In vitro and in vivo activities of the novel azole antifungal agent r126638

Towards a Standardized Procedure for the Production of Infective Spores to Study the Pathogenesis of Dermatophytosis

Dermatophytoses are superficial infections of human and animal keratinized tissues caused by filamentous fungi named dermatophytes. Because of a high and increasing incidence, as well as the emergence of antifungal resistance, a better understanding of mechanisms involved in adhesion and invasion by dermatophytes is required for the further development of new therapeutic strategies. In the last years, several in vitro and in vivo models have emerged to study dermatophytosis pathogenesis. However, the procedures used for the growth of fungi are quite different, leading to a highly variable composition of inoculum for these models (microconidia, arthroconidia, hyphae), thus rendering difficult the global interpretation of observations. We hereby optimized growth conditions, including medium, temperature, atmosphere, and duration of culture, to improve the sporulation and viability and to favour the production of arthroconidia of several dermatophyte species, including Trichophyton rubrum and Trichophyton benhamiae. The resulting suspensions were then used as inoculum to infect reconstructed human epidermis in order to validate their ability to adhere to and to invade host tissues. By this way, this paper provides recommendations for dermatophytes culture and paves the way towards a standardized procedure for the production of infective spores usable in in vitro and in vivo experimental models.

Antifungal activity of Camellia sinensis crude extracts against four species of Candida and Microsporum persicolor

OBJECTIVE OF THE STUDY

Candidiasis and dermatophytoses are benign infections in humans and animals, but they are very dreaded diseases in immunocompromised individuals. These infections become resistant to different treatments which make them more dangerous. In this work, we tried to find a new way for treating them. So we were interested in the antifungal activity of Camellia sinensis (tea); this plant is known to have many health benefits.

MATERIALS AND METHODS

We tested the ability of the acetone and aqueous crude extracts of the plant to inhibit in vitro the growth of Candida albicans, Candida glabrata, Candida tropicalis, Candida krusei and Microsporum persicolor. Then, the antifungal activity against these species was tested in vivo in mice.

RESULTS

The results showed that the acetone crude extract had the most important in vitro activity against all the fungi. But in vivo it was only the most active against Candida albicans, Candida glabrata, Candida tropicalis and Microsporum persicolor. Candida krusei was more sensitive to the aqueous crude extract.

CONCLUSION

These results indicated that tea could be considered to treat infections caused by the five tested species.

Treatment of seborrheic dermatitis: a comprehensive review

Seborrheic dermatitis (SD) is a chronic, recurring inflammatory skin disorder that manifests as erythematous macules or plaques with varying levels of scaling associated with pruritus. The condition typically occurs as an inflammatory response to Malassezia species and tends to occur on seborrheic areas, such as the scalp, face, chest, back, axilla, and groin areas. SD treatment focuses on clearing signs of the disease; ameliorating associated symptoms, such as pruritus; and maintaining remission with long-term therapy. Since the primary underlying pathogenic mechanisms comprise Malassezia proliferation and inflammation, the most commonly used treatment is topical antifungal and anti-inflammatory agents. Other broadly used therapies include lithium gluconate/succinate, coal tar, salicylic acid, selenium sulfide, sodium sulfacetamide, glycerin, benzoyl peroxide, aloe vera, mud treatment, phototherapy, among others. Alternative therapies have also been reported, such as tea tree oil, Quassia amara, and Solanum chrysotrichum. Systemic therapy is reserved only for widespread lesions or in cases that are refractory to topical treatment. Thus, in this comprehensive review, we summarize the current knowledge on SD treatment and attempt to provide appropriate directions for future cases that dermatologists may face.

Antifungal activity of acetone extracts from Punica granatum L., Quercus suber L. and Vicia faba L

Human and animal mycoses become more frequent and more resistant to traditional treatments. In this work, we tested the in vitro antifungal activity of acetonic extracts of Punica granatum L., Quercus suber L. and Vicia faba L. against seven pathogen fungi and the in vivo antifungal activity against Candida albicans and Trichophyton mentagrophytes. The phytochemical screening was also carried out and showed that the extracts contained mainly proanthocyanidins. Other polyphenols were also present but in low quantity. The acetone extract of V. faba L. gave a good in vitro inhibition of yeasts and was the most active for treating candidiasis in mice. It decreased the percentage of mortality with only 20μg. But the in vivo antifungal activity of this extract on T. mentagrophytes was low. It only showed a small diminution of crusting and erythema after the administration of 100μg. On the contrary, the acetone extracts of P. granatum L. had a poor activity against yeasts and a better one against moulds. It gave the best in vivo antifungal activity against T. mentagrophytes by healing animals with 40μg. The extract of P. granatum L. gave also an interesting in vivo antifungal activity against T. mentagrophytes with an active dose of 80μg.

Antifungal Treatment for Pityriasis Versicolor

BACKGROUND

Pityriasis versicolor (PV), also known as tinea versicolor, is caused by Malassezia species. This condition is one of the most common superficial fungal infections worldwide, particularly in tropical climates. PV is difficult to cure and the chances for relapse or recurrent infections are high due to the presence of Malassezia in the normal skin flora. This review focuses on the clinical evidence supporting the efficacy of antifungal treatment for PV.

METHOD

A systematic review of literature from the PubMed database was conducted up to 30 September 2014. The search criteria were "(pityriasis versicolor OR tinea versicolor) AND treatment", with full text available and English language required.

CONCLUSIONS

Topical antifungal medications are the first-line treatment for PV, including zinc pyrithione, ketoconazole, and terbinafine. In cases of severe or recalcitrant PV, the oral antifungal medications itraconazole and fluconazole may be more appropriate, with pramiconazole a possible future option. Oral terbinafine is not effective in treating PV and oral ketoconazole should no longer be prescribed. Maintenance, or prophylactic, therapy may be useful in preventing recurrent infection; however, at this time, there is limited research evaluating the efficacy of prophylactic antifungal treatment.

Resistance to antifungals that target CYP51

Fungal diseases are an increasing global burden. Fungi are now recognised to kill more people annually than malaria, whilst in agriculture, fungi threaten crop yields and food security. Azole resistance, mediated by several mechanisms including point mutations in the target enzyme (CYP51), is increasing through selection pressure as a result of widespread use of triazole fungicides in agriculture and triazole antifungal drugs in the clinic. Mutations similar to those seen in clinical isolates as long ago as the 1990s in Candida albicans and later in Aspergillus fumigatus have been identified in agriculturally important fungal species and also wider combinations of point mutations. Recently, evidence that mutations originate in the field and now appear in clinical infections has been suggested. This situation is likely to increase in prevalence as triazole fungicide use continues to rise. Here, we review the progress made in understanding azole resistance found amongst clinically and agriculturally important fungal species focussing on resistance mechanisms associated with CYP51. Biochemical characterisation of wild-type and mutant CYP51 enzymes through ligand binding studies and azole IC50 determinations is an important tool for understanding azole susceptibility and can be used in conjunction with microbiological methods (MIC50 values), molecular biological studies (site-directed mutagenesis) and protein modelling studies to inform future antifungal development with increased specificity for the target enzyme over the host homologue.

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.

New therapeutic options for onychomycosis

INTRODUCTION

Onychomycosis is a fungal infection of the nail apparatus that affects 10 - 30% of the global population. Current therapeutic options for onychomycosis have a low to moderate efficacy and result in a 20 - 25% rate of relapse and reinfection. New therapeutic options are needed to broaden the spectrum of treatment options and improve the efficacy of treatment.

AREAS COVERED

This review discusses the emerging pharmacotherapeutics; including topical reformulations of terbinafine, new azole molecules for systemic and topical administration, topical benzoxaboroles and topical polymer barriers. The paper also discusses device-based options, which may be designed to activate a drug or to improve drug delivery, such as photodynamic therapy and iontophoresis; laser device systems have also begun to receive regulatory approval for onychomycosis.

EXPERT OPINION

Device-based therapeutic options for onychomycosis are expanding more rapidly than pharmacotherapy. Systemic azoles are the only class of pharmacotherapy that has shown a comparable efficacy to systemic terbinafine; however terbinafine remains the gold standard. The most notable new topical drugs are tavaborole, efinaconazole and luliconazole, which belong to the benzoxaborole and azole classes of drugs. Photodynamic therapy, iontophoresis and laser therapy have shown positive initial results, but randomized controlled trials are necessary to determine the long-term success of these devices.

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.

In vitro profiling of pramiconazole and in vivo evaluation in Microsporum canis dermatitis and Candida albicans vaginitis laboratory models

The triazole antifungal pramiconazole (Stiefel, a GSK company) was compared with itraconazole, miconazole, and terbinafine in vitro and in vivo. Potent in vitro activities against Candida spp. (50% inhibitory concentration [IC₅₀], 0.04 to 1.83 μM) and Microsporum and Trichophyton spp. (IC₅₀, 0.15 to 1.34 μM) were obtained but not, however, against other filamentous molds and zygomycetes. In the M. canis guinea pig model and C. albicans vulvovaginitis rat model, pramiconazole was superior to the reference compounds after oral and topical administration.

Conazoles

This review provides a historical overview of the analog based drug discovery of miconazole and its congeners, and is focused on marketed azole antifungals bearing the generic suffix “conazole”. The antifungal activity of miconazole, one of the first broad-spectrum antimycotic agents has been mainly restricted to topical applications. The attractive in vitro antifungal spectrum was a starting point to design more potent and especially orally active antifungal agents such as ketoconazole, itraconazole, posaconazole, fluconazole and voriconazole. The chemistry, in vitro and in vivo antifungal activity, pharmacology, and clinical applications of these marketed conazoles has been described.

Emerging therapeutic agents for onychomycosis

Onychomycosis is a frequent disorder that represents the most prevalent fungal infection, particularly among older individuals. Diverse fungi of the dermatophyte, non-dermatophyte mold and yeast families have been reported to be responsible for onychomycosis. The output from the pharmaceutical industry of new antifungals to treat onychomycosis has been limited over the last decade. Present treatment options include both oral and topical drugs, with oral therapies giving better outcomes. However, neither of these treatment options provides high cure rates that are durable. At present, azoles and allylamines are keeping the pivotal roles. New derivatives with a favorable risk-benefit ratio and new formulations of older azoles seem to be promising. Thus, ongoing drug development activities have focused on novel delivery technologies to facilitate incorporation of existing antifungal drugs inside the nail plate and the discovery of new active antifungals.

Effect of culture medium on the disk diffusion method for determining antifungal susceptibilities of dermatophytes

We have evaluated a disk diffusion method to determine the activities of five drugs against 50 strains of dermatophytes and to assess the influence of the culture medium (antibiotic medium 3, high-resolution medium, and RPMI) on the inhibition zone diameters (IZD). There were no differences among the medium/drug combinations, except for itraconazole-RPMI, which showed the narrowest IZD.

Synthesis and antifungal activities of some aryl [3-(imidazol-1-yl/triazol-1-ylmethyl) benzofuran-2-yl] ketoximes

In this study, some aryl [3-(imidazol-1-yl/triazol-1-ylmethyl)benzofuran-2-yl] ketones, aryl (3-methyl-benzofuran-2-yl) ketoximes and aryl [3-(imidazol-1-yl/triazol-1-ylmethyl)benzofuran-2-yl] ketoximes were synthesised starting from 2-aryloyl-3-methyl-benzofuranes. The structure elucidation of the compounds was performed by IR, 1H-NMR, MASS spectroscopy and elemental analyses. Antifungal activities of the compounds were examined and moderate activity was obtained.

Pyrrolo[1,2-a][1,4]benzodiazepine: a novel class of non-azole anti-dermatophyte anti-fungal agents

Broad screening revealed compound 1a to be a novel anti-fungal agent with high specificity towards dermatophytes. The anti-fungal structure-activity relationship of this novel class of 5,6-dihydro-4H-pyrrolo[1,2-a][1,4]benzodiazepines is described together with its mode of action that appeared to be the inhibition of squalene epoxidase. Preliminary in vivo results of the most active compounds are also reported.

Activity of the Triazole Antifungal R126638 as Assessed by Corneofungimetry

BACKGROUND

R126638 is a novel triazole exhibiting potent in vitro and in vivo antifungal activity against fungal pathogens including dermatophytes and yeasts.

OBJECTIVE

To determine the antifungal activity in time in the stratum corneum of healthy volunteers after oral intake of R126638 at a daily dose of 100 or 200 mg for 1 week.

METHOD

Sixteen male volunteers were randomly allocated to oral treatment with either 100 or 200 mg of R126638 once daily for 1 week. Five cyanoacrylate skin surface strippings (CSSS) were obtained from the forearm of each subject before drug intake at day 1. CSSS were also collected during treatment at day 2 (24 h after the first drug intake, before the second drug intake), at day 4 (before the fourth drug intake) and at day 7 (10 h after the last drug intake). The post-treatment lingering effect was assessed at day 10 (3 days after treatment) and at day 14 (7 days after treatment). The corneofungimetry bioassay was performed on these CSSS to assess the antifungal profile of R126638. Cells of different fungal species (Trichophyton rubrum, Trichophyton mentagrophytes, Microsporum canis, Candida albicans and Malassezia globosa) were deposited and cultured for 10 days on CSSS in a sterile and controlled environment. The extent of fungal growth on the stratum corneum was determined using computerized image analysis.

RESULTS

R126638 clearly reduced the growth of all tested fungal species. The onset of effects of R126638 was evidenced at day 4 when it reached statistical significance for 3 of 5 species. At day 7, significance was reached for 4 of 5 species. During the posttreatment period, R126638 remained effective for 4 of 5 species at day 10, and this activity persisted until day 14 for 2 of 5 species.

CONCLUSION

A broad spectrum antifungal activity was rapidly expressed in the stratum corneum after oral intake of R126638. The drug likely reached the upper layers of the stratum corneum by diffusion and persisted in this location for at least 7 days after treatment.

Evaluation of disk diffusion method for determining eberconazole susceptibility of dermatophytes and influence of culture medium

We have evaluated a disk diffusion method to determine the activity of eberconazole against 50 strains of dermatophytes by testing three culture media (RPMI, antibiotic medium 3, and high resolution). No differences were found among the results obtained with the three media. A significant correlation between disk diffusion and microdilution methods was observed with AM3.

Pharmacotherapy of onychomycosis

Fungal infections of the nails are frequent in some segments of the population. Dermatophytes, yeasts and moulds are potential pathogens. A series of antifungal treatments are available to the clinician, differing by both their mechanistic nature and mode of administration. The pharmacodynamic and pharmacokinetic properties of each antifungal agent are distinct. This review focuses on the characteristics of amorolfine, bifonazole, ciclopirox, fluconazole, griseofulvin, itraconazole, ketoconazole, ravuconazole, R126638 and terbinafine. Single drug treatments and combined therapies are presented. None of the current drug regimens have demonstrated reliable efficacy against all cases of onychomycosis. Treatment failures, relapses and reinfections remain stubborn problems in the management of onychomycosis.

Synthesis and in Vitro and in Vivo Structure−Activity Relationships of Novel Antifungal Triazoles for Dermatology

In search for new compounds with potential for clinical use as antifungal agents in dermatology, a series of 12 azole compounds were synthesized stereospecifically and investigated specifically for their activity against dermatophyte fungal infections in animal models. This panel of azoles was studied in vitro and compared with itraconazole and terbinafine for their antifungal activity using a panel of 24 Candida spp. and 182 dermatophyte isolates. Three azoles (1c, 2c, and 4c) showed in vitro antifungal potency equivalent to itraconazole, but superior to terbinafine, against a panel of 24 Candida spp. with comparable or lower activity than that of itraconazole and terbinafine against 182 dermatophyte isolates and only rare activity against other pathogenic fungi. However, in vivo 1c and 4c, both given orally, demonstrated antifungal activity at least three times greater than itraconazole and were superior compared to terbinafine in M. canis infected guinea pigs. In a mouse model infected by T. mentagrophytes, again 4c, but not 1c, showed 5-fold superior activity over itraconazole and terbinafine. Compound 2c was effective in both models but less effective than itraconazole in these models. On the basis of these promising results, 4c is currently being clinically investigated for its potential as a novel antifungal agent against dermatophytosis.

The novel azole R126638 is a selective inhibitor of ergosterol synthesis in Candida albicans, Trichophyton spp., and Microsporum canis

R126638 is a novel triazole with in vitro activity similar to that of itraconazole against dermatophytes, Candida spp., and Malassezia spp. In animal models of dermatophyte infections, R126638 showed superior antifungal activity. R126638 inhibits ergosterol synthesis in Candida albicans, Trichophyton mentagrophytes, Trichophyton rubrum, and Microsporum canis at nanomolar concentrations, with 50% inhibitory concentrations (IC(50)s) similar to those of itraconazole. The decreased synthesis of ergosterol and the concomitant accumulation of 14 alpha-methylsterols provide indirect evidence that R126638 inhibits the activity of CYP51 that catalyzes the oxidative removal of the 14 alpha-methyl group of lanosterol or eburicol. The IC(50)s for cholesterol synthesis from acetate in human hepatoma cells were 1.4 microM for itraconazole and 3.1 microM for R126638. Compared to itraconazole (IC(50) = 3.5 microM), R126638 is a poor inhibitor of the 1 alpha-hydroxylation of 25-hydroxyvitamin D(3) (IC(50) > 10 microM). Micromolar concentrations of R126638 and itraconazole inhibited the 24-hydroxylation of 25-hydroxyvitamin D(3) and the conversion of 1,25-dihydroxyvitamin D(3) into polar metabolites. At concentrations up to 10 microM, R126638 had almost no effect on cholesterol side chain cleavage (CYP11A1), 11 beta-hydroxylase (CYP11B1), 17-hydroxylase and 17,20-lyase (CYP17), aromatase (CYP19), or 4-hydroxylation of all-trans retinoic acid (CYP26). At 10 microM, R126638 did not show clear inhibition of CYP1A2, CYP2A6, CYP2D6, CYP2C8, CYP2C9, CYP2C10, CYP2C19, or CYP2E1. Compared to itraconazole, R126638 had a lower interaction potential with testosterone 6 beta hydroxylation and cyclosporine hydroxylation, both of which are catalyzed by CYP3A4, whereas both antifungals inhibited the CYP3A4-catalyzed hydroxylation of midazolam similarly. The results suggest that R126638 has promising properties and merits further in vivo investigations for the treatment of dermatophyte and yeast infections.