Intervention by picroside II on FFAs induced lipid accumulation and lipotoxicity in HepG2 cells

Abstract

Background Accumulation of free fatty acids (FFAs) in hepatocytes is a hallmark of liver dysfunction and non-alcoholic fatty liver disease (NAFLD). Excessive deposition of FFAs alters lipid metabolism pathways increasing the oxidative stress and mitochondrial dysfunction. Attenuating hepatic lipid accumulation, oxidative stress, and improving mitochondrial function could provide potential targets in preventing progression of non-alcoholic fatty liver (NAFL) to non-alcoholic steatohepatitis (NASH). Earlier studies with Picrorhiza kurroa extract have shown reduction in hepatic damage and fatty acid infiltration in several experimental models and also clinically in viral hepatitis. Thus, the effect of P. kurroa's phytoactive, picroside II, needed mechanistic investigation in appropriate in vitro liver cell model. Objective(s) To study the effect of picroside II on FFAs accumulation, oxidative stress and mitochondrial function with silibinin as a positive control in in vitro NAFLD model. Materials and methods HepG2 cells were incubated with FFAs-1000μM in presence and absence of Picroside II-10 μM for 20 hours. Results HepG2 cells incubated with FFAs-1000μM lead to increased lipid accumulation. Picroside II-10μM attenuated FFAs-induced lipid accumulation (33%), loss of mitochondrial membrane potential (ΔΨm), ATP depletion, and production of reactive oxygen species (ROS). A concomitant increase in cytochrome C at transcription and protein levels was observed. An increase in expression of MnSOD, catalase, and higher levels of tGSH and GSH:GSSG ratios underlie the ROS salvaging activity of picroside II. Conclusion Picroside II significantly attenuated FFAs-induced-lipotoxicity. The reduction in ROS, increased antioxidant enzymes, and improvement in mitochondrial function underlie the mechanisms of action of picroside II. These findings suggest a need to develop an investigational drug profile of picroside II for NAFLD as a therapeutic strategy. This could be evaluated through the fast-track path of reverse pharmacology.

Protective Effect and Mechanism of Plant-Based Monoterpenoids in Non-alcoholic Fatty Liver Diseases

“…110 In NAFLD models of HepG2 hepatocytes with lipid deposition, picroside II attenuated lipid accumulation by the modification of FFA uptake and synthesis by attenuating FATP5, SCD1, and SREBP-1 111 and reducing lipotoxicity. 112 Picroside II also decreased the expression of gluconeogenic genes FOXO1 and PEPCK. 111 Improvement in the oxidative stress balance and mitochondrial function underlies the mechanisms of action of picroside II.…”

“…Picroside II is a methanol-soluble white or yellow crystalline powder and one of the iridoid glycosides present in Picrorhiza kurroa, which is a medicinal plant known for its clinical and experimental hepatoprotective activity; it has antioxidant, anti-inflammatory, and antiapoptotic activities . In NAFLD models of HepG2 hepatocytes with lipid deposition, picroside II attenuated lipid accumulation by the modification of FFA uptake and synthesis by attenuating FATP5, SCD1, and SREBP-1 and reducing lipotoxicity . Picroside II also decreased the expression of gluconeogenic genes FOXO1 and PEPCK .…”

“…Picroside II caused a decrease in ROS formation, along with an increase in the levels of antioxidant enzymes GSH, SOD, and CAT. Further, picroside II rescued mitochondrial dysfunction by preventing ATP decrease, reversing delta ΔΨ m loss, and upregulating cytochrome c and COX IV, in turn activating a single electron carrier in the electron transport chain catalyzing the reduction of an oxygen molecule to water, leading to more ATP …”