ANTIRADICAL PROPERTY OF CINNAMON REDUCES FRUCTOSE-INDUCED OXIDATIVE STRESS IN RAT LIVER

Abstract

ABSTRACT The ingestion of fructose as the sole source of carbohydrate in the diet has prooxidant effects in rats. The aim of the present study was to determine whether the administration of the cinnamon bark extract (CBEt) would prevent fructose-induced oxidative stress in rat liver. An aqueous extract of the bark was prepared, the total polyphenolic content of which was found to be 1.32 mM eugenol equivalents (EE). CBEt was administered at two different doses (0.2 mL containing 0.264 µmol EE and 2.0 mL containing 2.64 µmol EE) for 60 days to rats fed with a high-fructose diet (60 g/100 g diet). CBEt at a high dose (2.0 mL) reduced the formation of lipid peroxidation products, namely, thiobarbituric acid reactive substances (TBARS) and lipid hydroperoxides (LHPs) in the plasma and liver, and replenished the enzymatic and nonenzymatic antioxidant system in the blood and liver. The aqueous extract also inhibited TBARS formation induced by the Fe 2+ –ascorbate system in the control rat liver homogenate in vitro and scavenged superoxide and hydroxyl radicals in a dose-dependent manner. Among the various doses studied, the maximum inhibition of lipid peroxidation was observed at 264 µM EE. The positive effects of cinnamon could be attributed to the presence of phenolic phytochemicals in the water-soluble portion of the bark. PRACTICAL APPLICATIONS The insulin-potentiating actions of cinnamon in type 2 diabetes is documented in the literature. We investigated the effect of the administration of cinnamon (Cinnamomum zeylanicum) bark on the oxidant–antioxidant balance in high fructose-induced rat model of insulin resistance. Cinnamon bark (80 mg/day) reduced the formation of lipid peroxidation products and replenished the enzymatic and nonenzymatic antioxidant system in blood and liver. The aqueous extract of the bark remarkably inhibited lipid peroxidation induced by Fe2+–ascorbate system in the control rat liver in vitro and scavenged superoxide and hydroxyl radicals in a dose-dependent manner. The demonstration that cinnamon limits oxidative stress in this animal model of insulin resistance could be significant, considering the increased use of fructose in the food industry and the rising prevalence of type 2 diabetes. Regular inclusion of cinnamon in the daily diet could be beneficial in alleviating diseases that involve oxidative stress.