Andrographolide (Andro) suppresses proliferation and triggers apoptosis in many types of cancer cells. Taxifolin (Taxi) has been proposed to prevent cancer development similar to other dietary flavonoids. In the present study, the cytotoxic and apoptotic effects of the addition of Andro alone and Andro and Taxi together on human prostate carcinoma DU145 cells were assessed. Andro inhibited prostate cancer cell proliferation by mitotic arrest and activation of the intrinsic apoptotic pathway. Although the effect of Taxi alone on DU145 cell proliferation was not significant, the combined use of Taxi with Andro significantly potentiated the anti-proliferative effect of increased mitotic arrest and apoptosis by enhancing the cleavage of poly(ADP-ribose) polymerase, and caspases-7 and -9. Andro together with Taxi enhanced microtubule polymerization in vitro, and they induced the formation of twisted and elongated spindles in the cancer cells, thus leading to mitotic arrest. In addition, we showed that depletion of MAD2, a component in the spindle assembly checkpoint (SAC), alleviated the mitotic block induced by the two compounds, suggesting that they trigger mitotic arrest by SAC activation. This study suggests that the anti-cancer activity of Andro can be significantly enhanced in combination with Taxi by disrupting microtubule dynamics and activating the SAC.

Abrus cantoniensis is a common and popular vegetative food consumed as beverage, soup and folk medicine in the tropical and subtropical areas of Asia. It has been claimed valuable for cleansing toxicants in the liver. However, the functional effects of A. cantoniensis have not yet been scientifically explored. This study comprehensively evaluated the in vitro antioxidant and anti-proliferative capacities of the herbal extract and the main alkaloid abrine. Abrine was qualitatively and quantitatively determined in methanol extract (ME) using HPLC-DAD and LC-MS/MS. The results showed that ME, ethyl acetate fraction (EF) and abrine exhibited comparable ABTS radical cation scavenging activities and reducing power to two commercial antioxidants (BHT and Trolox). The EF exerted strong cellular antioxidant activity and selective cytotoxicity against three cancer cell lines in a dose-dependent manner. Biological assays revealed that the EF induced cell cycle arrest at G2/M and apoptosis in MCF-7 and Hep3B cells after 48 h of treatment. Thus, A. cantoniensis exerted potent cellular antioxidant and anti-proliferative properties, highlighting why it has been traditionally used as a functional food.