Abstract
Knowing that curcumin has low bioavailability when administered orally, and that piperine has bioenhancer activity by inhibition of hepatic and intestinal biotransformation processes, the aim of this study was to investigate the antidiabetic and antioxidant activities of curcumin (90 mg/kg) and piperine (20 or 40 mg/kg), alone or co-administered, incorporated in yoghurt, in streptozotocin (STZ)-diabetic rats. The treatment for 45 days of STZ-diabetic rats with curcumin-enriched yoghurt improved all parameters altered in this experimental model of diabetes: the body weight was increased in association with the weight of skeletal muscles and white adipose tissues; the progressive increase in the glycemia levels was avoided, as well as in the glycosuria, urinary urea, dyslipidemia, and markers of liver (alanine and aspartate aminotransferases and alkaline phosphatase) and kidney (urinary protein) dysfunction; the hepatic oxidative stress was decreased, since the activities of the antioxidant enzymes superoxide dismutase, catalase and gluthatione peroxidase were increased, and the levels of malondialdehyde and protein carbonyl groups were reduced. The dose of 20 mg/kg piperine also showed antidiabetic and antioxidant activities. The treatment of STZ-diabetic rats with both curcumin and 20 mg/kg piperine in yoghurt did not change the antidiabetic and antioxidant activities of curcumin; notably, the treatment with both curcumin and 40 mg/kg piperine abrogated the beneficial effects of curcumin. In addition, the alanine aminotransferase levels were further increased in diabetic rats treated with curcumin and 40 mg/kg piperine in comparison with untreated diabetic rats. These findings support that the co-administration of curcumin with a bioenhancer did not bring any advantage to the curcumin effects, at least about the antidiabetic and antioxidant activities, which could be related to changes on its biotransformation.
Highlights
Diabetes mellitus (DM) is a chronic endocrine disease characterized by disorders in the metabolism of carbohydrates, lipids and proteins due to a deficiency in the insulin production by pancreatic beta cells and/or to an increase in the insulin resistance in peripheral tissues
It can be observed that the induction of diabetes in rats was effective, since all groups started the experiment with blood glucose levels of approximately 25 mmol/L
When diabetic rats were treated with curcumin +40 mg/kg piperine (DC90P40), the improvement in the glycemia control promoted by curcumin was impaired, since the glycemia values were similar those observed in diabetic rats treated with yoghurt (DYOG)
Summary
Diabetes mellitus (DM) is a chronic endocrine disease characterized by disorders in the metabolism of carbohydrates, lipids and proteins due to a deficiency in the insulin production by pancreatic beta cells and/or to an increase in the insulin resistance in peripheral tissues. The International Diabetes Federation (IDF) estimated the world prevalence of DM for the years 2013 and 2035, showing alarming data: in 2013 more than 382 million people had diabetes, with estimation to rise to 592 million by 2035 [1] These epidemic proportions of DM all around the world, in parallel with the rise of obesity, are explained by the combination of some factors, for example the rapid urbanization, nutritional transition, and diminished physical activity [2]. Chronic hyperglycemia in DM accounts for the establishment of various impairments in many tissues, mainly those where the glucose uptake occurs in an insulin-independent manner; increased intracellular glucose levels results in an overproduction of reactive oxygen species (ROS) mostly via mitochondrial electron transport chain [4]. It is crescent the interest in the use of antioxidants, especially those from natural origin, in association with the conventional therapy for DM [7,8,9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
