Taiwankadsurins A, B, and C, three new C19 homolignans from Kadsura philippinensis.

[structures: see text] Three novel C19 homolignans, designated taiwankadsurins A (1), B (2), and C (3), were isolated from the aerial parts of Taiwanese medicinal plant Kadsura philippinensis. The structures of 1-3, which have a 3,4-{1'-[(Z)-2''-methoxy-2''-oxo-ethylidene]}-pentano(2,3-dihydro-benzo[b]furano)-3-(2'''-methoxycarbonyl-2'''-hydroxy-2''',3'-epoxide) skeleton, were determined by spectroscopic analyses, especially 2D NMR techniques (HMBC and NOESY). Compound 2 exhibited mild cytotoxicity against human KB and Hela tumor cells.