TY - JOUR

T1 - Kinetic studies of antioxidant properties of ovothiol A

AU - Osik, Nataliya A.

AU - Zelentsova, Ekaterina A.

AU - Tsentalovich, Yuri P.

N1 - Funding Information: Funding: This research was funded by the President of RF (project МК-2272.2020.3) in optical and LFP measurements and by the Russian Foundation for Basic Research (project 19-04-00092) in sample preparation. Publisher Copyright: © 2021 bybythetheauthors.authors.Li-Licensee MDPI, Basel, Switzerland.

PY - 2021/9

Y1 - 2021/9

N2 - Ovothiol A (OSH) is one of the strongest natural antioxidants. So far, its presence was found in tissues of marine invertebrates, algae and fish. Due to very low pKa value of the SH group, under physiological conditions, this compound is almost entirely present in chemically active thiolate form and reacts with ROS and radicals significantly faster than other natural thiols. In biological systems, OSH acts in tandem with glutathione GSH, with OSH neutralizing oxidants and GSH maintaining ovothiol in the reduced state. In the present work, we report the rate constants of OSH oxidation by H2O2 and of reduction of oxidized ovothiol OSSO by GSH and we estimate the Arrhenius parameters for these rate constants. The absorption spectra of reaction intermediates, adduct OSSG and sulfenic acid OSOH, were obtained. We also found that OSH effectively quenches the triplet state of kynurenic acid with an almost diffusion-controlled rate constant. This finding indicates that OSH may serve as a good photoprotector to inhibit the deleterious effect of solar UV irradiation; this assumption explains the high concentrations of OSH in the fish lens. The unique antioxidant and photoprotecting properties of OSH open promising perspectives for its use in the treatment of human disease.

AB - Ovothiol A (OSH) is one of the strongest natural antioxidants. So far, its presence was found in tissues of marine invertebrates, algae and fish. Due to very low pKa value of the SH group, under physiological conditions, this compound is almost entirely present in chemically active thiolate form and reacts with ROS and radicals significantly faster than other natural thiols. In biological systems, OSH acts in tandem with glutathione GSH, with OSH neutralizing oxidants and GSH maintaining ovothiol in the reduced state. In the present work, we report the rate constants of OSH oxidation by H2O2 and of reduction of oxidized ovothiol OSSO by GSH and we estimate the Arrhenius parameters for these rate constants. The absorption spectra of reaction intermediates, adduct OSSG and sulfenic acid OSOH, were obtained. We also found that OSH effectively quenches the triplet state of kynurenic acid with an almost diffusion-controlled rate constant. This finding indicates that OSH may serve as a good photoprotector to inhibit the deleterious effect of solar UV irradiation; this assumption explains the high concentrations of OSH in the fish lens. The unique antioxidant and photoprotecting properties of OSH open promising perspectives for its use in the treatment of human disease.

KW - Antioxidant

KW - Glutathione

KW - Ovothiol

KW - Rate constant

KW - Triplet quenching

UR - http://www.scopus.com/inward/record.url?scp=85114937340&partnerID=8YFLogxK

U2 - 10.3390/antiox10091470

DO - 10.3390/antiox10091470

M3 - Article

C2 - 34573105

AN - SCOPUS:85114937340

VL - 10

JO - Antioxidants

JF - Antioxidants

SN - 2076-3921

IS - 9

M1 - 1470

ER -