Methyl gallate and chemicals structurally related to methyl gallate protect human umbilical vein endothelial cells from oxidative stress

Methyl gallate (meGAL) is known as one of major antioxidants. To investigate whether meGAL protects human cells from oxidative stress, meGAL extracted from Korean medicinal plant, Cercis chinensis leaves, was primarily screened using cell viability assay against oxidative stress. Human umbilical vein endothelial cells (HUVECs) were treated with three different concentrations of meGAL for indicated time. After or during meGAL treatment, H(2)O(2)was, added and incubated. meGAL showed free radical scavenging effect at low concentration (0.02 mM) and cell protective effect against H2O2-mediated oxidative stress. meGAL recovered viability of HUVECs damaged by H2O2-treatment, reduced the lipid peroxidation (LPO) and decreased the internal reactive oxygen species (ROS) level elevated by H2O2-treatment. Free radical scavenging effect of meGAL was proven to be very high. Differential display reverse transcription-PCR analysis showed that meGAL upregulated the levels of regulator of chromatin condensation 1, type 1 sigma receptor and phosphate carrier protein expressions, respectively. Based on structural similarity compared with meGAL, 14 chemicals were chosen and viability assay was performed. Four chemicals, haematommic acid (56.2% enhancement of viability), gallic acid (35.0%), methylorsellinic acid (23.7%), and syringic acid (20.8%), enhanced more potent cell viability than meGAL, which showed only 18.1 % enhancement of cell viability. These results suggest that meGAL and four meGAL-related chemicals protect HUVECs from oxidative stress.