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Journal Article 2005; 26(6): 799-805 PubMed PMID: 16380691 Citation  Keywords:  Chromatography, High Pressure Liquid, Dihydropyridines:analysis, Histamine:chemistry, Malondialdehyde:chemistry, Neurotoxins:chemistry, Nitrogen Compounds:analysis, Protein Carbonylation,.   

OBJECTIVES: To explore the mechanism of carbonyl stress-related toxification on neurotransmitter histamine and the potential de-carbonylation function of histamine.

METHODS: The reaction mixture of malondialdehyde (MDA) and histamine (HA) at pH7.4, 37 degrees C was assayed by high performance liquid chromatography (HPLC), spectrophotometry and spectrofluorometry. The reaction products were assayed by LC/MS.

RESULTS: In physiological condition, the reaction of MDA and HA yielded two products: a nonfluorescent enaminal derivatives and a fluorescent 1,4-dihydropyridine adducts. The fluorescence maxima of the fluorescent products (Ex. 393 nm/Em. 464 nm) were similar to those of lipofuscin pigment. The fluorescence intensity of reaction mixture was in direct proportion to the MDA concentration.

CONCLUSIONS: HA can react with MDA to form stable products, a non-fluorescent enamine (product 1) and a fluorescent 1,4-dihydropyridine (product 2) which are ceroid/lipofuscin-related adducts. The reaction of HA with MDA may reveal toxic effect of unsaturated carbonyls in the brain and may reflect a novel de-carbonylation function of histamine under various pathological conditions....

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Journal Article 2005; 26(1): 61-66 PubMed PMID: 15726022 Citation  Keywords:  Chromatography, Liquid, Kinetics, Malondialdehyde:chemistry, Mass Spectrometry, Melatonin:chemistry, Molecular Weight, Spectrometry, Mass, Electrospray Ionization, Temperature, Thermodynamics,.   

OBJECTIVES: A purpose of this study is to determine whether melatonin, a novel antioxidant, can interact with malondialdehyde in an in vitro condition.

METHODS: The reaction kinetics and thermodynamics of this reaction have been performed and a new product has been identified using liquid chromatography onlining with mass spectrometry.

RESULTS: A new product generated with an interaction of melatonin and malondialdehyde has been identified to be a three-ring structure with a molecular weight 286, which has the specific wavelength absorption with the maximum at 345 nm. The reaction was completed within a few minutes and the product was proportional to the concentrations of the reactants. Based on its molecular weight and the deduced structure of the new product, we speculate that this reaction occurs between one melatonin molecule and one malondialdehyde and to form a 3 ring conjugated adduct.

CONCLUSION: This is the first report to show that melatonin directly interacts with malondialdehyde to form a new product. The findings suggest that melatonin may detoxify unsaturated carbonyls and protect against cellular damage induced by oxidative stress....

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