Biflavanones, Chalconoids, and Flavonoid Analogues from the Stem Bark of Ochna holstii

Abstract Two new biflavanones (1 and 2), three new bichalconoids (3?5), and 11 known flavonoid analogues (6?16) were isolated from the stem bark extract (CH3OH?CH2Cl2, 7:3, v/v) of Ochna holstii. The structures of the isolated metabolites were elucidated by NMR spectroscopic and mass spectrometric analyses. The crude extract and the isolated metabolites were evaluated for antibacterial activity against Bacillus subtilis (Gram-positive) and Escherichia coli (Gram-negative) as well as for cytotoxicity against the MCF-7 human breast cancer cell line. The crude extract and holstiinone A (1) exhibited moderate antibacterial activity against B. subtilis with MIC values of 9.1 ?g/mL and 14 ?M, respectively. The crude extract and lophirone F (14) showed cytotoxicity against MCF-7 with EC50 values of 11 ?g/mL and 24 ?M, respectively. The other isolated metabolites showed no significant antibacterial activities (MIC > 250 ?M) and cytotoxicities (EC50 ? 350 ?M).