Phytochemicals from Goniothalamus griffithii Induce Human Cancer Cell Apoptosis

Bioactive compounds extracted from leaves and twigs of Goniothalamus griffithii include pinocembrin (PCN) and goniothalamin (GTN). The objectives of this study were to investigate the cytotoxic activities of PCN and GTN and their influence on molecular signaling for cell death in several human cancer cell lines compared to normal murine fibroblast NIH3T3 cells. GTN exhibited the most potent cytotoxicity against MCF7 > HeLa > HepG2 > NIH3T3 cells with IC50 values of 7.33, 14.8, 37.1 and 65.4 M, respectively, whereas PCN was cytotoxic only to HepG2 cells with IC50 values of ~80 M. Apoptotic cell death was confirmed by staining the cells with annexin VFITC and propidium iodide (PI) employing flow cytometry. Apoptosis was shown by externalization of phosphatidylserine in goniothalamintreated MCF7 cells in a dose response manner. Positive PIstained cells with the typical morphology of apoptotic cells were increased dosedependently. Furthermore, reduction of mitochondrial transmembrane potential was found in goniothalamintreated MCF7, HepG2 and HeLa cells. GTN treatment in MCF7 increased caspase3, 8 and 9 activities while GTNinduced HeLa cells showed an increase of both caspase3 and 9 activities. But an increased caspase8 activity was demonstrated in GTN and PCNtreated MCF7 and HepG2 cells, respectively. Taken together, GTN and PCNinduced human cancer cell apoptosis was through different molecular mechanisms or signaling pathways, which might be due to different machineries in different types of cancer cells, as evidenced by the compoundmodulated caspase activities in both intrinsic and/or extrinsic pathways.