter broth dilution method. Bioinformatic analysis of olorofim binding to dihydroorotate dehydrogenase (DHODH) of dermatophytes was also performed, using Aspergillus fumigatus DHODH as a template. The in vivo efficacy of the drug was investigated, using a guinea pig model, experimentally infected with Microsporum gypseum. Microtiter assays confirmed the high in vitro sensitivity of dermatophytes to olorofim (MIC = 0.015-0.06 mg/liter). Amino acid sequence analysis indicated that DHODH is highly conserved among dermatophytes. The critical residues, in dermatophytes, involved in olorofim binding were similar to their counterparts in A. fumigatus DHODH, which explains their susceptibility to olorofim. Typical skin lesions of dermatophyte infection were observed in the guinea pig model at 7 days postinoculation. Following 1 week of daily topical administration of olorofim, similar to the clotrimazole group, the skin lesions were resolved and normal hair growth patterns appeared. In light of the in vitro and in vivo activity of olorofim against dermatophytes, this novel agent may be considered as a treatment of choice against dermatophytosis.

Fabrication and Characterization of Polymeric Pharmaceutical Emulgel Co-Loaded with Eugenol and Linalool for the Treatment of Trichophyton rubrum Infections

Trichophyton rubrum (T. rubrum) is the main cause of chronic dermatophytosis which is highly prevalent worldwide. This study was aimed to fabricate and characterize polymeric emulgel of eugenol and linalool for the treatment of T. rubrum infections. Using the slow emulsification method, the emulgel was prepared and characterized for thermodynamic stability, pH analysis, viscosity, spreadability, swelling behavior, %drug content, surface morphology, globules size, polydispersity index, surface charge (mV), thermal behavior, in vitro drug release and XRD studies. Biological activities of emulgel were conducted against T. rubrum in vitro and in vivo. Results indicated that emulgel formulations were thermodynamically stable. The pH of the formulations was within an acceptable range for skin. The viscosity and spreadability were optimum for the better patient compliance. The swelling behavior was 111.10 ± 1.25% after 90 min. The drug content was within the official pharmacopeia limit i.e., 100 ± 10%. The surface morphology revealed by scanning electron microscopy showed a spherical-shaped structure with characteristic larger cracks and wrinkles. The droplet size, PDI, and surface charge of the optimized emulgel were 888.45 ± 8.78 nm, 0.44 and -20.30 mV, respectively. The emulgel released 84.32% of eugenol and 76.93% of linalool after 12 h. There was complete disappearance of the diffraction peaks corresponding to the drugs after XRD analysis. In rabbits, the infection was safely and completely recovered after 12 days and the emulgel produced significant effects (p < 0.05) similar to the standard product Clotrim^®. It is concluded that the eugenol-linalool emulgel best described all its physical properties and can be applied topically for the treatment of T. rubrum infections.

RETRACTED: Preparation, characterizations and evaluation of antifungal activity of eugenol-linalool emulgel against anthrophilic dermatophytic trichophyton rubrum

This article has been retracted, and the online PDF has been watermarked “RETRACTION”. The retraction notice is available at https://doi.org/10.3233/MGC-219901.

Plant-derived isoquinoline alkaloids that target ergosterol biosynthesis discovered by using a novel antifungal screening tool

The ergosterol pathway is a prime antifungal target as it is required for fungal survival, yet is not involved in human homeostasis. Methods to study the ergosterol pathway, however, are often time-consuming. The minimum inhibitory concentration (MIC) assay is a simple research tool that determines the lowest concentration at which a novel antimicrobial is active in vitro with limited scope to determine the mechanism of action for a drug. In this study, we show that by adding hydrogen peroxide, an oxidative stressor, or glutathione (GSH), an antioxidant, to modify a commonly performed MIC assay allowed us to screen selectively for new antifungal drugs that target ergosterol biosynthesis in fungi. A human pathogen and dermatophyte, Microsporum gypseum, was used as a test organism. When exposed to ergosterol targeting drugs, the hydrogen peroxide treatment significantly decreased fungal survival by reducing ergosterol in the cell wall, whereas GSH increased survival of M. gypseum. Further, by performing a series of experiments with M. gypseum and Trichophyton rubrum, it was determined that the oxidative stress from hydrogen peroxide causes cell death at different developmental stages based on fungal species. These findings allow us to describe a simple, high-throughput method for simultaneously screening new antifungal drugs for activity and effects on the ergosterol pathway. By using this tool, two isoquinoline alkaloids were discovered to be potent inhibitors of ergosterol biosynthesis in vitro by reducing the amount of ergosterol without affecting the expression of 1,3-β-glucan. Both compounds also significantly reduced the severity of acanthosis, hyperkeratosis, spongiosis and dermal edema in vivo.

Nanoencapsulated hypericin in P-123 associated with photodynamic therapy for the treatment of dermatophytosis

The antifungal application of photodynamic therapy (PDT) has been widely explored. According to superficial nature of tinea capitis and the facility of application of light sources, the use of nanoencapsulated hypericin in P-123 associated with PDT (P123-Hy-PDT) has been a poweful tool to treat this pathology. Thus, the aim of this study was to evaluate the efficiency of P123-Hy-PDT against planktonic cells and in a murine model of dermatophytosis caused by Microsporum canis. In vitro antifungal susceptibility and in vivo efficiency tests were performed, including a skin toxicity assay, analysis of clinical signs by evaluating score, and photoacoustic spectroscopy. In addition, tissue analyses by histopathology and levels of pro-inflammatory cytokines, such as quantitative and qualitative antifungal assays, were employed. The in vitro assays demonstrated antifungal susceptibility with 6.25 and 12.5 μmol/L P123-Hy-PDI; these experiments are the first that have used this treatment of animals. P123-Hyp-mediated PDT showed neither skin nor biochemical alteration in vivo; it was safe for dermatophytosis treatment. Additionally, the treatment revealed rapid improvement in clinical signs at the site of infection after only three treatment sessions, with a clinical score confirmed by photoacoustic spectroscopy. The mycological reduction occurred after six treatment sessions, with a statistically significant decrease compared with untreated infected animals. These findings showed that P123-Hy-PDT restored tissue damage caused by infection, a phenomenon confirmed by histopathological analysis and proinflammatory cytokine levels. Our results reveal for the first time that P123-Hy-PDT is a promising treatment for tinea capitis and tinea corporis caused by M. canis, because it showed rapid clinical improvement and mycological reduction without causing toxicity.

In vitro models of dermatophyte infection to investigate epidermal barrier alterations

Fungal infections of the skin, known as dermatophytoses, are initiated at the epidermal barrier and lead to dysfunctions of the stratum corneum and cornified skin appendages. Dermatophytosis affects a significant part of the human population and, despite the availability of effective treatments, its prevalence is still increasing. Numerous dermatophyte species are able to induce lesions in both animals and humans, with different clinical pictures and host inflammatory responses. The understanding of the infectious process and of tissue responses has been impeded by discrepancies between observations in vivo or in research models. Indeed, cells cultured as monolayers do not undergo the keratinization process required to study the adherence and invasion of dermatophytes. Animal models lack relevance to study human dermatophytosis because of species-specific differences in the development of lesions and inflammatory responses. This review focuses on the recent development of cultured human skin equivalents, which partly overcomes those limitations and allows improved understanding of the pathogenesis of dermatophytosis in human being, especially the impacts of infection on epidermal barrier integrity.

[Antidermatophyte Activity of the Gentiopicroside-Rich n-Butanol Fraction from Gentiana siphonantha Maxim. Root on a Guinea Pig Model of Dermatophytosis]

BACKGROUND

Gentiana siphonantha Maxim. is a traditional medicine for the treatment of rheumarthritis, icterepatitis, pain and hypertension; it is rich in gentiopicroside with anti-inflammatory, antibacterial, and free radical-scavenging activities. This study was to evaluate the antidermatophyte activity of G. siphonantha on a guinea pig model in vitro and in vivo. Material andMethods: The antidermatophyte activities of 10 plants were tested by the broth microdilution method. Fractions and an extract of G. siphonantha were tested against Trichophyton mentagrophytes by the disc diffusion method. The morphological changes of T. mentagrophytes were observed. Component analysis of the n-butanol (n-BuOH) fraction was made by HPLC. Finally, the antifungal activity in an in vivo guinea pig model of dermatophytosis was examined.

RESULTS

G. siphonantha had strong antidermatophyte activity with MIC50 values of 32-64 μg/mL. The n-BuOH fraction of G. siphonantha showed the most potent activity compared to the other fractions. After being exposed to the n-BuOH fraction at 80 and 160 μg/mL, the hyphae were distorted and collapsed. Gentiopicroside is the main active ingredient in the n-BuOH fraction of G. siphonantha. The lesion scores of the guinea pig model of dermatophytosis significantly declined in the 10% and 30% extract and positive control groups in comparison with the untreated control group. Periodic acid-Schiff and hematoxylin/eosin staining displayed similar results.

CONCLUSION

The n-BuOH fraction of G. siphonantha demonstrated antidermatophyte efficacy in experimental dermatophytosis.

In vivo antifungal activity of dipyrithione against Trichophyton rubrum on guinea pig dermatophytosis models

The treatment of dermatophytosis has improved considerably over the past several decades following the introduction of the oral antifungals such as azoles and amphotericin B. However, these drugs have had limited success because the treated fungi often develop drug resistance, resulting in recurrence when applied in various topical formulations. Thus, there are constant needs for new topical agents that are effective against dermatophytosis. Dipyrithione is an attractive candidate to become an antifungal agent due to its broad spectrum of antimicrobial activities. In this study, we determined that dipyrithione could potently inhibit the growth of Trichophyton rubrum, which is the most common cause of dermatophytosis. The MIC₅₀ value of dipyrithione against T. rubrum was measured as 6.03 μM, as compared with miconazole (MIC₅₀: 1.38 μM). Additionally, the compound caused morphological changes in the fungi, which was examined using the morphological interference assay. The in vivo experiment further revealed that dipyrithione had a healing effect on the skin of guinea pigs infected with T. rubrum. Our studies have demonstrated that dipyrithione had a potent antifungal activity in vitro and in vivo, suggesting that it could be formulated as a potential antifungal lead compound in search for novel therapeutic agents against dermatophytosis.

Landscape of long non-coding RNAs in Trichophyton mentagrophytes-induced rabbit dermatophytosis lesional skin and normal skin

Emerging evidences suggest that long non-coding RNAs (lncRNAs) play important role in disease development. However, the role of rabbit lncRNAs in the pathogenesis of dermatophytosis remains elusive. The present study aimed to study and characterize lncRNA transcriptome in 8 T. mentagrophytes-induced female rabbit dermatophytosis lesional (TM) and 4 normal saline-infected (NS) skin biopsies using RNAseq. We identified 5883 lncRNAs in 12 strand-specific RNA-seq libraries and found 64 differentially expressed lncRNAs (q < 0.05) in TM relative to NS. As in other mammalian counterparts, rabbit lncRNAs were distributed in all chromosomes except the Y chromosome and were generally smaller in size and fewer in exon numbers compared to protein coding genes. Next, co-expression analysis revealed that 107 pairs between 32 DE lncRNAs and 96 protein coding genes showed a highly correlated expression (|r| > 0.8). Moreover, miRPara analysis of the lncRNAs revealed 173 lncRNAs with precursor sequences for 9561 probable novel miRNAs. Finally, q-PCR results validated the RNA-seq results with eight randomly selected lncRNAs. To the best of our knowledge, this is the first report on rabbit lncRNAs, and our results highlighted the potential role of lncRNAs in the pathogenesis of dermatophytosis.

In Vivo Evaluation of Galla chinensis Solution in the Topical Treatment of Dermatophytosis

Aim

Dermatophytosis is one of the main fungal diseases in humans and animals all over the world. Galla chinensis, a traditional medicine, has various pharmacological effects. The goal of this study was to evaluate the treatment effect of Galla chinensis solution (GCS) on dermatophytosis-infected dogs (Microsporum canis, Microsporum gypseum, and Trichophyton mentagrophytes, resp.).

Methods

The treatment effects of GCS were evaluated by mycological cure rates and clinical score comprised of three indices, including inflammation, hair loss, and lesion scale.

Results

The results showed that, in the three models of dermatophytosis, GCS significantly (P < 0.05) improved skin lesions and fungal eradication. GCS (10% and 5%) had higher efficacy compared to the positive control (Tujingpi Tincture). The fungal eradication efficacy exceeds 85% after treatment with GCS (10%, 5%, and 2.5%) on day 14.

Conclusion

The GCS has antidermatophytosis effect in dogs, which may be a candidate drug for the treatment of dermatophytosis.

Pathogenicity of Conidiobolus coronatus and Fusarium solani in mouse models

To study the pathogenicity of Conidiobolus coronatus (C. coronatus) and Fusarium solani (F. solani) in animal models. Immunocompromised mice were treated with cyclophosphamide and prednisolone via intraperitoneal injection before and after inoculation. According to pathogenic characteristics of different fungi, C. coronatus was used to infect mice via intravenous inoculation, intraperitoneal inoculation, gastrointestinal infusion and intradermal inoculation methods. And F. solani was used to infect mice by inoculation via the abraded or normal skin. In the group of immunocompromised mice, C. coronatus was isolated from the lung tissues of one mouse on day 7 and another on day 10 respectively. The corresponding histopathology revealed infiltration of local inflammatory cells in the lung tissue. Pathogenic lesions were observed in all normal and immunocompromised mice infected with F. solani via abraded skin. The lesions in the immunocompromised mice were more severe and persisted longer than those in the normal mice. Moreover, hyphae were mostly observed in the histopathological examination and fungal culture from the immunocompromised mouse. The pathogenicity of C. coronatus was relatively weak as it did not induce local infections and did not disseminate the disease in immunocompetent and immunocompromised mice. Therefore, F. solani is a type of opportunistic pathogenic fungus, and abraded skin is one of the causative routes of infection.

In vivo anti-Trichophyton Activities of Seed Oil Obtained from Caraganakorshinskii Kom

AIM

The objective of this study was to evaluate the effects of seed oil of Caragana korshinskii Kom. against Trichophyton mentagrophytes on an in vivo guinea pig model of dermatophytosis.

METHODS

The skin of albino guinea pigs was infected with T. mentagrophytes, and the animals were divided into five groups: negative control (NC group), positive control (PC group), vehicle control, CK50% group (received topical 50% seed oil of C.korshinskii), and CK100% group (received topical 100% seed oil of C.korshinskii). Evaluation of clinical efficacy was performed 72 h after the completion of a 10-day treatment regimen. Skin biopsy samples were processed for histopathological examination.

RESULTS

The infected untreated control guinea pigs showed patches of hair loss and ulcerated or scaly skin. Lower clinical scores indicate improved efficacy compared with NC. The lesion scores significantly declined in the CK50%, CK100%, and PC groups in comparison with the NC group. The CK50% group (45.31%) and the CK100% group (75%) showed clinical efficacy compared with the PC group (78.13%). In addition, no fungal elements, inflammation, or tissue destruction was observed in any of the PAS-stained sections of the infected skin in the groups treated with CK100% or 1% terbinafine.

CONCLUSION

Seed oil of C.korshinskii demonstrated high antifungal efficacy in experimental dermatophytosis.

VT-1161 dosed once daily or once weekly exhibits potent efficacy in treatment of dermatophytosis in a guinea pig model

Current therapies used to treat dermatophytoses such as onychomycosis are effective but display room for improvement in efficacy, safety, and convenience of dosing. We report here that the investigational agent VT-1161 displays potent in vitro antifungal activity against dermatophytes, with MIC values in the range of ≤0.016 to 0.5 μg/ml. In pharmacokinetic studies supporting testing in a guinea pig model of dermatophytosis, VT-1161 plasma concentrations following single oral doses were dose proportional and persisted at or above the MIC values for at least 48 h, indicating potential in vivo efficacy with once-daily and possibly once-weekly dosing. Subsequently, in a guinea pig dermatophytosis model utilizing Trichophyton mentagrophytes and at oral doses of 5, 10, or 25 mg/kg of body weight once daily or 70 mg/kg once weekly, VT-1161 was statistically superior to untreated controls in fungal burden reduction (P < 0.001) and improvement in clinical scores (P < 0.001). The efficacy profile of VT-1161 was equivalent to those for doses and regimens of itraconazole and terbinafine except that VT-1161 was superior to itraconazole when each drug was dosed once weekly (P < 0.05). VT-1161 was distributed into skin and hair, with plasma and tissue concentrations in all treatment and regimen groups ranging from 0.8 to 40 μg/ml (or μg/g), at or above the MIC against the isolate used in the model (0.5 μg/ml). These data strongly support the clinical development of VT-1161 for the oral treatment of onychomycosis using either once-daily or once-weekly dosing regimens.

Metalloprotease genes of Trichophyton mentagrophytes are important for pathogenicity

Metalloproteases (Mep) of the M36 family are important virulence factors for the host invasion by the dermatophyte Trichophyton mentagrophytes. Dermatophytes secrete keratinase to degrade human and animal keratin and invade the skin. In previous studies, primers designed from the MEP gene sequences of Aspergillus fumigatus and A. oryzae were used to amplify the MEP genes from T. mentagrophytes, and the five MEP genes (MEP1-MEP5) were expressed. Differences in the expression of these five MEP genes in different dermatophytes were observed in an in vitro protein induction study, indicating their different functions and proteolytic abilities. However, specific pathogenic functions and mechanisms of each of the metalloproteases, as well as differences in their proteolytic activities, remain uncertain. In the current study, Agrobacterium tumefaciens-mediated transformation (ATMT) was used to successfully transform five MEP genes, resulting in five MEP mutant strains. MEP3 showed strongest proteolytic activity, hair biodegradation ability, and animal pathogenicity among the mutant strains. The MEP4 and MEP5 mutants were the least pathogenic through the above tests. Therefore, we hypothesize that the MEP4 and MEP5 genes are most likely to significantly affect the pathogenicity of T. mentagrophytes.

Luliconazole for the treatment of fungal infections: an evidence-based review

Luliconazole is an imidazole antifungal agent with a unique structure, as the imidazole moiety is incorporated into the ketene dithioacetate structure. Luliconazole is the R-enantiomer, and has more potent antifungal activity than lanoconazole, which is a racemic mixture. In this review, we summarize the in vitro data, animal studies, and clinical trial data relating to the use of topical luliconazole. Preclinical studies have demonstrated excellent activity against dermatophytes. Further, in vitro/in vivo studies have also shown favorable activity against Candida albicans, Malassezia spp., and Aspergillus fumigatus. Luliconazole, although belonging to the azole group, has strong fungicidal activity against Trichophyton spp., similar to that of terbinafine. The strong clinical antifungal activity of luliconazole is possibly attributable to a combination of strong in vitro antifungal activity and favorable pharmacokinetic properties in the skin. Clinical trials have demonstrated its superiority over placebo in dermatophytosis, and its antifungal activity to be at par or even better than that of terbinafine. Application of luliconazole 1% cream once daily is effective even in short-term use (one week for tinea corporis/cruris and 2 weeks for tinea pedis). A Phase I/IIa study has shown excellent local tolerability and a lack of systemic side effects with use of topical luliconazole solution for onychomycosis. Further studies to evaluate its efficacy in onychomycosis are underway. Luliconazole 1% cream was approved in Japan in 2005 for the treatment of tinea infections. It has recently been approved by US Food and Drug Administration for the treatment of interdigital tinea pedis, tinea cruris, and tinea corporis. Topical luliconazole has a favorable safety profile, with only mild application site reactions reported occasionally.

Design and optimization of highly-selective fungal CYP51 inhibitors

While the orally-active azoles such as voriconazole and itraconazole are effective antifungal agents, they potently inhibit a broad range of off-target human cytochrome P450 enzymes (CYPs) leading to various safety issues (e.g., drug-drug interactions, liver toxicity). Herein, we describe rationally-designed, broad-spectrum antifungal agents that are more selective for the target fungal enzyme, CYP51, than related human CYP enzymes such as CYP3A4. Using proprietary methodology, the triazole metal-binding group found in current clinical agents was replaced with novel, less avid metal-binding groups in concert with potency-enhancing molecular scaffold modifications. This process produced a unique series of fungal CYP51-selective inhibitors that included the oral antifungal 7d (VT-1161), now in Phase 2 clinical trials. This series exhibits excellent potency against key yeast and dermatophyte strains. The chemical methodology described is potentially applicable to the design of new and more effective metalloenzyme inhibitor treatments for a broad array of diseases.

The natural diyne-furan fatty acid EV-086 is an inhibitor of fungal delta-9 fatty acid desaturation with efficacy in a model of skin dermatophytosis

Human fungal infections represent a therapeutic challenge. Although effective strategies for treatment are available, resistance is spreading, and many therapies have unacceptable side effects. A clear need for novel antifungal targets and molecules is thus emerging. Here, we present the identification and characterization of the plant-derived diyne-furan fatty acid EV-086 as a novel antifungal compound. EV-086 has potent and broad-spectrum activity in vitro against Candida, Aspergillus, and Trichophyton spp., whereas activities against bacteria and human cell lines are very low. Chemical-genetic profiling of Saccharomyces cerevisiae deletion mutants identified lipid metabolic processes and organelle organization and biogenesis as targets of EV-086. Pathway modeling suggested that EV-086 inhibits delta-9 fatty acid desaturation, an essential process in S. cerevisiae, depending on the delta-9 fatty acid desaturase OLE1. Delta-9 unsaturated fatty acids-but not saturated fatty acids-antagonized the EV-086-mediated growth inhibition, and transcription of the OLE1 gene was strongly upregulated in the presence of EV-086. EV-086 increased the ratio of saturated to unsaturated free fatty acids and phosphatidylethanolamine fatty acyl chains, respectively. Furthermore, EV-086 was rapidly taken up into the lipid fraction of the cell and incorporated into phospholipids. Together, these findings demonstrate that EV-086 is an inhibitor of delta-9 fatty acid desaturation and that the mechanism of inhibition might involve an EV-086-phospholipid. Finally, EV-086 showed efficacy in a guinea pig skin dermatophytosis model of topical Trichophyton infection, which demonstrates that delta-9 fatty acid desaturation is a valid antifungal target, at least for dermatophytoses.

Preparation and evaluation of antifungal efficacy of griseofulvin loaded deformable membrane vesicles in optimized guinea pig model of Microsporum canis--dermatophytosis

The present study is aimed at the encapsulation of griseofulvin in the deformable membrane vesicles (DMVs) for dermal delivery. Presently, griseofulvin is available only in conventional oral dosage forms that suffer from the issues of poor and highly variable bioavailability, numerous systemic side effects and long duration of treatment. Multi-lamellar drug-loaded DMVs of griseofulvin (Indian Patent Application 208/DEL/2009) were prepared by thin-film hydration method and were optimized for type and concentration of edge activator (EA). The optimized formulation was evaluated for vesicular shape, size, drug entrapment efficiency, drug content, pH, stability, spreadability, ex vivo skin permeation, dermatokinetics, skin sensitivity, in vitro antifungal assay and in vivo antifungal activity against Microsporum canis using guinea pig model for dermatophytosis. The optimized DMVs illustrated remarkably higher drug permeation and skin retention when compared with liposomes. A complete clinical and mycological cure was observed in animals treated with topical griseofulvin formulation in 10 days. The formulation was observed to be non-sensitizing, histopathologically safe, and stable at 5±3 °C, 25±2 °C and 40±2 °C for a period of six months. The results indicated that the topical formulation of DMVs of griseofulvin could be utilized as an alternative to reduce the encumbrance of conventional oral formulations.

Dermatophyte-host relationship of a murine model of experimental invasive dermatophytosis

Recognizing the invasive potential of the dermatophytes and understanding the mechanisms involved in this process will help with disease diagnosis and with developing an appropriate treatment plan. In this report, we present the histopathological, microbiological and immunological features of a model of invasive dermatophytosis that is induced by subcutaneous infection of Trichophyton mentagrophytes in healthy adult Swiss mice. Using this model, we observed that the fungus rapidly spreads to the popliteal lymph nodes, spleen, liver and kidneys. Similar to the human disease, the lymph nodes were the most severely affected sites. The fungal infection evoked acute inflammation followed by a granulomatous reaction in the mice, which is similar to what is observed in patients. The mice were able to mount a Th1-polarized immune response and displayed IL-10-mediated immune regulation. We believe that the model described here will provide valuable information regarding the dermatophyte-host relationship and will yield new perspective for a better understanding of the immunological and pathological aspects of invasive dermatophytosis.

Animal model of dermatophytosis

Dermatophytosis is superficial fungal infection caused by dermatophytes that invade the keratinized tissue of humans and animals. Lesions from dermatophytosis exhibit an inflammatory reaction induced to eliminate the invading fungi by using the host's normal immune function. Many scientists have attempted to establish an experimental animal model to elucidate the pathogenesis of human dermatophytosis and evaluate drug efficacy. However, current animal models have several issues. In the present paper, we surveyed reports about the methodology of the dermatophytosis animal model for tinea corporis, tinea pedis, and tinea unguium and discussed future prospects.

Antifungal activities of Astragalus verus Olivier. against Trichophyton verrucosum on in vitro and in vivo guinea pig model of dermatophytosis

Astragalus verus Olivier, Fabaceae has been used against ringworm in Kurdish ethnomedicine throughout millennia. The objective of this study was to evaluate the effects of A. verus extracts against Trichophyton verrucosum on in vitro and in vivo guinea pig model of dermatophytosis. The skin of albino guinea pigs was infected with T. verrucosum (1.0×10(7) conidia) and animals were divided into five groups (n=5 for each): negative control (NC), received a vehicle; positive control (PC), received topical terbinafine 1.0% and three other groups: AE10%, AE20% and AE40% which received topical 10%, 20% and 40% aqueous extract of A. verus, respectively. Evaluation of clinical efficacy was performed 72h after completion of a 7-day treatment regimen. Higher significant antifungal activities were observed in aqueous extract in the concentration 320 mg ml(-1) compared with acetone and methanol extracts. The aqueous extract showed minimum inhibitory concentration at 160 mg ml(-1) . Lower clinical scores indicate improved efficacy compared with NC. The lesion scores significantly declined in AE20%, AE40% and PC groups in comparison with NC group. The lesion scores in AE10% and AE20% groups were significantly higher than that of PC group. The AE10% group (18.3%) and AE20% group (39.43%) and AE40% group (66.19%) showed clinical efficacies compared with PC group (76.05%). In conclusion, aqueous extract showed promising antidermatophytic activity.

Topical Treatment of Dermatophytic Lesion on Mice (Mus musculus) Model

Antidermatophytic potential of three weed plants viz. Tridax procumbens L., Capparis decidua (forsk) Edgew and Lantana camara L. were explored and experimentally induced dermatophytic lesion was topically treated in mice. Microbroth dilution method was carried out for determination of MIC and MFC of different extracts of selected plants. In animal studies, mice were experimentally inoculated with Trichophyton mentagrophytes and infected animals were topically treated with 5 mg/g terbinafine and two concentrations, i.e., 5 and 10 mg/g of test extract ointment. Complete recovery from the infection was observed on 12th day of treatment for reference drug terbinafine (5 mg/g) and 10 mg/g concentration of test extract ointment whereas 5 mg/g concentration of test extract ointment showed complete cure on 16th day of treatment. Fungal burden was also calculated by culturing skin scrapings from infected animals of different groups. Test extract ointment successfully treated induced dermatophytosis in mice without any disease recurrence incidences, thereby indicating efficacy of test extract as an excellent topical antifungal agent for the cure of dermatophytosis.

Active compounds against tinea pedis dermatophytes from Ageratina pichinchensis var. bustamenta

Secondary metabolites 5-acetyl-3beta-angeloyloxy-2beta-(1-hydroxyisopropyl)-2,3-dihydrobenzofurane (1), 5-acetyl-3beta-angeloyloxy-2beta-(1-hydroxyisopropyl)-6-methoxy-2,3-dihydrobenzofurane (2), espeletone (3), encecalinol (4), O-methylencecalinol (5), encecalin (6), sonorol (7), taraxerol (8), (+)-beta-eudesmol (9), and a mixture of beta-sitosterol and stigmasterol, were isolated from the aerial parts of Ageratina pichinchensis var. bustamenta. The antimicrobial activity of compounds 6, 8 and 9, together with derivatives 9a and 9b against the most important dermatophytes responsible for tinea pedis infection, Trichophyton rubrum and T. mentagrophytes, and against Candida albicans and Aspergillus niger were determined, showing that the three natural products were active against both Trichophyton species. Ageratina pichinchensis var. bustamenta is used in folk medicine to treat skin infections and wounds, and this study confirms that the n-hexane extract contains metabolites which are responsible for these utilities.