Role of Tyrosine Isomers in Acute and Chronic Diseases Leading to Oxidative Stress - A Review

Author(s): Gergő A. Molnár, Szilárd Kun, Eszter Sélley, Melinda Kertész, Lívia Szélig, Csaba Csontos, Katalin Böddi, Lajos Bogár, Attila Miseta, István Wittmann.

Journal Name: Current Medicinal Chemistry

Volume 23 , Issue 7 , 2016

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Abstract:

Oxidative stress plays a major role in the pathogenesis of a variety of acute and chronic diseases. Measurement of the oxidative stress-related end products may be performed, e.g. that of structural isomers of the physiological para-tyrosine, namely meta- and ortho-tyrosine, that are oxidized derivatives of phenylalanine. Recent data suggest that in sepsis, serum level of meta-tyrosine increases, which peaks on the 2nd and 3rd days (p<0.05 vs. controls), and the kinetics follows the intensity of the systemic inflammation correlating with serum procalcitonin levels. In a similar study subset, urinary meta-tyrosine excretion correlated with both need of daily insulin dose and the insulin-glucose product in non-diabetic septic cases (p<0.01 for both). Using linear regression model, meta-tyrosine excretion, urinary meta-tyrosine/para-tyrosine, urinary ortho-tyrosine/para-tyrosine and urinary (meta- + orthotyrosine)/ para-tyrosine proved to be markers of carbohydrate homeostasis.

In a chronic rodent model, we tried to compensate the abnormal tyrosine isomers using para-tyrosine, the physiological amino acid. Rats were fed a standard high cholesterol-diet, and were given para-tyrosine or vehicle orally. High-cholesterol feeding lead to a significant increase in aortic wall meta-tyrosine content and a decreased vasorelaxation of the aorta to insulin and the glucagon-like peptide-1 analogue, liraglutide, that both could be prevented by administration of para-tyrosine.

Concluding, these data suggest that meta- and ortho-tyrosine are potential markers of oxidative stress in acute diseases related to oxidative stress, and may also interfere with insulin action in septic humans. Competition of meta- and ortho-tyrosine by supplementation of para-tyrosine may exert a protective role in oxidative stress-related diseases.

Keywords: Meta-tyrosine, ortho-tyrosine, para-tyrosine, sepsis, inflammation, oxidative stress, hormone resistance, carbohydrate metabolism.

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Article Details

VOLUME: 23
ISSUE: 7
Year: 2016
Page: [667 - 685]
Pages: 19
DOI: 10.2174/0929867323666160119094516

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