Anti-hyperglycemic activity of kiwifruit leaf (Actinidia deliciosa) in mice

The methanol extract of kiwifruit leaf suppressed the postprandial blood glucose level after an oral administration of soluble starch or sucrose in mice. The mechanism of action is proposed to be due to the alpha-amylase-inhibiting activity in the 90% aqueous methanol fraction and alpha-glucosidase-inhibiting activity in the n-buthanol fraction, based on the results of in vitro experiments.     

Antidiabetic effect of an active fraction extracted from dragon's blood (Dracaena Cochinchinensis)

The active fraction extracted from dragon's blood displayed an inhibitory effect on alpha-glucosidase activity with an IC50 of 0.152 microg/mL, which is nearly half of the crude material. Its inhibition on alpha-glucosidase was noncompetitive. In addition, when this fraction was orally administered to mice dosed with Acarbose (20 mg/kg), the active fraction (100, 300, 500 mg/kg) significantly suppressed increase of blood glucose levels after sucrose loading in a dose-dependent manner. These results suggest that this extract from dragon's blood exerts an anti-diabetic effect by suppressing intestinal carbohydrate absorption and thereby reducing the postprandial increase of blood glucose.     

Alpha-glucosidase inhibitory activity of a 70% methanol extract from ezoishige (Pelvetia babingtonii de Toni) and its effect on the elevation of blood glucose level in rats

The 70% methanol extract from ezoishige (Pelvetia babingtonii de Toni) inhibited the rat-intestinal alpha-glucosidase, sucrase and maltase activities, with IC50 values of 2.24 and 2.84 mg/ml. Sucrose was orally administered with or without the extract to rats at 1000 mg/kg. The postprandial elevation in the blood glucose level at 15 and 30 min after the administration of sucrose with the extract was significantly suppressed when compared with the control. These results suggest that the extract from ezoishige has potent alpha-glucosidase inhibitors and would be effective for suppressing postprandial hyperglycemia.     

α-Glucosidase Inhibitory Activity of a 70% Methanol Extract from Ezoishige (Pelvetia babingtonii de Toni) and Its Effect on the Elevation of Blood Glucose Level in Rats

The 70% methanol extract from ezoishige (Pelvetia babingtonii de Toni) inhibited the rat-intestinal α-glucosidase, sucrase and maltase activities, with IC₅₀ values of 2.24 and 2.84 mg/ml. Sucrose was orally administered with or without the extract to rats at 1000 mg/kg. The postprandial elevation in the blood glucose level at 15 and 30 min after the administration of sucrose with the extract was significantly suppressed when compared with the control. These results suggest that the extract from ezoishige has potent α-glucosidase inhibitors and would be effective for suppressing postprandial hyperglycemia.     

Suppressive effect of a hot water extract of adzuki beans (Vigna angularis) on hyperglycemia after sucrose loading in mice and diabetic rats

A hot water extract obtained by boiling adzuki beans (Vigna angularis) to produce bean paste for Japanese cake showed inhibitory activity against alpha-glucosidase, alpha-amylase, maltase, sucrase, and isomaltase after HP-20 column chromatography. The IC(50) values for each hydrolylase were 0.78 mg/ml (alpha-amylase), 2.45 mg/ml (maltase), 5.37 mg/ml (sucrase), and 1.75 mg/ml (isomaltase). The active fraction showed potential hypoglycemic activity in both normal mice and streptozotocin (STZ)-induced diabetic rats after an oral administration of sucrose, but did not show any effect on the blood glucose concentration after glucose administration, suggesting that the active fraction suppressed the postprandial blood glucose level by inhibiting alpha-glucosidase and alpha-amylase, irrespective of the endogenous blood insulin level.     

Control of postprandial hyperglycaemia by galactosyl maltobionolactone and its novel anti-amylase effect in mice

The ability to control carbohydrate digestion is useful in the treatment of diabetes mellitus and obesity. In the present study, we examined whether recently developed 4(2)-O-beta-D-galactosyl maltobionolactone (LG2O) having anti-amylase activity is able to control postprandial blood glucose concentration in mice. In addition, we tried to determine how LG2O regulates carbohydrate delivery in the gut lumen by conducting in vivo and in vitro studies. Male non-diabetic ddY mice and KK-A(y) mice, a spontaneously diabetic strain, had free access to a carbohydrate rich diet supplemented with LG2O (3 or 10 g/kg) for 0.5 hr, and blood glucose concentration was measured. LG2O suppressed any steep increase in postprandial blood glucose concentration in both ddY and KK-A(y) mice. Corresponding to the blood glucose response, LG2O also markedly suppressed any increase in postprandial plasma insulin concentration. After ingestion of the diet, LG2O produced a 1.5-3.5 fold increase in the gut contents and reducible sugar content in the small intestine but not in the stomach. Although alpha-amylase activity in the stomach was much lower compared with the activity in the small intestine, LG2O still strongly inhibited alpha-amylase activity in the stomach. In contrast, LG2O had little or no influence on alpha-amylase activity in the proximal intestine. From the in vitro carbohydrate digestion stimulation, LG2O at 7.5 mM decreased glucose production by 75% for dextrin, 25% for alpha-starch and 60% for raw starch. In conclusion, administration of LG2O inhibits carbohydrate digestion in the gut, and produces significant improvements in both blood glucose and insulin response following ingestion as part of the diet, and this evidence provides support for its therapeutic potential in treating diabetes mellitus and obesity.     

Inhibitory effects of pasuchaca (Geranium dielsiaum) extract on alpha-glucosidase in mouse

The methanolic extract of pasuchaca (Geranium dielsiaum) (PsEx) was found to suppress blood glucose elevation after oral administration of sucrose, maltose, and starch, but not after oral administration of glucose, in the mouse. In vitro examination of the inhibitory effect of PsEx on maltase activity revealed that PsEx strongly inhibited mouse small intestine maltase activity. Taken together, these results suggest that the inhibitory effect of PsEx on alpha-glucosidase activity might contribute to delay in carbohydrate digestion and subsequent lowering of the blood glucose level, thereby leading to prevention and cure of diabetes.     

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.     

Inhibitory Effects of Pasuchaca (Geranium dielsiaum) Extract on α-Glucosidase in Mouse

The methanolic extract of pasuchaca (Geranium dielsiaum) (PsEx) was found to suppress blood glucose elevation after oral administration of sucrose, maltose, and starch, but not after oral administration of glucose, in the mouse. In vitro examination of the inhibitory effect of PsEx on maltase activity revealed that PsEx strongly inhibited mouse small intestine maltase activity. Taken together, these results suggest that the inhibitory effect of PsEx on α-glucosidase activity might contribute to delay in carbohydrate digestion and subsequent lowering of the blood glucose level, thereby leading to prevention and cure of diabetes.     

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.     

Suppressive effects by leaves of the Dypsis lutescens palm on fat accumulation in 3T3-L1 cells and fat absorption in mice

The methanol extract of Dypsis lutescens leaves showed inhibitory effects on lipase activity in vitro and on triglyceride accumulation in 3T3-L1 pre-adipocytes. Further experiments using the extract on mice demonstrated a suppressive effect on the postprandial elevation of blood triglyceride level and an anti-obesity effect on obese mice induced by a high-fat diet. D. lutescens will accordingly be useful for preventing obesity.     

Anti-hyperglycemic effects of ginseng: Comparison between root and berry

Previous studies demonstrated that both ginseng root and ginseng berry possess anti-diabetic activity. However, a direct comparison between the root and the berry under the same experimental conditions has not been conducted. In the present study, we compared anti-hyperglycemic effect between Panax ginseng root and Panax ginseng berry in ob/ob mice, which exhibit profound obesity and hyperglycemia that phenotypically resemble human type-2 diabetes. We observed that ob/ob mice had high baseline glucose levels (195 mg/dl). Ginseng root extract (150 mg/kg body wt.) and ginseng berry extract (150 mg/kg body wt.) significantly decreased fasting blood glucose to 143 +/- 9.3 mg/dl and 150 +/- 9.5 mg/dl on day 5, respectively (both P < 0.01 compared with the vehicle). On day 12, although fasting blood glucose level did not continue to decrease in the root group (155 +/- 12.7 mg/dl), the berry group became normoglycemic (129 +/- 7.3 mg/dl; P < 0.01). We further evaluated glucose tolerance using the intraperitoneal glucose tolerance test. On day 0, basal hyperglycemia was exacerbated by intraperitoneal glucose load, and failed to return to baseline after 120 min. After 12 days of treatment with ginseng root extract (150 mg/kg body wt.), the area under the curve (AUC) showed some decrease (9.6%). However, after 12 days of treatment with ginseng berry extract (150 mg/kg body wt.), overall glucose exposure improved significantly, and the AUC decreased 31.0% (P < 0.01). In addition, we observed that body weight did not change significantly after ginseng root extract (150 mg/kg body wt.) treatment, but the same concentration of ginseng berry extract significantly decreased body weight (P < 0.01). These data suggest that, compared to ginseng root, ginseng berry exhibits more potent anti-hyperglycemic activity, and only ginseng berry shows marked anti-obesity effects in ob/ob mice.     

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.     

Effect and potential mechanism of action of sea cucumber saponins on postprandial blood glucose in mice

Postprandial blood glucose control is the major goal in the treatment of diabetes. Here, we investigated the effect of sea cucumber saponins (SCSs) on postprandial blood glucose levels. SCS inhibited yeast as well as rat intestinal α-glucosidase activity in a dose-dependent manner and showed better inhibition of yeast α-glucosidases compared to the positive control. Further studies were performed using ICR mice treated with SCS and starch or SCS alone by oral gavage. Unexpectedly, SCS increased postprandial blood glucose levels a short time (1 h) after oral gavage. The serum corticosterone (CORT) level showed a consistent correlation with glucose levels. In vitro experiments confirmed that SCS treatment increased the secretion of CORT in the Y1 adrenal cell line. Overall, these studies demonstrated that SCS gavage could inhibit α-glucosidase activity but cannot attenuate postprandial blood glucose level within short time periods. The underlying mechanisms are probably related to increased serum CORT levels.     

In silico profiling of analgesic and antihyperglycemic effects of ethanolic leaves extract of Amischotolype mollissima: Evidence from in vivo studies

The aim of this study is to assess the antioxidative profile and related pharmacological potentialities of the ethanolic extract of Amischotolype mollissima leaves, traditionally used in treating pain, injury, malarial fever, epilepsy and hyperacidity, followed by a computational approach for the analysis of bioactive compounds identified by GC–MS. In GC–MS analysis, the extract yielded ten compounds, with 4,6-di-t-butyl-2-alpha-methyl benzyl phenol having the highest amount. In vitro investigation of the antioxidative properties of the plant was conducted with 2,2-diphenyl-1-picryl hydrazyl (DPPH) radical and hydrogen peroxide scavenging assays. The amounts of secondary metabolites phenolics, flavonoids, and tannins were measured at 142 mg GAE/g, 534 mg QE/g, and 110 mg GAE/g, respectively. An acute toxicity study was carried out on mice, which revealed no toxicity up to the dosage of 4000 mg/kg bw. For the dosages of extract at 250 and 500 mg/kg bw, the writhing response test induced by acetic acid exhibited a statistically significant (p < 0.05) analgesic effect in mice. The oral glucose tolerance test (OGTT) and alpha-glucosidase enzyme inhibitory activity assay were used to examine the antihyperglycemic potential, in which the extract reduced the blood glucose level to 6.22 mmol/l and 3.82 mmol/l, at dosages of 250 and 500 mg/kg bw, respectively at 60 min in OGTT even though no activity was observed in the α-glucosidase enzyme inhibitory assay. In an antibacterial assay, the extract's minimum inhibitory concentration (MIC) against E. coli, P. aeruginosa, and S. aureus was determined to be 8, 16, and 8 µg/ml, respectively. This study shows that the usage of A. mollissima leaves in folklore medication is justified.     

Dose-Dependent Suppression of Tea Catechins with a Galloyl Moiety on Postprandial Hypertriglyceridemia in Rats

Tea has long been believed to be a healthy beverage, and its beneficial effects are almost all attributed to catechins. The effect of catechins on postprandial hypertriglyceridemia in rats was investigated in this study. A lipid emulsion administered orally to rats with (?)-epigallocatechin gallate at a dose of 100 mg/kg resulted in the increase in plasma triacylglycerol being significantly inhibited after 1 and 2 h compared to the case without (?)-epigallocatechin gallate. The effect of (?)-epigallocatechin was weaker than that of (?)-epigallocatechin gallate. A tea extract (THEA-FLAN 90S), mainly composed of catechins with a galloyl moiety, dose-dependently suppressed postprandial triacylglycerol after the administration of a lipid emulsion at doses of 50–200 mg/kg. The administration of the tea extract alone at a dose of 200 mg/kg had no effect on the plasma triacylglycerol level. These results strongly suggest that catechins with a galloyl moiety would be promising agents for suppressing dietary fat absorption through the small intestine.     

Effects of Ballota nigra on blood biochemical parameters and insulin in albino rats

Ingestion of aqueous 70% ethanol extract of Ballota nigra (400 mg/kg body weight for 7 days) by albino rats (n=10) was investigated to study its effects on glucose, total cholesterol, triglycerides, aspartate aminotransferase (AST), alanine aminotransferase (ALT), troponin I (TnI), serum creatine kinase (CK), total protein, total bilirubin and blood urea. Ballota nigra extract caused a significant decrease in blood glucose, total serum cholesterol and CK levels. Blood levels of TnI, AST, ALT, triglycerides, total bilirubin, total protein and blood urea were unchanged. The hypoglycemic effect of Ballota nigra extract on albino rats was further investigated by conducting a glucose tolerance test intraperitoneally (IPGTT). Healthy rats that were fasting for 18 hours followed by administration of a dose of 400 mg/kg body weight of the crude extract of Ballota nigra, orally. A significant decrease in blood glucose levels (after 15, 30, and 45 minutes) with a significant increase in serum insulin level (after 15 and 30 minute) was noted. These results suggest that, the crude extract of Ballota nigra have hypoglycemic, insulin-releasing and cholesterol lowering effects in rats.     

Ocimum sanctum aqueous leaf extract provides protection against mercury induced toxicity in Swiss albino mice

HgCl2 (5.0 mg/kg body weight) induced toxicity led to significant elevation of lipid peroxidation (LPO) level but decline in the glutathione content in liver of Swiss albino mice. In serum of HgCl2 treated mice there was significant elevation in serum glutamate oxaloacetate transaminase (SGOT) and serum glutamate pyruvate transaminase (SGPT) activities but significant decline in the alkaline phosphatase activity. Animals treated with O. sanctum extract (10 mg/kg body weight, po) before and after mercury intoxication showed a significant decrease in LPO level, SGOT and SGPT activities and increase in serum alkaline phosphatase activity and glutathione (GSH) content. Ocimum treatment alone did not alter SGOT, SGPT and alkaline phosphatase activities but significantly enhanced reduced glutathione. The results suggest that oral administration of Ocimum extract provides protection against HgCl2 induced toxicity in Swiss albino mice.     

Effect of bread containing resistant starch on postprandial blood glucose levels in humans

We examined the inhibitory effect of a single ingestion of bread containing resistant starch (bread containing about 6 g of resistant starch derived from tapioca per 2 slices) (test food) on the postprandial increase in blood glucose in male and female adults with a fasting blood glucose level between 100 and 140 mg/dl. Bread not containing resistant starch (placebo) was used as the control.The study was conducted in 20 subjects (9 men and 11 women with a mean age of 50.5+/-7.5 years) using the crossover method, with a single ingestion of either bread containing resistant starch or the placebo. Blood glucose and insulin were measured before ingestion, and at 0.5, 1, 1.5, and 2 h after ingestion. The blood glucose level before ingestion was stratified into a borderline group (blood glucose level >/= 111 mg/dl) and a normal group (blood glucose level 相似文献   

Dose-dependent suppression of tea catechins with a galloyl moiety on postprandial hypertriglyceridemia in rats

Tea has long been believed to be a healthy beverage, and its beneficial effects are almost all attributed to catechins. The effect of catechins on postprandial hypertriglyceridemia in rats was investigated in this study. A lipid emulsion administered orally to rats with (-)-epigallocatechin gallate at a dose of 100 mg/kg resulted in the increase in plasma triacylglycerol being significantly inhibited after 1 and 2 h compared to the case without (-)-epigallocatechin gallate. The effect of (-)-epigallocatechin was weaker than that of (-)-epigallocatechin gallate. A tea extract (THEA-FLAN 90S), mainly composed of catechins with a galloyl moiety, dose-dependently suppressed postprandial triacylglycerol after the administration of a lipid emulsion at doses of 50-200 mg/kg. The administration of the tea extract alone at a dose of 200 mg/kg had no effect on the plasma triacylglycerol level. These results strongly suggest that catechins with a galloyl moiety would be promising agents for suppressing dietary fat absorption through the small intestine.