Cytotoxic triterpenes from stem bark of Physocarpus intermedius.

Seven triterpenes (1-7), i.e., betulinic acid 1, ursolic acid 2, oleanolic acid 3, 3-O-caffeoyloleanolic acid 4, euscaphic acid 5, 2 alpha-hydroxyursolic acid 6 and maslinic acid 7 were isolated from the stem bark extract of P. intermedius as active principles responsible for the cytotoxicity against five cultured human tumor cell lines, i.e., A549 (non small cell lung), SK-OV-3 (ovary), SK-MEL-2 (melanoma), XF498 (central nerve system) and HCT-15 (colon), in vitro.