CYTOTOXIC GLYCOSIDES FROM ALBIZIA JULIBRISSIN

During the course of a study of leguminous plants, cytotoxicity was de monstrated by the crude saponin fraction of Albizia julibrissin. Follo wing chromatographic purification, the structures of three novel sapon ins, julibrosides I-III (1-3), inclusive of a cytotoxic principle, wer e elucidated. A comparison of the cytotoxicity of julibrosides (1-3) a nd their prosapogenins (4-15) prepared by alkaline hydrolysis clearly indicated that both an ha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyrano syl ester unit and a monoterpene-quinovopyranosyl moiety are crucial s ubstituents for cytotoxicity among this class of compounds. The hydrox y group at C-16 of aglycon may play an important role in mediating cyt otoxicity, and the N-acetyl-glucosamine moiety at C-3 seems to enhance activity because 3 showed the strongest cytotoxicity.