Medicinal plants of India with anti-diabetic potential

The juice of fresh leaves of Catharanthus roseus Linn. reduces blood glucose in normal and alloxan diabetic rabbits

BACKGROUND

The leaf juice or water decoction of Catharanthus roseus L. (Apocyanaceae) is used as a folk medicine for the treatment of diabetes all over the world. In the present investigation, the leaf juice of C. roseus has been evaluated for its hypoglycemic activity in normal and alloxan-induced diabetic rabbits.

METHODS

The blood glucose lowering activity of the leaf juice was studied in normal and alloxan-induced (100 mg/kg, i.v.) diabetic rabbits, after oral administration at doses of 0.5, 0.75 and 1.0 ml/kg body weight. Blood samples were collected from the marginal ear vein before and also at 4, 6, 8, 10, 12, 16, 18, 20 & 24 h after drug administration and blood glucose was analyzed by Nelson-Somogyi's method using a visible spectrophotometer. The data was compared statistically by using Student's t-test.

RESULTS

The leaf juice of C. roseus produced dose-dependent reduction in blood glucose of both normal and diabetic rabbits and comparable with that of the standard drug, glibenclamide. The results indicate a prolonged action in reduction of blood glucose by C. roseus and the mode of action of the active compound(s) of C. roseus is probably mediated through enhance secretion of insulin from the beta-cells of Langerhans or through extrapancreatic mechanism.

CONCLUSIONS

The present study clearly indicated a significant antidiabetic activity with the leaf juice of Catharanthus roseus and supports the traditional usage of the fresh leaves by Ayurvedic physicians for the control of diabetes.

Effects of Petroselinum crispum extract on pancreatic B cells and blood glucose of streptozotocin-induced diabetic rats

This study investigated both morphologically and biochemically whether parsley (Petroselinum crispum), which is used as a folk remedy to decrease blood glucose, has any antidiabetic effect on pancreatic B cells of rats. Parsley extract was given to male diabetic rats. In the diabetic group given parsley extract, it was detected that the number of secretory granules and cells in islets and other morphologic changes were not different from the control diabetic group, while the blood glucose levels in the diabetic group given the plant extract were reduced in comparison to the diabetic group. In addition, a decrease was observed in the weight of the control diabetic group and the diabetic group given the plant extract. It is suggested that the plant therapy can provide blood glucose homeostasis and cannot regenerate B cells of the endocrine pancreas.

Effect of herbal hypoglycemic agents on oxidative stress and antioxidant status in diabetic rats

In the present study the antioxidative potential ofMomordica charantia, Azadirachta indica, Allium sativum andOcimum sanctum was assessed in streptozotocin induced diabetic rats. Lipid peroxide levels were also measured in normal, diabetic and treated animals. Malondialdehyde (MDA) levels were significantly higher and antioxidant activity was found low in diabetic groups as compared to the control groups, and significant alteration in both the MDA levels and antioxidant activity was also observed when the above herbal hypoglycemic agents were given to diabetic rats. On the basis of our results we conclude thatM. charantia, A. indica, A. sativum andO. sanctum are not only useful in controlling the lipid peroxide levels but are also helpful in further strengthening the antioxidant potential.

Antihyperglycaemic effect of Cassia auriculata in experimental diabetes and its effects on key metabolic enzymes involved in carbohydrate metabolism

1. In experimental diabetes, enzymes of glucose and fatty acid metabolism are markedly altered. Persistent hyperglycaemia is a major contributor to such metabolic alterations, which lead to the pathogenesis of diabetic complications. To our knowledge, there are no available reports on the enzymes of hepatic glucose metabolism of Cassia auriculata flower against diabetes. The present study was designed to study the effect of Cassia auriculata flower extract (CFEt) on hepatic glycolytic and gluconeogenic enzymes. 2. Streptozotocin diabetic rats were given CFEt (0.15, 0.30 and 0.45 g/kg) or 600 microg/kg glibenclamide for 30 days. At the end of 30 days, blood glucose, plasma insulin, haemoglobin, glycosylated haemoglobin, glycolytic and gluconeogenic enzymes were assessed. 3. Administration of CFEt at 0.45 g/kg significantly decreased blood glucose, glycosylated haemoglobin and gluconeogenic enzymes and increased plasma insulin, haemoglobin and hexokinase activity. Similarly, administration of glibenclamide showed a significant effect; however, CFEt at 0.15 and 0.30 g/kg did not show any significant effect. 4. In conclusion, the observations show that the aqueous extract of CFEt possesses an antihyperglycaemic effect and suggest that enhanced gluconeogenesis during diabetes is shifted towards normal and that the extract enhances the utilization of glucose through increased glycolysis. The effect of CFEt was more prominent than that of glibenclamide.

Hypoglycemic and antihyperglycemic effect of Brassicajuncea diet and their effect on hepatic glycogen content and the key enzymes of carbohydrate metabolism

Plants in the form of food or other remedial forms have been used for the treatment of various human ailments. Diabetes is one such disorder in which various form of plants and herbal remedies have been tried. Brassicajuncea (BJ) seeds (Rai) are consumed in India as a spice in various food items. Previous studies have shown the hypoglycemic effect of this plant in rats. The present study was undertaken to study the hypoglycemic and antihyperglycemic of various strengths (5, 10 and 15%) of BJ seed diet in alloxan and streptozotocin induced diabetes in albino rats. In addition, key enzymes of carbohydrate metabolism (glucokinase--EC 2.7.1.1, hexokinase--EC 2.7.1.1, and phosphofructokinase--EC 2.7.1.11) and hepatic glycogen content was also assessed to understand the mechanism of action. BJ diet (10 and 15%) showed significant antihyperglycemic effect in alloxan (35 mg/kg) but not in STZ (60 mg/kg) rats. It also failed to modulate the hepatic glycogen content and enzyme activities.

Hypoglycemic and antihyperglycemic activity of Murraya koenigii leaves in diabetic rats

The commonly used spice curry patta (Murraya koenigii) is traditionally consumed by diabetics in southern part of India. Feeding of diet containing various doses of curry leaves (5, 10 and 15%) to normal rats for 7 days as well as mild diabetic (blood glucose levels >175 mg/dl induced by alloxan 35 mg/kg IP) and moderate diabetic rats (blood glucose levels >250 mg/dl induced by STZ 60 mg/kg IP) for 5 weeks showed varying hypoglycemic and anti-hyperglycemic effect. In normal rats, reduction in blood glucose was almost negligible (approximately 4% with 10 and 15% diet). In mild and moderate diabetic rats, feeding of 5, 10 and 15% diet caused a maximal reduction in blood sugar by 13.1, 16.3 and 21.4% (NS, P<0.05 and 0.005) and 3.2, 5.58, 8.21% (NS), respectively. The mechanism of action is further discussed in light of results of previous and the present study.