Antidiabetic effect of Symplocos cochinchinensis (Lour.) S. Moore. in type 2 diabetic rats

Aim

Symplocos cochinchinensis (Lour.) S. Moore. is used in Indian system of traditional medicine to treat diabetes mellitus. The present study aims to investigate the antidiabetic efficacy of the hexane extract of Symplocos cochinchinensis leaves in high fat diet-low streptozotocin (STZ) induced type 2 diabetic rats.

Materials and methods

The doses for the study were fixed based on Irwin test. The hypoglycemic effect of the hexane extract of Symplocos cochinchinensis leaves were studied in normal rats. Oral glucose and insulin tolerance tests were carried out. The antihyperglycemic effect of the hexane extract at 250 and 500 mg/kg was studied in high fat diet-low STZ induced type 2 diabetic rats for 28 days.

Results

The extracts showed no adverse effects up to 5 g/kg concentration. In hypoglycemic study, after treatment with hexane extract at 250 and 500 mg/kg the blood glucose was mildly reduced. In oral glucose tolerance test, the treatment with the hexane extract at 250 and 500 mg/kg showed a highly significant reduction of 12.07% and 23.58% in plasma glucose levels, respectively 30 min after glucose load. The insulin tolerance test also showed improved insulin sensitivity after 60 min of insulin treatment. In high fat diet-low STZ induced type 2 diabetic rats, after 28 days treatment with the hexane extract at 250 and 500 mg/kg reduced the plasma glucose level by 17.04% and 42.10%, respectively. A significant reduction in plasma insulin, plasma and hepatic total cholesterol (TC), triglycerides (TG) and free fatty acids (FFA) and a significant increase in liver glycogen were observed in treated diabetic rats.

Conclusion

This study demonstrated the potential antidiabetic property of hexane extract of Symplocos cochinchinensis leaves on type 2 diabetes mellitus, thus justifying its traditional usage.     

Effect of crude extract and fractions from Vitex megapotamica leaves on hyperglycemia in alloxan-diabetic rats

The effect of the crude extract, ethyl acetate and n-butanol fractions from Vitex megapotamica (Spreng) Moldenke on glycemia was investigated in diabetic rats. Oral administration of crude extract significantly reduced serum glucose levels in both normal and diabetic animals. In normal rats, serum glucose lowering was observed with 400 and 800 mg/kg at 2 and 2-3h, respectively after oral crude extract treatment. Nevertheless, the hypoglycemic effect of Vitex megapotamica in diabetic rats was evident at 1 and 2h and from 1 to 3h after treatment with 400 and 800 mg/kg, respectively. The ethyl acetate as well as n-butanol fractions were able to diminish glycemia in diabetic animals. The ethyl acetate fraction (400 and 800 mg/kg) produced the maximum hypoglycemic effect (28 and 20%, respectively) in diabetic rats and the same dose of the n-butanol fraction reduced the hyperglycemia only by 11% at 1h after treatment. Additionally, in hyperglycemic normal rats neither crude extract nor ethyl acetate fraction modified the glucose tolerance and the known tolbutamide effect on insulin release was clearly observed in this group. Thus, this study shows that Vitex megapotamica has an anti-hyperglycemic action, is able to ameliorate the diabetic state and, probably, is a source of hypoglycemic compounds.     

Assessment of antidiabetic potential of Cynodon dactylon extract in streptozotocin diabetic rats

This study was undertaken to investigate the hypoglycemic and antidiabetic effect of single and repeated oral administration of the aqueous extract of Cynodon dactylon (Family: Poaceae) in normal and streptozotocin induced diabetic rats, respectively. The effect of repeated oral administration of aqueous extract on serum lipid profile in diabetic rats was also examined. A range of doses, viz. 250, 500 and 1000mg/kg bw of aqueous extract of Cynodon dactylon were evaluated and the dose of 500mg/kg was identified as the most effective dose. It lowers blood glucose level around 31% after 4h of administration in normal rats. The same dose of 500mg/kg produced a fall of 23% in blood glucose level within 1h during glucose tolerance test (GTT) of mild diabetic rats. This dose has almost similar effect as that of standard drug tolbutamide (250mg/kg bw). Severely diabetic rats were also treated daily with 500mg/kg bw for 14 days and a significant reduction of 59% was observed in fasting blood glucose level. A reduction in the urine sugar level and increase in body weight of severe diabetic rats were additional corroborating factors for its antidiabetic potential. Total cholesterol (TC), low density lipoprotein (LDL) and triglyceride (TG) levels were decreased by 35, 77 and 29%, respectively, in severely diabetic rats whereas, cardioprotective, high density lipoprotein (HDL) was increased by 18%. These results clearly indicate that aqueous extract of Cynodon dactylon has high antidiabetic potential along with significant hypoglycemic and hypolipidemic effects.     

Polyphenols-rich Vernonia amygdalina shows anti-diabetic effects in streptozotocin-induced diabetic rats

Aim of the study

This study aims to investigate the hypoglycemic properties of Vernonia amygdalina Del. (VA) and its possible mechanisms of action in a single-dose STZ induced diabetic rat model.

Materials and methods

A dose-response study was conducted to determine optimum dose for the hypoglycemic effect of VA in STZ-induced diabetic rats. The optimum dose (400 mg/kg) was used throughout the 28-day chronic study. Body weight, food and water intakes of the rats were monitored daily. Fasting blood serum, pancreas, liver and soleus muscle were collected for biochemical analyses. Chemical composition of VA was analysed using HPLC and LC-ESI-MS.

Results

The study reveals that ethanolic extract of VA contains high level of polyphenols mainly 1,5-dicaffeoyl-quinic acid, dicaffeoyl-quinic acid, chlorogenic acid and luteolin-7-O-glucoside. In an oral glucose tolerance test, 400 mg/kg VA exhibited a significant improvement in glucose tolerance of the STZ-induced diabetic rats. 28-day treatment with 400 mg/kg VA resulted in 32.1% decrease in fasting blood glucose compared to diabetic control. VA also caused significant decrease (18.2% and 41%) in triglyceride and total cholesterol level. Besides, VA showed protective effect over pancreatic β-cells against STZ-induced damage, causing a slight increase in insulin level compared to diabetic control. VA administration also showed positive regulation of the antioxidant system, both enzymatic and non-enzymatic. Furthermore, VA was found to increase expression of GLUT 4 (24%) in rat skeletal muscle. Further tissue fractionation revealed that it can increase the GLUT 4 translocation (35.7%) to plasma membrane as well, suggesting that VA may stimulate skeletal muscle's glucose uptake. This observation is in line with the restoration in skeletal muscle glycogenesis of VA-treated group. However, no alteration was observed in GLUT 1 expression. In addition, VA also suppressed (40% inhibition) one of the key hepatic gluconeogenic enzymes, glucose-6-phosphatase (G6Pase).

Conclusions

VA possesses antihyperglycemic effect, most probably through increasing GLUT 4 translocation and inhibiting hepatic G6Pase. The polyphenols in the extract may be the candidates that are responsible for the above-mentioned biological activities.     

Antidiabetic activity of Vatairea macrocarpa extract in rats

In the present paper the anti-diabetic effects of stem-bark extract (ethanol 70%) of Vatairea macrocarpa, a traditional diabetes mellitus treatment widely used in Brazil, are reported. The extract was administered orally at a dose of 250 or 500 mg/kg, for 22 days, to normal and streptozotocin-diabetic rats. In extract treated (500 mg/kg) diabetic rats serum and urinary glucose, urinary urea, food and fluid intake were decreased, while body weight gain was increased, all of which indicate an improvement in diabetic state (p<0.05). No effects of the extract were observed in non-diabetic rats. In extract treated (500 mg/kg) diabetic group HOMA-R (homeostasis model for assessment of insulin resistance) was lower at the end of 22 days, as compared to diabetic non treated control group. Insulin was the reference substance used in the experiments. In an oral glucose tolerance test, the time to reach maximal glycemia was greater in diabetic 500 mg/kg treated group than in control group. These anti-diabetic effects could be related to an improved insulin resistance, although a possible effect on pancreatic B-cell function cannot be excluded. Thus, our data of sub-chronic experiments suggest that long-term use of V. macrocarpa stem-bark extract may be helpful in treating diabetic conditions.     

Parkinsonia aculeata aqueous extract fraction: biochemical studies in alloxan-induced diabetic rats

The antidiabetic effect of Parkinsonia aculeata water soluble fraction (WSF) made of aerial parts of the plant (leaves and flowers) was investigated in alloxan diabetic rats. Its effect was compared with that of insulin (positive control). The physico-metabolic parameters measured were: body weight, food and liquid intake, urinary volume, hepatic glycogen, serum glucose, total cholesterol, HDL-cholesterol, triglycerides, urinary glucose and urea, and the weight of epididymal adipose tissue, liver, kidneys and the skeletal muscles (soleus and extensor digitorum longus). Oral administration of WSF (125 or 250 mg/kg) for 16 days exhibited a significant reduction in serum and urinary glucose, urinary urea, total cholesterol, HDL-cholesterol and triglycerides in alloxan diabetic rats. An improvement of hepatic glycogen, a decrease of liquid and food intake, and a significantly positive actions in the weight of skeletal muscles (soleus and extensor digitorum longus) and kidneys were also observed, but just diabetic group treated with WSF at a dose of 125 mg/kg showed significant reduction in urinary volume, body weight, an improvement of epididymal adipose tissue and a positive action in liver weight. The effects of WSF on the physico-metabolic parameters was comparable to those observed in diabetic insulin treated group. The results of this work suggest that P. aculeate may have new clinical significant choice in diabetes mellitus illness, and could explain the basis for its traditional use to manage diabetes-related complications by rural community of northeast of Brazil.     

Chronic hypoglycemic effect of Malmea depressa root on n5-streptozotocin diabetic rats

The root of the "Elemuy" tree (Malmea depressa) is highly used in south east Mexico by the Mayan communities to treat type 2 diabetes. The long-term hypoglycemic effect (HbA1c) and the stimulation of insulin secretion resulting from the treatment with butanolic extract was studied using (n5-stz)-induced diabetic rats. We show that after 30 days of daily administration of 10 mg/kg of the butanolic extract, the glucose levels as well as the (HbA1c) levels were lower compared to the control group. This effect was also observed after 45 days of treatment, leading to the conclusion that the effects of chronic butanolic extract treatment are comparable to treatment with the standard drug Bieuglucon. In an acute experiment, we found that a single administration of the extract at a dose of 50 mg/kg stimulates insulin release, which is similar to the result seen with Tolbutamide administration. The new compound, 3-(3-hydroxy-2,4,5-trimethoxyphenyl) propane-1,2 diol, was isolated from the active fraction of the butanolic extract. The results presented here support the utility of the traditional use of the root and suggest that the active fraction of the plant extract could be developed as a phytomedicine.     

Antidiabetic activity and toxicity of Zizyphus spina-christi leaves

The effect of the butanol extract of Zizyphus spina-christi (L.), Willd (Rhamnaceae) leaves and its major saponin glycoside, christinin-A, on the serum glucose and insulin levels was studied in non-diabetic control, type-I (insulin-dependent) and type-II (non-insulin-dependent) diabetic rats. Pretreatment either with 100 mg/kg butanol extract or christinin-A potentiated glucose-induced insulin release in non-diabetic control rats. In type-II but not in type-I diabetic rats pretreatment with the butanol extract or christinin-A improved the oral glucose tolerance and potentiated glucose-induced insulin release. Treatment either with 100 mg/kg butanol extract or christinin-A reduced the serum glucose level and increased the serum insulin level of non-diabetic control and type-II diabetic rats but not of type-I diabetic rats. Effects of the butanol extract and christinin-A were similar. Pretreatment of non-diabetic control and type-II diabetic rats either with 100 mg/kg butanol extract or christinin-A enhanced the glucose lowering and insulinotropic effects of 5 g/kg glibenclamide. The hyperglycemic and hypoinsulinemic effects of 30 mg/kg diazoxide in non-diabetic control and type-II diabetic rats were inhibited and antagonized, respectively by pretreatment with the butanol extract or christinin-A. The relaxant effects of different concentrations of diazoxide on the isolated norepinephrine-contracted aortic strips were inhibited by 100 micromol/l christinin-A or 10 micromol/l glibenclamide. The combination of glibenclamide and christinin-A led to complete inhibition of the relaxant effects of different concentrations of diazoxide. At a dose level much higher than that required to produce satisfactory insulinotropic and hypoglycemic effects, the butanol extract of Zizyphus spina-christi leaves produced a depressant effect on the central nervous system in rats. Treatment of rats with 100mg/kg butanol extract for 3 months produced no functional or structural disturbances in liver and kidney and no haematological changes. In addition, the oral LD50 of the butanol extract in mice was 3820 mg/kg, while that of glibenclamide was 3160 mg/kg. Thus, Zizyphusspina-christi leaves appears to be a safe alternative to lower blood glucose. The safe insulinotropic and subsequent hypoglycemic effects of Zizyphus spina-christi leaves may be due to a sulfonylurea-like activity.     

Hypoglycemic and antihyperglycemic effect of Begonia malabarica Lam. in normal and streptozotocin induced diabetic rats

Aim of the study

The stem of Begonia malabarica was used traditionally by the Malasar tribe to treat diabetes. To validate the hypoglycemic and antihyperglycemic effects of the hexane, ethylacetate and methanol extracts obtained from an ethnomedicinal plant, Begonia malabarica.

Materials and methods

The doses for the study were fixed based on Irwin test. The hypoglycemic effect of hexane, ethylacetate and methanol extracts of Begonia malabarica stems were studied in normal animals. The antihyperglycemic effect of the methanol extract was studied in streptozotocin induced diabetic rats.

Results

In normal rats the treatment with the methanol extract of Begonia malabarica had shown a highly significant reduction (16.54 and 34.47%) in plasma glucose levels from the 0 h values at the dose of 100 and 200 mg/kg respectively. In streptozotocin induced diabetic rats the body weight of the Begonia malabarica methanol extract treated animals had shown a significant increase (13.38% at 200 mg/kg) after 4 weeks treatment. The plasma glucose levels were reduced significantly by 46.57 and 50.20% after 4 weeks treatment at 100 and 200 mg/kg respectively. Likewise the absolute kidney weight was also reduced in a significant manner. After 25 days treatment the Begonia malabarica methanol extract treated animals had shown low fasting plasma glucose levels (54.29, 61.34% in 100 and 200 mg/kg) and reduced postprandial plasma glucose levels (54.23, 65.96% in 100 and 200 mg/kg) when compared with diabetic control values. Serum insulin levels and liver glycogen levels were increased to 40.04 and 42.18% in 200 mg/kg Begonia malabarica methanol extract treated animals respectively. The treatment with Begonia malabarica methanol extract did not change the triglycerides and total cholesterol levels. The urea and creatinine levels were also reduced significantly by this treatment. The reduction in SGPT levels indicated the absence of toxicity of Begonia malabarica extract at this dose level.

Conclusion

This study supports the use of Begonia malabarica by the Malasar tribe for the treatment of diabetes. Fractionation of this extract may yield novel prototypes to manage diabetes mellitus.     

Butanol fraction of Khaya senegalensis root modulates β-cell function and ameliorates diabetes-related biochemical parameters in a type 2 diabetes rat model

Ethnopharmacological relevance

Khaya senegalensis A. Juss (Meliaceae) is commonly exploited for the traditional treatment of diabetes mellitus in Nigeria and Togo. The present study was conducted to examine the anti-diabetic activity of Khaya senegalensis butanol fraction (KSBF) of root ethanolic extract in a type 2 diabetes (T2D) model of rats.

Materials and methods

T2D was induced in rats by feeding a 10% fructose solution ad libitum for two weeks followed by a single intraperitoneal injection of streptozotocin (40 mg/kg body weight) and the animals were treated with 150 and 300 mg/kg body weight (BW) of the fraction for five days in a week. Relevant diabetes-related parameters were analyzed in all experimental animals.

Results

The KSBF treatment, at 300 mg/kg BW, significantly (p<0.05) reduced blood glucose level, improved oral glucose tolerance ability and β-cell function (HOMA-β), decreased insulin resistance (HOMA-IR), stimulated hepatic glycogen synthesis, ameliorated serum lipids alterations and prevented hepatic and renal damages compared to untreated diabetic rats. Additionally, the fraction insignificantly (p>0.05) improved weight gain, decreased food and fluid intake, stimulated insulin secretion and lowered serum fructosamine concentrations compared to untreated diabetic rats.

Conclusions

Data from this study suggests that orally administered KSBF, at 300 mg/kg BW, possess remarkable anti-type 2 diabetic activity and could ameliorate some diabetes-associated complications and hence can be considered as a source of potential anti-type 2 diabetic medicine.     

Hypoglycemic effect of Rehmannia glutinosa oligosaccharide in hyperglycemic and alloxan-induced diabetic rats and its mechanism

The hypoglycemic and anti-diabetic effect of Rehmannia glutinosa oligosaccharide (ROS) in glucose-induced hyperglycemic and alloxan-induced diabetic rats and its mechanism was investigated in this paper. It was found that pretreatment of ROS in normal rats with 100 mg/kg for 3 days, i.p., induced a partial prevention of hyperglycemia caused by glucose (2g/kg, i.p.), while when hyperglycemia was induced in adrenalectomized (ADX) rats, the preventive effect of ROS on hyperglycemia was lost. In alloxan-induced diabetic rats, ROS (100 mg/kg for 15 days, i.p.) showed a significant decrease in blood glucose level and hepatic glucose-6-phosphatase activity with an increase in hepatic glycogen content. Furthermore, ROS raised plasma insulin level and lowered plasma corticosterone level in alloxan-induced diabetic rats. The results indicated that oligosaccharide of Rehmannia glutinosa Libosch. exerted a significant hypoglycemic effect in normal and alloxan-induced diabetic rats. The regulatory mechanism of ROS on glucose metabolism was adrenal dependent and had a close relation with the neuroendocrine system.     

Evaluation of hypoglycemic activity of total lignans from Fructus Arctii in the spontaneously diabetic Goto-Kakizaki rats

Ethnopharmacological relevance

Fructus Arctii, called “Niubangzi” in China (Great burdock achene in English), is a well-known Chinese Materia Medica. It is the dried ripe fruit of Arctium lappa L. (family Asteraceae) and was included in the Chinese pharmacopoeia for its traditional therapeutic actions. Meanwhile it has been utilized extensively in a number of classical drug formulas as a major component for the treatment of noninsulin-dependent diabetes mellitus. It has also been reported recently that the clinical use of Fructus Arctii resulted in a satisfactory hypoglycemic effect in diabetic patients. The aim of this study was to investigate hypoglycemic activity of total lignans from Fructus Arctii (TLFA) in Goto-Kakizaki (GK) rats, a spontaneous type 2 diabetic animal model, and the mechanism of its hypoglycemic activity.

Materials and methods

Male GK rats and normal Wistar rats were used in this study, GK rats fed twice daily were given TLFA (300 mg/kg) or nateglinide (50 mg/kg) orally before each meal for 12 weeks. Besides common evaluation indexes of hypoglycemic activity such as blood glucose level, oral glucose tolerance test (OGTT), glycated hemoglobin, as well as lipid metabolism parameters such as cholesterol (CHOL), triglycerides (TG), et al., in rat serum. The effects of TLFA on insulin secretion and pancreas tissue sections, the levels of serum glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), and the α-glucosidase inhibitory activity of TLFA in vitro were investigated.

Results

TLFA demonstrated stable and long-lasting hypoglycemic activity in GK rats and showed significant improvement in glucose tolerance in glucose fed hyperglycemic GK rats. Both TLFA and nateglinide controlled the glycosylated hemoglobin levels of the experimental animals very well. Stimulation of insulin secretion was proved to be one of the hypoglycemic mechanism of TLFA, promoting the release of GLP-1 should be another one, and ɑ-glucosidase inhibitory activity of TLFA also contributes to its hypoglycemic activity. In this study, we didn't found that TLFA could effect the body weight of GK rats, which was also verified by the changes of biochemical parameters of blood in experimental rats.

Conclusion

The results of this study indicates that TLFA has significant hypoglycemic potential in GK rats, and it may be acting through stimulating insulin secretion, promoting the release of GLP-1, and decreasing intestinal absorption of glucose.     

Antihyperglycemic effects of total flavonoids from Polygonatum odoratum in STZ and alloxan-induced diabetic rats

Aim of the study

Total flavonids of Polygonatum(P) odoratum (TFP) were tested for anti-diabetic activity in streptozotocin (STZ)-induced diabetic mice and alloxan-induced diabetic rats.

Materials and methods

Rhizoma Polygonati Odorati, well-known Chinese traditional medicine, is widely used for treatment of diverse diseases for example diabetes. In our study, TFP was extracted by 70% ethanol and purified by macroreticular resin. The experiments were designed to detect the anti-diabetic activity of TFP by determination of blood glucose (BG) using one touch gluco-meter and insulin levels by using a radioimmunoassay kit in streptozotocin (STZ)-induced diabetic mice and alloxan-induced diabetic rats and alpha-amylase inhibitory activity by alpha-amylase inhibition assay in vitro.

Results

TFP had beneficial effects on regulation of blood glucose. Daily administration with 50–200 mg/kg body weight of TFP for 9 days can reduce significantly hyperglycemia in STZ-induced diabetic mice. Thirtieth day administration with TFP (50–200 mg/kg body weight) also decreased significantly fasting blood glucose in alloxan-induced diabetic rats. The hypoglycemic effect of TFP at 50 and 100 mg/kg is less than that of acarbose 20 mg/kg and gliclazide 15 mg/kg. The hypoglycemic effects of TFP at 200 mg/kg is similar to that of acarbose 20 mg/kg and gliclazide 15 mg/kg. TFP also could increase significantly the insulin level in alloxan-induced type 2 diabetic rats (P < 0.05) compared with control. Alpha-amylase inhibition assay in vitro showed that TFP inhibited significantly alpha-amylase activity in a dose-dependent manner.

Conclusions

TFP possess significant dose-dependent anti-diabetic activity. TFP is one of the primary hypoglycemic active compounds of Polygonatum odoratum which would worth further study and development.     

Effect of Sclerocarya birrea (Anacardiaceae) stem bark methylene chloride/methanol extract on streptozotocin-diabetic rats

Sclerocarya birrea (Anacardiaceae) is used as a traditional treatment of diabetes in Cameroon. In this study, we investigated the possible antidiabetic effect of the stem bark extract in diabetic rats. Diabetes was induced by intravenous injection of streptozotocin (STZ, 55 mg/kg) to male Wistar rats. Experimental animals (six per group), were treated by oral administration of plant extract (150 and 300 mg/kg body weight) and metformin (500 mg/kg; reference drug) for comparison, during 21 days. The stem bark methanol/methylene chloride extract of Sclerocarya birrea exhibited at termination, a significant reduction in blood glucose and increased plasma insulin levels in diabetic rats. The extract also prevented body weight loss in diabetic rats. The effective dose of the plant extract (300 mg/kg) tended to reduce plasma cholesterol, triglyceride and urea levels toward the normal levels. Four days after diabetes induction, an oral glucose tolerance test (OGTT) was also performed in experimental diabetic rats. The results showed a significant improvement in glucose tolerance in rats treated with Sclerocarya birrea extract. Metformin, a known antidiabetic drug (500 mg/kg), significantly decreased the integrated area under the glucose curve. These data indicate that Sclerocarya birrea treatment may improve glucose homeostasis in STZ-induced diabetes which could be associated with stimulation of insulin secretion.     

Studies on the glycemic and lipidemic effect of Murraya koenigii in experimental animals

Diabetes is often accompanied by lipid abnormalities, which contribute significantly to cardiovascular morbidity and mortality in diabetic patients. Previously, we have demonstrated potent hypoglycemic activity of lyophilized aqueous extract of Murraya koenigii leaves in normal and alloxan induced diabetic rabbits for short duration of 6 h. In this study, we examined the effect of 1 month oral administration of Murraya koenigii aqueous leaves extract in normal and STZ induced severe diabetic rats, at the dose of 300 mg/kg bw, on various biochemical parameters, viz., fasting blood glucose (FBG), total cholesterol (TC), HDL-cholesterol (HDL), triglyceride (TG), alkaline phosphatase (ALKP), serum glutamate oxaloacetate and pyruvate transaminases (SGOT and SGPT) and serum creatinine. In case of diabetic animals fasting blood glucose (FBG) levels of treated animals reduced by 48.2% after 30 days treatment with the aqueous leaves extract. A fall of 19.2 and 30.8% in TC and 22.97 and 37.1% in TG levels were also observed in the case of treated normal as well as diabetic rats, respectively. Feeding the extract increased the HDL-cholesterol level by 16 and 29.4% in normal and diabetic rats, respectively, as compared with their initial values. In the normal rats after 1 month of oral administration of the extract SGOT and SGPT levels were decreased by 21.7 and 25.0%. Serum alkaline phosphatase values of the treated normal animals were also reduced by 33% while negligible change was observed in the normal control animals. In the case of diabetic rats, SGOT and SGPT levels were reduced by 36.7 and 32.2%, respectively, whereas ALKP levels decreased by 39.7% after 1 month oral administration of the extract. The serum creatinine levels decrease in normal as well as in the diabetic animals by 17.75 and 18.2%, respectively, as compared to initial values. In the diabetic control animals the urinary sugar remains at +4 level but there was a decrease of 75% in urine sugar in the case of treated diabetic rats. This indicates that the aqueous extract of Murraya koenigii has favorable effect in bringing down the severity of diabetes.     

Antihyperglycemic and hypolipidemic effects of Costus speciosus in alloxan induced diabetic rats

Hyperglycemia, abnormal lipid and antioxidant profiles are the most usual complications in diabetes mellitus. In the present study, the antihyperglycemic, antihyperlipemic and antioxidant potency of an ethanol extract of Costus speciosus root was investigated in alloxan-induced diabetic male (Charles Foster) rats. Four groups of alloxan diabetic rats (n = 6) were administered orally with different doses of Costus speciosus root extract (150, 300 and 450 mg/kg BW) and a standard drug, glibenclamide (600 microg/kg BW), for 4 weeks. Two groups of rats (n = 6) served as normal and diabetic controls. While the diabetic controls showed significant abnormal carbohydrate, lipid and antioxidant profiles, administration of 150 mg/kg BW dose neither improved glucose nor lipid metabolism and antioxidant levels. Administration of 300 and 450 mg/kg BW doses, however, resulted in a reversal of diabetes and its complications. Both doses significantly brought down blood glucose concentration (26.76%, 34.68%), increased glycogenesis and decreased glyconeogenesis bringing the glucose metabolism toward normalcy. These doses also reversed the hyperlipidemia by reducing plasma total lipid (12.87%, 178.24%), cholesterol (21.92%, 30.77%) and triglyceride (25.32%, 33.99%) and improved hepatic antioxidant enzyme activities. The high dose (450 mg/kg BW) was found to have more potential antioxidant activities compared with glibenclamide. It is concluded that Costus speciosus root extract possesses anti-hyperglycemic, antihyperlipemic and antioxidative effects, which may prove to be of clinical importance in the management of diabetes and its complications.     

Effect of coriander seed (Coriandrum sativum L.) ethanol extract on insulin release from pancreatic beta cells in streptozotocin‐induced diabetic rats

Coriander (Coriandrum sativum L.) is grown as a spice crop all over the world. The seeds have been used to treat indigestion, diabetes, rheumatism and pain in the joints. In the present study, an ethanol extract of the seeds was investigated for effects on insulin release from the pancreatic beta cells in streptozotocin‐induced diabetic rats. Blood samples were drawn from the retro‐orbital sinus before and 1.5, 3 and 5 h after administration of the seed extract. Serum glucose levels were determined by the glucose oxidase method. To determine the insulin releasing activity, after extract treatment the animals were anaesthetized by diethyl ether, the pancreas was excised, fixed in 10% formaldehyde and embedded in paraffin for sectioning. Pancreatic sections of 5 µm were processed for examination of insulin‐releasing activity using an immunocytochemistry kit. The results showed that administration of the ethanol extract (200 and 250 mg/kg, i.p.) exhibited a significant reduction in serum glucose. Administration of streptozotocin decreased the number of beta cells with insulin secretory activity in comparison with intact rats, but treatment with the coriander seed extract (200 mg/kg) increased significantly the activity of the beta cells in comparison with the diabetic control rats. The extract decreased serum glucose in streptozotocin‐induced diabetic rats and increased insulin release from the beta cells of the pancreas. Copyright © 2008 John Wiley & Sons, Ltd.     

Effects of Averrhoa bilimbi leaf extract on blood glucose and lipids in streptozotocin-diabetic rats

The present study was designed to investigate the hypoglycemic and hypolipidemic activities of an ethanolic extract of Averrhoa bilimbi Linn. leaves (Oxalidaceae, Common name: Bilimbi) in streptozotocin (STZ)-diabetic rats. The optimal hypoglycemic dose (125 mg kg(-1)) was determined by performing the oral glucose tolerance test (OGTT) in both normal and STZ-diabetic rats. To investigate the effect of repeated administration of an ethanolic extract of Averrhoa bilimbi (ABe) leaves, diabetic rats were treated with vehicle (distilled water), ABe (125 mg kg(-1)) or metformin (500 mg kg(-1)) twice a day for 2 weeks. Like metformin, ABe significantly lowered blood glucose by 50% and blood triglyceride by 130% when compared with the vehicle. ABe also significantly increased the HDL-cholesterol concentrations by 60% compared with the vehicle. ABe thus significantly increased the anti-atherogenic index and HDL-cholesterol/total cholesterol ratio. However, like metformin, ABe did not affect total cholesterol and LDL-cholesterol concentrations, but significantly reduced the kidney lipid peroxidation level. These data show that ABe has hypoglycemic, hypotriglyceridemic, anti-lipid peroxidative and anti-atherogenic properties in STZ-diabetic rats.     

Antinociceptive, hypoglycemic and spasmolytic effects of Brickellia veronicifolia

INTRODUCTION: Brickellia veronicifolia (Kunth) Gray (Asteraceae) (BV) is broadly commercialized for treating gastrointestinal diseases (stomach aches, biliary colics and dyspepsia), arthritis, diabetes and painful inflammatory complaints. AIMS OF THE STUDY: In order to complete the preclinical pharmacological profile of BV, first the antinociceptive effect of an organic extract (BVE) and isolated metabolites on the hot plate and writhing tests was assessed. EXPERIMENTAL: Then, their potential hypoglycemic effects were analyzed in normoglycemic and diabetic rats; in addition, an oral glucose tolerance test (OGTT) was performed. Finally, the spasmolytic activity of BVE was assessed in vivo using the gastrointestinal motility test (GMT) in mice. RESULTS: The results revealed that BVE (100-600 mg/kg), 6-methoxysalicylic acid (1), 2-methoxybenzoic acid (2), benzyl-2,6-dimethoxybenzoate (3), and taraxasteryl acetate (4) showed significant analgesic effects. Compounds 2 and 3 were the most active (1-100mg/kg) in the hot plate and writhing tests, respectively. In the antidiabetic assays, BVE (100mg/kg) showed an important hypoglycemic action. Furthermore, at the same dose, it provoked a significant postprandial decrease of blood glucose level after 30 min of a glucose challenge. Finally, the GMT in mice revealed the spasmolytic activity in vivo of BVE (31.6 mg/kg). CONCLUSION: The overall information tends to support the vernacular uses of the plant.     

Anti-hyperglycemic activity of the leaves of Tetracera scandens Linn. Merr. (Dilleniaceae) in alloxan induced diabetic rats

Aim of the study

The present study was aimed to investigate the anti-diabetic potential of the leaves of Tetracera scandens Linn. Merr. (Dilleniaceae) in vivo with regard to prove its efficacy by local herbalists in the treatment of diabetes frailties.

Materials and methods

Crude aqueous (AQ) and methanol (MEOH) extracts of the leaves of T. scandens L. were administered to both normal and alloxan induced diabetic male albino rats (Wistar strain). The blood glucose levels were measured at 0, 2, 4, 6 and 8 h after oral administration of AQ and MEOH extracts.

Results

Significant reduction in glucose was observed in fasting blood glucose levels in the treated diabetic rats without causing any hypoglycemic effect compared to normal rats. Both polar extracts of the leaves of T. scandens L. exhibited significant anti-hyperglycemic activity at different doses and intervals. The highest anti-hyperglycemic effect (62.5%) was observed by the AQ extract at 0.25 g/kg body weight (b.w.) and MEOH extract (36.5%) at 0.5 g/kg b.w. after 8 h. The significant anti-hyperglycemic activity was found to be comparable with a known oral synthetic hypoglycemic drug, glibenclamide 0.25 mg/kg b.w.

Conclusion

This study provides scientific evidence that the leaves of T. scandens L. have anti-diabetic efficacy and justifies its utility by local herbalists. However, more experiments at the clinical levels are required to confirm the utility of this plant by traditional practitioners in the management of diabetes mellitus.