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.

To evaluate the antidiabetic effect of an aqueous extract of Aegle marmelos fruits

Effect of Aegle marmelos Fruits on Normal and Streptozotocin-Diabetic Wistar Rats

Department of Biochemistry, Annamalai University, Tamil Nadu, India

The present study evaluates the antidiabetic effect of an aqueous extract of Aegle marmelos fruits (AMFEt) in diabetes. Female albino Wistar rats were randomly divided into five groups: Normal (untreated), Normal + AMFEt, streptozotocin (STZ)-treated, STZ-treated + AMFEt, and STZ-treated + glibenclamide. Rats were rendered diabetic by STZ (45 mg/kg) administered intraperitoneally. AMFEt (250 mg/kg) was given twice daily for 1 month. Blood glucose, plasma insulin, glycosylated hemoglobin, liver glycogen, and change in body weight were determined. Food intake and water intake were monitored daily. An oral glucose tolerance test was also performed to determine the effect of this extract. The results show that glucose level and glycosylated hemoglobin were increased and plasma insulin and liver glycogen were decreased in diabetic rats, and that treatment with AMFEt reversed the effects of diabetes on these biochemical parameters to near-normal levels.

In our experiments 30 hypoglycaemic medicinal plants (known and less known) have been selected for thorough studies from indigenous folk medicines, Ayurvedic, Unani and Siddha systems of medicines. In all the experiments with different herbal samples (vacuum dried 95% ethanolic extracts), definite blood glucose lowering effect within 2 weeks have been confirmed in alloxan diabetic albino rats. Blood glucose values are brought down close to normal fasting level using herbal samples at a dose of 250 mg/kg once, twice or thrice daily, as needed. While evaluating comparative hypoglycaemic activity of the experimental herbal samples, significant blood glucose lowering activities are observed in decreasing order in the following 24 samples-Coccinia indica, Tragia involucrata, G. sylvestre, Pterocarpus marsupium, T. foenum-graecum, Moringa oleifera, Eugenia jambolana, Tinospora cordifolia, Swertia chirayita, Momordica charantia, Ficus glomerata, Ficus benghalensis, Vinca rosea, Premna integrifolia, Mucuna prurita, Terminalia bellirica, Sesbenia aegyptiaca, Azadirachta indica, Dendrocalamus hamiltonii, Zingiber officinale, Aegle marmelos, Cinnamomum tamala, Trichosanthes cucumerina and Ocimum sanctum. Present studies besides confirming hypoglycaemic activities of the experimental herbal samples, help identify more potent indigenous hypoglycaemic herbs (in crude ethanolic extract) from the comparative study of the reported experimental results.

To unravel the possible mechanism of glucose lowering activity, effects of ten different plant extracts in the regulation of serum cortisol and glucose concentrations were evaluated in male mice. While the extracts of Inula racemosa, Boerhaavia diffusa and Ocimum sanctum decreased the serum concentration of both cortisol and glucose, Aegle marmelos, Azadirachta indica and Gymnema sylvestre extracts could exhibit hypoglycaemic activity without altering the serum cortisol concentration. It appears that the hypoglycaemic effects of former three plant extracts are mediated through their cortisol inhibiting potency, whereas the mechanism for other plant extracts could be different. Lipid-peroxidation was not enhanced by any of the plant extracts (some were in fact, antiperoxidative in nature). As I. racemosa, B. diffusa and O. sanctum exhibited antiperoxidative, hypoglycaemic and cortisol lowering activities, it is suggested that these three plant extracts may potentially regulate corticosteroid induced diabetes mellitus.

Effect of Dianex, a herbal formulation on experimentally induced diabetes mellitus

Murraya koenigii, Mentha piperitae, Ocimum sanctum and Aegle marmelos

It is known that certain inorganic trace elements such as vanadium, zinc, chromium, copper, iron, potassium, sodium, and nickel play an important role in the maintenance of normoglycemia by activating the beta-cells of the pancreas. In the present study, the elemental composition in the leaves of four traditional medicinal plants (Murraya koenigii, Mentha piperitae, Ocimum sanctum, and Aegle marmelos) widely used in the treatment of diabetes-related metabolic disorders has been studied using atomic absorption spectroscopy. The levels of Cu, Ni, Zn, K, and Na were found to be in trace amounts, whereas Fe, Cr, and V levels were found in marginal levels. The importance of these elements in disorders related to diabetes is also briefly discussed.