Exploring the active compounds and potential mechanism of the anti-nonalcoholic fatty liver disease activity of the fraction from Schisandra chinensis fruit extract based on multi-technology integrated network pharmacology

Schisandra chinensis fruit is a well-known traditional Chinese medicine (TCM) that has been used to treat various liver diseases. Our previous study revealed that its extract is effective against nonalcoholic fatty liver disease (NAFLD).This study aimed to elucidate the active components and explore the underlying mechanisms of action of S. chinensis fruit in the treatment of NAFLD.A HepG2 cell model was used to screen the anti-NAFLD activity of the fraction from S. chinensis fruit extract. Ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS) was used to determine the components of the active fraction. Active compounds, potential targets, and key pathways were predicted for the active fraction treatment of NAFLD using network pharmacology. The anti-NAFLD effects of the active fraction and core active compound 3 were further validated using a high-fat diet (HFD)-induced NAFLD mouse model, intraperitoneal glucose tolerance test (IPGTT), and intraperitoneal insulin tolerance test (IPITT). Related hepatic mRNA expression was detected using quantitative reverse transcription-polymerase chain reaction (qRT-PCR) to preliminarily validate the mechanism.In vitro experiments showed that the active fraction of S. chinensis fruit ethanol (EtOH) extract was mainly concentrated in the soluble fraction of petroleum ether (PET). Thirty-seven lignans were identified in this active fraction using UPLC-Q-TOF/MS. Network pharmacology studies have indicated that its anti-NAFLD effects lie in three major active lignans (3, 24, and 27) contained in PET, which may regulate the insulin resistance signaling pathway. In vivo experiments demonstrated that PET and core active compound 3 treatment significantly attenuated hepatic steatosis and reduced the levels of serum alanine transaminase (ALT), aspartate transaminase (AST), insulin, malondialdehyde (MDA), hepatic triglyceride (TG), and total cholesterol (TC) in HFD-induced mice (P < 0.05). Moreover, treatment with PET and compound 3 alleviated glucose tolerance and insulin resistance. These beneficial effects can be achieved by regulating the expression of Pik3ca, Gsk3β, Jnk1, and Tnf-α.This study identified the main active fraction and compounds responsible for the anti-NAFLD activity of S. chinensis fruit. This mechanism may be related to regulation of the resistance pathway.