Four cytotoxic lignans were isolated from the stem bark of Bursera per
mollis (Burseraceae), namely, deoxypodophyllotoxin (1), beta-peltatin
methyl ether (2), picro-beta-peltatin methyl ether (3), and dehydro-be
ta-peltatin methyl ether (4). Also isolated was the inactive lignan, n
emerosin (5). Compounds 1 and 2 were potently cytotoxic when evaluated
against a panel of human cancer cell lines.