PHENYLPHENALENONE-TYPE PHYTOALEXINS FROM UNRIPE BUNGULAN BANANA FRUIT

Fourteen phenylphenalenone-type phyto alexins (1-14), including three new compounds, were isolated from the peel of unripe Musa acuminata [A AA] cv. Bungulan fruit which had been injured and then inoculated with conidia of Colletotrichum musae. These new phytoalexins were identifi ed as o-2,3-dihydroxy-4-(4'-hydroxyphenyl)phenalen-1-one (12), 9-(3',4 '-dimethoxyphenyl)-2-methoxyphenalen-1-one (13) and 9-(4'-hydroxypheny l)-2-methoxyphenalen-1-one (14). The ratios of the relative intensitie s of the [M](+)/[M-H](+) ions or [M-H2O](+)/[M-H2O-H](+) ions in the E I mass spectra were applied to discriminate between 4- and 9-phenylphe nalenones. An antifungal test on the phytoalexins showed that a phenol ic hydroxyl group was essential for the activity.