Changes in glycoprotein components in streptozotocin--nicotinamide induced type 2 diabetes: influence of tetrahydrocurcumin from Curcuma longa.

Curcuma longa (Zingiberaceae) has been used traditionally as antidiabetic, and has been proven scientifically to possess high antioxidant activity and anticancer properties. The active components of Curcuma longa such as curcumin and tetrahydrocurcumin (THC), a major colourless metabolite of curcumin also possesses antidiabetic, antiinflammatory and antioxidant activity. The ethnopharmacological value of this plant, the effect of THC on glycoproteins was carried out in normal and streptozotocin-nicotiniamide induced type 2 hyperglycaemic rats for 45 days. Glucose, plasma insulin and glycoprotein components in plasma and tissues (hexose, hexosamine, fucose and sialic acid) were determined. Oral administration of THC to diabetic rats showed a decrease in the level of blood glucose and plasma glycoproteins. The levels of plasma insulin and tissue sialic acid were increased where as the levels of tissue hexose, hexosamine and fucose were near normal in diabetic rats treated with THC. The present study indicates that the THC possesses a significant beneficial effect on glycoprotein moiety in addition to its antidiabetic effect. The effect of THC is more prominent than curcumin.