Cuspidatyl Ferulate, a Novel Phenolic Acid from Hyssopus cuspidatus Borris, Protects Hepatocytes Against Oxidative Damage via Keap1 Interaction

Lipotoxicity and oxidative stress are key pathogenic drivers in the development of Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD). The underlying mechanisms of MASLD are not fully understood, and approved pharmacotherapies remain elusive. Thus, exploring therapeutic targets and potential drugs for MASLD is still a major challenge. In our previous study, a new cuspidatyl ferulate (2,3-dihydroxy-4-carboxylic butyl (E)-4-[3-(4-hydroxy-3-methoxyphenyl)-2-propenoate], CuF) was first isolated and identified from <i>Hyssopus cuspidatus</i> Boriss (<i>H. cuspidatus</i>). Here, we investigated the effects of this novel phenolic acid on free fatty acid (FFA)-induced oxidative stress and lipid accumulation in HepG2 cells. Exposure to FFA significantly increased intracellular reactive oxygen species (ROS) levels and lipid accumulation. Notably, CuF treatment effectively reversed FFA-induced suppression of key antioxidant enzymes, including superoxide dismutase (SOD) and catalase (CAT), and attenuated lipid accumulation, as evidenced by reduced total cholesterol (TC) and triglyceride (TG) levels. Mechanistically, molecular docking and capillary electrophoresis analyses revealed that CuF directly interacts with Kelch-like ECH-associated protein 1 (Keap1), disrupting the Keap1-Nrf2 protein complex, thereby promoting nuclear translocation of Nrf2 and activating the antioxidant response pathway. In summary, our findings demonstrate that this novel phenolic acid exhibits strong antioxidant and anti-lipotoxic activities <i>in vitro</i>, offering a potential natural product-based drug candidate for MASLD therapy.