1998 年 4 巻 4 号 p. 282-284
We have identified two triterpene carboxylic acids of oleanolic acid and ursolic acid isolated from the leaves of loquat (Eriobotrya) by NMR spectroscopy. We have investigated the effects of oleanolic acid and ursolic acid on the growth of lymphoid leukemia Molt 4B cells and obtained results in which both compounds inhibited the proliferation of Molt 4B cells. In an in vitro experiment, ursolic acid inhibited ornithine decarboxylase (ODC) activity by 25.9% and 39.7% at the concentrations of 1 mM and 2 mM, respectively, while oleanolic acid inhibited ODC activity to a lesser extent than did ursolic acid. Both compounds slightly suppressed S-adenosylmethionine decarboxylase (AdoMetDC) activity. Polyamine contents were decreased in these compound-treated cells. These findings demonstrate that growth suppression of human Iymphoid Molt 4B cells by ursolic acid and oleanolic acid may result from the depletion of polyamines caused by the inhibition of ODC and AdoMetDC activities.