Biochemical study of the anti-diabetic effect of L-arginine in relation to hepatic glucose metabolism in streptozotocin-diabetic rats

An alternative strategy to treat diabetes is the use of various natural agents possessing hypoglycemic effect. Diabetes is associated with reduced plasma level of L-arginine. Growing evidence indicates that L-arginine may be a novel therapy for diabetes. The present study aimed to evaluate the improving effect of L-arginine on carbohydrate metabolism in streptozotocin [STZ]-diabetic rat liver. Diabetes was induced in adult male Wistar rats by intraperitoneal administration of STZ [50 mg/kg b.wt]. L-arginine was administered to animals in their drinking water [2.25g%] to subset of diabetic animals starting one week after induction of diabetes and continued for 5 weeks. Diabetic rats had elevated levels of blood glucose and glycosylated hemoglobin [HbA[1c]] and increased activities of liver glucose6-phosphatase and phosphorylase. Decreased levels of serum insulin and hepatic glycogen as well as activities of glucokinase, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase were also observed. L-arginine supplementation significantly ameliorates most of the measured parameters. In conclusion, L-argmnine supplementation may represent a potentially useful strategy for the management of diabetes

Hepatoprotective activity of quercetin against diethylnitrosamine - induced liver carcinogenesis in rats

Chemoprevention has emerged as a very effective preventive measure against carcinogenesis. Several bioactive compounds present in fruits and vegetables have revealed cancer protective and curative on carcinogenesis. In the present study, the efficacy of quercetin on oxidative and nitrosative stress markers, membrane integrity markers and alterations in DNA and RNA levels in diethylnitrosamine-induced liver carcinogenesis in rats was assessed. In liver cancer bearing animals there was an increase in serum liver function indices, liver malondialdehyde, nitric oxide, DNA and RNA levels, glucose-6-phosphate dehydrogenase and cytosolic cytochrome C oxidase [as a marker for mitochondrial membrane integrity] activities, along with decrease in superoxide dismutase, catalase, glucose-6-phosphatase [as a marker for plasma membrane integrity] and xanthine oxidase activities. Quercetin supplementation [50mg/kg body weight p.o.] attenuated all these alterations, which indicates the anticancer effect that was further confirmed by histopathological examination. Overall, the above data shows that quercetin could face the liver carcinogenesis induced by diethylnitrosamine. This is could be mediated through combating oxidative stress of free radicals and protecting the cellular membranes from the deleterious effects of diethylnitrosamine