The anti-HIV activity in the organic solvent extract of leaves of Buchenavia capitata was traced to a series of known flavonoid alkaloids, which represent a new chemotype for anti-HIV activity. The 13C-nmr assignments for this series of compounds have been revised. O-Demethylbuchenavianine [1] was the most active compound of the series but produced only moderate cytoprotective effects against HIV in cultured human lymphoblastoid (CEM-SS) cells. Compound 1 was cytotoxic also in the NCI human disease-oriented in vitro tumor screening panel and produced a pattern of modest differential cellular sensitivity.