Antioxidant and cytoprotective effects of L-Serine on human endothelial cells

Oxidative stress has been implicated as a prominent determinant in the development of several diseases such as atherosclerosis. Anti atherosclerotic effects of L-serine have been shown previously but its responsible mechanisms remained unidentified. This study aimed to investigate the antioxidant and cytoprotecrtive effects of L-serine and its possible mechanisms. For this purpose, cell viability analysis and nuclear factor-erythroid 2 (NF-E2)-related factor 2 (Nrf2) activity, heme oxygenase-1 (HO-1) concentration, total Nitric Oxide (NOx) production were evaluated in oxidative stress-induced Human Umbilical Vein Endothelial Cells (HUVECs) pretreated by L-serine. Cytoprotective effects of L-serine was measured through 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. Nrf2 activity and HO-1 concentration were determined in the cell lysate by commercial immunoassay methods. NOx was assayed in the supernatant of culture medium through colorimetric Griess method. Pretreatment with L-serine (0.1-3.2 mM) protected endothelial cells from hydrogen peroxide-mediated cell cytotoxicity (H2O2, 0.5 mM) and lead to significant induction of Nrf2 activity, HO-1 expresssion and NOx production. These findings demonstrated that L-serine has antioxidant and cytoprotective effects through the elevation of some crucial antioxidant factors such as Nrf2, HO-1 and NO.