Isolation of antibacterial compounds from hairy vetch (Vicia villosa) against grapevine crown gall pathogen

This study was conducted to investigate the efficacy of antibacterial compounds isolated from hairy vetch (Vicia villosa Roth) shoots against grapevine crown gall pathogen. The hairy vetch shoot powder was sequentially extracted and screened for antibacterial activity by the disc diffusion method. Ethyl acetate extract from the hairy vetch shoots was subjected to column chromatography on silica gel. The structures of the compounds were then elucidated by spectroscopic analysis and chromatographic assay. Three compounds were isolated and identified as bis (2-ethylhexyl) phthalate (compound 1), diethyl phthalate (compound 2), and p-hydroxybenzoic acid (compound 3). The compounds showed potential antibacterial effect as diameters of inhibition zones (7.3 +/- 0.3 to 11.2 +/- 0.4 mm) against Rhizobium vitis and Bacillus subtilis. The minimum inhibitory and minimum bactericidal concentrations of these compounds against the target bacteria were found to range from 62.5 to 125 and 125 to 250 mu g center dot mL(-1), respectively. The compounds also showed bactericidal activity based on the viable counts of the tested strain. These findings indicate that the isolated compounds could be used as possible candidates for control of crown gall disease in grapevines caused by R. vitis.