RESUMO
We evaluated the polypeptide profiles, inhibition of human salivary α-amylase activity, and hemagglutination properties of a commercial phaseolamin sample. We also performed an in vivo assay to investigate the effects of a commercial phaseolamin treatment (100, 500, or 1500 mg/kg) over 20 days on the glycemia, body weight, and serum biochemical parameters (total cholesterol, triglycerides, alanine aminotransferase, and aspartate aminotransferase) of nondiabetic and streptozotocin-induced diabetic rats. The in vitro evaluation showed defined protein profiles, low hemagglutination activity, and high α-amylase inhibition. None of the experimental groups treated with phaseolamin or acarbose showed decreases in body weight. Our data demonstrate that phaseolamin inhibits amylase activity in vitro, reduces blood glucose levels, decreases or attenuates some of the renal and hepatic effects of diabetes in streptozotocin-induced rats, and could therefore have therapeutic potential in the treatment or prevention of the complications of diabetes.
Assuntos
Diabetes Mellitus Experimental/enzimologia , Inibidores Enzimáticos/administração & dosagem , Extratos Vegetais/administração & dosagem , Lectinas de Plantas/administração & dosagem , alfa-Amilases/antagonistas & inibidores , Animais , Glicemia/metabolismo , Peso Corporal/efeitos dos fármacos , Diabetes Mellitus Experimental/tratamento farmacológico , Diabetes Mellitus Experimental/metabolismo , Inibidores Enzimáticos/química , Humanos , Masculino , Phaseolus/química , Extratos Vegetais/química , Lectinas de Plantas/química , Ratos , Ratos Wistar , alfa-Amilases/metabolismoRESUMO
Diabetes mellitus is a chronic disease involving persistent hyperglycemia, which causes an imbalance between reactive oxygen species and antioxidant enzymes and results in damage to various tissues, including the brain. Many societies have traditionally employed medicinal plants to control the hyperglycemia. Pouteria ramiflora, a species occurring in the savanna biome of the Cerrado (Brazil) has been studied because of its possible ability to inhibit carbohydrate digestion. Rats with streptozotocin-induced diabetes treated with an alcoholic extract of Pouteria ramiflora show an improved glycemic level, increased glutathione peroxidase activity, decreased superoxide dismutase activity, and reduced lipid peroxidation and antioxidant status. The extract also restored myosin-Va expression and the nuclear diameters of pyramidal neurons of the CA3 subregion and that of the polymorphic cells of the hilus. We conclude that Pouteria ramiflora extract exerts a neuroprotective effect against oxidative damage and myosin-Va expression and is able to prevent hippocampal neuronal loss in the CA3 and hilus subfields of diabetic rats. However, future studies are needed to understand the mechanism of action of Pouteria ramiflora extract in acute and chronic diabetes.
Assuntos
Encéfalo/patologia , Diabetes Mellitus Experimental/tratamento farmacológico , Diabetes Mellitus Experimental/patologia , Fármacos Neuroprotetores , Pouteria/química , Animais , Antioxidantes/metabolismo , Glicemia/metabolismo , Western Blotting , Peso Corporal/efeitos dos fármacos , Encéfalo/efeitos dos fármacos , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Imuno-Histoquímica , Peroxidação de Lipídeos/efeitos dos fármacos , Masculino , Miosina Tipo V/biossíntese , Estresse Oxidativo/fisiologia , Extratos Vegetais/farmacologia , Folhas de Planta/química , Células Piramidais/efeitos dos fármacos , Células Piramidais/metabolismo , Ratos , Ratos Wistar , Superóxido Dismutase/metabolismoRESUMO
The Ca(2+)/calmodulin complex interacts with and regulates various enzymes and target proteins known as calmodulin-binding proteins (CaMBPs). This group of proteins includes molecular motors such as myosins. In this study, we show that non-muscle myosin-IIB is overexpressed in the brains of diabetic rats. We isolated CaMBPs from the brains of non-diabetic rats and rats with streptozotocin-induced diabetes and purified them by immobilized-calmodulin affinity chromatography. The proteins were eluted with EGTA and urea, separated by SDS-PAGE, digested and submitted to peptide mass fingerprinting analysis. Thirteen intense bands were found in both types of brains, two were found exclusively in non-diabetic brains and four were found exclusively in diabetic brains. A large fraction of the eluted proteins contained putative IQ motifs or calmodulin-binding sites. The results of the myosin-IIB affinity chromatography elution, western blot and RT-PCR analyses suggest that myosin-IIB protein and mRNA are expressed at high levels in diabetic brains. This is the first study that has demonstrated differential expression of CaMBPs in diabetic and non-diabetic brain tissue through a comparative proteomic analysis, and it opens up a new approach to studying the relationship between the expression of myosins in the brain, hyperglycemia and intracellular calcium regulation.