Rosmarinic acid exerts an antagonistic effect on nonalcoholic fatty liver disease by regulating the YAP1/TAZ‐PPARγ/PGC‐1α signaling pathway

Rosmarinic acid (RA) is a water‐soluble phenolic compound extracted from Boraginaceae and Lamiaceae . This study was designed to investigate the role and mechanism of action of RA in improving nonalcoholic fatty liver disease (NAFLD). Male SD rats maintained on a high fat diet and L02 cells stimulated with oleic acid were treated with RA. Our results showed that RA significantly reduced total cholesterol, triglycerides, low‐density lipoprotein cholesterol, alanine aminotransferase, aspartate aminotransferase, and malondialdehyde levels and increased high‐density lipoprotein cholesterol, superoxide dismutase and adenosine triphosphate levels both in vivo and in vitro. Hematoxylin and eosin staining and oil red O staining showed that RA had a good lipid‐lowering effect and substantial protective effects on liver injury. Transmission electron microscopy and JC‐1 fluorescence results showed that RA could improve mitochondrial damage in hepatocytes. Additionally, flow cytometry results indicated that RA inhibited ROS generation and apoptosis in L02 cells. The impaired hepatocytes were restored by using RA in NAFLD models characterized by down‐regulating YAP1 and TAZ, meanwhile up‐regulating PPARγ and PGC‐1α. When YAP1 was over‐expressed, RA reduced the expression of YAP1; however, the action of RA was significantly blocked by silencing YAP1. The experimental results indicated that RA markedly alleviated NAFLD by repairing mitochondrial damage and regulating the YAP1/TAZ‐PPARγ/PGC‐1α signaling pathway.