In vitro activity of CAY-1, a saponin from Capsicum frutescens, against Microsporum and Trichophyton species.

Dermatomycoses are among the world's most common diseases and their incidence has increased over recent years, particularly in immunosuppressed patients. In previous studies, the saponin CAY-1 from cayenne pepper (Capsicum frutescens), has shown antifungal activities against Candida albicans and Aspergillus spp. We therefore studied the in vitro antifungal activity of CAY-1 against non-germinating conidia and hyphae of clinical isolates of the dermatophytes Trichophyton mentagrophytes, T. rubrum, T. tonsurans and Microsporum canis. We used a microdilution method to assess the growth inhibitory activities of CAY-1 against conidia (CLSI document M38-A) and a colorimetric procedure (XTT method) to investigate the metabolic inhibitory activity of CAY-1 against hyphae. The minimal inhibitory concentrations (complete visual growth inhibition) of CAY-1 against non-germinating conidia ranged from 10-20 microg/ml for all dermatophyte isolates included in this investigation. In addition, we found >90% inhibition of hyphal metabolic activity of these same isolates with 10-20 microg/ml of CAY-1. Results indicate that CAY-1 merits further investigation as a potential agent for the treatment of dermatomycoses.