Gentianella turkestanerum Showed Protective Effects on Hepatic Injury by Modulating the Endoplasmic Reticulum Stress and NF-κB Signaling Pathway

Abstract

Objective: To investigate the protective effects of Gentianella turkestanerum extraction by butanol (designated as GBA) on hepatic cell line L02 injury induced by carbon tetrachloride (CCl4) and hydrogen peroxide (H2O2). Methods: L02 cells were incubated with 5 µg/mL, 10 µg/mL, 20 µg/mL, 40 µg/mL, 60 µg/mL, 80 µg/mL and 100 µg/mL GBA for 24 hours, and then MTT assay was used to screen the cytotoxicity for GBA. Cells were divided into blank control group, CCl4/H2O2 model group, treated by CCl4 (20 mmol/L) or H2O2 (100 µmol/L); silymarin+CCl4/H2O2 group, treated by CCl4 (20 mmol/L) or H2O2 (100 µmol/L) and 5 µg/mL silymarin; GBA+CCl4/H2O2 group, treated by CCl4 (20 mmol/L) or H2O2 (100 µmol/L) and GBA (5 µg/mL, 10 µg/mL and 20 µg/mL). MTT assay was performed to determine the cellular activity. Malondialdehyde (MDA) content was determined using a commercial kit. The alanine transaminase (ALT), aspartate transaminase (AST) in the supernatant was determined. PE-Annexin V/7-ADD method was utilized to determine the apoptosis of cells. RT-PCR was used to evaluate the expression of endoplasmic reticulum stressrelated genes (CHOP, PERK, IRE1 and ATF6) mRNA. Western blot analysis was performed to determine the expression of CHOP, Caspase 12 and NF-κB protein. Results: Cellular survival after GBA (5 µg/mL, 10 µg/mL and 20 µg/mL) incubation was ≥ 75%. After GBA incubation, levels of ALT and AST showed a significant decrease (P < 0.05), while that of the MDA showed a significant decrease (P < 0.05). The apoptosis in the CCl4 or H2O2 group showed a significant increase compared to the control group (P < 0.05). In contrast, GBA-preincubation could attenuate the cellular apoptosis compared to the CCl4 or H2O2 group, which displayed a dose-dependent manner (P < 0.05). The expression of CHOP, PERK, IRE1 and ATF6 mRNA was significantly up-regulated in the presence of CCl4 or H2O2 (P < 0.05). Whereas, GBA induced a significant decrease in these mRNA thereafter (P < 0.05), together with a decrease in CHOP and Caspase 12 proteins (P < 0.05). Besides, it could attenuate the expression of NF-κB p65 in nuclear protein. Conclusions: G. turkestanerum could inhibit the lipid peroxidation and increase the antioxidant activity. Also, it could inhibit the cellular apoptosis through down-regulating the transcriptional level of ERS related genes and proteins. This process was associated with the nuclear translocation of NF-κB p65 protein.