The study evaluated the protective effects of Cissus quadrangularis stem extract (CQEt) on oxidant-antioxidant balance and insulin resistance (IR) in rats fed high fat-high fructose diet (HFFD) and also tested its free-radical scavenging property in vitro. Rats were fed either control diet or HFFD for 15 days, following which the diet was fortified with CQEt at a dose of 10 g/100g diet. After 60 days, HFFD caused deleterious metabolic effects, including hyperglycemia, IR and liver dysfunction. Rats fed HFFD alone showed increased activities of hepatocellular enzymes in plasma, lipid deposition, significant decline in antioxidants, and elevated lipid peroxidation indices and protein carbonyl in liver. CQEt addition significantly improved insulin sensitivity, reduced liver damage and oxidative changes, and brought back the antioxidants and lipids towards normal. Histopathology of the liver confirmed the changes induced by HFFD and the heptoprotective effect of CQEt. The effects of CQEtin vivo were comparable with that of standard drug, metformin. Through in vitro assays, CQEt was found to contain large quantities of polyphenols, vitamins C and E. CQEt exhibited radical scavenging ability in a dose-dependent manner. These data suggest that CQEt affords hepatoprotection by its antioxidant and insulin-sensitizing activities.
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