Selective induction of apoptosis in glioma tumour cells by a Gynostemma pentaphyllum extract

At low concentration H(2)O(2) is an important signal molecule in proliferation of tumour cells. We report about a study investigating the effect of an ethanolic extract from Gynostemma pentaphyllum on proliferation of C6 glioma tumour cells and cellular H(2)O(2) concentration. The proliferation of these cells was maximal at about 1 muM extracellular H(2)O(2). HPLC-finger prints of the extract revealed a set of saponines as essential components. In C6 glioma cells the extract caused increase in super oxide dismutase (SOD) activity, in the amount of SOD protein, and in cellular H(2)O(2) concentration. It inhibited cell proliferation and induced activation of caspase 3 as indication of apoptosis. No effect of the extract was observed on the proliferation of astrocytes of a primary cell culture. From these findings we suggest that the ethanolic extract from Gynostemma pentaphyllum may selectively shift the H(2)O(2) concentration to toxic levels exclusively in tumour cells due to increased SOD activity. It may have a high potency in cancer therapy and cancer prophylaxis.