Effects of lupeol on insulin receptor substrate-2 and its phosphorylation in the liver of high-fat diet and sucrose-induced type-2 diabetic rats.

Background: Lupeol is a triterpenoid, is found in vegetables such as white cabbage, pepper, cucumber, and tomato, in fruits such as olive, fig, mango, strawberry, and red grapes, and in medicinal plants. Objectives: The study aimed to identify the effects of lupeol on insulin receptor substrate-2 (IRS-2) and its phosphorylation (IRS-2Ser636) protein expression in liver tissue of Type-2 diabetic rats. Materials and Methods: Lupeol was administered orally to Type-2 diabetic rats (25 mg/kg body weight) for a period of 30 days. After the treatment period, animals were anesthetized and liver from control and experimental animals was dissected out and used for the protein expression of IRS-2 and p-IRS-2Ser636. Results: In Type-2 diabetic animals, the protein expression of IRS-2 significantly reduced. Conversely, tyrosine phosphorylation IRS-2 (IRS-2Tyr636) was elevated in high-fat diet-induced Type-2 diabetic rats when compared with control. The lupeol administration to diabetic rats significantly restored the altered levels of IRS-2 proteins in the liver. Conclusion: It is concluded from the present findings that lupeol regulates insulin signaling molecules (IRS-2) as a result of increase in insulin sensitivity in Type-2 diabetic rats. [ABSTRACT FROM AUTHOR]