Amelioration by chicory seed extract of diabetes- and oleic acid-induced non-alcoholic fatty liver disease (NAFLD)/non-alcoholic steatohepatitis (NASH) via modulation of PPARα and SREBP-1

Abstract

We evaluated the effect of chicory (Cichorium intybus L.) seed extract (CI) on hepatic steatosis caused by early and late stage diabetes in rats (in vivo), and induced in HepG2 cells (in vitro) by BSA-oleic acid complex (OA). Different dosages of CI (1.25, 2.5 and 5 mg/ml) were applied along with OA (1 mM) to HepG2 cells, simultaneously and non-simultaneously; and without OA to ordinary non-steatotic cells. Cellular lipid accumulation and glycerol release, and hepatic triglyceride (TG) content were measured. The expression levels of sterol regulatory element-binding protein-1c (SREBP-1c) and peroxisome proliferator-activated receptor alpha (PPARα) were determined. Liver samples were stained with hematoxylin and eosin (H&E). Significant histological damage (steatosis-inflammation-fibrosis) to the cells and tissues and down-regulation of SREBP-1c and PPARα genes that followed steatosis induction were prevented by CI in simultaneous treatment. In non-simultaneous treatment, CI up-regulated the expression of both genes and restored the normal levels of the corresponding proteins; with a greater stimulating effect on PPARα, CI acted as a PPARα agonist. CI released glycerol from HepG2 cells, and targeted the first and the second hit phases of hepatic steatosis. A preliminary attempt to characterize CI showed caffeic acid, chlorogenic acid, and chicoric acid, among the constituents.

Keywords: 0.1% Tween in phosphate buffer saline; 1,1-diphenyl-2-picryl hydrazyl radical; 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide; 50% inhibition concentration; ACAT; AGE; ALT; ANOVA; AST; BSA; BSA–oleic acid complex; BSDL; CI; CON; CYP7A1; Chicory; Cichorium intybus (chicory) extract; DMEM; DMSO; DPPH; Diabetic rat; Dulbecco’s Modified Eagle’s Medium; ECL; FA; FBS; FFA; H&E; HCC; HL; HPLC; HRP; HepG2; HepG2 cells; IC50; LDH; MTT; NAFLD; NASH; NIA; OA; OD; ORO; Oil red O; PBST; PPARα; PTP1B; PVDF; Polyvinylidene fluoride; RIPA; ROS; SDS; SDS-PAGE; SDS-polyacrylamide gel; SREBP-1c; STZ; Steatosis; T2DM; TG; acyl-CoA:cholesterol acyltransferase; advanced glycation end-products; alanine aminotransferase; analysis of variance; aspartate aminotranferase; bile salt-dependent lipase; bovine serum albumin; cholesterol 7 alpha-hydroxylase, cholesterol 7-alpha-monooxygenase, or cytochrome P450 7A1; control; dimethylsulfoxide; enhanced chemiluminescence; fatty acid; fetal bovine serum; free fatty acid; hematoxylin and eosin; hepatic lipase; hepatocellular carcinoma; high performance liquid chromatography; horseradish peroxidase; human hepatoma cell line; lactate dehydrogenase; niacinamide; non-alcoholic fatty liver disease; non-alcoholic steatohepatitis; optical density; peroxisome proliferator-activated receptor alpha; protein tyrosine phosphatase 1B; radioimmunoprecipitation assay buffer; reactive oxygen species; retention time; sodium dodecyl sulfate; sterol regulatory element-binding protein-1c; streptozotocin; t(R); triglyceride; type 2 diabetes mellitus.