Antifungal properties of olive leaf extracts and their phenolic compounds

Abstract

Olive (Olea europaea L.) leaf extracts were obtained using water or different organic solvents such as acetone, methanol and ethyl acetate. Antimicrobial activities of the extracts and some phenolic components were investigated to screen against 30 fungal strains (Alternaria alternata, Aspergillus chevalieri, A. chrysogenum, A. elegans, A. flavus [three strains], A. fumigatus, A. nidulans, A. niger [two strains], A. oryzae, A. parasiticus[four strains], A. tamari, P. verrucosum, A. versicolor, A. wentii, Fusarium oxysporum, F. semitectum, Mucor racemosus, Neurospora crassa, Penicillium citrinum, P. echinulatum, P. griseofulvum, P. italicum, P. roqueforti and Rhizopus oligosporus) using the disc diffusion method. In this study, in terms of inhibition activity, it was determined that aqueous extract was the best as it completely inhibited the growth of 10 molds, followed by acetone and methanol extracts, which were effective against eight molds, and diethyl ether extract, which was effective against 7 out of 30 test fungi. The inhibition zones ranged from 7 to 21 mm. Comparing the sensitivity of the fungi with all crude olive leaf extracts and pure phenolic compounds, we found that A. parasiticus((4)) was the most resistant strain while A. wentii was the most sensitive.