The Molecular Mechanism Tetrahydrocurcumin as an Antihyperlipidemic Agent

Hyperlipidemia is one of the major risk factors of cardiovascular complication in diabetes. A study was undertaken to evaluate the antihyperlipidemic activity of tetrahydrocurcumin (THC). Curcuma longa (Zingiberaceae) is commonly used in the treatment of diabetes by ayurvedic physicians. Curcumin is a biologically active component isolated from the rhizome of Curcuma longa that possess antidiabetic and has been proven scientifically for high antioxidant activity and anticancer properties. THC is one of the major colorless metabolite of curcumin. THC has been reported to exhibit the same physiological and pharmacological properties of curcumin. Curcumin is rapidly metabolized during absorption from the intestine, yielding THC, which has shown the strongest antioxidant activity among all curcuminoids. The levels of total cholesterol, triglycerides, free fatty acids, phospholipids, LDL-cholesterol, VLDL-cholesterol and HMG-CoA reductase activity were significantly increased whereas the level of HDL-cholesterol was significantly decreased in serum, liver and kidney of STZ and nicotinamide induced diabetic rats. In STZ diabetic rats treated with THC and curcumin, the levels of lipids and HMG-CoA reductase activity were significantly decreased while the level of HDL-cholesterol was significantly increased. It was observed that antihyperlipidemic effect may be due to improvement in glycaemic control and increased plasma insulin activity, which may result in STZ and nicotinamide induced diabetic rats treated with THC and curcumin to maintain serum and tissue lipids in normal level. The THC administration showed more effective than curcumin. Fatty acids composition of total lipids was significantly altered in liver, kidney and brain of STZ and nicotinamide induced diabetic rats. There was an increase in the levels of palmitic acid and stearic acid with significant decrease in the levels of linolenic acid and arachidonic acid were observed in the tissue of diabetic rats. These polyunsaturated fatty acids are the major targets for reactive oxygen species (ROS) damage. This study showed that administration of THC and curcumin resulted in a significant protection against the changes in the fatty acid composition in STZ and nicotinamide induced diabetic rats.