Protective effects of Quercus salicina on alloxan-induced oxidative stress in HIT-T15 pancreatic β cells

Abstract

The present study was designed to investigate the protective effect of hot water extracts from Quercus salicina leaves (QSWE) on alloxan-induced oxidative stress in HIT-T15 Syrian hamster pancreatic insulinoma cells. The HIT-T15 cells were treated with alloxan (1 mM) for 1 h and then co-incubated with the QSWE for 24 h. Alloxan significantly decreased the viability of the HIT-T15 cells (P<0.05). QSWE did not exhibit significantly cytotoxic effects and increased the viability of the HIT-T15 cells in a concentration-dependent manner. To further investigate the protective effects of QSWE on alloxan-induced oxidative stress in HIT-T15 cells, the cellular levels of reactive oxygen species (ROS), lipid peroxidation and endogenous antioxidant enzymes, including catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-px), were analyzed. QSWE decreased the intracellular levels of ROS and lipid peroxidation and increased the activity of antioxidant enzymes. These results suggest that QSWE exerted cytoprotective activity against alloxan-induced oxidative stress in HIT-T15 cells through the inhibition of lipid peroxidation, reduction of ROS levels and stimulation of antioxidant enzyme activity. In addition, QSWE also increased the insulin secretion activity of the alloxan-treated HIT-T15 cells.

Keywords: Quercus salicina; cell viability; insulin secretion; pancreatic β cells; reactive oxygen species.

Figure 1.

Effects of Quercus salicina leaf hot water extract (QSWE) on cell viability in HIT-T15 pancreatic cells. Data are representative of three independent experiments as mean ± SD. ^a–bMean values with different letters on the bars are significantly different from each other(P<0.05) according to Duncan’s multiple range test.

Figure 2.

Effects of Quercus salicina leaf hot water extract (QSWE) on cell viability in 1 mM alloxan (ALX)-treated HIT-T15 pancreatic cells. Data are representative of three independent experiments as mean ± SD. ^a–eMean values with different letters on the bars are significantly different from each other (P<0.05) according to Duncan’s multiple range test.

Figure 3.

Effects of Quercus salicina leaf hot water extract (QSWE) on intra-cellular reactive oxygen species (ROS) levels in 1 mM alloxan (ALX)-treated HIT-T15 pancreatic cells. Data are representative of three independent experiments as mean ± SD. ^a–eMean values with different letters on the bars are significantly different from each other(P<0.05) according to Duncan’s multiple range test.

Figure 4.

Effects of Quercus salicina leaf hot water extract (QSWE) on intracellular malonaldehyde (MDA) levels in 1 mM alloxan (ALX)-treated HIT-T15 pancreatic cells. Data are representative of three independent experiments as mean ± SD. ^a–dMean values with different letters on the bars are significantly different from each other (P<0.05) according to Duncan’s multiple range test.

Figure 5.

Effects of Quercus salicina leaf hot water extract (QSWE) on insulin levels in (A) normal and (B) 1 mM alloxan (ALX)-treated HIT-T15 pancreatic cells. Data are representative of three independent experiments as mean ± SD. ^a–fMean values with different letters on the bars are significantly different (P<0.05) according to Duncan’s multiple range test.