Antitumor effects of dammarane-type saponins from steamed Notoginseng

Six dammarane-type saponins were extracted from steamed Panax notoginseng. Their chemical structures were identified spectroscopically as ginsenosides Rh-1 (1), Rg(1) (2), 20 (S)-Rg(3) (3), 20 (R)-Rg(3) (4), Rb-3 (5), and Rb-1 (6). Compounds (0.1-10 mu M) were tested for inhibition of tumor necrosis factor-alpha (TNF)-induced nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kappa B) luciferase reporter activity using a human kidney 293T cell-based assay. Ginsenoside Rb-3 (5) showed the most significant activity with an IC50 of 8.2 mu M. This compound also inhibited the induction of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) messenger Ribonucleic acid (mRNA) in a dose-dependent manner after HepG2 cells had been treated with TNF-alpha (10 ng/mL).