Anti-proliferative Activities of Two Flavonols with Unsubstituted B-ring from the Leaves of Platanus acerifolia

The anti-proliferative activities against five cancer cell lines of two flavonols (1, 2) with unsubstituted B ring isolated from the ethanol extract of the leaves of Platanus acerifolia were investigated. The results showed that compound 1 possessed a noteworthy anti-proliferative activity against MGC-803 cells with an IC50 value of 17.26 +/- 1.04 mu M, and compound 2 was less active than 1 with an IC50 value of 20.29 +/- 1.37 mu M compared with 41.94 +/- 1.58 mu M for the positive control group. In addition, the results of Hoechst 33258 staining, AO/EB staining and annexinV-FITC assays indicated that 1 caused a significant MGC-803 cellular apoptosis in a dose-dependent manner. The further mechanisms showed that compound 1 induced the production of ROS, decreased the mitochondrial membrane potential, and altered pro- and anti-apoptotic proteins, leading to activation of caspase-9 and caspase-3 in the process of cellular apoptosis. The present investigation indicated that compound 1 could be used as a potential anti-cancer candidate.