Kinetic studies of purified malate dehydrogenase in liver of streptozotocin-diabetic rats and the effect of leaf extract of Aegle marmelose (L.) Correa ex Roxb.

The functional basis of diabetes-mellitus to a certain extent, can be elucidated by studying diabetes-induced changes in metabolic enzymes. Malate dehydrogenase (MDH), is an enzyme directly involved in glucose metabolism. The kinetic parameters of MDH and its purified cytosolic isozyme, S-MDH, have been studied in the liver of streptozotocin-diabetic rats; also the potential of the leaf extract of A. marmelose as an anti-diabetic agent was investigated. The Km of the liver enzyme increased significantly, in both crude and purified preparations in the diabetic state when compared to the respective controls. Insulin as well as leaf-extract treatment of the diabetic rats brought about a reversal of Km values to near normal. Vmax of purified S-MDH was significantly higher in the diabetic state when compared to the control. Insulin and leaf extract treatment did not reverse this change. Since MDH is an important enzyme in glucose metabolism, the variation in its quantitative and qualitative nature may contribute to the pathological status of diabetes. The fact that leaf extract of A. marmelose was found to be as effective as insulin in restoration of blood glucose and body weight to normal levels, the use of A. marmelose as potential hypoglycemic agent is suggested.

Effect of leaf extract of Aegle marmelose (L.) Correa ex Roxb. on histological and ultrastructural changes in tissues of streptozotocin induced diabetic rats.

Light and electron microscopic examination of tissues of rats rendered diabetic with a smaller dose of 45 mg/kg of body weight of streptozotocin were carried out in the present study. The dose of the drug given altered the function of pancreatic beta-cells and the acinar cells. The changes in the acinar cells were coarsening of endoplasmic reticulation (ER) and alterations in their secretory function. The changes in the liver were (1) dialation of veins, (2) loss of usual concentric arrangement of hepatocytes, (3) liver fibrosis and (4) decrease in glycogen content. The kidney tubules were thickened and the glomerulus was expanded. The leaf extract of Aegle marmelose reversed the altered parameters to near normal. The treatment of leaf extract on diabetic pancreas showed improved functional state of pancreatic beta-cells. The results indicate the potential hypoglycemic nature of the leaf extract, helping in regeneration of damaged pancreas.