In vitro Anti-angiogenic Effects of Tea Saponin and Tea Aglucone on Human Umbilical Vein Endothelial Cells

Abstract

Green tea is a popular beverage world-wide, especially in Asian countries. Its health benefits, derived from the Camellia sinensis leaves, have been studied over the years. However, few reports are available about the health effects of tea saponin (TS), an important component of Camellia sinensis leaves, and tea aglucone (TA). In this present study, we investigated the effect of TS and TA on the proliferation, migration, invasion and tube formation of human umbilical vein endothelial cells (HUVECs). TS inhibited the proliferation of HUVECs in a dose-dependent manner, with an IC50 of 7.5 ± 0.6 μM. Inconsistent with the well-reported mechanisms of apoptotic induction and cell cycle arrest by steroidal saponins, effects of TS on apoptosis and cell cycle progression in HUVECs were not detected. The autophagic vacuoles in the TS-treated HUVECs, observed with transmission electron microscopy, suggested the involvement of autophagic induction in the growth inhibition of HUVECs. When treated with TS, cell migration, invasion and tube formation potency of HUVECs were markedly suppressed. TA also suppressed the proliferation of HUVECs, with an IC50 of 25.3 ± 1.2 μM. In comparison with TS, TA inhibited the migration, invasion, and tube formation of HUVECs less effectively. Our data about the anti-angiogenic effects of TS and TA, presented for the first time, would provide a new insight into the health potential for green tea.