Antibacterial Activity of Selected Isoflavonoids

Abstract

Six isoflavonoids [from bean and soybean] were screened in both semisolid agar and liquid media for antibacterial activity against 20 phytopathogenic and saprophytic isolates representing the genera Pseudomonas, Xanthomonas and Achromobacter. Results of the 2 bioassay systems showed that coumestrol and formononetin lacked significant antibacterial activity. Phaseollin and pisatin were slightly to moderately inhibitory to a few isolates. Phaseollinisoflavan exhibited slight to moderate activity against several pseudomonads but strongly inhibited the xanthomonads and Achromobacter spp. Kievitone was the most inhibitory compound tested, significantly affecting the growth of a large proportion of the isolates. The xanthomonads and Achromobacter isolates tended to be more strongly inhibited by the active compounds than the pseudomonads. Preliminary results suggest that phaseolinisoflavan and kievitone are bactericidal to some isolates.