Abstract

Problems associated with fungal resistance to antifungal agents are increasing worldwide. There is need to find sources of novel antifungal drugs and endophytic fungi could be another interesting source. In this study, 213 culturable endophytic fungi isolated from leaves and branches of Rhodomyrtus tomentosa from Thailand were screened for their ability to produce antifungal agents. Crude extracts from 177 out of 213 fungal isolates exhibited inhibitory activity against human pathogenic fungi, evaluated by a microbroth dilution method. Of the 349 active extracts out of 617 extracts tested, 43.5% inhibited Penicillium marneffei; 16.5 to 20.8% inhibited two strains of Cryptococcus neoformans; 6.0% Microsporum gypseum; 5.0% Candida albicans, with minimal inhibitory concentrations (MIC) of 1 to 200 mg/ml. 22 endophytic fungi showing strong antifungal activity (MICs of 1 to 8 mg/ml) were identified by morphological and molecular methods. They mainly belonged to the generaColletotrichum, Diaporthe, Guignardia and Phomopsis. The results of this work indicate that endophytic fungi from R. tomentosa can be a good source of potential antifungal natural products.

Key words: Rhodomyrtus tomentosa, antifungal activity, endophytic fungi, molecular identification.