Inhibitory effect of a quercetin metabolite, quercetin 3-O-beta-D-glucuronide, on lipid peroxidation in liposomal membranes.     

M Shirai  J H Moon  T Tsushida  J Terao 《Journal of agricultural and food chemistry》2001,49(11):5602-5608

To study the antioxidant activity of quercetin 3-O-beta-D-glucuronide (Q3GA), which is one of the quercetin metabolites in the blood after intake of quercetin-rich food, the inhibitory effect of Q3GA on lipid peroxidation was estimated using phosphatidylcholine large unilamellar vesicles (PC LUV) as a biomembrane model. Iron ion, an aqueous peroxyl radical generator, a peroxynitrite generator, or lipoxygenase was used as the inducer of lipid peroxidation. In all cases, Q3GA inhibited lipid peroxidation significantly, although its inhibitory effect was lower than that of quercetin aglycon. The ultrafiltration of PC LUV containing Q3GA revealed that Q3GA has low but significant affinity with the membranes of phospholipid bilayers. It is therefore likely that Q3GA acts as an efficient antioxidant in membranous lipid peroxidation through its localization in the phospholipid bilayer. This conjugated quercetin metabolite seems to retain the ability to protect cellular and subcellular membranes from peroxidative attack by reactive oxygen species and peroxidative enzymes.  相似文献   

Quantification of polyphenolics and their antioxidant capacity in fresh plums     

Kim DO  Chun OK  Kim YJ  Moon HY  Lee CY 《Journal of agricultural and food chemistry》2003,51(22):6509-6515

Total phenolics, total flavonoids, and antioxidant capacity of 11 cultivars of fresh plums were determined using spectrophotometric methods. Identification and quantification of individual polyphenolics were performed using reversed-phase high-performance liquid chromatography equipped with a diode array detector. The total phenolic contents of various cultivars widely varied from 125.0 to 372.6 mg/100 g expressed as gallic acid equivalents. The level of total flavonoids in fresh plums ranged between 64.8 and 257.5 mg/100 g expressed as catechin equivalents. Antioxidant capacity, expressed as vitamin C equivalent antioxidant capacity (VCEAC), ranged from 204.9 to 567.0 mg/100 g with an average of 290.9 mg/100 g of fresh weight. Cv. Beltsville Elite B70197 showed the highest amounts of total phenolics and total flavonoids and the highest VCEAC. A positive relationship (correlation coefficient r (2)() = 0.977) was presented between total phenolics and VCEAC, suggesting polyphenolics would play an important role in free radical scavenging. The level of IC(50) value of superoxide radical anion scavenging activity of the plum cultivars ranged from 13.4 to 45.7 mg of VCEAC/100 g. Neochlorogenic acid was the predominant polyphenolic among fresh plums tested. Flavonols found in plum were commonly quercetin derivatives. Rutin was the most predominant flavonol in plums. Various anthocyanins containing cyanidin aglycon and peonidin aglycon were commonly found in all plums except for cv. Mirabellier and NY 101.  相似文献   

Kinetic study of oxalic acid inhibition on enzymatic browning   总被引：6，自引：0，他引：6  

Son SM  Moon KD  Lee CY 《Journal of agricultural and food chemistry》2000,48(6):2071-2074

Oxalic acid has a strong antibrowning activity. The inhibitory pattern on catechol-PPO model system appeared to be competitive, with a K(i) value of 2.0 mM. When the PPO was incubated with oxalic acid, the activity was not recovered via dialysis, but the inactivated enzyme partially recovered its activity when cupric ion was added. Comparing the relative antibrowning effectiveness of oxalic acid with other common antibrowning agents, oxalic acid with I(50) value of 1.1 mM is as effective as kojic acid and more potent than cysteine and glutathione.  相似文献   

Single nucleotide polymorphism discovery and linkage mapping of lipoxygenase-2 gene (Lx 2) in soybean     

Moon Young Kim  Bo-Keun Ha  Tae-Hwan Jun  Eun-Young Hwang  Kyujung Van  Yong In Kuk  Suk-Ha Lee 《Euphytica》2004,135(2):169-177

Lipoxygenase-2 (Lx ₂) in soybean seed is mainly responsible for generation of grassy-beany and bitter flavors. Genetic elimination of this flavor can be accelerated by the development of single nucleotide polymorphism (SNP) markers linked to Lx ₂. A frame map based on simple sequence repeat (SSR) markers was constructed first using a recombinant inbred line (RIL) population of Pureunkong × Jinpumkong 2. Sixty-five SSR markers were incorporated into 13 linkage groups (LGs) spanning a total of 737 cM. Among five primer pairs designed from the Lx ₂ gene sequence, one produced an amplicon with sequence variations between Pureunkong and Jinpumkong 2. Three SNPs, T/C, G/A and C/A, were identified at 251,367 and 420 bp, respectively, in the intron region of the 804 bp amplified product. Using single base chain extension based on the capture probe sequence in the 5' region of the T/C SNP, the 90 RILs were genotyped for each allele of Lx ₂. The allelic segregation for the SNP linked toLx ₂ was in accordance with the expected ratio of 1:1 in the RIL population. Based on the results of linkage analysis between Lx ₂ and the SSR markers, Lx ₂ was found to be positioned on one end of LG F in the frame map, flanked by the SSR markers Satt522 and Sat074. This study demonstrates that SNP markers closely linked to Lx ₂can be developed to facilitate marker-assisted selection and fine mapping of the region around this locus. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

The role of glycogen phosphorylase in the regulation of glycogenolysis by insulin and glucagon in isolated eel (Anguilla rostrata) hepatocytes   总被引：1，自引：0，他引：1  

Glen D. Foster  T. W. Moon 《Fish physiology and biochemistry》1990,8(4):299-309

The effects of porcine, scombroid, and salmon insulins, and bovine and anglerfish glucagons on glycogen depletion and glycogen phosphorylase (GPase) activities were examined in freshly isolated American eel (Anguilla rostrata) hepatocytes. Eel liver GPase in crude homogenates was activated (increase in % GPase a) by phosphorylating conditions and was rapidly inactivated (less than 1 h) when a phosphatase inhibitor (fluoride) was absent. Caffeine inhibits, and AMP activates, the b form of GPase consistent with their effects on rat liver GPase. Both mammalian and fish glucagons increased glucose production in eel hepatocytes, but had more ambiguous effects on glycogen levels and GPase activities. The magnitude of bovine glucagon effects were dependent on the initial glycogen content of the cells; only at glycogen concentrations less than approximately 70 μmoles.g⁻¹ did glucagon significantly increase % GPase a. Anglerfish glucagon significantly increased cyclic AMP (cAMP) concentrations by 90% at 10⁻⁷ M, but had no effects at 10⁻⁹ M and 10⁻⁸ M. Scombroid and salmon insulins maintained hepatocyte glycogen concentrations and decreased glucose production, with these effects more pronounced at low (10⁻⁹ to 10⁻⁸ M) rather than high (10⁻⁷ M) hormone concentrations. Porcine and salmon insulins decreased total GPase and % GPase a activities, and salmon insulin decreased CAMP levels, but only at 10⁻⁸ M (by 44%). Glycogen is, therefore, depleted by glucagon and maintained by insulin in freshly isolated American eel hepatocytes, and these changes are accomplished, at least in part, by changes in the activities of GPase. Changes in cAMP do not explain all of the observed hormone effects.  相似文献   

Insulin binding to isolated hepatocytes of Atlantic salmon and rainbow trout     

Erika M. Plisetskaya  Elena Fabbri  Thomas W. Moon  Joaquim Gutiérrez  Celestina Ottolenghi 《Fish physiology and biochemistry》1993,11(1-6):401-409

The questions addressed in this study were: 1) whether insulin added to the incubation medium can down-regulate ¹²⁵I insulin binding to isolated hepatocytes of Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss); 2) whether quantitative assessment of insulin processing can be made on isolated fish liver cells; 3) how ambient temperatures can affect insulin binding, and down-regulation of insulin receptors. After isolation and a short (up to 4h) “metabolic recovery period”, liver cells were used either directly in ¹²⁵I insulin binding assay or first preincubated for 18h at 4°C or for 3h at 15°C, with or without mammalian or salmon insulin in concentrations ranging from 1 to 1000 nM. Preincubation at 15°C, decreased binding capacity (number of binding sites per liver cell) in all five independent hepatocyte preparations treated with 1000 nM insulin and in four out of five preparations treated with 100 nM insulin. At 4°C insulin binding sites were down-regulated in less than 50% of all hepatocyte preparations and only in the presence of 1000 nM insulin. Differential quantitive assessment was made of a) intact free insulin; b) insulin degraded; c) intact insulin bound to the cell membrane; d) internalized but degraded insulin, and e) intact insulin internalized by liver cells. Hepatocytes preincubated with 100 – 1000 nM insulin at 15°C bound and internalized less ¹²⁵I insulin. We hypothesize that in vivo, at water temperatures of 15°C and higher, extreme physiological levels of plasma insulin may regulate the numbers of insulin receptors in the salmonid liver. In contrast, in fish inhabiting cold waters the regulation of insulin receptors by circulating plasma insulin seems to be of little physiological importance. Presented in part at the Western Regional Conference on Comparative Endrocrinology, Tempe, Arizona, U.S.A., 1991 and at the Meeting of Italian Society of Experimental Biology, Sorrento, Italy, 1991. Supported by grants from NSF of the USA#DCB 8915935 to E.M.P., NSERC of Canada OPGA 6944 to T.W.M., North Atlantic Treaty Organization (NATO) grant #0926/87 to C.O. and E.M.P., and CYCIT grant of Spain to J.G.  相似文献   

Actions of epinephrine on the contractility of fast and slow skeletal muscle fibres in teleosts     

T. P. Johnson  T. W. Moon  I. A. Johnston 《Fish physiology and biochemistry》1991,9(1):83-89

Fast and slow muscle fibers were isolated from the myotomes of atlantic cod (Gadus morhua L.) and sculpin (Myoxocephalus scorpius L.). Epinephrine was found to have no effect on twitch or sub-tetanic contractions in fast muscle fibres. Isoprenaline (10^–6M) had no effect on the contractility of slow muscle fibres. In contrast, epinephrine elicited a dose-dependent decrease in the half-time for twitch relaxation (t_1/2r), and in most cases a decrease in twitch amplitude. The maximum decrease in t_1/2r was around 5–20% of control values (at 10^–6M epinephrine), with a half maximal response at about 30 nmol l^–1. Responses to epinephrine were unaffected by propranolol and reversed by phentolamine, consistent with the stimulation of -adrenoreceptors. 10^–6M epinephrine produced a rise in cAMP levels from 1.8 to 3.1 pmol mg dry wt^–1 in cod slow fibres. However, the cellular mechanism underlying the action of epinephrine is unclear since forskolin, a potent activator of adenylate cyclase activity, where it has been investigated, was found to increase not decrease twitch duration and amplitude. The responses of fast and slow fibres to epinephrine and its antagonists were similar in summer (13°C) and winter acclimatized (5–6°C) sculpin.It is suggested that epinephrine may act to modulate the active state of slow muscle fibres at high cruising speeds and thereby increase swimming performance.  相似文献   

Restricted growth of U-type infectious haematopoietic necrosis virus (IHNV) in rainbow trout cells may be linked to casein kinase II activity     

Park JW  Moon CH  Harmache A  Wargo AR  Purcell MK  Bremont M  Kurath G 《Journal of fish diseases》2011,34(2):115-129

  相似文献   

Metabolic actions of glucagon-family hormones in liver   总被引：1，自引：0，他引：1  

Thomas P. Mommsen  Thomas W. Moon 《Fish physiology and biochemistry》1989,7(1-6):279-288

This review addresses direct and indirect metabolic actions of hormones co-encoded in the preproglucagon gene of fishes. Emphasis is placed on a critical analysis of the effects of glucagon and glucagon-like peptide (GLP) and the current knowledge of the respective modes of action is reviewed. In mammals GLPs exert no direct metabolic actions. In fish liver, GLP and glucagon act on similar targets of intermediary metabolism by enhancing flux through glycogenolysis, lipolysis and gluconeogenesis. Increases in substrate oxidation are not uniform. Hormonal activation of glycogen phosphorylase and triglyceride lipase and inhibition of pyruvate kinase are implicated in these actions. Hormone-dependent hyperglycemia, depletion of hepatic glycogen and increases in free fatty acids are noticeablein vivo. Glucagon also activates hepatic amino acid uptake and ammonia excretion. Glucagon actions are accompanied by large increases in hepatic cAMP and increased phosphorylation of pyruvate kinase. Metabolic effects measured after GLP administration are associated with minor, if any, increases in cAMP and effects on pyruvate kinase are variable. We hypothesize that different hepatic receptors with differing modes of intracellular message transduction are involved in glucagon and GLP actions while targetting identical metabolic routes. Responses of different species of fish cover a wide spectrum, and variation of response with the circannual cycle of experimental animals makes comparisons of results, even within one species, difficult.  相似文献   

Cooperative action of alpha-glucanotransferase and maltogenic amylase for an improved process of isomaltooligosaccharide (IMO) production   总被引：2，自引：0，他引：2  

Lee HS  Auh JH  Yoon HG  Kim MJ  Park JH  Hong SS  Kang MH  Kim TJ  Moon TW  Kim JW  Park KH 《Journal of agricultural and food chemistry》2002,50(10):2812-2817

Maltogenic amylase and alpha-glucanotransferase (alpha-GTase) were employed in an effort to develop an efficient process for the production of isomaltooligosaccharides (IMOs). Bacillus stearothermophilus maltogenic amylase (BSMA) and alpha-GTase from Thermotoga maritima were overexpressed in Escherichia coli using overexpression vectors. An IMO mixture containing 58% of various IMOs was produced from liquefied corn syrup by the hydrolyzing and transglycosylation activities of BSMA alone. When BSMA and alpha-GTase were reacted simultaneously, the IMO content increased to 68% and contained relatively larger IMOs compared with the products obtained by the reaction without alpha-GTase. Time course analysis of the IMO production suggested that BSMA hydrolyzed maltopentaose and maltohexaose most favorably into maltose and maltotriose and transferred the resulting molecules simultaneously to acceptor molecules to form IMOs. alpha-GTase transferred donor sugar molecules to the hydrolysis products such as maltose and maltotriose to form maltopentaose, which was then rehydrolyzed by BSMA as a favorable substrate.  相似文献