Malaysian propolis, metformin and their combination, exert hepatoprotective effect in streptozotocin-induced diabetic rats.

AIMS: Hepatic oxidative stress and weak antioxidant defence system resulting in hepatic lesion, has been reported in diabetic rats. The present study investigated the possible hepatoprotective effects of Malaysian propolis (MP) in diabetic rats, on the background that MP has been reported to have anti-hyperglycemic, antioxidant and anti-inflammatory effects.

MATERIALS AND METHODS: Sprague-Dawley rats were randomly divided into 5 groups, namely: normal control (NC), diabetic control (DC), diabetic on 300 mg/kg b.w. MP, diabetic on 300 mg/kg b.w. metformin, and diabetic on MP and metformin combined therapy. Treatment was done orally for 4 weeks, and NC and DC groups received distilled water as vehicle.

KEY FINDINGS: Results showed increased fasting blood glucose and serum markers of hepatic lesion (aspartate aminotransferase, alkaline phosphatase, alanine aminotransferase and gamma-glutamyl transferase), increased hepatic lactate dehydrogenase activity, decreased hepatic superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase and glutathione reductase activities, increased immunoexpressions of nuclear factor kappa B, tumor necrosis factor-α, interleukin(IL)-1β and caspase-3, and decreased immunoexpressions of IL-10 and proliferating cell nuclear antigen in the liver of DC group. Histopathology of the liver revealed numerous hepatocytes with pyknotic nuclei and inflammatory infiltration, while periodic acid-schiff staining decreased in the liver of DC group. Treatment with MP attenuated these negative effects and was comparable to metformin. Furthermore, these effects were better attenuated in the combined therapy-treated diabetic rats.

SIGNIFICANCE: Malaysian propolis attenuates hepatic lesion in DM and exerts a synergistic protective effect with the anti-hyperglycemic medication, metformin.