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Polyphenol Present (polyphenol + present)
Selected AbstractsOxidation of oleuropein studied by EPR and spectrophotometryEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 2 2008Evaggelia D. Tzika Abstract The autoxidation at alkaline pH and enzymatic oxidation by mushroom tyrosinase of oleuropein, the dominant biophenol present in the fruits and leaves of Olea europea, was followed by both electron paramagnetic resonance (EPR) and absorption spectroscopy. For comparison, the same oxidation processes were applied to 4-methylcatechol, a simple polyphenol present in olive mill wastewaters. EPR spectra of stable o -semiquinone radicals produced during autoxidation at pH,12 and short-lived o -semiquinone free radicals produced during autoxidation at pH,9.0 or tyrosinase action and stabilized by chelation with a diamagnetic metal ion (Mg2+) were recorded for both polyphenols, and the corresponding hyperfine splitting constants were determined. The UV-Vis spectral characteristics of the oxidation of polyphenols were highly dependent on the type of polyphenol, oxidant type and the pH of the reaction. The kinetic behavior of tyrosinase in the presence of oleuropein and 4-methylcatechol was followed by recording spectral changes at 400,nm (absorption maximum) over time. The tysosinase activity with oleuropein showed a pronounced pH optimum at pH,6.5 and a minor one around pH,8. From the data analysis of the initial rate at pH,6.5, the kinetic parameters Km = 0.34,±,0.03,mM and Vmax = 0.029,±,0.002 ,A400,min,1 were determined for oleuropein. [source] Concentration-dependent effect of (,) epicatechin in hypertensive patientsPHYTOTHERAPY RESEARCH, Issue 10 2010Navneet Kumar Abstract Non-vitamin polyphenolic compounds are ubiquitous in food plants and therefore potentially present in human plasma in a diet-dependent concentration. The aim of this study was to evaluate the concentration-dependent effect of (,) epicatechin, a polyphenol present in green tea with antioxidant activity, on various biomarkers of oxidative stress. The current study examined the in vitro concentration-dependent (10,4,M to 10,7,M) effects of (,) epicatechin on biomarkers of oxidative stress viz. malondialdehyde (MDA), reduced glutathione (GSH), membrane sulfhydryl (-SH) group and protein carbonyl content in hypertensive patients and normal ones. This effect seems to be due to ability of (,) epicatechin to reduce MDA and protein carbonyl content while increase in GSH and membrane -SH group in hypertensive patients. It can be concluded that (-) epicatechin exerts an antioxidant action inside the cell, responsible for the observed modulation of cellular response to oxidative challenges. Copyright © 2010 John Wiley & Sons, Ltd. [source] Anthelminthic and antiallergic activities of Mangifera indica L. stem bark components Vimang and mangiferinPHYTOTHERAPY RESEARCH, Issue 10 2003D. García Abstract This study investigated the antiallergic and anthelmintic properties of Vimang (an aqueous extract of Mangifera indica family stem bark) and mangiferin (the major polyphenol present in Vimang) administered orally to mice experimentally infected with the nematode, Trichinella spiralis. Treatment with Vimang or mangiferin (500 or 50 mg per kg body weight per day, respectively) throughout the parasite life cycle led to a signi,cant decline in the number of parasite larvae encysted in the musculature; however, neither treatment was effective against adults in the gut. Treatment with Vimang or mangiferin likewise led to a signi,cant decline in serum levels of speci,c anti- Trichinella IgE, throughout the parasite life cycle. Finally, oral treatment of rats with Vimang or mangiferin, daily for 50 days, inhibited mast cell degranulation as evaluated by the passive cutaneous anaphylaxis test (sensitization with infected mouse serum with a high IgE titre, then stimulation with the cytosolic fraction of T. spiralis muscle larvae). Since IgE plays a key role in the pathogenesis of allergic diseases, these results suggest that Vimang and mangiferin may be useful in the treatment of diseases of this type. Copyright © 2003 John Wiley & Sons, Ltd. [source] Resveratrol is efficiently glucuronidated by UDP-glucuronosyltransferases in the human gastrointestinal tract and in Caco-2 cellsBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 4 2006Nicole Sabolovic Abstract Resveratrol (3, 5, 4,-trihydroxy- trans -stilbene), a natural polyphenol present in grapes and peanuts, has been reported to exert a variety of potentially therapeutic effects. The aim of this study was to determine the contribution of the gastrointestinal (GI) tract to the glucuronidation of this compound and its cis -isomer, which also occurs naturally. For this purpose, glucuronidation of the two resveratrol isomers was investigated in human microsomes prepared from: stomach, duodenum, four segments of the remaining small intestine (S-1 to S-4) and colon, and from the human intestinal cell lines Caco-2 and PD-7. cis - and trans -Resveratrol were efficiently glucuronidated in the GI tract with the formation of both 3- O - and 4,- O -glucuronides, however, the two stereoisomers were glucuronidated at different rates depending on the donor and the segment considered. Microsomes prepared from Caco-2 and PD-7 cells also efficiently glucuronidated cis -resveratrol and, to a lesser extent, the trans -isomer, however, only the 3- O -glucuronide was formed. Among the UDP-glucuronosyltransferases (UGT) that are known to be expressed in the GI tract, the isoforms UGT1A1, 1A6, 1A8, 1A9 and 1A10 were active in glucuronidating trans - and/or cis -resveratrol. The results demonstrate that the GI tract may contribute significantly to the first pass metabolism of these naturally occurring polyphenols. Copyright © 2006 John Wiley & Sons, Ltd. [source] Inhibitory effect of phenolics extracted from sorghum genotypes on Aspergillus parasiticus (NRRL 2999) growth and aflatoxin productionJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 6 2007CV Ratnavathi Abstract The inhibitory activity of bioactive polyphenols present in six sorghum genotypes,two red (AON 486 and IS 620), two yellow (LPJ and IS 17779) and two white (SPV 86 and SPV 462) varieties,on Aspergillus parasiticus (NRRL 2999) growth and aflatoxin production was evaluated. In the first experiment the production of aflatoxins in the six sorghum genotypes after removal of surface phenolics by acidic methanol treatment was studied and compared with that in untreated grains. Aflatoxin production was found to be fourfold higher in treated grains. The total phenols and bioactive polyphenols extracted by acidic methanol were quantified using the Folin,Denis method and the bovine serum albumin,benzidine conjugate procedure respectively. In the second experiment the effect of extracted sorghum phenolics under in vitro conditions on fungal growth and aflatoxin production was studied at two concentrations (0.01% and 0.1%) of phenolics. Extracted phenolics added to yeast extract sucrose (YES) medium at 0.1% concentration showed an inhibitory effect on aflatoxin production. At 0.01% phenolic concentration, aflatoxin production was minimal on day 3 after infection. At other time points the aflatoxin content was similar to that in the control. At 9 days after infection the fungal biomass in IS 620 was significantly lower than that in the control. At 0.1% phenolic concentration, aflatoxin production was minimal and the red genotype IS 620 showed maximum resistance. Fungal biomass was lowest at all growth stages in IS 620 as compared with the control. Polyphenol oxidase (PPO) activity was not detected in A. parasiticus grown on YES medium (control). PPO activity was not induced in A. parasiticus by the addition of phenolics to the liquid culture medium (no PPO activity was detected in the culture medium). The inhibitory activity of bioactive polyphenols could be attributed to the lack of PPO enzyme in this fungus. Copyright © 2007 Society of Chemical Industry [source] | ||||||||||