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Houghton MJ, Kerimi A, Tumova S, Boyle JP, Williamson G. Quercetin preserves redox status and stimulates mitochondrial function in metabolically-stressed HepG2 cells. Free Radic Biol Med 2018; 129:296-309. [PMID: 30266680 DOI: 10.1016/j.freeradbiomed.2018.09.037] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 09/18/2018] [Accepted: 09/23/2018] [Indexed: 01/15/2023]
Abstract
Hyperglycemia augments formation of intracellular reactive oxygen species (ROS) with associated mitochondrial damage and increased risk of insulin resistance in type 2 diabetes. We examined whether quercetin could reverse chronic high glucose-induced oxidative stress and mitochondrial dysfunction. Following long-term high glucose treatment, complex I activity was significantly decreased in isolated mitochondria from HepG2 cells. Quercetin dose-dependently recovered complex I activity and lowered cellular ROS generation under both high and normal glucose conditions. Respirometry studies showed that quercetin could counteract the detrimental increase in inner mitochondrial membrane proton leakage resulting from high glucose while it increased oxidative respiration, despite a decrease in electron transfer system (ETS) capacity, and lower non-ETS oxygen consumption. A quercetin-stimulated increase in cellular NAD+/NADH was evident within 2 h and a two-fold increase in PGC-1α mRNA within 6 h, in both normal and high glucose conditions. A similar pattern was also found for the mRNA expression of the repulsive guidance molecule b (RGMB) and its long non-coding RNA (lncRNA) RGMB-AS1 with quercetin, indicating a potential change of the glycolytic phenotype and suppression of aberrant cellular growth which is characteristic of the HepG2 cells. Direct effects of quercetin on PGC-1α activity were minimal, as quercetin only weakly enhanced PGC-1α binding to PPARα in vitro at higher concentrations. Our results suggest that quercetin may protect mitochondrial function from high glucose-induced stress by increasing cellular NAD+/NADH and activation of PGC-1α-mediated pathways. Lower ROS in combination with improved complex I activity and ETS coupling efficiency under conditions of amplified oxidative stress could reinforce mitochondrial integrity and improve redox status, beneficial in certain metabolic diseases.
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Affiliation(s)
- Michael J Houghton
- School of Food Science and Nutrition, Faculty of Maths and Physical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Asimina Kerimi
- School of Food Science and Nutrition, Faculty of Maths and Physical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Sarka Tumova
- School of Food Science and Nutrition, Faculty of Maths and Physical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - John P Boyle
- Leeds Institute of Cardiovascular and Metabolic Medicine, Faculty of Medicine and Health, University of Leeds, Leeds LS2 9JT, UK
| | - Gary Williamson
- School of Food Science and Nutrition, Faculty of Maths and Physical Sciences, University of Leeds, Leeds LS2 9JT, UK.
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The acute effects of citrus flavanones on the metabolism of glycogen and monosaccharides in the isolated perfused rat liver. Toxicol Lett 2018; 291:158-172. [PMID: 29626522 DOI: 10.1016/j.toxlet.2018.04.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 03/06/2018] [Accepted: 04/02/2018] [Indexed: 10/17/2022]
Abstract
Citrus flavanones are often linked to their antihyperglycemic properties. This effect may be in part due to the inhibition of hepatic gluconeogenesis through different mechanisms. One of the possible mechanisms appears to be impairment of oxidative phosphorylation, which may also interfere with glycogen metabolism. Based on these facts, the purpose of the present study was to investigate the effects of three citrus flavanones on glycogenolysis in the isolated perfused rat liver. Hesperidin, hesperetin, and naringenin stimulated glycogenolysis and glycolysis from glycogen with concomitant changes in oxygen uptake. At higher concentrations (300 μM), hesperetin and naringenin clearly altered fructose and glucose metabolism, whereas hesperidin exerted little to no effects. In subcellular fractions hesperetin and naringenin inhibited the activity of glucose 6-phosphatase and glucokinase and the mitochondrial respiration linked to ADP phosphorylation. Hesperetin and naringenin also inhibited the transport of glucose into the cell. At a concentration of 300 μM, the glucose influx rate inhibition was 83% and 43% for hesperetin and naringenin, respectively. Hesperidin was the less active among the assayed citrus flavanones, indicating that the rutinoside moiety noticeably decrease the activity of these compounds. The effects on glycogenolysis and fructolysis were mainly consequence of an impairment on mitochondrial energy metabolism. The increased glucose release, due to the higher glycogenolysis, together with glucose transport inhibition is the opposite of what is expected for antihyperglycemic agents.
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Gruse J, Görs S, Tuchscherer A, Otten W, Weitzel JM, Metges CC, Wolffram S, Hammon HM. The Effects of Oral Quercetin Supplementation on Splanchnic Glucose Metabolism in 1-Week-Old Calves Depend on Diet after Birth. J Nutr 2015; 145:2486-95. [PMID: 26400967 DOI: 10.3945/jn.115.218271] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 08/27/2015] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Inadequate colostrum supply results in insufficient intake of macronutrients and bioactive factors, thereby impairing gastrointestinal development and the maturation of glucose metabolism in neonatal calves. The flavonoid quercetin has been shown to have health-promoting properties, including effects in diabetic animals. However, quercetin interacts with intestinal glucose absorption and might therefore exert negative effects in neonates. OBJECTIVE We evaluated the interaction between neonatal diet and quercetin feeding on splanchnic glucose metabolism in neonatal calves. METHODS Calves (n = 28) were assigned to 4 groups and fed either colostrum or a milk-based formula on days 1 and 2 and supplemented daily with 148 μmol quercetin aglycone/kg body weight [colostrum with quercetin (CQ+)/formula with quercetin (FQ+)] or without this substance [colostrum without quercetin (CQ-)/formula with quercetin (FQ-)] from days 2-8. From day 3 onward, all calves received milk replacer. A xylose absorption test was performed on day 3, and on day 7, blood samples were collected to study glucose first-pass uptake after [(13)C6]-glucose feeding and intravenous [6,6-(2)H2]-glucose bolus injection. Plasma concentrations of metabolites and hormones were measured by taking additional blood samples. A biopsy specimen of the liver was harvested on day 8 to measure the mRNA expression of gluconeogenic enzymes. RESULTS Higher postprandial plasma concentrations of glucose, lactate, urea, adrenaline, noradrenaline, insulin, and glucagon on day 7 in colostrum-fed calves indicate that metabolic processes were stimulated. Postabsorptive xylose and glucose plasma concentrations each increased by an additional 26%, and splanchnic glucose turnover decreased by 35% in colostrum-fed calves, suggesting improved glucose absorption and lower splanchnic glucose utilization in colostrum-fed calves. Quercetin supplementation resulted in higher noradrenaline concentrations and enhanced peak absorption and oxidation of [(13)C6]-glucose by 10%. Liver mitochondrial phosphoenolpyruvate carboxykinase mRNA abundance was reduced by 34% in colostrum-deprived calves. CONCLUSIONS Feeding colostrum during the first 2 d of life is crucial for maturation of splanchnic glucose metabolism in calves. Supplementing quercetin improves gastrointestinal absorption capacity, particularly in colostrum-deprived calves.
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Affiliation(s)
| | - Solvig Görs
- Institutes of Nutritional Physiology "Oskar Kellner"
| | | | | | - Joachim M Weitzel
- Reproductive Biology, Leibniz Institute for Farm Animal Biology (FBN), Dummerstorf, Germany; and
| | | | - Siegfried Wolffram
- Institute of Animal Nutrition and Physiology, Faculty of Agricultural and Nutritional Sciences, Christian-Albrechts-University of Kiel, Kiel, Germany
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Maciej J, Schäff CT, Kanitz E, Tuchscherer A, Bruckmaier RM, Wolffram S, Hammon HM. Bioavailability of the flavonol quercetin in neonatal calves after oral administration of quercetin aglycone or rutin. J Dairy Sci 2015; 98:3906-17. [PMID: 25795488 PMCID: PMC7094564 DOI: 10.3168/jds.2015-9361] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Polyphenols, such as flavonoids, are secondary plant metabolites with potentially health-promoting properties. In newborn calves flavonoids may improve health status, but little is known about the systemically availability of flavonoids in calves to exert biological effects. The aim of this study was to investigate the oral bioavailability of the flavonol quercetin, applied either as quercetin aglycone (QA) or as its glucorhamnoside rutin (RU), in newborn dairy calves. Twenty-one male newborn German Holstein calves were fed equal amounts of colostrum and milk replacer according to body weight. On d 2 and 29 of life, 9 mg of quercetin equivalents/kg of body weight, either fed as QA or as RU, or no quercetin (control group) were fed together with the morning meal. Blood samples were taken before and 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 12, 24, and 48 h after feed intake. Quercetin and quercetin metabolites with an intact flavonol structure (isorhamnetin, tamarixetin, and kaempferol) were analyzed in blood plasma after treatment with glucuronidase or sulfatase by HPLC with fluorescence detection. Maximum individual plasma concentration was depicted from the concentration-time-curve on d 2 and 29, respectively. Additional blood samples were taken to measure basal plasma concentrations of total protein, albumin, urea, and lactate as well as pre- and postprandial plasma concentrations of glucose, nonesterified fatty acids, insulin, and cortisol. Plasma concentrations of quercetin and its metabolites were significantly higher on d 2 than on d 29 of life, and administration of QA resulted in higher plasma concentrations of quercetin and its metabolites than RU. The relative bioavailability of total flavonols (sum of quercetin and its metabolites isorhamnetin, tamarixetin, and kaempferol) from RU was 72.5% on d 2 and 49.6% on d 29 when compared with QA (100%). Calves fed QA reached maximum plasma concentrations of total flavonols much earlier than did RU-fed calves. Plasma metabolites and hormones were barely affected by QA and RU feeding in this experiment. Taken together, orally administrated QA resulted in a greater bioavailability of quercetin than RU on d 2 and 29, respectively, and quercetin bioavailability of quercetin and its metabolites differed markedly between calves aged 2 and 29 d.
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Affiliation(s)
- J Maciej
- Institute of Nutritional Physiology "Oskar Kellner,", Leibniz Institute for Farm Animal Biology (FBN), Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany
| | - C T Schäff
- Institute of Nutritional Physiology "Oskar Kellner,", Leibniz Institute for Farm Animal Biology (FBN), Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany
| | - E Kanitz
- Institute of Behavioural Physiology, Leibniz Institute for Farm Animal Biology (FBN), Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany
| | - A Tuchscherer
- Institute of Genetics and Biometry, Leibniz Institute for Farm Animal Biology (FBN), Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany
| | - R M Bruckmaier
- Veterinary Physiology, Vetsuisse Faculty, University of Bern, 3001 Bern, Switzerland
| | - S Wolffram
- Institute of Animal Nutrition and Physiology, Christian Albrechts University Kiel, 24118 Kiel, Germany
| | - H M Hammon
- Institute of Nutritional Physiology "Oskar Kellner,", Leibniz Institute for Farm Animal Biology (FBN), Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany.
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Prasath GS, Pillai SI, Subramanian SP. Fisetin improves glucose homeostasis through the inhibition of gluconeogenic enzymes in hepatic tissues of streptozotocin induced diabetic rats. Eur J Pharmacol 2014; 740:248-54. [PMID: 25064342 DOI: 10.1016/j.ejphar.2014.06.065] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 06/13/2014] [Accepted: 06/17/2014] [Indexed: 11/26/2022]
Abstract
Liver plays a vital role in blood glucose homeostasis. Recent studies have provided considerable evidence that hepatic glucose production (HGP) plays an important role in the development of fasting hyperglycemia in diabetes. From this perspective, diminution of HGP has certainly been considered for the treatment of diabetes. In the present study, we have analyzed the modulatory effects of fisetin, a flavonoid of strawberries, on the expression of key enzymes of carbohydrate metabolism in STZ induced experimental diabetic rats. The physiological criterions such as food and fluid intake were regularly monitored. The levels of blood glucose, plasma insulin, hemoglobin and glycosylated hemoglobin were analyzed. The mRNA and protein expression levels of gluconeogenic genes such as phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) were determined by immunoblot as well as PCR analysis. Diabetic group of rats showed significant increase in food and water intake when compared with control group of rats. Upon oral administration of fisetin as well as gliclazide to diabetic group of rats, the levels were found to be decreased. Oral administration of fisetin (10 mg/kg body weight) to diabetic rats for 30 days established a significant decline in blood glucose and glycosylated hemoglobin levels and a significant increase in plasma insulin level. The mRNA and protein expression levels of gluconeogenic genes, such as phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase), were decreased in liver tissues upon treatment with fisetin. The results of the present study suggest that fisetin improves glucose homeostasis by direct inhibition of gluconeogenesis in liver.
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Affiliation(s)
- Gopalan Sriram Prasath
- Department of Biochemistry, University of Madras, Guindy Campus, Chennai 600025, Tamil Nadu, India
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Mito MS, Castro CVD, Peralta RM, Bracht A. Effects of Ranolazine on Carbohydrate Metabolism in the Isolated Perfused Rat Liver. ACTA ACUST UNITED AC 2014. [DOI: 10.4236/ojmc.2014.44007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Citrus flavanones affect hepatic fatty acid oxidation in rats by acting as prooxidant agents. BIOMED RESEARCH INTERNATIONAL 2013; 2013:342973. [PMID: 24288675 PMCID: PMC3833034 DOI: 10.1155/2013/342973] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 09/17/2013] [Accepted: 09/18/2013] [Indexed: 01/30/2023]
Abstract
Citrus flavonoids have a wide range of biological activities and positive health effects on mammalian cells because of their antioxidant properties. However, they also act as prooxidants and thus may interfere with metabolic pathways. The purpose of this work was to evaluate the effects of three citrus flavanones, hesperidin, hesperetin, and naringenin, on several parameters linked to fatty acid oxidation in mitochondria, peroxisomes, and perfused livers of rats. When exogenous octanoate was used as substrate, hesperetin and naringenin reduced the mitochondrial NADH/NAD+ ratio and stimulated the citric acid cycle without significant changes on oxygen uptake or ketogenesis. When fatty acid oxidation from endogenous sources was evaluated, hesperetin and naringenin strongly reduced the mitochondrial NADH/NAD+ ratio. They also inhibited both oxygen uptake and ketogenesis and stimulated the citric acid cycle. Hesperidin, on the other hand, had little to no effect on these parameters. These results confirm the hypothesis that citrus flavanones are able to induce a more oxidised state in liver cells, altering parameters related to hepatic fatty acid oxidation. The prooxidant effect is most likely a consequence of the ability of these substances to oxidise NADH upon production of phenoxyl radicals in the presence of peroxidases and hydrogen peroxide.
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Vilaça R, Mendes V, Mendes MV, Carreto L, Amorim MA, de Freitas V, Moradas-Ferreira P, Mateus N, Costa V. Quercetin protects Saccharomyces cerevisiae against oxidative stress by inducing trehalose biosynthesis and the cell wall integrity pathway. PLoS One 2012; 7:e45494. [PMID: 23029052 PMCID: PMC3445532 DOI: 10.1371/journal.pone.0045494] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Accepted: 08/20/2012] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Quercetin is a naturally occurring flavonol with antioxidant, anticancer and anti-ageing properties. In this study we aimed to identify genes differentially expressed in yeast cells treated with quercetin and its role in oxidative stress protection. METHODS A microarray analysis was performed to characterize changes in the transcriptome and the expression of selected genes was validated by RT-qPCR. Biological processes significantly affected were identified by using the FUNSPEC software and their relevance in H(2)O(2) resistance induced by quercetin was assessed. RESULTS Genes associated with RNA metabolism and ribosome biogenesis were down regulated in cells treated with quercetin, whereas genes associated with carbohydrate metabolism, endocytosis and vacuolar proteolysis were up regulated. The induction of genes related to the metabolism of energy reserves, leading to the accumulation of the stress protectant disaccharide trehalose, and the activation of the cell wall integrity pathway play a key role in oxidative stress resistance induced by quercetin. CONCLUSIONS These results suggest that quercetin may act as a modulator of cell signaling pathways related to carbohydrate metabolism and cell integrity to exert its protective effects against oxidative stress.
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Affiliation(s)
- Rita Vilaça
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- Departamento de Biologia Molecular, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Vanda Mendes
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- Centro de Investigação em Química, Faculdade de Ciências da Universidade do Porto, Porto, Portugal
| | - Marta Vaz Mendes
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Laura Carreto
- Departamento de Biologia e Centro de Estudos do Ambiente e do Mar, Universidade de Aveiro, Aveiro, Portugal
| | - Maria Amélia Amorim
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- Departamento de Biologia Molecular, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Victor de Freitas
- Centro de Investigação em Química, Faculdade de Ciências da Universidade do Porto, Porto, Portugal
| | - Pedro Moradas-Ferreira
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- Departamento de Biologia Molecular, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Nuno Mateus
- Centro de Investigação em Química, Faculdade de Ciências da Universidade do Porto, Porto, Portugal
| | - Vítor Costa
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- Departamento de Biologia Molecular, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
- * E-mail:
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Colturato CP, Constantin RP, Maeda AS, Constantin RP, Yamamoto NS, Bracht A, Ishii-Iwamoto EL, Constantin J. Metabolic effects of silibinin in the rat liver. Chem Biol Interact 2012; 195:119-32. [DOI: 10.1016/j.cbi.2011.11.006] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 11/11/2011] [Accepted: 11/15/2011] [Indexed: 10/15/2022]
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Niklas J, Nonnenmacher Y, Rose T, Sandig V, Heinzle E. Quercetin treatment changes fluxes in the primary metabolism and increases culture longevity and recombinant α₁-antitrypsin production in human AGE1.HN cells. Appl Microbiol Biotechnol 2011; 94:57-67. [PMID: 22202969 DOI: 10.1007/s00253-011-3811-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Revised: 11/29/2011] [Accepted: 12/01/2011] [Indexed: 10/14/2022]
Abstract
Addition of the flavonoid quercetin to cultivations of the α(1)-antitrypsin (A1AT) producing human AGE1.HN.AAT cell line resulted in alterations of the cellular physiology and a remarkable improvement of the overall performance of these cells. In a first screening in 96-well plate format, toxicity and the effect of quercetin on the lactate/glucose ratio was analyzed. It was found that quercetin treatment reduced the lactate/glucose ratio dose dependently. An increase in culture longevity, viable cell density (160% of control), and A1AT concentration (from 0.39 g/L in the control to 0.76 g/L with quercetin, i.e., 195% of the control) was observed in batch cultivation with 10 μM quercetin compared to the control. A detailed analysis of quercetin effects on primary metabolism revealed dose-dependent alterations in metabolic fluxes. Quercetin addition resulted in an improved channeling of pyruvate into the mitochondria accompanied by reduced waste product formation and stimulation of TCA cycle activity. The observed changes in cellular physiology can be explained by different properties of quercetin and its metabolites, e.g., inhibition of specific enzymes, stimulation of oxidation of cytoplasmic, and mitochondrial NADH resulting in reduced NADH/NAD(+) ratio, and cytoprotective activity. The present study shows that the addition of specific effectors to the culture medium represents a promising strategy to improve the cellular metabolic phenotype and the production of biopharmaceuticals. The provided results contribute, additionally, to an improved understanding of quercetin action on the metabolism of human cells in a general physiological context.
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Affiliation(s)
- Jens Niklas
- Biochemical Engineering Institute, Saarland University, 66123 Saarbrücken, Germany
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Constantin RP, Constantin J, Pagadigorria CLS, Ishii-Iwamoto EL, Bracht A, de Castro CV, Yamamoto NS. Prooxidant activity of fisetin: effects on energy metabolism in the rat liver. J Biochem Mol Toxicol 2010; 25:117-26. [PMID: 20957679 DOI: 10.1002/jbt.20367] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Revised: 06/18/2010] [Accepted: 07/07/2010] [Indexed: 11/08/2022]
Abstract
Flavonols, which possess the B-catechol ring, as quercetin, are capable of producing o-hemiquinones and to oxidize NADH in a variety of mammalian cells. The purpose of this study was to investigate whether fisetin affects the liver energy metabolism and the mitochondrial NADH to NAD+ ratio. The action of fisetin on hepatic energy metabolism was investigated in the perfused rat liver and isolated mitochondria. In isolated mitochondria, fisetin decreased the respiratory control and ADP/O ratios with the substrates α-ketoglutarate and succinate. In the presence of ADP, respiration of isolated mitochondria was inhibited with both substrates, indicating an inhibitory action on the ATP-synthase. The stimulation of the ATPase activity of coupled mitochondria and the inhibition of NADH-oxidase activity pointed toward a possible uncoupling action and the interference of fisetin with mitochondrial energy transduction mechanisms. In livers from fasted rats, fisetin inhibited ketogenesis from endogenous sources. The β-hydroxybutyrate/ acetoacetate ratio, which reflects the mitochondrial NADH/NAD+ redox ratio, was also decreased. In addition, fisetin (200 μM) increased the production of (14)CO2 from exogenous oleate. The results of this investigation suggest that fisetin causes a shift in the mitochondrial redox potential toward a more oxidized state with a clear predominance of its prooxidant activity.
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de Oliveira AL, Eler GJ, Bracht A, Peralta RM. Purinergic effects of a hydroalcoholic Agaricus brasiliensis (A. blazei) extract on liver functions. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:7202-7210. [PMID: 20507067 DOI: 10.1021/jf100804k] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The effects of a hydroalcoholic extract of Agaricus brasiliensis (A. blazei) on functional parameters in the perfused rat liver were examined with emphasis on its content of nucleotides and nucleosides. Several nucleosides and nucleotides were identified in the A. brasiliensis extract, which was active on several liver functions. A significant part of the effects is the result of the purinergic action of nucleosides and nucleotides: pressure increment, glycogenolysis stimulation, transient inhibition of oxygen consumption, and redox state changes. Other phenomena such as the stimulation of gluconeogenesis, ureogenesis, and oxygen consumption are more likely consequences of the metabolic transformation of substrates contained within the extract, especially amino acids. It seems apparent that consumption of A. brasiliensis represents not only the ingestion of metabolic precursors but also the ingestion of substances that, even at low concentrations, can exert important signaling functions in the liver as well as in the organism as a whole.
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Constantin RP, Constantin J, Pagadigorria CLS, Ishii-Iwamoto EL, Bracht A, Ono MDKC, Yamamoto NS. The actions of fisetin on glucose metabolism in the rat liver. Cell Biochem Funct 2010; 28:149-58. [PMID: 20084677 DOI: 10.1002/cbf.1635] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Fisetin is a flavonoid dietary ingredient found in the smoke tree (Cotinus coggyria) and in several fruits and vegetables. The effects of fisetin on glucose metabolism in the isolated perfused rat liver and some glucose-regulating enzymatic activities were investigated. Fisetin inhibited glucose, lactate, and pyruvate release from endogenous glycogen. Maximal inhibitions of glycogenolysis (49%) and glycolysis (59%) were obtained with the concentration of 200 microM. The glycogenolytic effects of glucagon and dinitrophenol were suppressed by fisetin 300 microM. No significant changes in the cellular contents of AMP, ADP, and ATP were found. Fisetin increased the cellular content of glucose 6-phosphate and inhibited the glucose 6-phosphatase activity. Gluconeogenesis from lactate and pyruvate or fructose was inhibited by fisetin 300 microM. Pyruvate carboxylation in isolated intact mitochondria was inhibited (IC(50) = 163.10 +/- 12.28 microM); no such effect was observed in freeze-thawing disrupted mitochondria. It was concluded that fisetin inhibits glucose release from the livers in both fed and fasted conditions. The inhibition of pyruvate transport into the mitochondria and the reduction of the cytosolic NADH-NAD(+) potential redox could be the causes of the gluconeogenesis inhibition. Fisetin could also prevent hyperglycemia by decreasing glycogen breakdown or blocking the glycogenolytic action of hormones.
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