C-geranylated chalcones from the stems of Angelica keiskei with superoxide-scavenging activity

An ethyl acetate-soluble fraction of a methanol extract from the stems of Angelica keiskei was subjected to chromatographic separation to give three new chalcones, designated as xanthokeismins A-C (1-3), in addition to a known chalcone, xanthoangelol B (4). The structures of 1-3 were determined on the basis of the analysis of their spectroscopic data. Compounds 1-4 exhibited potent superoxide-scavenging activity.