Two new benzophenones were isolated from the leaves of Hypericum carinatum. Their structures were established on the basis of 2D NMR spectroscopic analyses and mass spectrometry as cariphenone A (6-benzoyl-5,7-dihydroxy-2,2,8-trimethyl-2H-chromene) (1) and cariphenone B (8-benzoyl-5,7-dihydroxy-2,2,6-trimethyl-2H-chromene) (2). Five known compounds, the phloroglucinol derivative uliginosin B (3), 1-eicosanol, sitosterol, stigmasterol, and campesterol, were also characterized. Compounds 1-3 were evaluated for their total antioxidant capacity through a total radical-trapping parameter assay. Only compound 1 showed moderate antioxidant activity, exhibiting inhibition of chemiluminescence similar to that of quercetin at the same concentration.
Recently the crude methanol extracts of six Hypericum species were analysed against a panel of microorganisms and it was found that H. caprifoliatum Cham. & Schlecht., H. myrianthum Cham. & Schlecht. and H. polyanthemum Klotzsch ex Reichardt were the most active. This paper reports the activity of the hexane, chloroform and methanol fractions of these plants as well as the activity of some isolated compounds against Staphylococcus aureus determined by bioautographic procedures.
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