The antiproliferative activity of prodelphinidin B-2 3′-O-gallate from green tea leaf is through cell cycle arrest and Fas-mediated apoptotic pathway in A549 cells

Prodelphinidin B-2 3′-O-gallate, a proanthocyanidin gallate isolated from green tea leaf, was investigated for its anti-proliferative activity in human non-small cell lung cancer A549 cells. The results showed that prodelphinidin B-2 3′-O-gallate inhibited the proliferation of A549 cells with no detectable toxic effects on normal WI-38 cells as measured by the XTT assay. Flow cytometric analysis showed that prodelphinidin B-2 3′-O-gallate blocked cell cycle progression in the G0/G1 phase. In addition, prodelphinidin B-2 3′-O-gallate effectively induced A549 cell apoptosis as determined by assessing the nucleosome level in cytoplasm. Enzyme-linked immunosorbent assay showed that the G0/G1 phase arrest is due to p53-independent induction of p21/WAF1. An enhancement in Fas/APO-1 and its two form ligands, membrane-bound Fas ligand (mFasL) and soluble Fas ligand (sFasL), might be responsible for the apoptotic effect induced by prodelphinidin B-2 3′-O-gallate. We suggested that prodelphinidin B-2 3′-O-gallate's activities might be potentially contribute to its overall chemopreventive effects against lung cancer, and can possibly be considered for future therapeutic application.