Isolation and characterization of a novel oligomeric proanthocyanidin with significant anti-cancer activities from grape stems ( Vitis vinifera )

Novel proanthocyanidin fractions from grape stem extracts were purified using Amberlite XAD-1180N, Sephadex-LH-20, Toyopearl HW40F and reverse phase high-performance liquid chromatography. Two key compounds were estimated as epigallocatechin-(epicatechin) 7 gallate using electron-spray ionization time-of-flight mass spectrometry. Epigallocatechin-(epicatechin) 7 gallate (compound 1 ) showed significant anti-cancer activity in PC-3 prostate cancer cells. In particular, compound 1 suppressed the gene expression of fatty acid-binding protein 5 ( FABP5 ), which is involved in promoting cell proliferation and metastasis in prostate cancer cells.