Abstract
The present study investigated the effects of quercetin glucosides, which were isolated from the Chinese onion (Allium chinense), garlic (Allium sativum), onion (Allium cepa L.) and the Welsh onion (Allium fistulosum L.) in HepG2, HT-29 and PC-3 cancer cell lines. Quercetin-3,4'-di-O-glucoside (3,4'-Qdg) and quercetin-4'-O-glucoside (4'-Qmg) comprise ~98% of the flavonoids in the methanol extract of onion. A small amount of 3,4'-Qdg is present in the Welsh onion and Chinese onion, whereas 4'-Qmg is also present in the Welsh onion. In HepG2 cells, 4'-Qmg was demonstrated to exhibit more significant growth inhibition compared with 3,4'-Qdg and quercetin 3-β-D-glucoside, but exhibited less inhibitory effects in PC-3 and HT-29 cells. These results suggest the anti-proliferative potential of 4'-Qmg in various cancer cell lines and the health benefits of the genus Allium. The findings indicate the potential of 4'-Qmg as an anticancer agent for further development.