Mulberry leaf extract inhibits obesity and protects against diethylnitrosamine-induced hepatocellular carcinoma in rats

Mulberry leaf has been recognized as a traditional Chinese medicinal plant, which was distributed throughout the Asia. The aqueous extract of mulberry leaf extract (MLE) has various biologically active components such as polyphenols and flavonoids. However, the inhibitory effect of MLE in hepatocarcinogenesis is poorly understood. In this study, we determined the role of MLE supplementation in preventing hepatocarcinogenesis in a carcinogen-initiated high-fat diet (HFD)-promoted Sprague-Dawley (SD) rat model. The rats were fed an HFD to induce obesity and spontaneous hepatomas by administering 0.01% diethylnitrosamine (DEN) in their drinking water for 12 weeks (HD group), and also to fed MLE through oral ingestion at daily doses of 0.5%, 1%, or 2%. At the end of the 12-week experimental period, the liver tumors were analyzed to identify markers of oxidative stress and antioxidant enzyme activities, and their serum was analyzed to determine their nutritional status and liver function. Histopathological analysis revealed that MLE supplementation significantly suppressed the severity and incidence of hepatic tumors. Furthermore, compared with the HFD + DEN groups, the expression of protein kinase C (PKC)-α and Rac family small GTPase 1 (Rac1) was lower in the MLE groups. These findings suggest that MLE prevents obesity-enhanced, carcinogen-induced hepatocellular carcinoma development, potentially through the protein kinase C (PKC)α/Rac1 signaling pathway. MLE might be an effective chemoprevention modality for nonalcoholic fatty liver disease (NAFLD)/nonalcoholic steatohepatitis (NASH)-related hepatocarcinogenesis.