Selenium enrichment improves anti-proliferative effect of oolong tea extract on human hepatoma HuH-7 cells

Selenium (Se)-enriched tea is attracting increasing interests due to its significantly improved health benefits. This study was to investigate the anti-proliferative effects of Se-enriched oolong tea against human hepatoma HuH-7 cells. Compared with regular oolong tea extract (TE, 0.04 μg selenium/g), Se-enriched oolong tea extract (Se-TE, 0.51 μg selenium/g) exhibited more prominent anti-proliferative effect against HuH-7 cells with an IC₅₀ of 203.1 μg/mL, mainly due to the synergistic effects of organic selenium and tea polyphenols. Our results found that Se-TE increased intracellular ROS production, arrested the cell cycle at G2/M phase, and thus induced cell apoptosis. In addition, western blotting assay revealed the increased expressions of the p53, Bax, caspase 3, and a reduction of Bcl-2 and CDK2, resulting in Se-TE-induced apoptosis. The improved anti-proliferative effect makes Se-enriched oolong tea extract a promising health-promoting ingredient in food industry.