Pycnanthuquinone C: a new terpenoid-quinone from Pycnanthus angolensis.

A new compound containing a unique terpenoid-quinone skeleton, pycnanthuquinone C (1) along with the known sargachromenol (2), prunetin (3), biochanin A (4), calopiptin (5), (12 S,13 S)-12,13-dihydroxylabda-8(17),14-dien-18-oic acid (6), (12 R,13 S)-12,13-dihydroxylabda-8(17),14-dien-18-oic acid (7), and sitosterol 3- O-beta- D-glucopyranoside (8), were isolated from the stem bark of Pycnanthus angolensis. Their structures were elucidated by spectroscopic means and comparison with published data. The antifungal activity of compounds 1, 2 and 3 was evaluated.