Biflavonoids with cytotoxic and antibacterial activity from Ochna macrocalyx

Abstract

Six biflavonoid and related compounds were isolated from the ethanolic extract of Ochna macrocalyx bark. One is a new compound, the isoflavanone dimer dehydroxyhexaspermone C (1). Previously isolated compounds obtained from the bark are biisoflavonoid hexaspermone C (2), tetrahydrofuran derivative ochnone (3), furobenzopyran derivative cordigol (4), and biflavonoids calodenin B (5) and dihydrocalodenin B (6). Although 3 has already been isolated, its spectral data are presented here for the first time. Isolated compounds were tested for cytotoxic activity on MCF-7 breast cancer cells using the MTF reduction assay method. Compound 5 showed cytotoxic activity (7 ± 0.5 μM) and 6 showed moderate cytotoxicity (35 ± 7 μM). In antibacterial assays performed using three strains of multi-drug resistant (mdr) Staphylococcus aureus (RN4220, XU212 and SA-1199-B) compounds 5 and in particular 6 showed strong antibacterial activity (MlCs 5:64, 8, 16 μg/mL 6:8, 8, 8 μg/mL, respectively). The ethanolic extract of the bark also showed NF-κB inhibitory activity.