Effect of salvianolic acid B on oxidative stress in a cell model of nonalcoholic fatty liver disease

Objective To establish a cell model of nonalcoholic fatty liver disease ( NAFLD) by inducing HepG2 cells with oleic acid ( OA) in vitro, and to investigate the effect of salvianolic acid B ( Sal B) on oxidative stress in NAFLD cells and its possible mechanisms via the intervention of NAFLD cells with Sal B. Methods HepG2 cells were divided into control group, model group ( treated with OA) , and intervention group ( treated with OA + Sal B) . The CCK8 method was used to plot the standard cell growth curve, and the optimal drug intervention concentration and intervention time were determined for OA. Oil red O staining was used to observe intracellular lipid accumulation.The levels of alanine aminotransferase ( ALT) , aspartate aminotransferase ( AST) , triglyceride ( TG) , and total cholesterol ( TC) were measured. A fluorescence microscope was used to measure the content of reactive oxygen species ( ROS) in cells. The TBA method was used to measure the content of malondialdehyde ( MDA) in cells. RT-qPCR and Western blot were used to measure the mRNA and protein expression of SOD2 and SIRT3. After SIRT3 was upregualted with SIRT3 overexpression plasmid, Sal B intervention was performed. Western blot was used to screen out the optimal ratio of transfection reagent to plasmid, and the change in relative expression of SIRT3 and SOD2 was measured. A one-way analysis of variance was used for comparison between multiple groups, and the least significant difference t-test was used for further comparison between two groups. Results The optimal concentration of OA for modeling was 1 mmol/L. The model group had higher levels of ALT and AST in cell culture supernatant than the control group, and the intervention group had lower levels of ALT and AST than the model group; there were significant differences between the three groups ( F = 1240. 075 and 471. 989, both P < 0. 05) . The model group had higher levels of TG and TC in cells than the control group, and the intervention group had lower levels of TG and TC than the model group; there were significant differences between the three groups ( F = 97. 530 and 39. 824, both P < 0. 01) . The model group had a higher MDA level than the control group, and the intervention group had a significantly lower MDA level than the model group; there was a significant difference between the three groups ( F = 336. 67, P < 0. 01) . There were significant differences in the mRNA expression of SIRT3 and SOD2 between the three groups ( F = 119. 35 and 32. 005, both P < 0. 01) ; the model group had significantly lower mRNA expression of SIRT3 and SOD2 than the control group ( P < 0. 05) , and the intervention group had significantly higher mRNA expression of SIRT3 and SOD2 than the model group ( P < 0. 05) . There were significant differences in the protein expression of SIRT3 and SOD2 between the three groups ( F = 67. 093 and 70. 314, both P < 0. 01) ; the model group had significantly lower protein expression of SIRT3 and SOD2 than the control group ( P < 0. 01) , and the intervention group had significantly higher protein expression of SIRT3 and SOD2 than the model group ( P < 0. 01) . The Western blot showed significant differences in the protein expression of SIRT3 and SOD2 between the empty plasmid+ Sal B group, plasmid group, empty plasmid group, and plasmid + Sal B group ( F = 287. 2 and 179. 8, both P < 0. 01) ; the empty plasmid + Sal B group and plasmid group had significantly higher protein expression of SIRT3 and SOD2 than the empty plasmid group ( P < 0. 05) , and the plasmid + Sal B group had significantly higher protein expression of SIRT3 and SOD2 than the plasmid group ( P < 0. 05) . Conclusion Sal B can reduce lipid accumulation and oxidative stress response in NAFLD cells and thus exert a protective effect on NAFLD cells.