Propriedade hipoglicemiante, hipocolesterolêmica e antioxidante de proteínas de folhas de Moringa oleifera Lam

Abstract

Moringa oleifera is a plant native to northeastern India widely used in Indian folk medicine due to its various pharmacological properties. Ethnopharmacological studies have demonstrated that compounds derived from parts of this plant, especially leaves, have hypoglycemic activity in diabetic animal models and in humans, allowing its use in folk medicine. The hypoglycemic action of M. oleifera leaves has been attributed to compounds from plant secondary metabolism, however studies showing the involvement of proteins as antidiabetic substances are scarce. The aim of this study was to obtain a protein fraction of M. oleifera leaves and evaluate its hypoglycemic effects on diabetic animal models. For this, the leaf proteins were extracted followed by ammonium sulfate precipitation (0-90%). After exhaustive dialysis, this material was lyophilized to obtain the protein fraction named Mo-PFL. As experimental animal model, alloxan-induced diabetic mice were used. Initially Mo-PFL was intraperitoneally administered at doses of 100, 300 and 500 mg/Kg body weight. The dose of 500 mg/Kg body weight was more effective in reducing blood glucose after 1, 3 and 5 hours of Mo-PFL administration. This hypoglycemic effect was not observed by the intragastric route. This effect was also reduced when boiled Mo-PFL was intraperitoneally administered. Daily intraperitoneal administration of Mo-PFL at a dose of 500 mg/Kg body weight for 20 days caused a significant reduction in blood glucose level and also exerted antioxidant and hypocholesterolemic effects. Electrophoretic pattern of Mo-PFL showed a variety of protein bands, which were susceptible to in vitro pepsin and trypsin digestion. A Dot Blot immunoassay showed cross reactivity between human anti-insulin antibody and Mo-PFL, suggesting the presence of insulin-like epitopes in M. oleifera leaf protein. Overall, these data show that some proteins derived from M. oleifera leaves may contribute to the hypoglycemic effect observed in the present work.