Antibacterial and cytotoxic activity of prenylated bicyclic acylphloroglucinol derivatives from Hypericum amblycalyx

Abstract

Two new bicyclic acylphloroglucinol derivs., hypercalyxone A (I) and B (II), were isolated from the petroleum ether ext. of the aerial parts of H. amblycalyx, together with 2 further compds. (1-[5,7-dihydroxy-2-methyl-2-(4-methylpent-3-enyl)-chroman-8-yl]-2-methylpropan-1-one [III] and 1-[5,7-dihydroxy-2-methyl-2-(4-methylpent-3-enyl)-chroman-8-yl]-2-methylbutan-1-one [IV]), which have been described only as semisynthetic products. In addn., the known triterpene lup-20(29)-en-3-one was obtained. Structure elucidation was based on 1D and 2D NMR studies, as well as on data derived from mass spectrometry. The 4 acylphloroglucinol derivs. were evaluated for their cytotoxic and antibacterial activity. All compds. showed moderate cytotoxic activity against KB and Jurkat T cancer cells. Esp. III and IV exhibited strong antibacterial activity against different Gram-pos. strains.