Three acylphloroglucinol derivatives have been isolated from the hexane and acetone extracts of the aerial parts of Hypericum densiflorum Pursch. The compounds were characterized by NMR spectroscopy and mass spectrometry and identified as 4-geranyloxy-2,6-dihydroxybenzophenone (1), 4-geranyloxy-1-(2-methylpropanoyl)- phloroglucinol (2) and 4-geranyloxy-1-(2-methylbutanoyl)-phloroglucinol (3). Compounds 1-3 were evaluated for in vitro cell proliferation inhibitory activity against human breast (MCF-7), lung (NCI H460), CNS (SF-268), stomach (AGS) and colon (HCT-116) tumor cell lines; antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA); inhibition of cyclooxygenase (COX-1 and -2) enzymes; and antioxidant activity in the lipid peroxidation (LPO) assay. All three compounds showed moderate to strong antitumor, antibacterial, antioxidant and inhibition of COX-2 activities. Also, this is the first reported occurrence of compound 3 in the Hypericum genus.
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