Glycemic control and therapeutic effect of Nigella sativa and Curcuma longa on rats with streptozotocin-induced diabetic hepatopathy

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This study investigated the possible antidiabetic role and therapeutic crucial action of two medicinal plants namely Curcuma longa L. (Zingiberaccae) rhizome and Nigella sativa L. (Ranunculaceae) seeds compared to the currently available antidiabetic drug gliclazide (diamicron) against diabetic complication induced liver injury in rats. Experimental diabetes was induced by a single-dose (40 mg kg-1, intraperitoneally, i.p.) streptozotocin (STZ)-injection and the two studied plants were administered orally (300 mg kg-1 b.wt. either each alone or in their synergistic combination) for 30 days commenced 2 weeks after induction of diabetes. The following parameters were measured: blood glucose (marker of hyperglycemia), blood fructosamine, hemoglobin (Hb) and albumin (indices of diabetic protein glycation), hepatic glycolytic enzymes, hexokinase (HK), pyruvate kinase (PK) and lactate dehdrogenase (LDH) as well as hepatic gluconeogenic enzyme, phophoenolpyruvate carboxykinase (PEPCK) (to assess the mechanism (s) of hypoglycemic action of the used plants), hepatic oxidative stress markers, Nitric Oxide (NO) and malondialdehyde (MDA, marker of lipid peroxidation), hepatic antioxidant markers including superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR) and reduced glutathione (GSH). Blood alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were also measured as markers of liver function. The results revealed that induction of diabetes induces metabolic disorder and oxidative hepatopathy indicated by the deviation in the above markers in both blood and livers of diabetic rats. Oral administration of either C. longa rhizome or N. sativa seeds or their synergistic combination successfully modulated the diabetic increase in blood glucose and fructosamine to their normal levels as well as the consequence diabetic decrease in the Hb and albumin levels, indicating their potential antidiabetic and antiglycating abilities. The plants also effectively have beneficial action in up-regulating of hepatic glycolytic enzymes and down regulating the gluconcogenic enzyme which have the major role in diabetic hyperglycemia and this may demonstrate the mechanisms of glycemic control of these plants. Furthermore, ingestion of the current plants effectively modulated hepatic oxidative tissue damage indicated by amelioration of the deterioration occurred in oxidative stress and antioxidants markers in hepatic of diabetic animals and ensured by normalization of liver function blood enzymes activities, confirming their potential antioxidant activity. Supplementation of diabetic animals with gliclazide modulated diabetic induced alteration in most of the above studied markers. These results suggest that either C. longa rhizome or N. sativa seeds or their synergistic combination have multi-beneficial actions in controlling diabetes and consequence complication induced in liver and may candidate as natural antidiabetic drugs. © 2009 Academic Journals Inc.

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