Mechanism investigation of anti-NAFLD of Shugan Yipi Granule based on network pharmacology analysis and experimental verification

As a classical traditional Chinese patent medicine, Shugan Yipi Granule is widely used in China to treat non-alcoholic fatty liver disease (NAFLD) recently. Our previous study confirmed that Shugan Yipi Granule are effective in NAFLD. However, its underlying mechanism is still unknown. This study aims to investigate the mechanism of Shugan Yipi Granule on NAFLD based on network pharmacology prediction, liquid chromatography-mass spectrometry (LC-MS) analysis and in vitro verification. We obtained the active ingredients and targets of Shugan Yipi Granule and NAFLD from 6 traditional Chinese medicine databases, and the crucial components and targets screened by protein-protein interaction (PPI) network were used for molecular docking. Plasma metabolomics of NAFLD patients treated with Shugan Yipi Granule for one month was analyzed using LC-MS methods and MetaboAnalyst 4.0 to obtain significant differential metabolites and pathways. Finally, free fatty acid (FFA) induced HepG2 cells were treated with different concentrations of quercetin and kaempferol, then oil red o (ORO) and triglyceride (TG) level were tested to verify the lipid deposition of the cell. Network pharmacology analysis showed that the main active ingredients of Shugan Yipi Granule include quercetin, kaempferol and other 58 ones, as well as 188 potential targets. PI3K/Akt signaling pathway was found to be the most relevant pathway for the treatment of NAFLD. Non-targeted metabolomics showed that quercetin and kaempferol were significantly up-regulated differential metabolites and were involved in metabolic pathways such as thyroid hormone signaling. In vitro results showed that quercetin, kaempferol were effective in reducing lipid deposition and TG content by inhibiting cellular fatty acid uptake. Ultimately, with the network pharmacology and serum metabolomics analysis, quercetin and kaempferol were found to be the important active ingredients and significantly up-regulated differential metabolites of Shugan Yipi Granule against NAFLD, which we inferred that they may regulate NAFLD through PI3K/Akt signaling pathway and thyroid hormone metabolism pathway. The in vitro experiment verification results showed that quercetin and kaempferol attenuated the lipid accumulation and TG content by inhibiting the fatty acid uptake in the FFA-induced HepG2 cell. Current study provides the necessary experimental basis for subsequent in-depth mechanism research.