Erythrina poeppigiana-derived phytochemical exhibiting antimicrobial activity against Candida albicans and methicillin-resistant Staphylococcus aureus.

Abstract

To screen five phytochemicals isolated from Erythrina poeppigiana (Leguminosae) for antimicrobial activity against both Candida albicans and methicillin-resistant Staphylococcus aureus (MRSA). Roots of E. poeppigiana were macerated with acetone and the chloroform-soluble fraction of the residue was subjected to repeated silica gel column chromatography using various eluting solvents. Structures of the isolated compounds were determined by extensive spectroscopic studies. Each compound was dissolved in dimethyl sulphoxide and added to agar plates (final concentration: 1.56-100 microg ml(-1)) and minimum inhibitory concentrations (MICs) against C. albicans and MRSA were determined. Spectral data indicated the presence of three different types of phytochemicals; isoflavonoids (erypoegin A, demethylmedicarpin and sandwicensin), alpha-methyldeoxybenzoin (angolensin) and cinnamylphenol (erypostyrene). While all compounds showed anti-MRSA activity in this concentration range, isoflavonoids and alpha-methyldeoxybenzoin failed to inhibit the growth of C. albicans. Erypostyrene (E-1-[2-hydroxy-4-methoxy-5-(gamma,gamma-dimethylallyl)benzyl]-2-(4-hydroxyphenyl)ethylene) exhibited not only the highest anti-MRSA activity (MIC value of 6.25 microg ml(-1)) but also anti-candidal potency (MIC value of 50 microg ml(-1)). The compound reduced viable cell numbers of C. albicans and MRSA by approximately 1 of 2000 and 1 of 1000 after 1 h incubation at each MIC, respectively. A new cinnamylphenol, erypostyrene, possessed anti-candidal and anti-MRSA activity. Erypostyrene could be a leading candidate for development of antimicrobial agents with anti-candidal and anti-MRSA activity.