TY - JOUR

T1 - Influence of viscosity on mechanism and products of radical reactions of kynurenic acid and tryptophan

AU - Savina, E. D.

AU - Tsentalovich, Yu P.

AU - Sherin, P. S.

N1 - Funding Information: This work was financially supported by the Russian Science Foundation (Project No. 18-73-10014). Publisher Copyright: © 2021, Springer Science+Business Media LLC.

PY - 2021/12

Y1 - 2021/12

N2 - Under UV-A light and anaerobic conditions, the photodegradation of kynurenic acid and tryptophan significantly decreases with an increase in the viscosity of the medium without significant changes in the composition of the formed products. The recombination products of tryptophan radicals (covalently linked dimeric forms) exhibit the most pronounced decrease. The observed effects are due to restrictions of mobility of the formed radicals and a longer stay in the radical cage as compared to the behavior in aqueous solutions. This leads to an increase in the efficiency of the back electron transfer with the restoration of the initial reagents, which is the main decay pathway for the radicals. The backside of cage effect is an increase in quantities of covalently bound adducts of kynurenic acid and tryptophan. In the case of a living cell, similar changes in the composition of the radical reaction products can be expected.

AB - Under UV-A light and anaerobic conditions, the photodegradation of kynurenic acid and tryptophan significantly decreases with an increase in the viscosity of the medium without significant changes in the composition of the formed products. The recombination products of tryptophan radicals (covalently linked dimeric forms) exhibit the most pronounced decrease. The observed effects are due to restrictions of mobility of the formed radicals and a longer stay in the radical cage as compared to the behavior in aqueous solutions. This leads to an increase in the efficiency of the back electron transfer with the restoration of the initial reagents, which is the main decay pathway for the radicals. The backside of cage effect is an increase in quantities of covalently bound adducts of kynurenic acid and tryptophan. In the case of a living cell, similar changes in the composition of the radical reaction products can be expected.

KW - back electron transfer

KW - free radicals

KW - kynurenic acid

KW - photochemical reaction

KW - quantum yield

KW - tryptophan

KW - water—glycerol mixtures

UR - http://www.scopus.com/inward/record.url?scp=85123519116&partnerID=8YFLogxK

U2 - 10.1007/s11172-021-3350-9

DO - 10.1007/s11172-021-3350-9

M3 - Article

AN - SCOPUS:85123519116

VL - 70

SP - 2339

EP - 2346

JO - Russian Chemical Bulletin

JF - Russian Chemical Bulletin

SN - 1066-5285

IS - 12

ER -