Assessment of in vitro antifungal activities of various extracts of indigenous Bahraini medicinal plants

The in vitro antifungal activity of the aqueous, ethanol, chloroform, petroleum ether, and residue extracts from 10 indigenous Bahraini plants used in folk medicine for the treatment of various diseases is reported. Extract efficacy was evaluated using the agar well diffusion assay against four filamentous fungi and two yeasts monitored by standard antifungal disks. The results showed that all but, in particular, ethanol and chloroform of the examined plant extracts reveal variable degree of bioactivity against at least two of the tested microbes. The highest ethanol extract activity was exhibited by Cressa cretica L. against Penicillium citrinum Thom (32.2 mm) followed by Candida albicans (C. P. Robin) Berkhout (25.7 mm). The diffusable metabolites of Heliotropium curassavicum also demonstrated marked inhibitory effect against the same microorganisms. Chloroform extract of Emex spinosa Campd. displayed an elevated potency against Alternaria alternata (Fries) Keissler (27.9 mm) and Saccharomyces cerevisiae (27.5 mm). Zone of inhibition against other fungi varied from 19.9 min to 25.9 mm, indicating a novel class of metabolite. However, the highest growth inhibition was encountered with Fagonia indica Burnt f. against Penicillium citrinum (29.3 mm). With the exception of chloroform extracts from cultivated soils, various extracts of plants randomly collected from saline-affected soils exhibited higher fungal radius inhibition than plants from cultivated soils. The significance of these results in relation to ethnobotanical data are discussed.