Induction of Mitochondria-mediated Apoptosis in Human Gastric Adenocarcinoma SGC-7901 Cells by Kuraridin and Nor-kurarinone Isolated from Sophora Flavescens

The study was designed as one of a series to find novel anticancer compounds from Chinese herbs. For this purpose, we screened an ethanol extract of 300 herbs against SGC-7901 cells. Sophora flavescen was included in those showing potential cytotoxic activity. Target compounds were therefore isolated and analyzed on analytical HPLC. Chromatography showed only one peak with a purity of 97%. The ESI-MS spectrum showed two molecular ions: m/z 424(M+) and 438(M+). Furthermore, combining the data of 1HNMR and 13CNMR, it was deduced that this product was a mixture of two compounds; kuraridin (1) and nor-kurarinone (2). The concentration was [1]:[2]=9:10, the chemical structural formulae are C25H28O6 and C26H30O6. In this study, mechanisms involved by the mixture of compounds 1 and 2-induced growth inhibition including apoptosis and G2/M phase arrest in human gastric adenocarcinoma SGC-7901 cells were examined for the first time. Triggering of the mitochondrial apoptotic pathway was demonstrated by loss of mitochondrial membrane potential, reduction in the Bcl-2/Bax ratio, and significant activation and cleavage of caspase-3. Additionally, the production of reactive oxygen species (ROS) was also increased. Taken together, our results indicated that the cytotoxic efficacy of the mixture of compounds 1 and 2 is mainly due to induction of cell cycle arrest and apoptosis.