Antihyperglycemic effect of aqueous and ethanolic extracts of Gongronema latifolium leaves on glucose and glycogen metabolism in livers of normal and streptozotocin-induced diabetic rats

The present study was designed to investigate the antihyperglycemic effects of aqueous and ethanolic extracts from Gongronema latifolium leaves on glucose and glycogen metabolism in livers of non-diabetic and streptozotocin-induced diabetic rats. To investigate the effects of aqueous or ethanolic leaf extracts of G. latifolium, non-diabetic and STZ diabetic rats were treated twice daily (100 mg/Kg) for two weeks. Diabetic rats showed a significant decrease in the activities of hepatic hexokinase (HK), phosphofructokinase (PFK) and glucose-6-phosphate dehydrogenase (G6PDH) and an increase in glucokinase (GK) activity. The levels of hepatic glycogen and glucose were also increased in diabetic rats. However, there were no significant differences in the activities of glucose-6-phosphatase (G6Pase) in treated and untreated diabetic rats. The ethanolic extract significantly increased the activities of HK (p<0.01), PFK (p<0.001) and G6PDH (p<0.01) in diabetic rats, decreased the activity of GK (p<0.05) and the levels of hepatic glycogen (p<0.01) and both hepatic (p<0.001) and blood glucose (40%). The aqueous extract of G. latifolium was only able to significantly increase the activities of HK and decrease the activities of GK but did not produce any significant change in the hepatic glycogen and both hepatic and blood glucose content of diabetic rats. Our data show that the ethanolic extract from G. latifolium leaves has antihyperglycemic potency, which is thought to be mediated through the activation of HK, PFK, G6PDH and inhibition of GK in the liver. The ethanolic extract is under further investigation to determine the chemical structure of the active compound(s) and its/their mechanism of action.     

Antihyperglycemic activity of Woodfordia fruticosa (Kurz) flowers extracts in glucose metabolism and lipid peroxidation in streptozotocin-induced diabetic rats

The ethanolic extract of W. fruticosa flowers (250 and 500 mg/kg) significantly reduced fasting blood glucose level and increased insulin level after 21 days treatment in streptozotocin diabetic rats. The extract also increased catalase, superoxide dismutase, glutathione reductase, glutathione peroxidase activities significantly and reduced lipid peroxidation. Glycolytic enzymes showed a significant increase in their levels while a significant decrease was observed in the levels of the gluconeogenic enzymes in ethanolic extract treated diabetic rats. The extract has a favourable effect on the histopathological changes of the pancreatic beta-cells in streptozotocin induced diabetic rats. The results suggest that W. fruticosa possess potential antihyperglycemic effect by regulating glucose homeostasis and antioxidant efficacy in streptozotocin-induced diabetic rats.     

Antihyperglycemic activity of herb extracts on streptozotocin-induced diabetic rats

We investigated the effects of herb extracts, Rhus verniciflua, Agrimonia pilosa, Sophora japonica, and Paeonia suffruticosa, on the lowering of blood glucose levels and thiobarbituric acid reactive substances (TBARS) in streptozotocin (STZ)-induced diabetic rats. After 4 weeks, oral administration of Rhus verniciflua extract (50 mg/kg) exhibited a significant decrease in blood glucose levels in diabetic rats (P<0.05). Blood TBARS concentrations, the products of glucose oxidation in blood, were also lowered by Rhus verniciflua extract supplementation. In addition, Sophora japonica and Paeonia suffruticosa extracts significantly reduced TBARS levels versus diabetic controls. Serum concentrations of liver-function marker enzymes, GOT and GPT, were also restored by Rhus verniciflua (50 mg/kg) supplementation in diabetic rats.     

Effect of Bergenia crassifolia L. extracts on weight gain and feeding behavior of rats with high-caloric diet-induced obesity

The objective of this study was to evaluate the feeding behavior and weight gain in rats with high-calorie diet-induced obesity that are treated with Bergenia crassifolia black and fermented leaves extracts. The daily dietary intake of all treated animals was reduced to 40% compared with the control group on day 22 of the experiment. A significant improvement in glucose tolerance was noted after 7 days of treatment with the Bergenia extracts. In rats treated with an extract of black leaves for 7 days, a significant reduction in the serum triglyceride level, 45% (p < 0.05), compared with the control group was observed. However, the treatment did not affect the cholesterol level. Our results provide evidence for the potential use of B. crassifolia as an appetite and energy intake suppressant.     

Alterations in lipid peroxidation,lipid profile,insulin sensitivity,and hepatic histopathological changes in diabetic rats following the treatment with Salvadora persica

We examined the effects of various partitions of Salvadora persica extract on lipid profile (LP), lipid peroxidation, and insulin sensitivity (IS) of diabetic rats. The rats were divided into normal control, diabetic control (DC), standard, sham, and test groups. The test groups were treated with an oral dose of 200, 400, and 600 mg/kg of crude, aqueous, and ethyl acetate partition of S. persica extract. After 21 days of experiment, the fasting blood glucose (FBS), LPs, lipid peroxidation, IS, liver enzymes levels, liver histopathology, and body weight alteration were evaluated. A significant decrease in FBS and lipid profile (except HDL) were observed in rats treated with various dose of extract compared with the DC rats ( P < 0.05). Treating diabetic rats with various extracts of S. persica meaningfully decreased the level of malondialdehyde ( P < 0.05). Animals treated with various dose of aqueous extract showed better results ( P < 0.01). On the basis of used indirect indexes to determine IS, all partitions of extracts showed anti-insulin resistance effects in diabetic rats. On the basis of our statistical analyzing, treating diabetic rats with all of the three extracts of S. persica decreased the elevated levels of alanine phosphatase, aspartate aminotransferase, and alanine transferase. Also, pathological changes in the liver tissue were reduced following treatment with the S. persica. In conclusion, our results give evidence that the S. persica extract, especially aqueous partition, has a healing effect on diabetes and can be considered as an alternative therapy for this disease.     

Biochemical study of the anti-diabetic action of the Egyptian plants Fenugreek and Balanites

Fenugreek and Balanites are two plants commonly used in Egyptian folk medicine as hypoglycemic agents. In the present study, the effects of 21 days oral administration of Fenugreek seed and Balanites fruit extracts (1.5 g/kg bw) on the liver and kidney glycogen content and on some key liver enzymes of carbohydrate metabolism in STZ-diabetic rats were studied. In addition, the effects of these two plant extracts on the intestinal α-amylase activity in vitro and starch digestion and absorption in vivo were also examined. Results indicated that single injection of STZ (50 mg/kg bw) caused 5-folds increase in the blood glucose level, 80% reduction in serum insulin level, 58% decrease in liver glycogen and 7-folds increase in kidney glycogen content as compared to the normal levels. The activity of glucose-6-phosphatase was markedly increased, whereas, the activities of both glucose-6-phosphate dehydrogenase and phospho-fructokinase were significantly decreased in the diabetic rat liver. Administration of Fenugreek extract to STZ-diabetic rats reduced blood glucose level by 58%, restored liver glycogen content and significantly decreased kidney glycogen as well as liver glucose-6-phosphatase activity. Meanwhile, Balanites extract reduced blood glucose level by 24% and significantly decreased liver glucose-6-phosphatase activity in diabetic rats. On the other hand, our results demonstrated that both the Fenugreek and Balanites extracts were able to in vitro inhibit α-amylase activity in dose-dependent manner. Fenugreek was more potent inhibitor than Balanites. This inhibition was reversed by increasing substrate concentration in a pattern which complies well with the effect of competitive inhibitors. Furthermore, this in vitro inhibition was confirmed by in vivo suppression of starch digestion and absorption induced by both plant extracts in normal rats. These findings suggest that the hypoglycemic effect of Fenugreek and Balanites is mediated through insulinomimetic effect as well as inhibition of intestinal α-amylase activity.     

Hypoglycemic effect of Hibiscus rosa sinensis L. leaf extract in glucose and streptozotocin induced hyperglycemic rats

Investigations were carried out to evaluate the effect of aqueous extract of H. rosa sinensis leaves on blood glucose level and glucose tolerance using Wistar rats. Repeated administration of the extract (once a day for seven consecutive days), at an oral dose equivalent to 250 mg kg(-1), significantly improved glucose tolerance in rats. The peak blood glucose level was obtained at 30 min of glucose load (2 g kg(-1)), thereafter a decreasing trend was recorded up to 120 min. The data exhibit that repeated ingestion of the reference drug tolbutamide, a sulphonylurea and the extract brings about 2-3 fold decrease in blood glucose concentration as compared to single oral treatment. The results clearly indicate that tolbutamide improves the glucose tolerance by 91% and extract does so only by 47%. At 250 mg kg(-1), the efficacy of the extract was 51.5% of tolbutamide (100mg kg(-1)). In streptozotocin diabetic rats, no significant effect was observed with the extract, while glibenclamide significantly lowered the glucose level up to 7 hr. These data suggest that hypoglycemic activity of H. rosa sinensis leaf extract is comparable to tolbutamide and not to glibenclamide treatment.     

Insulin secretagogue effect of Ichnocarpus frutescence leaf extract in experimental diabetes: a dose-dependent study

Ichnocarpus frutescence (L.) R.Br. is an evergreen plant and many preparations have been used in traditional Indian medicine for centuries to treat several illnesses including diabetes. However, scientific evidence supporting these actions is lacking. In the present study we prepared various extracts of I. frutescence (IF) leaves which were tested against streptozotocin-induced diabetic rats. IF leaf methanolic extract (IFLMExt) showed significant plasma glucose lowering effect. Therefore, we prepared IFLMExt, which was tested against different types of glycemia (normal, glucose-fed hyperglycemic and streptozotocin-induced diabetic rats) for their potential to induce insulin secretion and cellular insulin responses. Fasting plasma glucose (FPG) levels were determined at different doses and times following treatment with IFLMExt or with vehicle in normal, glucose fed-hyperglycemic and diabetic rats. Oral administration of IFLMExt led to a significant blood glucose-lowering effect in glucose-fed hyperglycemic and diabetic rats. The hypoglycemic effect was observed at doses of 100 and 200 mg/(kg bw) after 6 and 2 h administration, respectively, in glucose-fed hyperglycemic rats. The maximum effect of IFLMExt was detected at 2 h with 200 mg/(kg bw) in diabetic animals and this profile was maintained for the next 6 h (37.23%) but increased after that at 24 h. Oral administration of IFLMExt daily for 45 days to diabetic rats significantly reduced the FPG (54.5%) to near normal. After 7 days of streptozotocin administration plasma insulin decreased in diabetic controls compared to normal controls. Treatment with IFLMExt significantly prevented the decrease in plasma insulin levels from day 0 to 45 in comparison to diabetic controls. Oral administration of n-hexane fraction led to a significant glucose-lowering effect in diabetic rats (54.50%). Histopathological examination showed that IFLMExt extract protected the pancreatic tissue from streptozotocin-induced damage enormously. Oral administration of IFLMExt extract and n-hexane fraction to normal and streptozotocin-induced diabetic rats decreased plasma glucose levels without hypoglycemic effect. The results suggest that methanolic extract and n-hexane fraction of IF may provide new therapeutic avenues against diabetes.     

Cytoprotective and anti-diabetic effects of Derris reticulata aqueous extract

The current study was aimed to investigate pancreatic protective and anti-diabetic activities of the aqueous extract of Derris reticulata stem. First, we evaluated a cytoprotective potential of D. reticulata extract on alloxan-induced damage in vitro. Treatment with D. reticulata extract at the doses of 250 and 500 μg/ml significantly increased cell viability of the pancreatic β-cell line RINm5F after exposure of alloxan. The anti-hyperglycemic activity of D. reticulata extract was further studied in alloxan-induced diabetic rats. A significant reduction in blood glucose level along with an increase in body weight was observed in diabetic rats treated with D. reticulata extract at 250 mg/kg body weight for 15 days. Serum aspartate transaminase and alanine transaminase levels were also significantly decreased compared to diabetic control rats. In accordance with in vitro cytoprotective effect, histopathological examination revealed that pancreatic islet cells of the extract-treated diabetic rat were less damage than those of the untreated diabetic group. In order to find another possible mechanism of action underling hypoglycemic activity, the effect on glucose absorption was examined using everted sac jejunum. The results showed that D. reticulata extract suppressed glucose absorption from small intestine. To corroborate safety use of D. reticulata extract, acute oral toxicity was also conducted in rats. Our results showed that none of the tested doses (250, 500, 1,000, and 2,000 mg/kg) induced signs of toxicity or mortality after administration of the extract. The results suggested that D. reticulata extract possess anti-diabetic activity, which resulting from its pancreatic cytoprotective effect and inhibition of intestinal glucose absorption.     

Blood glucose in marine penaeid prawns: I. Neuroendocrine regulation in Parapenaeopsis hardwickii (Miers). (Crustacea,Decapoda, Penaeidae)

In the present investigation on femaleP. hardwickii, the blood glucose level in bilateral eyestalk extirpated, reinjected with ES extract as well as normal prawns, administered with ES, different concentrations of BR and ThG extracts, was estimated quantitatively after fifteen minutes and two hours. During all treatments there was an immediate hike in blood glucose level after fifteen minutes but after 24 hr. of eyestalk ablation the level does not differ significantly (P > 0.05) from controls. There was a significant (P < 0.01) enhancement in blood glucose level in the cauterized eyestalkless and normal prawns injected with ES extract after 2 hr. There was a considerable (93% level of confidence) decrease in blood glucose level of normal prawns after injecting higher concentrations of BR and ThG extracts. There was an obvious change in blood glucose level due to the endocrine hormones injected from other prawns of the related family. ES extracts ofP. stylifera produced a significant (P < 0.01) increase, whereas higher concentration of BR and ThG extracts caused considerable (92% level of confidence) decrease in blood glucose level after injecting in cauterized eyestalkless prawns. The extracts of the same endocrine centres fromMetapenaeus monocerus did not induce any significant (P > 0.05) alteration in blood glucose quantity ofP. hardwickii. Hence from the above findings it may be inferred that, the hormones produced by eyestalks (X organ-Sinus gland Complex) posses a hyperglycemic factor, whereas hormones released from BR and ThG might be having a property to cause hypoglycemia (?).     

Histopathological changes in Poecilia latipinna male gonad due to Tribulus terrestris administration

Tribulus terrestris is a traditionally known non-toxic aphrodisiac herb for maleness. It was experimented recently to understand the effect and mechanism on mono sex production in Poecilia latipinna. It would help to develop a new eco-friendly way to masculinize P. latipinna, since males have higher commercial value than females. The different concentration (100, 150, 200, 250 and 300 mg/L) of T. terrestris extract and a control were tested for their effect on sex transformation/reversal in P. latipinna by immersing the newly born young ones in the respective concentrations for 2 mo. The obtained results indicate that a dose dependant masculinization is obtained due to T. terrestris administration, which improved the male proportion. Histological results revealed that the testes of fish treated with T. terrestris extract contained all stages of spermatogenesis, clearly demonstrating that the administration of T. terrestris extract to P. latipinna stimulated spermatogenesis. Thus, it is discernible that 0-d-old hatchlings of P. latipinna exposed to T. terrestris extract orient/reverse their sex more towards maleness besides yielding better growth and spermatogenesis which is a mandate for fancy fish industry.     

Aphrodisiac properties of Tribulus Terrestris extract (Protodioscin) in normal and castrated rats

Tribulus terrestris (TT) has long been used in the traditional Chinese and Indian systems of medicine for the treatment of various ailments and is popularly claimed to improve sexual functions in man. Sexual behaviour and intracavernous pressure (ICP) were studied in both normal and castrated rats to further understand the role of TT containing protodioscin (PTN) as an aphrodisiac. Adult Sprague-Dawley rats were divided into five groups of 8 each that included distilled water treated (normal and castrated), testosterone treated (normal and castrated, 10 mg/kg body weight, subcutaneously, bi-weekly) and TT treated (castrated, 5 mg/kg body weight, orally once daily). Decreases in body weight, prostate weight and ICP were observed among the castrated groups of rats compared to the intact group. There was an overall reduction in the sexual behaviour parameters in the castrated groups of rats as reflected by decrease in mount and intromission frequencies (MF and IF) and increase in mount, intromission, ejaculation latencies (ML, IL, EL) as well as post-ejaculatory interval (PEI). Compared to the castrated control, treatment of castrated rats (with either testosterone or TT extract) showed increase in prostate weight and ICP that were statistically significant. There was also a mild to moderate improvement of the sexual behaviour parameters as evidenced by increase in MF and IF; decrease in ML, IL and PEI. These results were statistically significant. It is concluded that TT extract appears to possess aphrodisiac activity probably due to androgen increasing property of TT (observed in our earlier study on primates).     

Hypoglycemic activity of leaf organic extracts from Smallanthus sonchifolius: Constituents of the most active fractions

The aim of the present study was to determine the in vivo hypoglycemic activity of five organic extracts and enhydrin obtained from yacon leaves. The main constituents of the most active fraction were identified. Five organic extracts and pure crystalline enhydrin were administered to normoglycemic, transiently hyperglycemic and streptozotocin (STZ)-diabetic rats. The fasting and post-prandial blood glucose, and serum insulin levels were estimated and an oral glucose tolerance test (OGTT) was performed for the evaluation of hypoglycemic activity and dose optimization of each extract.We found that the methanol, butanol and chloroform extracts showed effective hypoglycemic activity at minimum doses of 50, 10 and 20 mg/kg body weight, respectively, and were selected for further experiments. Oral administration of a single-dose of each extract produced a slight lowering effect in the fasting blood glucose level of normal healthy rats, whereas each extract tempered significantly the hyperglycemic peak after food ingestion. Daily administration of each extract for 8 weeks produced an effective glycemic control in diabetic animals with an increase in the plasma insulin level. Phytochemical analysis of the most active fraction, the butanol extract, showed that caffeic, chlorogenic and three dicaffeoilquinic acids were significant components. Additionally, enhydrin, the major sesquiterpene lactone of yacon leaves, was also effective to reduce post-prandial glucose and useful in the treatment of diabetic animals (minimum dose: 0.8 mg/kg body weight).The results presented here strongly support the notion that the phenolic compounds above as well as enhydrin are important hypoglycemic principles of yacon leaves that could ameliorate the diabetic state.     

Hepatoprotective activity of Leucas hirta against CCl4 induced hepatic damage in rats

Methanol and aqueous leaf extracts of L. hirta demonstrated hepatoprotective activity against carbon tetrachloride induced liver damage in rats. The parameters studied were serum total bilirubin, total protein, alanine transaminase, aspartate transaminase and alkaline phosphatase activities. The hepatoprotective activity was also supported by histopathological studies of liver tissue. Results of the biochemical studies of blood samples of CCl4 treated animals showed significant increase in the levels of serum markers and decrease in total protein level reflecting the liver injury caused by CCl4. Whereas blood samples from the animals treated with methanol and aqueous leaf extracts showed significant decrease in the levels of serum markers and increase in total protein indicating the protection of hepatic cells. The results revealed that methanol leaf extract followed by aqueous extract of L. hirta could afford significant protection against CCl4 induced hepatocellular injury.     

The hormonal effects of Tribulus terrestris and its role in the management of male erectile dysfunction--an evaluation using primates, rabbit and rat.

Hormonal effects of Tribulus terrestris (TT) were evaluated in primates, rabbit and rat to identify its usefulness in the management of erectile dysfunction (ED). TT extract was administered intravenously, as a bolus dose of 7.5, 15 and 30 mg/kg, in primates for acute study. Rabbits and normal rats were treated with 2.5, 5 and 10mg/kg of TT extract orally for 8 weeks, for chronic study. In addition, castrated rats were treated either with testosterone cypionate (10mg/kg, subcutaneously; biweekly for 8 weeks) or TT orally (5mg/kg daily for 8 weeks). Blood samples were analyzed for testosterone (T), dihydrotestosterone (DHT) and dehydroepiandrosterone sulphate (DHEAS) levels using radioimmunoassay. In primates, the increases in T (52%), DHT (31%) and DHEAS (29%) at 7.5mg/kg were statistically significant. In rabbits, both T and DHT were increased compared to control, however, only the increases in DHT (by 30% and 32% at 5 and 10mg/kg) were statistically significant. In castrated rats, increases in T levels by 51% and 25% were observed with T and TT extract respectively that were statistically significant. TT increases some of the sex hormones, possibly due to the presence of protodioscin in the extract. TT may be useful in mild to moderate cases of ED.     

Protective effect of Tribulus terrestris linn on liver and kidney in cadmium intoxicated rats

Administration of cadmium (Cd) significantly increased the peroxidation markers such as malondialdehyde and protein carbonyls along with significant decrease in antioxidant markers such as super oxide dismutase and reduced glutathione in liver and kidney tissues. Cadmium also caused a significant alteration in hepatic and renal functional markers in serum viz. total protein, albumin, alanine transaminase, blood urea nitrogen and creatinine. Prominent pathological changes observed in liver were severe vascular and sinusoidal congestion with diffuse degenerative changes and mononuclear infiltration into peripheral areas, while the kidney showed vascular and glomerular congestion, cloudy swelling of tubular epithelium. Coadministration of ethonolic extract of T. terrestris or vitamin E along with Cd significantly reversed the Cd induced changes along with significant reduction in Cd load.     

Kaempferol and quercetin isolated from Euonymus alatus improve glucose uptake of 3T3-L1 cells without adipogenesis activity

Euonymus alatus as a folk medicine in China has been clinically used to treat type 2 diabetes for many years, and also exerts beneficial effects on hyperglycemia of diabetic animals. Our previous studies have isolated kaempferol and quercetin from the extract of E. alatus. In the present study, we investigated the possible mechanism of antidiabetic activity of these compounds. Kaempferol and quercetin could significantly improve insulin-stimulated glucose uptake in mature 3T3-L1 adipocytes. In addition, further experiments showed that kaempferol and quercetin served as weak partial agonists in the peroxisome proliferator-agonist receptor gamma (PPARgamma) reporter gene assay. Kaempferol and quercetin could not induce differentiation of 3T3-L1 preadipocytes as traditional PPARgamma agonist. When added together with the PPARgamma agonist rosiglitazone to 3T3-L1 preadipocytes, they could inhibit 3T3-L1 differentiation in a dose-dependent manner. Competitive ligand-binding assay confirmed that kaempferol and quercetin could compete with rosiglitazone at the same binding pocket site as PPARgamma. Kaempferol and quercetin showed significant inhibitory effects on NO production in response to lipopolysaccharide treatment in macrophage cells in which the PPARgamma was overexpressed; rosiglitazone was less potent than kaempferol and quercetin. These observations suggest that kaempferol and quercetin potentially act at multiple targets to ameliorate hyperglycemia, including by acting as partial agonists of PPARgamma.     

Effect of pterostilbene on hepatic key enzymes of glucose metabolism in streptozotocin- and nicotinamide-induced diabetic rats

The purpose of this study was to investigate the effect of pterostilbene and its effect on key enzymes of glucose metabolism. Diabetic rats were orally administered with pterostilbene (10, 20, 40 mg/kg) for 2, 4 and 6 weeks on glucose was determined. Administration of pterostilbene at 40 mg/kg significantly decreases plasma glucose. Based on these data, the higher dose, 40 mg/kg pterostilbene, was selected for further evaluation. Oral administration of pterostilbene for 6 weeks on glucose, insulin levels and hepatic enzymes in normal and streptozotocin (STZ)-nicotinamide-induced diabetic rats. A significant decrease in glucose and significant increase in plasma insulin levels were observed in normal and diabetic rats treated with pterostilbene. Treatment with pterostilbene resulted in a significant reduction of glycosylated hemoglobin and an increase in total hemoglobin level. The activities of the hepatic enzymes such as hexokinase was significantly increased whereas glucose-6-phosphatase, fructose-1,6-bisphosphatase were significantly decreased by the administration of pterostilbene in diabetic rats. A comparison was made between the action of pterostilbene and the antidiabetic drug--metformin.     

Antidiabetic properties of polysaccharide- and polyphenolic-enriched fractions from the brown seaweed Ascophyllum nodosum

We screened seaweed species from Atlantic Canada for antidiabetic activity by testing extracts for alpha-glucosidase inhibitory effect and glucose uptake stimulatory activity. An aqueous ethanolic extract of Ascophyllum nodosum was found to be active in both assays, inhibiting rat intestinal alpha-glucosidase (IC50 = 77 microg/mL) and stimulating basal glucose uptake into 3T3-L1 adipocytes during a 20-minute incubation by about 3-fold (at 400 microg/mL extract). Bioassay-guided fractionation of the A. nodosum extract showed that alpha-glucosidase inhibition was associated with polyphenolic components in the extract. These polyphenolics, along with other constituents appeared to be responsible for the stimulatory activity on glucose uptake. However, attempts to further concentrate this activity through fractionation techniques were unsuccessful. A crude polyphenol extract (PPE), an enriched polyphenolic fraction (PPE-F1) and a polysaccharide extract (PSE) were prepared from commercial A. nodosum powder and administered to streptozotocin-diabetic mice for up to 4-weeks by daily gavage at 200 mg/kg body mass. PPE and PPE-F1 improved fasting serum glucose level in diabetic mice; however, the effect was only statistically significant at day 14. In addition, PPE-F1 was shown to blunt the rise in blood glucose after an oral sucrose tolerance test in diabetic mice. Mice treated with PPE and PPE-F1 had decreased blood total cholesterol and glycated serum protein levels compared with untreated diabetic mice, whereas PPE also normalized the reduction in liver glycogen level that occurred in diabetic animals. All 3 A. nodosum preparations improved blood antioxidant capacity.     

Antihyperglycemic Activity of Herb Extracts on Streptozotocin-Induced Diabetic Rats

We investigated the effects of herb extracts, Rhus verniciflua, Agrimonia pilosa, Sophora japonica, and Paeonia suffruticosa, on the lowering of blood glucose levels and thiobarbituric acid reactive substances (TBARS) in streptozotocin (STZ)-induced diabetic rats. After 4 weeks, oral administration of Rhus verniciflua extract (50 mg/kg) exhibited a significant decrease in blood glucose levels in diabetic rats (P<0.05). Blood TBARS concentrations, the products of glucose oxidation in blood, were also lowered by Rhus verniciflua extract supplementation. In addition, Sophora japonica and Paeonia suffruticosa extracts significantly reduced TBARS levels versus diabetic controls. Serum concentrations of liver-function marker enzymes, GOT and GPT, were also restored by Rhus verniciflua (50 mg/kg) supplementation in diabetic rats.