β-Glucan administration to diabetic rats reestablishes redox balance and stimulates cellular pro-survival mechanisms

The mechanisms underlying the beneficial effect observed in diabetic rats after treatment with a commercially available β-glucan-enriched extract (BGEE) were examined. Multiple low-dose streptozotocin (STZ) diabetes was used (40 mg STZ/kg) as a model for type 1 diabetes. BGEE was administered daily (80 mg/kg) for 4 weeks, starting from the last day of the STZ treatment. In vitro and in vivo experiments suggest that significant free radical scavenging and antioxidant activities of BGEE were responsible for a systemic adjustment of the redox disturbance and reduction of DNA damage in the liver and kidney of diabetic rats. BGEE-treated diabetic rats also displayed increased Akt kinase activity and decreased pro-caspase-3 degradation, implying that BGEE mediates its beneficial effects through activation of the cellular pro-survival pathway. We conclude that β-glucan administration under diabetic conditions promotes a systemic improvement that can be expected to increase the organism’s resistance to the onset of diabetic complications.     

Protective effect of tetrahydrocurcumin and chlorogenic acid against streptozotocin–nicotinamide generated oxidative stress induced diabetes

The present study was undertaken to investigate the protective effect of tetrahydrocurcumin (THC) and chlorogenic acid (CGA) against streptozotocin (STZ)–nicotinamide (NA)-induced type 2 diabetes in adult Wistar rats. Diabetes was induced in experimental rats weighing 180–220 g, by a single intraperitoneal (i.p.) injection of STZ (45 mg/kg BW), 15 min after the (i.p.) administration of NA (110 mg/kg BW). THC (80 mg/kg BW) and CGA (5 mg/kg BW) were orally administered to diabetic rats for a period of 45 days. Fasting plasma glucose, glycosylated haemoglobin (HbA_1C), thiobarbituric acid reactive substances (TBARS) and lipid hydroperoxides (LOOH) were significantly increased, whereas insulin, total haemoglobin (Hb), non-enzymic antioxidants (reduced glutathione (GSH), vitamin C, vitamin E and ceruloplasmin) were decreased significantly in diabetic rats. Though the diabetic rats treated with THC and CGA individual exerts beneficial effects in all the biochemical parameters in (STZ)-induced diabetic rats. The combined treatment with THC and CGA normalized all the above-mentioned biochemical parameters in STZ-induced diabetic rats. Normal pancreatic histological architecture in THC and CGA treated diabetic rats revealed that these phytochemical exert higher degree of protection when administered in combination than single treatment of individual compounds.     

Chromium(III) in cactus pad and its possible role in the antihyperglycemic activity

The antihyperglycemic activity of cactus pads and pulp fruit of species of Opuntia genus has been documented; however, the mechanism of action has not yet been clarified. Thus, cactus pad and pulp fruit extracts of Opuntia dillenii were used to evaluate their effects on blood glucose concentration and glycemic curve of Sprague–Dawley rats. After acute administration, no significant differences were observed in the glycemic curve among cactus pad, pulp fruit and control groups. However, the glycemic peaks and glycemic curves obtained in the groups corresponding to both cactus pad and pulp fruit as well as the Cr(III) group were less pronounced than in the control group after 8 days of daily intake. Besides, a slight decrease of fasting blood glucose was observed, maintaining within the normal levels, after 8 days of daily intake of cactus pad extract. Therefore, the possible role of Cr(III) present in high amounts in these vegetable foods was suggested, for the first time, to explain their antihyperglycemic activity.     

Flavanoid rich ethyl acetate fraction of Musa paradisiaca inflorescence down-regulates the streptozotocin induced oxidative stress,hyperglycaemia and mRNA levels of selected inflammatory genes in rats

Musa paradisiaca inflorescence is a commonly used vegetable. The purpose of this study was to evaluate the antioxidant; hypoglycaemic and anti-inflammatory activities of flavanoid rich fraction of M. paradisiaca inflorescence (MPIF) in streptozotocin (STZ) induced diabetes mellitus. Diabetic rats were treated with MPIF (200 mg/kg body weight/day) for 60 days. Diabetic rats showed significant (p < 0.05) increase in blood glucose, HbA₁C and lipid peroxidation products (LPO) and reduction in the activities of antioxidant enzymes in liver. The activities of inflammatory markers COX-2 and 5-LOX in monocytes and mRNA expressions of NF-κB, TGF-β₁, TNF-α and IL-6 in liver were significantly (p < 0.05) increased in diabetic group. In addition, the histopathological analysis of liver showed that severe steatosis and inflammation in diabetic group. But all these parameters were significantly (p < 0.05) reduced to near normal level and restored the histopathological alterations in MPIF treated group. In addition, HPLC and ESI-MS analysis of MPIF revealed that the presence of gallic acid (4.49 g%), quercetin (1.13 g%) and epicatechin. This indicates that the supplementation of MPIF may be beneficial as food supplement for the prevention or attenuation of diabetic complications.     

Antihyperlipidemic effect of diosmin: A citrus flavonoid on lipid metabolism in experimental diabetic rats

The present study was hypothesized to evaluated the antihyperlipidemic effect of diosmin (DS) on lipid metabolism in experimental diabetic rats. Diabetes was induced male albino Wistar rats by intraperitoneal administration of streptozotocin (STZ) (45 mg/kg b.w.) 15 min after the ip administration of nicotinamide (NA) (110 mg/kg b.w.). DS were administered to diabetic rats intragastrically at 100 mg/kg b.w. for 45 days. The levels of plasma and tissue lipids (cholesterol, triglycerides) (TGs), free fatty acids (FFAs) and phospholipids (PLs), low density, very low-density lipoproteins (LDL and VLDL), and high-density-cholesterol (HDL-C) were measured. The activities of 3-hydroxy 3-methylglutaryl coenzyme A (HMG-CoA) reductase, lipoprotein lipase (LPL) and lecithin cholesterol acyl transferase (LCAT) were assayed. The levels of plasma and tissue lipids decreased with significant increase in HDL-C levels. The altered activities of lipid metabolic enzymes were restored to near normal. The present findings suggest that DS can potentially ameliorate lipid abnormalities in experimental diabetes.     

Asiatic acid prevents lipid peroxidation and improves antioxidant status in rats with streptozotocin-induced diabetes

Oxidative stress is a common pathogenesis of diabetes mellitus and asiatic acid (AA) plays an important role in ameliorating those difficulties. The present study was designed the protective effects of AA on altered lipid peroxidation products, enzymic and nonenzymic antioxidants in streptozotocin (STZ)-induced diabetic rats. Diabetes was induced in experimental rats by single dose STZ (40 mg/kg b.w.) injection. Diabetic rats showed significantly increased levels of plasma glucose, thiobarbituric acid reactive substances, lipid hydroperoxides, aspartate aminotransferase, alanine aminotransferase, bilirubin, creatine kinase, urea, uric acid, creatinine and decreased levels of plasma insulin. The activities of enzymatic antioxidants such as superoxide dismutase, catalase, glutathione peroxidase and glutathione-S-transferase and the levels of non-enzymatic antioxidants such as vitamin C, vitamin E and reduced glutathione were decreased in diabetic rats. Oral treatment with AA (20 mg/kg b.w.) showed near normalized levels of plasma glucose, insulin, lipid peroxidation products, enzymatic and nonenzymatic markers in diabetic rats. The results demonstrate that AA possesses potent antioxidant effect comparable with glibenclamide in improving antihyperglycemia and attenuating antioxidant status in diabetic rats.     

Myricetin modulates streptozotocin–cadmium induced oxidative stress in long term experimental diabetic nephrotoxic rats

Oxidative stress plays a pivotal role in the development of diabetic nephropathy. The present study was aimed to evaluate the modulatory potential of myricetin on streptozotocin (STZ)–cadmium (Cd) induced oxidative stress in diabetic nephrotoxic rats. Diabetic nephrotoxicity was induced by single intraperitoneal injection of STZ at a dose of (40 mg/kg body weight (b/w)) and Cd as cadmium chloride (CdCl₂) (100 p.p.m.). Myricetin was administered to diabetic nephrotoxic rats by intraperitoneally at 1.0 mg/kg b/w for a period of 12 weeks to assess its effects on fasting plasma glucose, plasma insulin, total haemoglobin, glycosylated haemoglobin, lipid peroxidation products viz., thiobarbituric acid reactive substances (TBARS), lipid hydroperoxides (LOOH), protein carbonyl content (PCO) and non-enzymatic antioxidants namely vitamins C and E and reduced glutathione (GSH) and also enzymatic antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and glutathione reductase (GR). Improvement of antioxidant status in myricetin supplemented diabetic nephrotoxic rats revealed its cellular protective effect. Histopathology of liver and kidney confirmed the protective effects of myricetin in diabetic nephrotoxic rats. The outcome of this study concludes that myricetin could be therapeutic flavonol for regulating oxidative mechanism in STZ–Cd induced diabetic nephrotoxic rats.     

A high-resistance-starch rice diet reduces glycosylated hemoglobin levels and improves the antioxidant status in diabetic rats

Diabetes mellitus is a common problem in developed countries. An improved postprandial hyperglycemic peak is one of the main therapeutic targets in diabetic patients. The Wistar rats with streptozotocin (STZ)-induced diabetes were divided into cornstarch (control) and Japonica rice groups, which were fed 640 g starch/kg diets for 4 weeks. The area (means ± SD) under the glucose curve of cornstarch was 173.8 ± 6.9 and Japonica rice diet was 154.3 ± 8.7 mmol × min/L, and the area (means ± SD) under the insulin curve of cornstarch was 12.9 ± 0.1 and Japonica rice diet was 12.0 ± 0.6 nmol × min/L. The glycosylated hemoglobin levels, serum fructosamine and cholesterol concentrations in diabetic rats fed the Japonica rice diet were significantly lower than the control group (P < 0.05). The decreased malondialdehyde levels and increased superoxide dismutase activity and total radical-trapping antioxidant parameter in plasma were also found in rat fed the Japonica rice diet compared to the control. These results suggested that the diet containing high-resistance-starch Japonica rice might reduce glycosylated hemoglobin levels, serum cholesterol concentrations and raised the antioxidant status in the blood.     

Antidiabetic Activity of Durian (Durio Zibethinus Murr.) and Rambutan (Nephelium Lappaceum L.) Fruit Peels in Alloxan Diabetic Rats

The present study was carried out to evaluate the in alloxan (150 mg/kgb.wt) induced diabetic rats. The ethanolic extract of Durian (Durio zibethinus Murr.) and rambutan (Nephelium lappaceum L.) fruit peels administered orally to the diabetic rats for 11 days, produced significant decrease in the level of blood glucose. The highest percentage reduction in blood glucose levels were shown of rambutan fruit peels extract with dose 500 mg/kgb.w and the value of persentage reduction were 61.76±4.26%.     

Antihyperglycaemic efficacy of kombucha in streptozotocin-induced rats

Kombucha is a fermented tea beverage produced by fermenting sugared black tea with kombucha mat (consists of bacteria and yeast strains). Diabetes mellitus is group of metabolic disorders characterized by hyperglycaemia resulting from defects in insulin secretion, action or both. The present study was aimed to delineate the antihyperglycaemic effect of lyophilized extract of kombucha in streptozotocin-induced experimental rats. After the experimental period of 45 days we observed that kombucha supplementation with 6 mg/kg bw significantly decreased glycosylated haemoglobin (HbA_1c) and increased the levels of plasma insulin, haemoglobin and tissue glycogen which was decreased up on streptozotocin (STZ) treatment and also significantly reversed the altered activities of gluconeogenic enzymes such as glucose-6-phosphatase, fructose-1,6-bisphosphatase and glycolytic enzymes such as hexokinase in the tissues of experimental rats. Thus, our results substantiate that kombucha found to exert hypoglycaemic effect in STZ-induced diabetic rats. These findings suggest that kombucha may be considered as a potential functional food candidate for future applications as functional food supplement for the treatment and prevention of diabetes.     

Antihyperglycemic, antihyperlipidemic, and antioxidant effects of Chaenomeles sinensis fruit extract in streptozotocin-induced diabetic rats

The rising incidence of diabetes mellitus (DM) is alarming and becoming a major health problem worldwide, which is mainly associated with hyperglycemia, abnormal lipid, and antioxidant profiles. Herbal medicines are being used by about 80% of the world population primarily in the developing countries for primary health care, including DM. Based on these facts, in this study, the antihyperglycemic, antihyperlipidemic, and antioxidant properties of Chaenomeles sinensis fruits extract (CSFE) were investigated in streptozotocin (STZ)-induced (55 mg/kg body weight) diabetic rats. CSFE was found to be rich in total phenolics and flavonoid contents. The following assays were performed: fasting blood glucose, hemoglobin (Hb), blood urea nitrogen (BUN), serum total cholesterol (TC), serum triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), serum glutamic pyruvic transaminase/alanine aminotransferase (SGPT/ALT), serum glutamic oxaloacetic transaminase/aspartate aminotransaminase (SGOT/AST), liver glycogen content and superoxide dismutase (SOD), reduced glutathione (GSH), and catalase (CAT) contents in liver and kidney. Oral administration of CSFE (500 mg/kg body weight) significantly decreased fasting blood glucose, BUN, and serum TC, TG, LDL-C, SGPT/ALT, and SGOT/AST, while it increased blood Hb content and HDL-C in diabetic rats. Furthermore, CSFE treatment significantly increased liver glycogen content, SOD, GSH, and CAT levels in diabetic rats. The results showed that CSFE significantly inhibited the progression of diabetes induced by STZ, and the inhibitory effect of CSFE on diabetes might be associated with its hypoglycemic effect, modulation of lipid metabolism, and its ability to scavenge free radicals.     

Temperature shows greater impact on bovine Longissimus dorsi muscle glycogen debranching enzyme activity than does salt concentration

The degradation of glycogen progresses by the co-operation of two enzymes: glycogen phosphorylase (phosphorylase) and glycogen debranching enzyme (GDE). We studied the effect of temperature (4–42 °C) and salt concentration (0–3% NaCl) on bovine M. longissimus dorsi GDE activity. GDE activity (n = 4) decreased significantly with decreasing temperature from about 40–4 °C. GDE exhibited 52% activity at 25 °C and 11% at 4 °C compared to its optimum activity measured at 39 °C. In rapidly chilled meat, the reduction in GDE activity may substantially delay the rate of glycolysis. However, residual GDE activity at 4 °C seems sufficient to enable the attainment of normal ultimate pH if the available time is long enough. An increase in salt concentration from 0% to 2% and to 3% induced a significant (P < 0.001) increase in the ultimate pH of ground bovine meat (n = 6), but showed no effect on GDE activity.     

β-酪啡肽-7对大鼠血糖及脂质过氧化的影响

目的:观察β-酪啡肽-7(β-casomorphin-7,β-CM-7)对糖尿病大鼠的降血糖作用并初步阐明其作用机制。方法:2月龄SD雄性大鼠40只,用链脲佐菌素(STZ)致大鼠糖尿病,造模成功后将大鼠分为4个组:空白对照组、糖尿病对照组、胰岛素治疗组(优泌林3.7×10-8mol/(只.d))、实验组(β-CM-7 7.5×10-8mol/(只.d))。实验周期30d。测定血清中血糖含量、脂质过氧化物丙二醛(MDA)水平、超氧化物歧化酶(SOD)的活性、胰岛素和胰高血糖素的含量以及腿肌糖原、肝脏糖原的含量。结果:β-CM-7组与胰岛素治疗组大鼠血糖明显下降;同时血清中MDA水平降低,SOD活性升高,与糖尿病对照组相比,具有显著性差异(P<0.05);β-CM-7组胰岛素含量较糖尿病组有所增加,肌糖原含量较空白组显著升高(P<0.05)。结论:β-CM-7具有减轻链脲佐菌素性糖尿病大鼠氧自由基损伤、促进胰岛素分泌、加速肌糖原的合成、降低血糖的作用。     

Blood pressure-lowering properties of chokeberry (Aronia mitchurinii,var. Viking)

The blood pressure-lowering properties of lyophilized chokeberry juice and polyphenols were monitored using in vitro angiotensin-converting enzyme (ACE) inhibition measurement and a 10 day in vivo study with spontaneously hypertensive rats (SHR). Juice and polyphenols indicated weak ACE-inhibitory activity. The IC₅₀ values for polyphenols and juice were 1.5–2.5 and 4.5 mg dry matter/ml, respectively. In the SHR study the blood pressure-lowering effects of juice and polyphenol extract seemed to be short-term and were generally highest after 3 h from administration (50 mg/kg/day) when mean reductions in systolic blood pressure were 20 ± 8 and 15 ± 7 mm Hg, respectively. Corresponding mean decreases in diastolic blood pressure were 23 ± 6 and 13 ± 2 mm Hg in juice and polyphenol groups, respectively. It was concluded that both chokeberry juice and polyphenols had blood pressure-lowering effects. We hypothesize that chokeberry polyphenols enhance endothelial nitric oxide production with an ACE-independent mechanism, e.g. by activation of endothelial nitric oxidase enzyme; this is yet to be verified.     

Perinatal consumption of flaxseed oil and flaxseed flour has beneficial effects on cardiac fibrosis of male offspring from rat dams with experimental diabetes

Maternal diabetes during critical periods of development can affect the health of adult offspring. Nevertheless, studies suggest that the presence of functional foods, such as flaxseed, can reverse the effects of metabolic programming. This study evaluated the effect of maternal consumption of flaxseed flour and a flaxseed oil based diets in left ventricular histomorphometry and in blood pressure in adult male offspring of diabetic rats. Rats (n = 24) were induced into diabetes with a high-fat diet (60% lipid) and streptozotocin (35 mg·kg^− 1). After diabetes confirmation (glucose > 300 mg/dL), rats were sent to mating, and afterward pregnancy confirmed, they were allocated into four groups: control group (CG), high fat group (HG), flaxseed oil group (FOG) and flaxseed flour group (FFG). At weaning, six males of each group were separated and fed with a commercial diet chow until they reached 100 days of life, moment in which they were euthanized. The systolic blood pressure, the thickness of the left ventricular wall and collagen volume density were analyzed. Exposure to a hyperglycemic environment led to an increased systolic blood pressure, nevertheless FOG showed a significant reduction when compared to HG (p < 0.001). The left ventricular wall thickness was significantly lower in FFG (p = 0.030) and a minor amount of collagen in the left ventricle was found in FOG and FFG (p < 0.001). Those results suggest that a diet with flaxseed flour and flaxseed oil avoids the cardiac remodeling of offspring from diabetic dams.     

Amelioration of hyperglycemia,hyperlipidemia, oxidative stress and inflammation in steptozotocin-induced diabetic rats fed a high fat diet by riceberry supplement

Dark purple riceberry bran contains a higher dietary fiber and antioxidant compounds than unpigmented rice bran. Riceberry supplement (RB) was used to evaluate the effects on biochemical parameters, skeletal muscle glucose transporter 4 (GLUT4), oxidative stress and inflammation in a streptozotocin (STZ)-induced diabetes rat. To elucidate the effects were due to dietary fiber supplementation and/or bioactive components, equivalent amounts of dietary fiber present in RB were also fed to STZ-induced diabetic rats. Diabetes Sprague–Dawley rats (non-FBG ? 16.65 mM) were randomly divided into five groups: DM fed a high fat (HF) diet, DM-RB1 fed 5% RB, DM-RB2 fed 41% RB, DM-F1 fed 0.6% fiber and DM-F2 fed 5% fiber. After 12 weeks, significant improvement of BG, insulin, HbA1_C, IPGTT and GLUT4 levels were observed in DM-RB1 and DM-RB2 groups. Hyperlipidemia was significantly improved in DM-RB2 and DM-F2 groups. Oxidative stress (TBARS), antioxidant enzymes (SOD, CAT, and GPx), antioxidant capacity (ORAC), pro-inflammation cytokine (TNF-α and IL-6) were improved in DM-RB1 and DM-RB2 groups. Improvement of pancreas and spleen histology was found in DM-RB1 and DM-RB2 groups. These indicate the potential of RB to improve hyperglycemia and hyperlipidemia conditions as well as alleviate oxidative stress and inflammation.     

Hepatoprotective effect of peptic hydrolysate from salmon pectoral fin protein byproducts on ethanol-induced oxidative stress in Sprague–Dawley rats

Bioactive peptides were generated by pepsin hydrolysis from salmon pectoral fin protein byproduct, and the hepatoprotective effect of the peptic hydrolysate (PH) on ethanol-induced oxidative stress was investigated in Sprague–Dawley rats. Administration of ethanol for 4 weeks significantly (p < 0.05) increased serum markers of liver damage, such as alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and lactate dehydrogenase; however, these activities decreased significantly (p < 0.05) after PH administration. Elevated thiobarbituric acid reactive substance levels in liver tissue and serum decreased significantly (p < 0.05) following administration of PH. Ethanol exposure significantly (p < 0.05) decreased glutathione contents in liver and serum, and hepatic antioxidant enzyme activities such as superoxide dismutase and glutathione peroxidase, while the PH treatment significantly (p < 0.05) increased these altered parameters. These results indicate that the PH had a protective effect against ethanol-induced hepatotoxicity that was comparable to that of silymarin, which was supported by evaluating liver histopathology in the rats.     

Acute intake of mulberry leaf aqueous extract affects postprandial glucose response after maltose loading: Randomized double-blind placebo-controlled pilot study

Mulberry leaf extract was investigated as a potent alpha-glucosidase inhibitor, especially for individuals with prediabetes. We evaluated the effect of the ingestion of mulberry leaf aqueous extract (MLAE) on postprandial glucose responses in healthy subjects. We carried out a randomized, double-blind, placebo-controlled trial to determine the intake amount of MLAE (1.25, 2.5, or 5 g) and time necessary to impact postprandial blood glucose levels after 75 g of maltose loading in 50 healthy subjects. Ingestion of MLAE led to a decrease in postchallenge acute glucose levels following intake of 2.5 or 5 g of MLAE at 30 and 60 min (P = 0.0137 and 0.0423, respectively). There was no significant difference between pre- and simultaneous administration of MLAE. The ingestion of MLAE resulted in improved postprandial glycemic control in healthy subjects.     

Soy sterols in the regulation of thyroid functions,glucose homeostasis and hepatic lipid peroxidation in mice

The potential of phytosterols, isolated from soy beans in the alterations of thyroid function, glucose metabolism and hepatic lipid peroxidation was evaluated in adult mice. Dual effects were observed with two different concentrations of soy sterols. Its administration at 5.0 mg/kg for 21 days significantly increased the serum thyroxine and insulin levels, but reduced the levels of serum triiodothyronine and glucose; activities of hepatic 5′monodeiodinase and glucose-6-phophatase as well as lipid peroxidation, with a concomitant increase in superoxide dismutase, catalase and reduced glutathione, exhibiting hypothyroid and glucose lowering properties. Most of these effects were comparable to that of a standard antithyroid drug, propylthiouracil. However, administration of 10.0 mg/kg of soy sterol significantly enhanced serum glucose and hepatic lipid peroxidation. Findings suggest that soy sterols, at a moderate concentration potentially ameliorates hyperthyroidism and diabetes mellitus, but at higher concentration it may exert adverse effects.     

Blood-pressure-lowering effect of fermented buckwheat sprouts in spontaneously hypertensive rats

A practical antihypertensive food, neo-fermented buckwheat sprouts (neo-FBS), was produced from buckwheat sprouts by lactic fermentation. The neo-FBS preparation gave a 12.7 times better yield and had a 10 times more potent blood-pressure-lowering (BPL) effect than conventionally prepared products. Neo-FBS decreased both systolic and diastolic blood pressure in spontaneously hypertensive rats (SHRs) at a dose of 0.010 mg/kg, an effect comparable to 1.0 mg/kg captopril, an anti-hypertensive drug. Orally administered neo-FBS (10 mg/kg) significantly decreased angiotensin I-converting enzyme (ACE) activity in the lung, thoracic aorta, heart, kidney, and liver of SHRs. Neo-FBS had a detectable relaxing effect on a phenylephrine-precontracted thoracic aorta in SHRs at 0.5 μg/mL and the EC₅₀ value was 8.3 ± 1.4 μg/mL. The ACE inhibition and vasorelaxation activities were found to be responsible for the excellent BPL effect of neo-FBS. As SHR is a standard model for human hypertension, neo-FBS may also have BPL effects in human patients.