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4 Hydroxyphenylacetic Acid

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Jia-hong Lin – One of the best experts on this subject based on the ideXlab platform.

  • Simultaneous Detection of 3-Nitrotyrosine and 3-Nitro-4Hydroxyphenylacetic Acid in Human Urine by Online SPE LC-MS/ MS and Their Association with Oxidative and Methylated DNA Lesions
    Chemical research in toxicology, 2015
    Co-Authors: Mu-rong Chao, Yu-wen Hsu, Hung-hsin Liu, Jia-hong Lin

    Abstract:

    Reactive nitrogen species (RNS) can modify proteins at tyrosine and tryptophan residues, and they are involved in the pathogenesis of various human diseases. In this study, we present the first liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based method that enables the simultaneous measurement of urinary 3-nitrotyrosine (3-NTYR) and its metabolite 3-nitro-4Hydroxyphenylacetic Acid (NHPA). After the addition of stable isotope-labeled internal standards, urine samples were purified and enriched using manual solid-phase extraction (SPE) and HPLC fractionation followed by online SPE LC-MS/MS analysis. The limits of quantification in urine were 3.1 and 2.5 pg/mL for 3-NTYR and NHPA, respectively. Inter- and intraday imprecision was

  • simultaneous detection of 3 nitrotyrosine and 3 nitro 4 Hydroxyphenylacetic Acid in human urine by online spe lc ms ms and their association with oxidative and methylated dna lesions
    Chemical Research in Toxicology, 2015
    Co-Authors: Mu-rong Chao, Yu-wen Hsu, Hung-hsin Liu, Jia-hong Lin

    Abstract:

    Reactive nitrogen species (RNS) can modify proteins at tyrosine and tryptophan residues, and they are involved in the pathogenesis of various human diseases. In this study, we present the first liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based method that enables the simultaneous measurement of urinary 3-nitrotyrosine (3-NTYR) and its metabolite 3-nitro-4Hydroxyphenylacetic Acid (NHPA). After the addition of stable isotope-labeled internal standards, urine samples were purified and enriched using manual solid-phase extraction (SPE) and HPLC fractionation followed by online SPE LC-MS/MS analysis. The limits of quantification in urine were 3.1 and 2.5 pg/mL for 3-NTYR and NHPA, respectively. Inter- and intraday imprecision was <15%. The mean relative recoveries of 3-NTYR and NHPA in urine were 89-98% and 90-98%, respectively. We further applied this method to 65 urinary samples from healthy subjects. Urinary samples were also analyzed for N-nitrosodimethylamine (NDMA) as well as oxidative and methylated DNA lesions, namely, 8-oxo-7,8-dihydroguanine (8-oxoGua), 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo), N7-methylguanine (N7-MeG), and N3-methyladenine (N3-MeA), using reported LC-MS/MS methods. Urinary 3-NTYR and NHPA levels were measured at concentrations of 63.2 ± 51.5 and 77.4 ± 60.8 pg/mL, respectively. Urinary 3-NTYR and NHPA levels were highly correlated with each other and with 8-oxoGua and 8-oxodGuo. Our findings demonstrated that a relationship exists between oxidative and nitrative stress. However, 3-NTYR and NHPA were correlated with N7-MeG and N3-MeA but not with NDMA, suggesting that NDMA may not be a representative biomarker of N-nitroso compounds that are induced by RNS.

Mu-rong Chao – One of the best experts on this subject based on the ideXlab platform.

  • Simultaneous Detection of 3-Nitrotyrosine and 3-Nitro-4Hydroxyphenylacetic Acid in Human Urine by Online SPE LC-MS/ MS and Their Association with Oxidative and Methylated DNA Lesions
    Chemical research in toxicology, 2015
    Co-Authors: Mu-rong Chao, Yu-wen Hsu, Hung-hsin Liu, Jia-hong Lin

    Abstract:

    Reactive nitrogen species (RNS) can modify proteins at tyrosine and tryptophan residues, and they are involved in the pathogenesis of various human diseases. In this study, we present the first liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based method that enables the simultaneous measurement of urinary 3-nitrotyrosine (3-NTYR) and its metabolite 3-nitro-4Hydroxyphenylacetic Acid (NHPA). After the addition of stable isotope-labeled internal standards, urine samples were purified and enriched using manual solid-phase extraction (SPE) and HPLC fractionation followed by online SPE LC-MS/MS analysis. The limits of quantification in urine were 3.1 and 2.5 pg/mL for 3-NTYR and NHPA, respectively. Inter- and intraday imprecision was

  • simultaneous detection of 3 nitrotyrosine and 3 nitro 4 Hydroxyphenylacetic Acid in human urine by online spe lc ms ms and their association with oxidative and methylated dna lesions
    Chemical Research in Toxicology, 2015
    Co-Authors: Mu-rong Chao, Yu-wen Hsu, Hung-hsin Liu, Jia-hong Lin

    Abstract:

    Reactive nitrogen species (RNS) can modify proteins at tyrosine and tryptophan residues, and they are involved in the pathogenesis of various human diseases. In this study, we present the first liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based method that enables the simultaneous measurement of urinary 3-nitrotyrosine (3-NTYR) and its metabolite 3-nitro-4Hydroxyphenylacetic Acid (NHPA). After the addition of stable isotope-labeled internal standards, urine samples were purified and enriched using manual solid-phase extraction (SPE) and HPLC fractionation followed by online SPE LC-MS/MS analysis. The limits of quantification in urine were 3.1 and 2.5 pg/mL for 3-NTYR and NHPA, respectively. Inter- and intraday imprecision was <15%. The mean relative recoveries of 3-NTYR and NHPA in urine were 89-98% and 90-98%, respectively. We further applied this method to 65 urinary samples from healthy subjects. Urinary samples were also analyzed for N-nitrosodimethylamine (NDMA) as well as oxidative and methylated DNA lesions, namely, 8-oxo-7,8-dihydroguanine (8-oxoGua), 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo), N7-methylguanine (N7-MeG), and N3-methyladenine (N3-MeA), using reported LC-MS/MS methods. Urinary 3-NTYR and NHPA levels were measured at concentrations of 63.2 ± 51.5 and 77.4 ± 60.8 pg/mL, respectively. Urinary 3-NTYR and NHPA levels were highly correlated with each other and with 8-oxoGua and 8-oxodGuo. Our findings demonstrated that a relationship exists between oxidative and nitrative stress. However, 3-NTYR and NHPA were correlated with N7-MeG and N3-MeA but not with NDMA, suggesting that NDMA may not be a representative biomarker of N-nitroso compounds that are induced by RNS.

Umeo Takahama – One of the best experts on this subject based on the ideXlab platform.

  • Nitration of the salivary component 4Hydroxyphenylacetic Acid in the human oral cavity: enhancement of nitration under Acidic conditions.
    European journal of oral sciences, 2009
    Co-Authors: Umeo Takahama, Hitoshi Imamura, Sachiko Hirota

    Abstract:

    4Hydroxyphenylacetic Acid (HPA) and nitrite are present in human mixed whole saliva, and HPA can be nitrated by peroxidase/hydrogen peroxide (H(2)O(2))/nitrite systems in the oral cavity. Thus, the objectives of the present study were to estimate the concentrations of HPA, nitrated HPA [4-hydroxy-3-nitrophenylacetic Acid (NO(2)HPA)], nitrite, and thiocyanate (SCN(-)) in saliva from 73 patients with periodontal diseases and to elucidate the conditions necessary to induce nitration of HPA. High concentrations of HPA, nitrite, and SCN(-) were found in the saliva of patients older than 50 yr of age. NO(2)HPA was detected in seven patients who were older than 60 yr of age. Nitrite-dependent formation of NO(2)HPA by a bacterial fraction prepared from mixed whole saliva was faster at pH 5.3 than at pH 7, and increased as the rate of H(2)O(2) formation increased. The formation of NO(2)HPA was inhibited by SCN(-) and by salivary antioxidants such as uric Acid, ascorbic Acid, and glutathione. These results suggest that nitration can proceed at an Acidic site in the oral cavity where H(2)O(2) is produced under conditions of decreased concentrations of SCN(-) and of antioxidants.

  • Quercetin-dependent inhibition of nitration induced by peroxidase/H2O2/nitrite systems in human saliva and characterization of an oxidation product of quercetin formed during the inhibition.
    Journal of agricultural and food chemistry, 2005
    Co-Authors: Sachiko Hirota, Umeo Takahama, Ryo Yamauchi

    Abstract:

    Local pH in the oral cavity can decrease to below 7 at the site where Acid-producing bacteria are proliferating. Effects of pH on nitration of 4Hydroxyphenylacetic Acid were studied using dialyzed human saliva. Dialyzed saliva nitrated 4Hydroxyphenylacetic Acid to 4-hydroxy-3-nitrophenylacetic Acid in the presence of nitrite and H2O2. The rate of the nitration was dependent on pH, and the maximal rate was observed between pH 5.5 and 7.2. The optimum pH seemed to reflect rates of formation of nitrogen dioxide and 4Hydroxyphenylacetic Acid radicals. Quercetin inhibited the nitration. The quercetin-dependent inhibition might be due to scavenging of nitrogen dioxide and 4Hydroxyphenylacetic Acid radicals, which were formed by salivary peroxidase-dependent oxidation of nitrite and 4Hydroxyphenylacetic Acid, respectively, and competition with nitrite and 4Hydroxyphenylacetic Acid for peroxidase in saliva. An oxidation product of quercetin was formed during inhibition of the nitration by quercetin. The oxi…

  • quercetin and the glucosides inhibit nitration of a salivary component 4 Hydroxyphenylacetic Acid catalyzed by salivary polymorphonuclear leukocytes
    Food Science and Technology Research, 2003
    Co-Authors: Sachiko Hirota, Umeo Takahama

    Abstract:

    Mixed whole human saliva contains 4Hydroxyphenylacetic Acid (HPA), nitrite and polymorphonuclear leukocytes. Salivary leukocytes nitrated HPA to 4-hydroxy-3-nitrophenylacetic Acid in the presence of nitrite, and phorbol myristate acetate stimulated the nitration. Quercetin and the glucosides, which are found in the oral cavity after ingestion of quercetin-rich foods, inhibited the leukocyte-dependent nitration. The inhibition by quercetin and the glucosides was in part due to the flavonol-dependent scavenging of nitrogen dioxide which was formed by myeloperoxidase-dependent oxidation of nitrite. Salivary components, SCN and uric Acid, also inhibited the nitration. The above re-sults suggest that quercetin can cooperate with SCN and uric Acid to prevent nitration in the oral cavity.