Analysis of antimicrobial activity of flavonoids and saponins isolated from the shoots of oats (Avena sativa L.)

Crude extracts from the shoots of oat cv. Quoll were tested against four species of bacteria and eight species of fungi. Bacterial growth was not inhibited. The mycelia growth of all Pyrenophora species tested, except Pyrenophora avenae DAR 33699, was inhibited by the crude extract, whereas the mycelia growth of Fusarium graminearum, Mycosphaerella pinodes and Rhizoctonia solani was not affected. Partially purified fractions with high concentrations of flavone-C-glycosides had no inhibitory effect against P. teresf. sp. teres and P. teres f. sp. maculata. The saponin 26-desglucoavenacoside B accounted for most of the activity against P. teres f. sp. teres with a minor contribution from the other saponins, 26-desglucoavenacoside A and avenacosides A and B