Tyrosine as important contributor to the antioxidant capacity of seminal plasma.
A novel post-addition method, based on the trapping of ABTS-radicals, is applied for studying the total antioxidant capacity of seminal plasma. A remarkable profile is observed, in which seminal plasma quenches radicals in a continuous, relatively slow fashion. Five putative antioxidants present in seminal plasma were studied using the same assay. Some of the compounds such as ascorbic acid, alpha-tocopherol and uric acid exert immediate, fast radical trapping, whereas hypotaurine and tyrosine give rise to the same slow radical trapping curve as seminal plasma. Due to this slow, continuous radical trapping, quantification of the total antioxidant capacity (expressed as trolox equivalent antioxidant capacity, TEAC) strongly depends on the chosen time point after onset of radical trapping. When determined during the slow antioxidant trapping phase, tyrosine has a powerful antioxidant capacity, which in combination with its relatively high plasma concentration makes it an important contributor to the total antioxidant capacity of seminal plasma.
van Overveld
F W
FW
IVF Center, Division of Reproductive Endocrinology and Fertility, Institute of Endocrinology, Reproduction and Metabolism, Vrije Universiteit Medical Center, De Boelelaan 1117, 1081 HV, Amsterdam, The Netherlands.
Haenen
G R
GR
Rhemrev
J
J
Vermeiden
J P
JP
Bast
A
A
D000578:Amidines; D000975:Antioxidants / Q000378:metabolism* / Q000494:pharmacology; D001205:Ascorbic Acid / Q000378:metabolism / Q000494:pharmacology; D052160:Benzothiazoles; D004357:Drug Synergism; D005609:Free Radicals / Q000378:metabolism; D006801:Humans; D007202:Indicators and Reagents; D008297:Male; D016877:Oxidants; D010084:Oxidation-Reduction; D012661:Semen / Q000378:metabolism*; D013053:Spectrophotometry; D013451:Sulfonic Acids; D013654:Taurine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D014443:Tyrosine / Q000378:metabolism* / Q000494:pharmacology; D014527:Uric Acid / Q000378:metabolism / Q000494:pharmacology; D014810:Vitamin E / Q000378:metabolism / Q000494:pharmacology
D000578:Amidines; D000975:Antioxidants; D052160:Benzothiazoles; D005609:Free Radicals; D007202:Indicators and Reagents; D016877:Oxidants; D013451:Sulfonic Acids; D014810:Vitamin E; D013654:Taurine; D014527:Uric Acid; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; D014443:Tyrosine; C003949:hypotaurine; C046728:2,2'-azobis(2-amidinopropane); D001205:Ascorbic Acid