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Three new acylphloroglucinol derivatives have been isolated from the hexane extract of the aerial parts of Hypericum prolificumL.:? prolificin A (1), prolifenone A (2), and prolifenone B (3). The structures were elucidated on the basis of extensive 2D NMR and MS data. All three compounds 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. Prolificin A showed growth inhibition of all cell lines with IC50values ranging from 23 to 36 M. Prolifenones A and B were inactive at the concentrations tested.

A new dimeric withanolide, ashwagandhanolide (1), was isolated from the roots of an Ayurvedic medicinal herb, Withania somnifera. A detailed spectroscopic evaluation revealed its identity as a dimer with an unusual thioether linkage. Compound 1displayed growth inhibition against human gastric (AGS), breast (MCF-7), central nervous system (SF-268), colon (HCT-116), and lung (NCI H460) cancer cell lines, with IC50values in the range 0.43-1.48 g/mL. In addition, it inhibited lipid peroxidation and the activity of the enzyme cyclooxygenase-2 in vitro.