Cytotoxic triterpenoids from the fruits of Zizyphus jujuba.

The following eleven triterpenoic acids were isolated from the fruits of Zizyphus jujuba (Rhamnaceae): colubrinic acid, alphitolic acid, 3-O-cis-p-coumaroylalphitolic acid (3), 3-O-trans-p-coumaroylalphitolic acid (4), 3-O-cis-p-coumaroylmaslinic acid, 3-O-trans-p-coumaroylmaslinic acid, betulinic acid (7), oleanolic acid, betulonic acid (9), oleanonic acid and zizyberenalic acid. The in vitro cytotoxicities of the triterpenoic acids against K562, B16(F-10), SK-MEL-2, PC-3, LOX-IMVI, and A549 tumor cell lines were investigated by the sulforhodamin B (SRB) method. Among these compounds, the lupane-type triterpenes, such as compounds 3, 4, 7, and 9, showed high cytotoxic activities. In particular, the cytotoxic activities of 3-O-p-coumaroylalphitolic acids (compounds 3 and 4) were better than those of non-coumaroic triterpenenoids (compounds 7 and 9). These results suggest that the coumaroyl moiety at the C-3 position of the lupane-type triterpene may play an important role in enhancing cytotoxic activity.