Chalcones, coumarins, and flavanones from the exudate of Angelica keiskei and their chemopreventive effects

From an ethyl acetate-soluble fraction of the exudate obtained from the stems of Angelica keiskei (Umbelliferae), 17 compounds, viz. five chalcones (1–5), seven coumarins (6–12), three flavanones (13–15), one diacetylene (16), and one 5-alkylresorcinol (17), were isolated. These compounds were evaluated with respect to their inhibitory effects on the induction of Epstein-Barr virus early antigen (EBV-EA) by 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells, which is known to be a primary screening test for antitumor-promoters. With the exception of three compounds (10, 16, and 17), all other compounds tested showed potent inhibitory effects on EBV-EA induction (92–100% inhibition at 1×103 mol ratio/TPA). In addition, upon evaluation of these compounds for the inhibitory effects against activation of (±)-(E)-methyl-2-[(E)-hydroxy-imino]-5-nitro-6-methoxy-3-hexemide (NOR 1), a nitric oxide (NO) donor, as a primary screening test for antitumor-initiators, two chalcones (2 and 3) and six coumarins (6-11) exhibited potent inhibitory effects.