Anticancer effects of gallic acid isolated from Indonesian herbal medicine, Phaleria macrocarpa (Scheff.) Boerl, on human cancer cell lines

Abstract

The natural antioxidant gallic acid (GA) was isolated from fruits of a medicinal Indonesian plant, Phaleria macrocarpa (Scheff.) Boerl. The structure was identified on the basis of spectroscopic analysis and comparison with authentic compound. GA demonstrated a significant inhibition of cell proliferation in a series of cancer cell lines and induced apoptosis in esophageal cancer cells (TE-2) but not in non-cancerous cells (CHEK-1). Observation of the molecular mechanism of apoptosis showed that GA up-regulated the pro-apoptosis protein, Bax, and induced caspase-cascade activity in cancer cells. On the other hand, GA down-regulated anti-apoptosis proteins such as Bcl-2 and Xiap. In addition, GA also induced down-regulation of the survival Akt/mTOR pathway. In non-cancerous cells, we observed delayed expression of pro-apoptosis related proteins. Our results suggest that GA might be a potential anticancer compound. However, in depth in vivo studies are needed to elucidate the exact mechanism.