| Abstract
| - Thirteen secolignans, including eight new ones (1−8), were isolated from the EtOAc extract of Peperomia dindygulensis.The structures were mainly elucidated by 1D and 2D NMR and MS experiments, the relative configurations weredetermined by NOE correlations, and the absolute configurations were established by the optical rotations and CDspectra. Cytotoxicity and MDR (multidrug resistance) reversal activity of the isolated compounds were examined.Compounds 6 and 7, peperomins B (10) and E (12), showed moderate to strong growth inhibitory activity against amalignant lung tumor cell (VA-13) with IC50 values of 15.2, 13.5, 13.9, and 1.93 μM, respectively, and also inhibitedthe growth of a normal lung fibroblast cell (WI-38) at the same levels. Compound 7 and peperomin E (12) exhibitedinhibitory activity against a liver tumor cell (HepG2) with IC50 values of 22.3 and 12.1 μM. Compounds 5 and 7 andpeperomins A, B, C, and E (9−12) enhanced calcein accumulation in MDR 2780 cells at 25 μg/mL. Compounds 2, 3,7, and peperomin E (12) showed inhibitory activity on induction of the intercellular adhesion molecule-1 (ICAM-1).
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