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Journal ArticleDOI

Antidiabetic effects of quercetin in streptozocin-induced diabetic rats.

01 Jul 2003-Comparative Biochemistry and Physiology C-toxicology & Pharmacology (Comp Biochem Physiol C Toxicol Pharmacol)-Vol. 135, Iss: 3, pp 357-364
TL;DR: Quercetin, a flavonoid with antioxidant properties brings about the regeneration of the pancreatic islets and probably increases insulin release in streptozocin-induced diabetic rats; thus exerting its beneficial antidiabetic effects; however, it may be of little value in normoglycemic animals.
Abstract: Effects of the intraperitoneal injection of quercetin in streptozocin-induced diabetic and normal rats were investigated and compared. Although quercetin had no effect on plasma glucose level of normal animals, it significantly and dose-dependently decreased the plasma glucose level of streptozocin-induced diabetic rats. Glucose tolerance tests of the diabetic animals approached those of normal rats, their plasma cholesterol and triglycerides were reduced significantly, while their hepatic glucokinase activity was significantly increased upon quercetin treatment. In normal rats, quercetin did not affect the glucose tolerance test, but resulted in an increase of plasma cholesterol and triglycerides and a decrease in hepatic glucokinase activity. No significant pathologic changes were noted in hepatocytes or kidney tubules and glomeruli, while the number of pancreatic islets significantly increased in both treated normal and diabetic groups. It is concluded that quercetin, a flavonoid with antioxidant properties brings about the regeneration of the pancreatic islets and probably increases insulin release in streptozocin-induced diabetic rats; thus exerting its beneficial antidiabetic effects. However, it may be of little value in normoglycemic animals.
Citations
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Journal ArticleDOI
TL;DR: To confirm the implications of polyphenol consumption for prevention of insulin resistance, metabolic syndrome and eventually type 2 diabetes, human trials with well-defined diets, controlled study designs and clinically relevant end-points together with holistic approaches e.g., systems biology profiling technologies are needed.
Abstract: Polyphenols, including flavonoids, phenolic acids, proanthocyanidins and resveratrol, are a large and heterogeneous group of phytochemicals in plant-based foods, such as tea, coffee, wine, cocoa, cereal grains, soy, fruits and berries. Growing evidence indicates that various dietary polyphenols may influence carbohydrate metabolism at many levels. In animal models and a limited number of human studies carried out so far, polyphenols and foods or beverages rich in polyphenols have attenuated postprandial glycemic responses and fasting hyperglycemia, and improved acute insulin secretion and insulin sensitivity. The possible mechanisms include inhibition of carbohydrate digestion and glucose absorption in the intestine, stimulation of insulin secretion from the pancreatic β–cells, modulation of glucose release from the liver, activation of insulin receptors and glucose uptake in the insulin-sensitive tissues, and modulation of intracellular signalling pathways and gene expression. The positive effects of polyphenols on glucose homeostasis observed in a large number of in vitro and animal models are supported by epidemiological evidence on polyphenol-rich diets. To confirm the implications of polyphenol consumption for prevention of insulin resistance, metabolic syndrome and eventually type 2 diabetes, human trials with well-defined diets, controlled study designs and clinically relevant end-points together with holistic approaches e.g., systems biology profiling technologies are needed.

948 citations


Cites result from "Antidiabetic effects of quercetin i..."

  • ...Quercetin has been studied also in STZ-diabetic rats by intraperitoneal injection, and the preservation of islet cells and restoration of insulin production has been observed in two studies [76,77]....

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  • ...Quercetin [184,185] [43,184] [37,39] [73] [76,77] [73,76,79] [101] Quercetin 3-glucoside [34] Quercetin 4’-glucoside [34] Quercetin 3-rhamnoside [196]...

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Journal ArticleDOI
TL;DR: It is suggested that QE treatment has protective effect in diabetes by decreasing oxidative stress and preservation of pancreatic beta-cell integrity.

782 citations

Journal ArticleDOI
TL;DR: In this article, the authors proposed a structure-classification method for plant phenolic compounds, namely, Bioflavonoids, for predicting and controlling food quality, and showed that a better understanding of their structures and biological activities indicates their potentials as therapeutic agents and also for predicting food quality.
Abstract: Phenolic compounds form one of the main classes of secondary metabolites. They display a large range of structures and are responsible for the major organoleptic characteristics of plant-derived foods and beverages, particularly color and taste properties. They also contribute to the nutritional qualities of fruits and vegetables. Among these compounds, flavonoids constitute one of the most ubiquitous groups of plant phenolics. Owing to their importance in food organoleptic properties and human health, a better understanding of their structures and biological activities indicates their potentials as therapeutic agents and also for predicting and controlling food quality. Due to the variety of pharmacological activities in the mammalian body, flavonoids are more correctly referred as “nutraceuticals”. Keywords : Bioflavonoids, Structure-Classification, Nutraceuticals, Antimicrobial activities, Anti-oxidant activity, Metabolic effects Tropical Journal of Pharmaceutical Research Vol. 7 (3) 2008: pp. 1089-1099

615 citations

Journal ArticleDOI
TL;DR: This article aims to provide a comprehensive review on various plant species from Indian biosphere and their constituents, which have been shown to display potent hypoglycemic activity.

498 citations

Journal ArticleDOI
TL;DR: Results show that rutin exhibits antihyperglycaemic and antioxidant activity in streptozotocin-induced diabetic rats.
Abstract: Flavonoids are non-nutritive dietary components that are widely distributed in plants. The present study investigated the antihyperglycaemic and antioxidant effect of rutin, a polyphenolic flavonoid in normal and streptozotocin-induced diabetic Wistar rats. Diabetes as induced in rats by an intraperitoneal injection of streptozotocin. Rutin was orally administered to normal and diabetic rats for a period of 45 days. Fasting plasma glucose, glycosylated haemoglobin, thiobarbituric acid reactive substances and lipid hydroperoxides were significantly (P<0.05) increased, whereas insulin, C-peptide, total haemoglobin, protein levels, non-enzymic antioxidants (glutathione, vitamin C, vitamin E and ceruloplasmin) were decreased significantly (P<0.05) in diabetic rats. Oral administration of rutin to diabetic rats significantly (P<0.05) decreased fasting plasma glucose, glycosylated haemoglobin and increased insulin, C-peptide, haemoglobin and protein levels. Administration of rutin also decreased thiobarbituric acid reactive substances and lipid hydroperoxides and increased the non-enzymic antioxidants significantly (P<0.05). Treatment of normal rats with rutin did not significantly (P<0.05) alter any of the parameters studied. These results show that rutin exhibits antihyperglycaemic and antioxidant activity in streptozotocin-induced diabetic rats.

442 citations

References
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Journal ArticleDOI
TL;DR: An investigation of the biochemical changes following experimental liver injury felt the need of a simple, rapid, and accurate method for determining the protein fractions in small amounts of serum and began with Kingsley’s biuret procedure.

15,717 citations


"Antidiabetic effects of quercetin i..." refers methods in this paper

  • ...Protein concentration in the liver supernatants was measured using the biuret reagent (Gornall et al., 1949) using bovine serum albumin as a standard....

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Journal ArticleDOI

9,424 citations


"Antidiabetic effects of quercetin i..." refers methods in this paper

  • ...Serum alanine aminotransferase was measured on the blood obtained from fed animals killed for hepatic glucokinase assay using a kit (Zist Chemie, Tehran, Iran) prepared according to the procedure of Reitman and Frankel (1975) and the results were expressed in units per liter....

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Journal ArticleDOI
TL;DR: An enzymatic method is described for determination of total serum cholesterol by use of a single aqueous reagent and has excellent precision.
Abstract: An enzymatic method is described for determination of total serum cholesterol by use of a single aqueous reagent. The method requires no prior treatment of sample and the calibration curve is linear to 600 mg/dl. Cholesterol esters are hydrolyzed to free cholesterol by cholesterol ester hydrolase (EC 3.1.1.13). The free cholesterol produced is oxidized by cholesterol oxidase to cholest-4-en-3-one with the simultaneous production of hydrogen peroxide, which oxidatively couples with 4-aminoantipyrine and phenol in the presence of peroxidase to yield a chromogen with maximum absorption at 500 nm. The method is reproducible, and the results correlate well with those obtained by automated Liebermann—Burchard procedures (AA-2 and SMA 12/60) and the method of Abell et al. The present method affords better specificity than those previously reported and has excellent precision.

8,750 citations


"Antidiabetic effects of quercetin i..." refers methods in this paper

  • ..., Tehran, Iran) prepared according to the procedures of Allain et al. (1974) and Fossati and Prencipe (1982), respectively....

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  • ..., Tehran, Iran) prepared according to the procedures of Allain et al. (1974) and Fossati and Prencipe (1982), respectively. Serum alanine aminotransferase was measured on the blood obtained from fed animals killed for hepatic glucokinase assay using a kit (Zist Chemie, Tehran, Iran ) prepared according to the procedure of Reitman and Frankel (1975) and the results were expressed in units per liter....

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  • ...Plasma cholesterol and triglycerides(TG) were measured on tail blood obtained from fasted animals using enzymatic kits(Pars Azemoon Co., Tehran, Iran) prepared according to the procedures of Allain et al. (1974) and Fossati and Prencipe (1982), respectively....

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Journal Article
TL;DR: The cytotoxic action of both these diabetogenic agents is mediated by reactive oxygen species, however, the source of their generation is different in the case of alloxan and streptozotocin.
Abstract: Alloxan and streptozotocin are widely used to induce experimental diabetes in animals. The mechanism of their action in B cells of the pancreas has been intensively investigated and now is quite well understood. The cytotoxic action of both these diabetogenic agents is mediated by reactive oxygen species, however, the source of their generation is different in the case of alloxan and streptozotocin. Alloxan and the product of its reduction, dialuric acid, establish a redox cycle with the formation of superoxide radicals. These radicals undergo dismutation to hydrogen peroxide. Thereafter highly reactive hydroxyl radicals are formed by the Fenton reaction. The action of reactive oxygen species with a simultaneous massive increase in cytosolic calcium concentration causes rapid destruction of B cells. Streptozotocin enters the B cell via a glucose transporter (GLUT2) and causes alkylation of DNA. DNA damage induces activation of poly ADP-ribosylation, a process that is more important for the diabetogenicity of streptozotocin than DNA damage itself. Poly ADP-ribosylation leads to depletion of cellular NAD+ and ATP. Enhanced ATP dephosphorylation after streptozotocin treatment supplies a substrate for xanthine oxidase resulting in the formation of superoxide radicals. Consequently, hydrogen peroxide and hydroxyl radicals are also generated. Furthermore, streptozotocin liberates toxic amounts of nitric oxide that inhibits aconitase activity and participates in DNA damage. As a result of the streptozotocin action, B cells undergo the destruction by necrosis.

2,884 citations


"Antidiabetic effects of quercetin i..." refers background in this paper

  • ...Chemicals with antioxidant properties and free radical scavengers in particular prevent autopoly (ADP-ribosyl)-ation of PARP and by stabilizing Reg gene transcriptional complex, result in the regeneration of b-cells and protect pancreatic islets against cytotoxic effects of STZ or alloxan (Szkudelski, 2001)....

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  • ...…with antioxidant properties and free radical scavengers in particular prevent autopoly (ADP-ribosyl)-ation of PARP and by stabilizing Reg gene transcriptional complex, result in the regeneration ofb-cells and protect pancreatic islets against cytotoxic effects of STZ or alloxan(Szkudelski, 2001)....

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  • ...…quercetin as an antioxidant and a free radical scavenger prevents autopoly(ADPribosyl)-ation of PARP, thereby stabilizing Reg gene transcriptional complex and resulting in the regeneration ofb-cells and protection of pancreatic islets against STZ or alloxan(Akiyama et al., 2001; Szkudelski, 2001)....

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  • ...Calcium does not play a significant role in necrosis ofb-cells by STZ since calcium channel antagonists do not protect b-cells against this drug(Szkudelski, 2001)....

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Journal ArticleDOI
TL;DR: In this direct colorimetric procedure, serum triglycerides are hydrolyzed by lipase, and the released glycerol is assayed in a reaction catalyzed by glycersol kinase and L-alpha-glycerol-phosphate oxidase in a system that generates hydrogen peroxide.
Abstract: In this direct colorimetric procedure, serum triglycerides are hydrolyzed by lipase, and the released glycerol is assayed in a reaction catalyzed by glycerol kinase and L-alpha-glycerol-phosphate oxidase in a system that generates hydrogen peroxide. The hydrogen peroxide is monitored in the presence of horseradish peroxidase with 3,5-dichloro-2-hydroxybenzenesulfonic acid/4-aminophenazone as the chromogenic system. The high absorbance of this chromogen system at 510 nm affords useful results with a sample/reagent volume ratio as low as 1:150, and a blank sample measurement is not needed. A single, stable working reagent is used; the reaction is complete in 15 min at room temperature. The standard curve is linear for triglyceride concentrations as great as 13.6 mmol/L. Average analytical recovery of triglycerides in human sera is 100.1%, and within-run and between-run precision studies showed CVs of less than or equal to 1.6 and less than or equal to 3.0%, respectively. The method is suitable for automation.

2,758 citations


"Antidiabetic effects of quercetin i..." refers methods in this paper

  • ...Plasma cholesterol and triglycerides(TG) were measured on tail blood obtained from fasted animals using enzymatic kits(Pars Azemoon Co., Tehran, Iran) prepared according to the procedures of Allain et al. (1974) and Fossati and Prencipe (1982), respectively....

    [...]