Efeito da casca de jabuticaba (Myrciaria jaboticaba (Vell.) Berg.) sobre estresse oxidativo e resposta inflamatória em modelo de diabetes mellitus tipo 2 em ratos

Abstract

Type 2 diabetes mellitus (DM2) is a multifactorial disease mainly characterized by metabolic disorders related to insulin. Hyperglycemia is one of the causes of excessive generation of reactive oxygen species (ROS) leading to oxidative stress. In addition, DM2 is associated with increased inflammatory response. There is an intensive search for novel therapeutic drugs because the synthetic drugs currently used have side-effects and have their effectiveness reduced along the time of use. The jaboticaba (Myrciaria jaboticaba Vell Berg) peel powder (JAB) exhibit high antioxidant capacity and anti-inflammatory action due to the presence of polyphenols. The aim of this study was to evaluate the potential of JAB to prevent biochemical changes, oxidative stress, inflammatory response and pancreatic damage in a DM2 model induced by high-fat diet and a singular injection of streptozotocin (STZ; 35 mg/kg) in Wistar rats. After DM2 induction, instead of drinking water, the animals received vehicle (water containing 0.5% carboxymethyl cellulose) or JAB at 2.7 (JAB-I), 5.4 (JAB-II) or 10.8 (JAB-III) g/L of drinking water (equivalent to 0.07, 0.14 and 0.28 g anthocyanins/L, respectively). After 8 weeks of treatment animals were killed to evaluate the glycemia, insulinemia, oxidative stress and inflammatory markers were evaluated in the serum, besides antioxidant enzymes activities were evaluated in the blood and the histological changes in pancreatic tissue. Increased glycemia and fructosamine levels, insulin resistance and epididymal fat were observerd in the DM2 rats beyond decreased number and area of pancreatic islets. All JAB doses prevented the increase in glycemia over time, whereas JAB-III also reduced the end glycemia, fructosamine levels and the insulin resistance. JAB-I and JAB-II prevented body weight gain over the experiment, whereas JAB-I also decreased the amount of epididymal fat. Furthermore, JAB-I and JAB-III increased the area of pancreatic islets of diabetic rats. In addition, JAB-II and JAB-III treatment reduced the levels of oxidized LDL, whereas JAB-II treatment also reduced protein oxidation in diabetic rats. JAB treatment also prevented the decrease in the activities of glutathione peroxidase, catalase and thioredoxin reductase in the diabetic rats but did not change the decrease in the activity of superoxide dismutase. Only JAB-III treatment prevented the diabetes-induced increase in the inflammatory markers (IL-6, IL-1 and TNF-α). These findings suggest that JAB could have a beneficial effect against diabetes, reducing the hyperglycemia, the insulin resistance, oxidative stress and inflammatory response, besides decreasing pancreatic damage.