Antifungal activity of secondary metabolites present in Psidium guajava leaves against dermatophytes

Abstract

Dermatophytes are a group of fungi that commonly cause skin diseases in animals and humans. Psidium guajava is a fruit tree with high medicinal value commonly used to cure various skin ailments. Methanol leaf extract of Psidium guajava was used to screen for the antifungal activity against five species of dermatophytes; Epidermophyton floccosum, Trichophyton rubrum, T. mentagrophytes, Microsporum gypseum and M. canis. The antifungal activity of the extract was tested using the agar well diffusion method from which the methanol crude extract revealed the highest antifungal activity exhibiting 22.5 mm against E. floccosum. Preliminary analysis of secondary metabolites was performed for the methanol crude extract which revealed the presence of many bio-active compounds including saponins, steroids and alkaloids. It was then subjected to fractionation and hexane, chloroform, ethyl acetate and aqueous fractions were obtained. Ethyl acetate fraction exhibited the highest antifungal activity against the test organisms recording 27.13 mm against M. canis. The secondary metabolites present in this chosen fraction were separated using thin layer chromatography (TLC) followed by the detection under UV light (365 nm and 254 nm). Contact bioautography was performed against the tested dermatophyte species using the detected spots from UV to determine the growth inhibitory activities. The secondary metabolites that were separated by TLC were identified using specific spray reagents which revealed the presence of alkaloids, steroids and flavonoids. Thus, P. guajava possesses different types of secondary metabolites which are effective antifungal compounds against dermatophytes.

Key words: dermatophytes, Psidium guajava, secondary metabolites, antifungal activity