R Ghosh, I Dhande, V Kakade, R Vohra, V Kadam, Mehra
diabetes mellitus, hypoglycemic activity, rats
R Ghosh, I Dhande, V Kakade, R Vohra, V Kadam, Mehra. Antihyperglycemic activity of Madhuca longifolia in alloxan -induced diabetic rats. The Internet Journal of Pharmacology. 2008 Volume 6 Number 2.
Diabetes is a chronic metabolic disease that is showing an alarming increase in prevalence in developing countries such as India. It is characterized by defects in insulin secretion, insulin action or both, thus causing disturbance in the metabolism of carbohydrates, fat and proteins and is associated with the complications such as atherosclerosis, myocardial infarction and neuropathy . Type 1 has two subtypes namely type 1A and 1B. Type 1A is characterized by insulin deficiency due to beta-cell destruction whereas type 1B is idiopathic without autoimmune destruction . It has been predicted that worldwide the prevalence of diabetes in adults will increase to 5.4% by the year 2025 from the prevalence rate of 4% in 1995. Asian-Indians have been identified as one of the ethnic groups with a high prevalence of diabetes mellitus and a high familial aggregation of type 2 diabetes. Diabetes has become a problem of great magnitude recently. It is estimated that 10-12% of the urban and 4-6% of the rural population of India are now diabetic .
Traditional and indigenous methods have been employed in order to prevent diabetes mellitus in India since ancient times. Currently available treatment options fail to maintain tight glycemic control over time and are accompanied by various side effects. Therefore, there is a need to develop newer treatment strategies such as hypoglycemic agents of plant origin as they are known to have fewer adverse effects . Many herbs and plant products have been shown to have antihyperglycemic action .
Materials And Methods
Collection of plant material
The leaves of
Preparation of hydroethanolic extract
The hydroethanolic extract of
Healthy adult male Wistar albino rats weighing 150 ± 10 grams were used for the study. The rats were housed individually in polypropylene cages, maintained under standard conditions (12-h light and 12-h dark cycle; 25±5 0C; 35-60 % humidity), fed with standard rat pellet diet and provided water
Acute toxicity study
Acute oral toxicity study was performed as per OECD 423 guidelines. Albino rats (n = 6) of either sex selected by random sampling were used for acute toxicity study. The animals were kept fasting overnight and provided only with water, after which the extracts were administered orally at 175 mg/kg body weight and observed for 14 days for mortality and behavior. Since no mortality was seen the test was repeated with doses corresponding to a dose progression of factor 3.2. The extract was found to be safe up to a dose 2000 mg/kg. On the basis of this study the doses for the antidiabetic study were selected.
Diabetic Profile test
Estimation of blood glucose levels
Fasting blood glucose was estimated by glucose oxidase method .
Estimation of Triglyceride level
Triglyceride levels were checked in the different animal groups by enzyme colorimetric methods using Enzokit (Ranbaxy) .
Estimation of Glucose-6-phosphate dehydrogenase (G-6-PD) activity in RBCs
G-6-PD activity was estimated using a kit employing the hemoglobin normalization procedure .
Estimation of total and HDL cholesterol
HDL cholesterol was analyzed by Erba diagnostic kit and total cholesterol was estimated by cholesterol oxidase phenol 4-aminoantipyrine peroxidase method .
Rats were randomly divided into six groups with six animals each. Group I served as a control group and received 10 ml/kg body weight (b.w.) of 0.5 % sodium carboxymethyl cellulose solution (Na CMC). Group II served drug control group and received 300 mg/kg b.w. of MLH extract. Group III served as diabetic control and received 10 ml/kg b.w. 0.5 % of Na CMC. Group IV and V were treated with 150 mg/kg and 300 mg/kg b.w. of MLH extract respectively. Group VI served as a standard and received 600µg/kg of glibenclamide.
During fasting, animals were fed distilled water alone. Aqueous extract treatment was carried out for 30 days.
All the group data were statistically evaluated and the significance of various treatments was calculated using Student’s t-test. All results were expressed as mean ± S.D .
Acute effect of MLH on blood glucose levels of diabetic animals
The hydroethanolic extract of
Values are given as mean ± S.E.M. n=6. Diabetic control and drug control were compared with the corresponding values of the control. Experimental groups were compared with their corresponding values on the 0th day.
*p<0.05; **p<0.01; NS- not significant.
Effect on triglyceride level
Glibenclamide and MLE (150 and 300 mg/kg) decreased the triglyceride levels by 44.82%, 23.94% and 36.40% when compared to diabetic control respectively as shown in Table 2.
Effect on glucose-6-phosphate dehydrogenase
Increase in glucose-6-phosphate dehydrogenase level was seen in drug treated animals which is shown in Table 2.
Effect on lipid profile
Total serum cholesterol decreased significantly (p<0.001) by 26.81%, 40.77%, and 43.17% under the influence of 150 mg/kg, 300 mg/kg extract and glibenclamide respectively compared to diabetic control as shown in Table 2. After 30 days of administration, 150 mg /kg and 300 mg /kg of MLH increased the HDL cholesterol by 11.02 % ( p<0.5) and by 29.02% (p<0.001) respectively while glibenclamide increased it by 23.21 % as compared to diabetic control.
Values are given as mean ± S.E.M. n=6 Diabetic control and drug control were compared with the corresponding values of the control. Experimental groups were compared with their corresponding values of diabetic control.
*p<0.05; **p<0.01; NS- not significant.
The present work has detected the antidiabetic effect of the MLE in alloxan-induced diabetic rats. Alloxan causes a massive reduction in insulin release, by the destruction of the beta cells of the islets of Langerhans and inducing hyperglycemia . MLE lowered the blood glucose levels in normal rats within and in glucose loaded animals, in which the pancreatic cells are still fully intact. Hydroethanolic extract of the drug might be able to stimulate insulin secretion in normal rats, as did glibenclamide. Thus the results obtained show that oral administration of MLE produces a significant decrease in blood glucose levels in alloxan diabetic rats on both acute and long term administration. In contrast, the significant increase in plasma glucose levels of untreated diabetic rats may be due to progressive severity of untreated diabetes.
The most common lipid abnormalities in diabetes are hypertriglyceridemia and hypercholesterolemia . Hypertriglyceridemia is also associated in metabolic consequences of hypercoagulability, hyperinsulinemia, insulin resistance and glucose intolerance . Administration of MLE and glibenclamide significantly (p<0.001) improved hypertriglyceridemia and hypercholesterolemia. The observed hypolipidemic effect may be due to decreased blood glucose levels and decreased cholesterogenesis and fatty acid synthesis .
Activity of G-6-PD, the first regulatory enzyme of pentose phosphate pathway was found to be decreased in diabetic animals and increased in MLE treated animals; the activity was higher in comparison to untreated diabetic animals indicating improvement in glucose utilization by this pathway . High blood glucose level leads to increased activation of cyclic adenosine monophosphate dependent protein kinase thus causing decreased G-6-PD activity. Due to this, nicotinamide adenine dinucleotide phosphate-oxidase formation is low, leading to minimization of oxidative stress and cell death . Significant (p<0.001) lowering of total cholesterol and rise in HDL cholesterol is a very desirable biochemical state for prevention of atherosclerosis and ischemic conditions . Observed decrease in the ratio of total cholesterol/HDL cholesterol (atherogenic index) lessons the risk of heart disease. Comparable effect as glibenclamide on total cholesterol but improved HDL levels with plant extract in contrast to glibenclamide is again of great potential clinical interest.
The ethanolic extract of