Antihyperglycemic and antioxidant activities of total alkaloids from Catharanthus roseus in streptozotocin-induced diabetic rats

We evaluated the hypoglycemic and antioxi- dant effects of the total alkaloids of leaves and twigs of Catharanthus roseus Linn. （CTA） in streptozotocin （STZ）- induced diabetic rats. The hypoglycemic effect was mea- sured by blood glucose and plasma insulin level. Oxidative stress was measured in heart, liver and kidney by levels of antioxidant markers, free radical scavengers and lipid peroxides i.e. superoxide dismutase （SOD）, catalase （CAT）, glutathione （GSH） and thiobarbituric acid reactive substances （TBARS）. Biochemical parameters, i.e. aspar- tate aminotransferase （AST）, alanine aminotransferase （ALT）, alkaline phosphate （ALP） were observed in diabetic control and treated rats. Oral administration of CTA for 30 days was followed by a significant （P 〈 0.05） decrease in fasting blood glucose and increase in insulin level as compared with untreated diabetic rats. Also it significantly （P 〈 0.05） reduced ALT, AST and ALP. The treatment also resulted in significant （P 〈 0.05） reductions in GSH, SOD, CAT, and decrease in TBARS in the heart, liver and kidney of diabetic rats. The results suggest that CTA can effectively normalize the impaired antioxidant status in STZ-induced diabetes in a dose-dependent manner.CTA exerted rapid protective effects against lipid peroxi- dation by scavenging of free radicals and reducing the risk of diabetic complications.

Antihyperglycemic Activity of Moringa oleifera Lam Leaf Functional Tea in Rat Models and Human Subjects

Maintenance of glycemic control is important in preventing diabetes and its associated complications. Considering the current recommended approach for the use of functional foods and their bioactive components in the prevention and management of diabetes, the aim of this study was to determine the antihyperglycemic effect of Moringa oleifera functional tea in rat models and in normoglycemic human volunteers using the oral glucose tolerance test (OGTT). Moringa tea prepared by extracting Moringa leaf powder in distilled water (1:20 mg/ml) at 97°C for 30 min was administered at different doses to male Wistar rats and human volunteers prior to glucose loading. Blood glucose was measured at intervals of 30 min for 150 min. Consumption of Moringa tea prior to glucose loading suppressed the elevation in blood glucose in all cases compared to controls that did not receive the tea initially. The degree and pattern of decrease however, were dose dependent. In rats, intermediate doses of 20 ml/kg BW were more effective in reducing blood glucose overall (18.2%) vs 13.3% and 6% at doses of 10 and 30 ml/kg BW respectively. In humans, the final decrease in blood glucose was not significantly different for high 400 ml (19%) and low 200 ml (17%) doses. Of interest here was the pattern of decrease, being significantly higher (p < 0.05) at 30 min with 200 ml (22.8%) than with 400 ml (17.9%). It is suggested that low doses exert their antihyperglycemic effect more at intestinal level by inhibiting glucose absorption, whereas high doses exert their effect more in circulation. We conclude that Moringa oleifera tea has potential as a functional food in the management of hyperglycemia.

Danhong Huayu Koufuye combined with metformin attenuated diabetic retinopathy in Zucker diabetic fatty rats

AIM: To evaluate effects of Danhong Huayu Koufuye (DHK, a Chinese medicinal formulae) alone or combined with metformin on diabetic retinopathy (DR) in Zucker diabetic fatty (ZDF) rats, an animal model of obese type -2 diabetes, and then to investigate the mechanisms. METHODS: ZDF (fa/fa) rats were administered with vehicle (distilled water), metformin, DHK, and DHK plus metformin. Electrophysiological and histological analysis were applied to evaluated effects of DHK alone or combined with metformin on DR. The levels of fasting blood glucose (FBG) and glycosylated hemoglobin (HbA1c) in blood were measured to evaluate the antihyperglycemic activity of DHK. Furthermore, levels of nitric oxide (NO), malondialdehyde (MDA) and activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) in serum were measured to study effects of DHK on oxidative stress in ZDF rats. In addition, body weight, lipidic indexes and insulin level were also assessed. RESULTS: DHK combined with metformin significantly reversed the prolongation of latency times of flash electroretinogram (FERG) and oscillatory potentials (OPs) in diabetic rats. Furthermore, DHK alone or combined with metformin showed a remarkable suppression of retinal neovascularization and amelioration of retinal internal limiting membrane morphology. Moreover, DHK alone or plus metformin reduced FBG (P<0.05), HbA1c 1094 (P<0.01) and MDA (P<0.01) levels in diabetic rats. In addition, reductions in levels of triglycerides (TG) (P<0.01) and low density lipoprotein cholesterol (LDL-c) (P<0.01 and P<0.05, respectively) were also observed in diabetic rats treated with DHK alone or plus metformin. CONCLUSION: DHK in combination with metformin had a preventive and therapeutic effect on DR in type-2 diabetic rats, and the possible mechanisms may be alleviating hyperglycemia, reducing oxidative stress and improving lipid metabolism.

Antihyperglycemic Effect of Various Fractions from Residues of Blumea balsamifera

Objective To evaluate the antihyperglycemic activities of various fractions from theresidues of Blumea balsamifera（BB）,and to properly utilize the waste resource.MethodsThe antihyperglycemic activities were evaluated by the suppression on serum glucose level in vivo andα-glucosidase inhibition assay in vitro.The high-,mid-,and low-dose（1,0.5,and 0.25 g/kg of the herb）fractions were ig given to mice for 8 d.The serum glucose was monitored at 1 and 12 h after feeding.Results The fasting and postprandial serum glucose levels of mice treated with high-dose petroleum ether fraction,ethyl acetate fraction,butyl alcohol fraction,methanol fraction,and water extract from BB were 4.45,4.39,4.43,4.15,3.74 mmol/L and 6.98,6.23,6.45,6.26,5.88 mmol/L,respectively,while those in vehicle control group were 5.63 and 7.50 mmol/L.There are four different inhibiting manners by the results ofα-glucosidase inhibition assay.Conclusion The residues of BB have anti-diabetes activities after steam distillation.