Antidiabetic effect of Nelumbo nucifera (Gaertn) extract: Part II

Earlier studies showed that the extract of Nelumbo nucifera Gaertn., an aquatic Indian plant, produced hypoglycaemia and an improvement of glucose tolerance in normal rabbits. Further investigations were undertaken. Chronic administration of plant extracts (test drugs) to normal rats did not produce a sustained fall of fasting blood sugar levels although daily doses caused hypoglycaemia as an acute effect; concurrent glucose tolerance studies showed beneficial effects. In vitro studies with rat hemidiaphragms revealed that test drug treatment of donor animals significantly enhanced the effect of insulin. The improvement of glucose tolerance therefore may also be due to increased peripheral glucose utilization caused by increased sensitivity of skeletal muscles to endogenous insulin. Comparative studies were also carried out in moderately diabetic rabbits using test drugs (equivalent to 1000 mg/kg of crude material) and standard drugs phenformin and tolbutamide (100 mg/kg each). The test drugs showed acute and chronic effects in suppressing hyperglycaemia, but were less potent than standard drugs. However, test drugs significantly improved glucose tolerance in these animals. With severely diabetic rabbits, these drugs proved to be ineffective even at four-fold higher doses. Toxicity studies in normal rats did not show any deleterious effect on kidney, heart or liver during an 8-week study period.     

Effect of Fenugreek Fiber on Satiety,Blood Glucose and Insulin Response and Energy Intake in Obese Subjects

Eighteen healthy obese subjects participated in a single blind, randomized, crossover study of three test breakfasts, containing 0 g (control), 4 g or 8 g of isolated fenugreek fiber. Subjects recorded ratings of hunger, satiety, fullness and prospective food consumption using visual analog scales (VAS) every 30 min for 3.5 h. Postprandial blood glucose and insulin responses were measured. Energy intake from an ad libitum lunch buffet and for the remainder of the day was assessed. The 8 g dose of fenugreek fiber significantly increased mean ratings of satiety and fullness, and reduced ratings of hunger and prospective food consumption (P < 0.05). Palatability was significantly reduced with increasing doses of fenugreek fiber (P < 0.05). No differences were observed for area under the curve (AUC) for blood glucose among treatments. An increase in insulin AUC was found with 8 g fenugreek fiber. Energy intake at an ad libitum lunch buffet was significantly lower for 8 g than 4 g fenugreek fiber, but not significantly different from control, although there was a trend towards a lower intake (p = 0.11). No differences were observed for energy intake for the remainder of the day. Fenugreek fiber (8 g) significantly increased satiety and reduced energy intake at lunch, suggesting it may have short‐term beneficial effects in obese subjects. Satiety results were not related to postprandial blood glucose. Copyright © 2009 John Wiley & Sons, Ltd.     

Effect of Agarista mexicana and Verbesina persicifolia on Blood Glucose Level of Normoglycaemic and Alloxan-diabetic Mice and Rats

Blood glucose levels of normal and alloxan-treated diabetic mice and rats were determined after oral administration of various doses of the chloroform extracts of A. mexicana and V. persicifolia . From the data obtained, it is concluded that the oral administration of 100 and 150 mg/kg of chloroform extracts of these plants produced a significant hypoglycaemic effect in normal as well as in diabetic mice and rats. In addition the extracts altered glucose tolerance in alloxan induced diabetic rats, enhanced glucose uptake in skeletal muscle and significantly inhibited glycogenolysis in the liver. These results indicate that the hypoglycaemic effect may be similar to tolbutamide.     

Hypoglycaemic effects of myrtle oil in normal and alloxan-diabetic rabbits

Myrtus communis L. (Myrtaceae) leaves as well as the volatile oil (Myrtii Oleum; MO) obtained from the leaves are used to lower the blood glucose level in type-2 diabetic patients in Turkish folk medicine. However, little attention has been paid to the therapeutic use of this plant. The present study was designed to investigate the oral hypoglycaemic activity of single and multiple doses of MO in normal and alloxan-diabetic rabbits. MO did not show any effect in normoglycaemic rabbits either in single or multiple dose administrations, but a good hypoglycaemic activity was observed 4 h after the administration to diabetic animals at 50 mg/kg. To investigate the effect of MO on repeated administration in both normal and diabetic rabbits, it was administered in 50 and 100 mg/kg doses once a day for one week. MO significantly lowered blood glucose by 51% in alloxan-diabetic rabbits on the fourth hour and the following days at a dose of 50 mg/kg (P < 0.001). The hypoglycaemic dose (50 mg/kg) was also determined by performing the oral glucose tolerance test (OGTT) in normal rabbits. The hypoglycaemic effect of the MO was 21% higher in rabbits, which received the glucose load orally, when compared with control group. However, MO did not affect serum insulin concentrations in normal and alloxan-diabetic rabbits but reduced the serum triglyceride concentrations by 14% in alloxan-diabetic rabbits. The above observations show that MO exerts hypoglycaemic as well as mild hypotriglyceridemic activity in diabetic animals. The reduction in blood glucose level may be due to the reversible inhibition of alpha-glucosidases present in the brush-border of the small intestinal mucosa, higher rate of glycolysis as envisaged by the higher activity of glucokinase, as one of the key enzymes of glycolysis, and enhanced rate of glycogenesis as evidenced by the higher amount of liver glycogen present after MO administration.     

Hypoglycaemic activity of Spathodea campanulata stem bark decoction in mice

Decoction of the stem bark of Spathodea campanulata (SC) exerted a hypoglycaemic activity in streptozotocin (SZ) diabetic mice. Later, the decoction, washed with chloroform, was divided in water and butanol fractions. Both had a hypoglycaemic activity but were devoid of any influence on insulin levels in SZ diabetic mice. The decoction also decreased blood glucose levels in a glucose tolerance test (GTT) in normal mice.     

Hypoglycaemic Activity of Culinary Pleurotus ostreatus and P. cystidiosus Mushrooms in Healthy Volunteers and Type 2 Diabetic Patients on Diet Control and the Possible Mechanisms of Action

This study determined the oral hypoglycaemic effect of suspensions of freeze dried and powdered (SFDP) Pleurotus ostreatus (P.o) and Pleurotus cystidiosus (P.c), using healthy human volunteers and Type 2 diabetic patients on diet control at a dose of 50 mg/kg/body weight, followed by a glucose load. The possible hypoglycaemic mechanisms were evaluated using rats, by examining intestinal glucose absorption and serum levels of insulin, glucokinase (GK) and glycogen synthase kinase (GSK). The P.o and P.c showed a significant reduction (P < 0.05) in fasting and postprandial serum glucose levels of healthy volunteers and reduced the postprandial serum glucose levels and increased the serum insulin levels (P < 0.05) of Type 2 diabetic patients. The P.o and P.c increased the intestinal absorption of glucose but simultaneously reduced the serum glucose levels (P < 0.05) in rats. Both mushrooms reduced the serum GSK and promoted insulin secretion while P.c increased serum GK (P < 0.05). The hypoglycaemic activity of P.o and P.c makes mushrooms beneficial functional foods in diabetes mellitus. The mechanism of hypoglycaemic activity of P.o and P.c is possibly by increasing GK activity and promoting insulin secretion and thereby increasing the utilization of glucose by peripheral tissues, inhibiting GSK and promoting glycogen synthesis. Copyright © 2014 John Wiley & Sons, Ltd.     

Antidiabetic effects of Tinospora crispa in rats

In Malaysia, an aqueous extract of Tinospora crispa stems is taken orally to treat diabetes mellitus. In the present study, normal and alloxan-diabetic rats were used to evaluate the hypoglycaemic properties of the extract. A hypoglycaemic effect was observed in moderately diabetic rats with concomitant improvement in insulinaemia. After a 2-week treatment with the extract (4 g/l in the drinking water), these rats also showed improvement in glucose tolerance. Moreover, acute intravenous treatment with the extract (50 mg/kg) caused an increase in plasma insulin levels. The data support the traditional belief that T. crispa extract could improve diabetic conditions by virtue of its action on the endocrine pancreas.     

Antidiabetic activity of resveratrol,a known SIRT1 activator in a genetic model for type‐2 diabetes

In the present study, resveratrol, a polyphenolic SIRT1 activator was evaluated for its SIRT1 activation in an in vitro fluorescent based assay (EC₅₀: 7 μM ). The efficacy of resveratrol was also evaluated in ob/ob mice for its antidiabetic and associated metabolic effects. Mice aged 5–8 weeks were included in four groups; control and resveratrol at 5, 15, 50 mg/kg, b.i.d. and were dosed orally. After 4 weeks of drug treatment, body weights were noted and random blood glucose and insulin was estimated for the antidiabetic effect. Animals were also subjected to the oral glucose tolerance test to observe any improvement in the glucose excursion. Triglycerides, total cholesterol, adiponectin and free fatty acid levels were also estimated. The results showed that resveratrol exhibited significant antihyperglycemic activity with an improvement in the insulin levels compared with the control mice. There was also a significant improvement observed in the glucose excursion in the oral glucose tolerance test performed for 120 min; although an insignificant improvement in the triglycerides, total cholesterol, adiponectin and free fatty acid levels was observed at different doses of resveratrol tested. The present findings suggest that resveratrol is an antihyperglycemic agent and drugs similar to resveratrol can be considered as an effective therapeutic adjuvant for the current treatment of diabetes mellitus. Copyright © 2010 John Wiley & Sons, Ltd.     

Hypoglycemic effect of a novel dialysed fenugreek seeds extract is sustainable and is mediated, in part, by the activation of hepatic enzymes

A novel preparation of a dialysed aqueous extract of fenugreek seeds (FSE) that stimulates the insulin signalling pathway was reported previously (Vijayakumar et al., 2005). The present study was designed to investigate the long-term effects (multiple dose effect) of this FSE preparation on the blood glucose level and body weight, and a short-term effect (single dose effect) on serum insulin and hepatic enzymes, in experimentally induced diabetic conditions. The multiple dose effect of FSE on the glucose level and body weight was studied in alloxan (AXN)-diabetic mice in comparison with the vehicle treated control diabetic mice. Intraperitoneal (i.p.) administration of FSE (15 mg/kg body weight (BW)) for 5 consecutive days reduced hyperglycemia in AXN-diabetic mice on day 5 and this effect was further sustained for 10 days. The FSE-induced hypoglycemic effect was accompanied without any reduction in the body weight compared with the diabetic mice in which the body weight was reduced significantly. A single dose effect of FSE on hepatic glucokinase (GK) and hexokinase (HK) enzymes was studied in streptozotocin (STZ)-diabetic mice. Intraperitoneal administration of FSE (15 mg/kg BW) by 90 min decreased the blood glucose levels significantly (p < 0.01) in STZ-diabetic mice and the effect was comparable to that achieved by insulin (1.5 U/kg BW) injection. This effect was associated with a significant enhancement in the liver GK and HK activities on a par with that of insulin. In normal glucose loaded mice, FSE improved the intraperitoneal glucose tolerance accompanied by a reduction in serum insulin concentration. These results are indicative of an extra-pancreatic mode of action of FSE. The present study concludes that this novel FSE preparation corrects metabolic alterations associated with diabetes by exhibiting insulin-like properties and has a potential for clinical applications.     

Oral hypoglycaemic activity of some medicinal plants of Sri Lanka

Investigations were carried out to evaluate the oral hypoglycaemic activity of some Sri Lankan medicinal plants. Approximately 40 plants available locally are reputed to have oral hypoglycaemic activity. Of these, the mostly widely used are (a) Salacia reticulata (Celastraceae) (b) Aegle marmelos (Rutaceae) and (c) Momordica charantia (Cucurbitaceae). Aqueous decoctions of these plants were investigated for their ability to lower the fasting blood glucose level and improve the glucose tolerance in laboratory animals. The results indicate that the aqueous decoctions of all three plants possess significant hypoglycaemic effect. The magnitude of this effect showed time related variation with the three plants. The highest oral hypoglycaemic activity and the maximum improvement of the oral glucose tolerance were associated with the extract of Momordica charantia while the least but significant effects were shown by Salacia reticulata.     

The antidiabetic activity of the herbal preparation ADD-199 in mice: a comparative study with two oral hypoglycaemic drugs

The antidiabetic and antioxidant effects of the herbal preparation ADD-199 were investigated in STZ-induced diabetic C(3)H mice and results were compared with two allopathic hypoglycaemic drugs, glibenclamide and metformin. Plasma glucose, insulin and lipids as well as liver glycogen, lipids and lipid peroxidation were measured following treatment for 8 weeks. The results indicated that plasma insulin levels in normal controls at termination were about 76 micromol/L compared to trace levels in untreated diabetic mice. Glibenclamide and ADD-199 increased insulin levels in diabetic mice up to 70% of levels in untreated non-diabetic mice whilst metformin had no effect. Basal plasma glucose levels in diabetic controls (18.8 mM) were reduced to 14.0 mM by 100 mg/kg ADD-199 in <2 weeks compared to 4 and 6 weeks for glibenclamide and metformin, respectively. This hypoglycaemic effect of ADD-199 appeared to be associated with the alkaloidal content of the extract. Treatment with ADD-199 or the hypoglycaemic agents reversed the observed elevation in plasma lipids but increased hepatic glycogen, triacylglycerol and cholesterol levels. Treatment also increased glucose uptake by isolated diaphragms and attenuated hepatic lipid peroxidation. These antihyperglycaemic and antioxidant actions of ADD-199 at a dose of 100mg/kg/day are comparable to those of the maximum daily therapeutic doses of glibenclamide (0.25 mg/kg) and metformin (50 mg/kg). These could explain the basis for use of this plant extract to manage diabetes mellitus (DM).     

Hypoglycaemic activity of Geranium core-core,Oxalis rosea and Plantago major extract in rats

The hypoglycaemic activity of ‘Core-core’ (Geranium core-core, Geraniaceae), ‘Culle’ (Oxalis rosea, Oxalidaceae) and ‘Llantén’ (Plantago major, Plantaginaceae) crude extracts was assessed in normoglycaemic rats. Furthermore, the hypoglycaemic activity of Core-core extract was evaluated in alloxan-diabetic rats. A single oral dose of 500 mg/kg Core-core extract significantly reduced glycaemia in normal rats under glucose tolerance test conditions (p < 0.01), while Culle and Llantén were devoid of activity. The effect was lower than a single oral dose of 100 mg/kg tolbutamide. After 7 days oral treatment at 250 mg extract/kg body weight, Core-core significantly reduced glycaemia (p<0.01) in normal rats under oral glucose tolerance conditions. In alloxan-diabetic rats, a single oral dose of 500 mg/kg and chronic treatment at 250 mg/kg Core-core extract significantly reduced glycaemia in glucose tolerance test conditions at p < 0.05 and p < 0.01, respectively. During the acute oral toxicity study, animals treated with Core-core extract exhibited no symptoms of drug-induced toxicity with doses up to 5 g/kg.     

Phlorizin-like effect of Fraxinus excelsior in normal and diabetic rats

The purpose of this study was to determine the underlying mechanism of the hypoglycaemic activity of the aqueous extract perfusion of Fraxinus excelsior L. (FE) in normal and streptozotocin-induced diabetic rats. The aqueous extract was administered intravenously and the blood glucose changes were determined within four hours after starting the treatment. Plasma insulin concentrations and glycosuria were determined. The aqueous extract at a dose of 10 mg/kg/h produced a significant decrease in blood glucose levels in normal rats (P < 0.001) and even more in diabetic rats (P < 0.001). This hypoglycaemic effect might be due to an extra-pancreatic action of the aqueous extract of FE, since the basal plasma insulin concentrations were unchanged after FE treatment. A potent increase of glycosuria was observed both in normal and diabetic rats (P < 0.001). We conclude that aqueous extract perfusion of FE caused a potent inhibition of renal glucose reabsorption. This renal effect might be at least one mechanism explaining the observed hypoglycaemic activity of this plant in normal and diabetic rats.     

Antihyperglycemic effect of the fruit-pulp of Eugenia jambolana in experimental diabetes mellitus

The oral antihyperglycemic effect of the water and ethanolic extracts of the fruit-pulp of Eugenia jambolana (EJ) was investigated in alloxan-induced diabetic with fasting blood glucose between 120 and 250 mg/dl as well as severely diabetic rabbits (fasting blood glucose above 250 mg/dl). Water extract was found to be more effective than the ethanolic extract in reducing fasting blood glucose and improving blood glucose in glucose tolerance test. Chromatographic purification of the water extract yielded not only two hypoglycaemic fractions (F-III more active than F-IV) but indicated the presence of hyperglycemic compounds (F-I and F-II) also in the water extract of Eugenia jambolana fruits. When administered as a single dose of 25 mg/kg of body weight; F-III could reduce fasting blood glucose from 174.0 +/- 4.6 to 137.3 +/- 5.4 mg/dl in diabetic (21% fall) and from 266.0 +/- 5.4 to 202.2 +/- 5.2 mg/dl in severely diabetic rabbits (24% fall). After treatment of diabetic and severely diabetic rabbits daily once with 25mg/kg, body weight with F-III for 7 and 15 days, respectively, there was fall in fasting blood glucose (38% diabetic; 48% severely diabetic) and improvement in blood glucose during glucose tolerance test (48%) in diabetic rabbits. Further, there was increase in the plasma insulin levels in both diabetic (24.4%) and severely diabetic rabbits (26.3%). The in vitro studies with pancreatic islets showed that the insulin release was nearly two and half times more than that in untreated diabetic rabbits. The mechanism of action of FIII fraction appears to be both pancreatic by stimulating release of insulin and extra pancreatic by directly acting on the tissues.     

Effects of three different doses of a fruit extract of Terminalia chebula on metabolic components of metabolic syndrome,in a rat model

There is documented evidence of the use of Terminalia chebula for various ailments in the Ayurvedic literature. The extract has been shown to possess glucose lowering activity and to improve insulin sensitivity in animal models of type 2 diabetes mellitus. The present study was carried out to study the dose response relationship of this extract in a rat model of metabolic syndrome. Six groups of rats were fed a high fructose diet (HFD) for a period of 20 days to induce metabolic syndrome. Three doses of fruit extract of T. chebula 50, 100 and 200 mg/kg were administered orally and pioglitazone 2.7 mg/kg was used as a positive control. Blood samples were collected at days 0, 20 and 40 from the tail vein. Systolic blood pressure (SBP) was measured using the tail cuff method and an oral glucose tolerance test (OGTT) was done on the day of blood collection. Administration of HFD for 20 days significantly increased fasting blood glucose (FBG), SBP and the area under the curve of OGTT. On day 40 the FBG in the 50, 100 and 200 mg/kg group was 97.33 ± 5.82 (NS), 86.83 ± 5.08 (p = 0.038) and 85.67 ± 6.74 (p = 0.15), respectively. These results show that the fruit extract of T. chebula exerts a significant and dose‐dependent glucose lowering effect in the rat model of metabolic syndrome. Copyright © 2009 John Wiley & Sons, Ltd.     

Hypoglycaemic action of the flavonoid fraction of Cuminum nigrum seeds

The seeds of Cuminum nigrum were screened phytochemically and were found to contain 8% flavonoids and 0.01% alkaloids. When studied for their effect on blood glucose levels, oral administration of the flavonoid contents of the plant caused a hypoglycaemic effect at a dose range of 0.5 to 1.5 g/kg, both in normal and alloxan-diabetic rabbits. The hypoglycaemic effect started 2 h after drug administration, reaching a maximum within 4-8 h and the blood glucose levels returned close to normal within 24 h of drug administration. The glibenclamide (5 mg/kg), produced a hypoglycaemic effect in the normal rabbits, whereas it had no effect on the blood glucose levels of alloxan-diabetic rabbits. The alkaloids isolated from C. nigrum seeds, however, failed to exert any significant hypoglycaemic effect in either the normal or diabetic rabbits. A 7 day acute toxicity study in rabbits did not produce any apparent adverse effect at doses as high as 5 g/kg orally. These data indicate that the total flavonoid contents of C. nigrum seeds exhibited considerable hypoglycaemic activity in rabbits and may therefore be responsible for the previously reported antidiabetic activity of the seeds. Furthermore, it is conceivable that the C. nigrum flavonoids possess insulin triggering and/or insulin-like properties.     

Antidiabetic and hypocholesterolaemic effects of fenugreek

The seeds of Trigonella foenum graecum (fenugreek) have been reported to have antidiabetic and hypocholesterolaemic properties in both animal models and humans. Activity has been attributed largely to fenugreek's saponin and high fibre content, and is probably not related to its major alkaloid trigonelline. Antihyperglycaemic effects have been linked to delayed gastric emptying caused by the fibre content, and to (unidentified) components that inhibit carbohydrate digestive enzymes. Fenugreek administration may increase plasma insulin levels in vivo. Its major free amino acid, 4-hydroxyisoleucine, stimulates insulin secretion from perfused pancreas in vitro. The hypocholesterolaemic effect has been attributed to increased conversion of hepatic cholesterol to bile salts due to loss, in the faeces, of complexes of these substances with fenugreek fibre and saponins. Fenugreek treatment selectively reduces the LDL and VLDL fractions of total cholesterol, and HDL-cholesterol has also been reported to increase in alloxan-induced diabetic rats and type II diabetic individuals following treatment with fenugreek. Fenugreek administration has not been reported to cause any toxicological effects. Its regular consumption may therefore be beneficial in the management of diabetes and the prevention of atherosclerosis and coronary heart disease. © 1998 John Wiley & Sons, Ltd.     

Hypoglycaemic effect of Clausena anisata (Willd) Hook methanolic root extract in rats

This study was designed to examine the hypoglycaemic effect of Clausena anisata (Willd) Hook [family: Rutaceae] root methanolic extract in normal (normoglycaemic) and in streptozotocin-treated diabetic rats. Young adult, male Wistar rats (Rattus norvegicus) weighing 250-300 g were used. Diabetes mellitus was induced in the group of diabetic 'test' rats by intraperitoneal injections of streptozotocin (STZ, 90 mg/kg). In one set of experiments, graded doses of the methanolic root extract of C. anisata (CAME, 100-800 mg/kg p.o.) were administered to both fasted normal and fasted diabetic rats. In another set of experiments, 800 mg/kg of CAME, a dose of the plant extract which produced maximal hypoglycaemic effect in both fasted normal and diabetic rats in the previous set of experiments, was used. The hypoglycaemic effect of this single dose of C. anisata root methanolic extract (i.e. CAME, 800 mg/kg p.o.) was compared with those of insulin (5 micro U/kg s.c.) and glibenclamide (0.2 mg/kg p.o.) in both fasted normal and fasted diabetic rats. Following acute treatment, relatively moderate to high doses of CAME (100-800 mg/kg p.o.) produced dose-dependent, significant reductions (P<0.05-0.001) in the blood glucose concentrations of both fasted normal and fasted diabetic rats. On their own, both insulin (5 micro U/kg s.c.) and glibenclamide (0.2 mg/kg p.o.) produced significant reductions (P<0.01-0.001) in the blood glucose concentrations of the fasted normal and diabetic rats. At a dose of 800 mg/kg p.o., CAME reduced the mean basal blood glucose concentrations of fasted normal and fasted diabetic rats by 57.52 and 51.30%, respectively. C. anisata contains a diverse group of chemical compounds (see Table 1). Since methanol extractives of plants are usually known to contain many chemical compounds, each of which is capable of producing definite biological activities via different mechanisms, it is difficult to draw any logical conclusion on the mechanism of the hypoglycaemic effect of such a diverse mixture of chemical compounds contained in the plant extract used in this study. While it is possible that the hypoglycaemic effect of the plant extract may be due, at least in part, to its terpenoid and coumarin contents, the mechanism of its hypoglycaemic action remains largely speculative, and is unlikely to be due to the stimulation of pancreatic beta-cells and subsequent secretion of insulin. Although C. anisata root methanolic extract is less potent than insulin as an antidiabetic agent, the results of this experimental animal study indicate that the herb possesses hypoglycaemic activity; and thus lend credence to the suggested folkloric use of C. anisata root in the management and/or control of adult-onset, Type-2 diabetes mellitus in some communities of South Africa.     

Improvement on lipid metabolic disorder by 3'-deoxyadenosine in high-fat-diet-induced fatty mice

This study explores the effects of 3'-deoxyadenosine, a compound from Cordyceps militaris, on lipid metabolic disorder induced by a high-fat-diet in C57BL/6 mice. These mice had an obese body, lipid metabolic disorder and insulin resistance and were treated orally with 100 mg/kg/day 3'-deoxyadenosine (DA), 15 mg/kg/day rosiglitazone and 150 mg/kg/day fenofibrate, respectively. Compared to the model mice, the body weight gain in DA-treated mice were decreased by 66.5%, serum triglyceride and total cholesterol levels were decreased by 20.7% and 16.7%, respectively, and the triglyceride content in the skeletal muscle was reduced by 41.2%. This treatment also had a significant effect on insulin resistance. In DA-treated mice, the serum insulin levels and homeostasis model assessment of the insulin resistance index were decreased by 30% and 46%, respectively, and the areas under the glucose-time curve were depressed by 18% in the insulin tolerance test and by 21.5% in the oral glucose tolerance test. Finally, the value of glucose infusion rates and insulin induced-glucose uptake into the skeletal muscle in the hyperinsulinemic-euglycemic clamp test were increased by 18% and 41%, respectively, compared to those in the model mice. This data suggests that the effects of DA on lipid metabolic disorder induced by a high-fat-diet may be linked to its improvement on insulin resistance, especially concerning the increase of insulin sensitivity in the skeletal muscle.     

Hypoglycaemic Effects of Shokatsu-Cha (Xiao-Ke-Ca ) in Streptozotocin-induced Diabetes Mellitus

Shokatsu-cha is a novel formula for diabetic mellitus based on the traditional Chinese medicine and composed of Dioscoreae rhizoma, Adenophorae radix, Rehmanniae radix, Anemarrhenae rhizoma, Platycodi radix, Salviae miltiorrhizae radix, Epimedii folium and Lycii fructus . The hypoglycaemic effect of Shokatsu-cha was evaluated in streptozotocin (STZ)-induced diabetic mice and rats. When orally administered once a day for 10 days to the mice intraperitoneally injected with STZ, the Shokatsu-cha extract suppressed the increase of the blood glucose level during administration. In the in situ intestine circulation method, the Shokatsu-cha extract and its ethanol-eluted fraction inhibited the glucose absorption in STZ-induced diabetic rats. The ethanol-eluted fraction also inhibited the increase of blood glucose level in an oral glucose tolerance test using diabetic mice. This study indicates that a part of the hypoglycaemic effect of Shokatsu-cha is based on its inhibitory action on intestinal glucose absorption in diabetes.