Effect of Tetrahydrocurcumin Compared to Curcumin in Carbohydrate Metabolism and Glycoprotein Components in Type 2 Diabetes - Systematic Review

Abstract

Pancreatic β-cell dysfunction and insulin resistance are the two hallmarks of type 2 diabetes mellitus. Treatment of diabetes without any side effects is still a challenge to the medical system. There is an increasing demand by patients to use the natural products with antidiabetic activity, because insulin and oral hypoglycemic drugs are having so many side effects. Curcumin is a biologically active component isolated from the rhizome of Curcuma longa that possess antidiabetic and has been proven scientifically to possess high antioxidant activity and anticancer properties. Tetrahydrocurcumin (THC) is a major curcuminoid metabolite of curcumin, naturally occurring in turmeric. The interest in THC research is increasing because it is superior to curcumin in its solubility in water, chemical stability, bioavailability, and anti-oxidative activity. Many in vitro and in vivo studies have revealed that THC exerts antidiabetic effects through various mechanisms, including modulation of oxidative stress, xenobiotic detoxification, inflammation, proliferation, metastasis, programmed cell death, and immunity. The activities of glycolytic enzymes such as hexokinase and glucose-6-phosphate dehydrogenase were found to be decreased whereas the activities of gluconeogenic enzymes (glucose-6-phosphatase and fructose-1,6-bisphosphatase) and polyol pathway enzyme-sorbitol dehydrogenase were significantly increased in diabetic control rats. In addition, the oligosaccharide moieties of glycoproteins (hexose, hexosamine, fucose and sialic acid) were also significantly increased in plasma and tissues of diabetic control rats. THC and curcumin administration to diabetic rats significantly reversed the above changes when compared to diabetic control rats. In diabetic controls, hepatic and skeletal muscle glycogen content was decreased significantly as compared to non-diabetic controls. Treatment with THC and curcumin increased the hepatic and skeletal muscle glycogen significantly. The antidiabetic and antioxidant effects of THC are more potent than those of curcumin at the same dose. The antihyperglycemic action of THC might be mediated via an enhancement of insulin action, as it is evidenced by the increased levels of insulin in diabetic rats treated with THC, which may be responsible for the reversal of changes in carbohydrate enzymes and glycoprotein components. The THC administration showed more effective than curcumin.