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Oxidation of melatonin and its catabolites, N1-acetyl-N2 -formyl-5-methoxykynuramine and N1-acetyl-5-methoxykynuramine, by activated leukocytes.
J Pineal Res. 2004 Oct; 37(3):171-5.JP

Abstract

N(1)-acetyl-N(2)-formyl-5-methoxykynuramine (AFMK) and N(1)-acetyl-5-methoxykynuramine (AMK), two melatonin catabolites, have been described as potent antioxidants. We aimed to follow the kinetics of AFMK and AMK formation when melatonin is oxidized by phorbol myristate acetate (PMA) and lipopolysaccharide (LPS)-activated leukocytes. An HPLC-based method was used for AFMK and AMK determination in neutrophil and peripheral blood mononuclear cell cultures supernatants. Samples were separated isocratically on a C18 reverse-phase column using acetonitrile/H(2)O (25:75) as the mobile phase. AFMK was detected by fluorescence (excitation 340 nm and emission 460 nm) and AMK by UV-VIS absorbance (254 nm). Activation of neutrophils and mononuclear cells with PMA produces larger amounts of AFMK than activation with LPS, probably due to the lower levels of reactive oxygen species formation and myeloperoxidase (MPO) degranulation that occurs when cells are stimulated with LPS. The concentration of AMK found in the supernatant was about 5-10% (from 18-hr cultures) compared with AFMK. This result may reflect its reactivity. Indeed AMK, but not AFMK, is easily oxidized by activated neutrophils in a MPO and hydrogen peroxide-dependent reaction. In conclusion, we defined a simple procedure for the determination of AFMK and AMK in biological samples and demonstrated the capacity of leukocytes to oxidize melatonin and AMK.

Authors+Show Affiliations

Silva SO
Departamento de Anàlises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, São Paulo, Brazil.
Rodrigues MR
No affiliation info available
Carvalho SR
No affiliation info available
Catalani LH
No affiliation info available
Campa A
No affiliation info available
Ximenes VF
No affiliation info available

MeSH

CatalaseCells, CulturedChromatography, High Pressure LiquidHumansHydrogen PeroxideKineticsKynuramineLeukocytesLipopolysaccharidesMelatoninNeutrophil ActivationOxidation-ReductionPeroxidaseSpectrophotometry, UltravioletSuperoxide DismutaseTetradecanoylphorbol Acetate

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

15357661

Citation

Silva, Sueli O., et al. "Oxidation of Melatonin and Its Catabolites, N1-acetyl-N2 -formyl-5-methoxykynuramine and N1-acetyl-5-methoxykynuramine, By Activated Leukocytes." Journal of Pineal Research, vol. 37, no. 3, 2004, pp. 171-5.
Silva SO, Rodrigues MR, Carvalho SR, et al. Oxidation of melatonin and its catabolites, N1-acetyl-N2 -formyl-5-methoxykynuramine and N1-acetyl-5-methoxykynuramine, by activated leukocytes. J Pineal Res. 2004;37(3):171-5.
Silva, S. O., Rodrigues, M. R., Carvalho, S. R., Catalani, L. H., Campa, A., & Ximenes, V. F. (2004). Oxidation of melatonin and its catabolites, N1-acetyl-N2 -formyl-5-methoxykynuramine and N1-acetyl-5-methoxykynuramine, by activated leukocytes. Journal of Pineal Research, 37(3), 171-5.
Silva SO, et al. Oxidation of Melatonin and Its Catabolites, N1-acetyl-N2 -formyl-5-methoxykynuramine and N1-acetyl-5-methoxykynuramine, By Activated Leukocytes. J Pineal Res. 2004;37(3):171-5. PubMed PMID: 15357661.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Oxidation of melatonin and its catabolites, N1-acetyl-N2 -formyl-5-methoxykynuramine and N1-acetyl-5-methoxykynuramine, by activated leukocytes. AU - Silva,Sueli O, AU - Rodrigues,Maria R, AU - Carvalho,Sandra R Q, AU - Catalani,Luiz H, AU - Campa,Ana, AU - Ximenes,Valdecir F, PY - 2004/9/11/pubmed PY - 2005/2/24/medline PY - 2004/9/11/entrez SP - 171 EP - 5 JF - Journal of pineal research JO - J Pineal Res VL - 37 IS - 3 N2 - N(1)-acetyl-N(2)-formyl-5-methoxykynuramine (AFMK) and N(1)-acetyl-5-methoxykynuramine (AMK), two melatonin catabolites, have been described as potent antioxidants. We aimed to follow the kinetics of AFMK and AMK formation when melatonin is oxidized by phorbol myristate acetate (PMA) and lipopolysaccharide (LPS)-activated leukocytes. An HPLC-based method was used for AFMK and AMK determination in neutrophil and peripheral blood mononuclear cell cultures supernatants. Samples were separated isocratically on a C18 reverse-phase column using acetonitrile/H(2)O (25:75) as the mobile phase. AFMK was detected by fluorescence (excitation 340 nm and emission 460 nm) and AMK by UV-VIS absorbance (254 nm). Activation of neutrophils and mononuclear cells with PMA produces larger amounts of AFMK than activation with LPS, probably due to the lower levels of reactive oxygen species formation and myeloperoxidase (MPO) degranulation that occurs when cells are stimulated with LPS. The concentration of AMK found in the supernatant was about 5-10% (from 18-hr cultures) compared with AFMK. This result may reflect its reactivity. Indeed AMK, but not AFMK, is easily oxidized by activated neutrophils in a MPO and hydrogen peroxide-dependent reaction. In conclusion, we defined a simple procedure for the determination of AFMK and AMK in biological samples and demonstrated the capacity of leukocytes to oxidize melatonin and AMK. SN - 0742-3098 UR - https://www.unboundmedicine.com/medline/citation/15357661/Oxidation_of_melatonin_and_its_catabolites_N1_acetyl_N2__formyl_5_methoxykynuramine_and_N1_acetyl_5_methoxykynuramine_by_activated_leukocytes_ DB - PRIME DP - Unbound Medicine ER -