Cytotoxic triterpenes from the twigs of Celtis philippinensis.

Two triterpene esters, 3beta-trans-sinapoyloxylup-20(29)-en-28-ol (1) and 3beta-trans-feruloyloxy-16 beta-hydroxylup-20(29)-ene (2), were isolated as cytotoxic constituents from the chloroform-soluble extract of the twigs of Celtis philippinensis, along with five known triterpenes, 3beta-O-(E)-feruloylbetulin (3), 3beta-O-(E)-coumaroylbetulin (4), betulin (5), 20-epibryonolic acid (6), and ursolic acid (7). The structures of 1 and 2 were assigned from their 1D and 2D NMR spectroscopic data. All isolates were evaluated for cytotoxicity against several human cancer cell lines.