Abstract
Hyperlipidemia is a common chronic disease characterized by elevated levels of lipids in the blood. There is some evidence that suggests that berberine (BBR) might be beneficial for the treatment of hyperlipidemia. However, its low intestinal bioavailability limits its potential therapeutic action. In the present study, we explored the effect and the underlying mechanism of berberine-cinnamic acid co-crystal (BBR-CA), which is self-assembled from CA and BBR and displays a high intestinal bioavailability. In mice, BBR-CA showed the ability to decrease body weight gain and hepatic lipid accumulation in animals fed a high-fat diet. To further characterize the molecular basis of this effect, we established a hyperlipidemia cell model by treating human hepatocellular carcinoma cells (HepG2) with free fatty acids. Similarly to our in vivo experiments, lipid accumulation in free fatty acids-induced HepG2 cells was also reduced by BBR-CA. We hypothesized that BBR-CA might act through the regulation of sterol regulatory element-binding proteins-1 (SREBP-1), a key factor regulating lipid synthesis, and, indeed, SREBP-1 protein expression was inhibited by BBR-CA treatment, resulting in the decreased expression of its downstream proteins stearoyl-CoA desaturase 1 and acetyl-CoA carboxylase. Furthermore, the phosphorylation of phosphatidylinositol 3-kinase (PI3K), AKT and mammalian target of rapamycin (mTOR) was inhibited by BBR-CA, contributing to decreased active SREBP-1 in the nucleus, and was reversed and enhanced by the PI3K agonist recilisib and inhibitor LY294002, respectively. Taken together, our results suggest that BBR-CA could function by modulating the PI3K/AKT/mTOR signaling pathway, resulting in decreased nuclear expression of SREBP-1, as well as reduced expression of stearoyl-CoA desaturase 1 and acetyl-CoA carboxylase, thus alleviating hyperlipidemia. Further experimental validation is required to confirm these results.