caa a22 4500 605512973 CHVBK 20210128100658.0 cr unu---uuuuu 210128e20150801xx s 000 0 eng 10.1007/s00894-015-2758-2 doi (NATIONALLICENCE)springer-10.1007/s00894-015-2758-2 Free-radical scavenging by tryptophan and its metabolites through electron transfer based processes [Elektronische Daten] [Adriana Pérez-González, Juan Alvarez-Idaboy, Annia Galano] Free-radical scavenging by tryptophan and eight of its metabolites through electron transfer was investigated in aqueous solution at physiological pH, using density functional theory and the Marcus theory. A test set of 30 free radicals was employed. Thermochemical and kinetic data on the corresponding reactions are provided here for the first time. Two different pathways were found to be the most important: sequential proton loss electron transfer (SPLET) and sequential double proton loss electron transfer (SdPLET). Based on kinetic analyses, it is predicted that the tryptophan metabolites kynurenic acid and xanthurenic acid are the best free-radical scavengers among the tested compounds; they were estimated to be at least 24 and 12 times more efficient than Trolox for scavenging •OOH. These findings are in line with previous reports suggesting that the antioxidant activity that has been attributed to tryptophan is actually due to its metabolites, and they demonstrate the particular importance of phenolic metabolites to such activity. Graphical Abstract Kynurenic acid (KNA) and xanthurenic acid (XNA) are the major contributors to the free-radical scavenging activity of tryptophan Springer-Verlag Berlin Heidelberg, 2015 Free-radical scavenger nationallicence Rate constants nationallicence Single electron transfer nationallicence Pérez-González Adriana Departamento de Física y Química Teórica, Facultad de Química, Universidad Nacional Autónoma de México, 04510, México, DF, Mexico aut Alvarez-Idaboy Juan Departamento de Física y Química Teórica, Facultad de Química, Universidad Nacional Autónoma de México, 04510, México, DF, Mexico aut Galano Annia Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, Col. Vicentina. Iztapalapa, C. P. 09340, México, DF, Mexico aut Journal of Molecular Modeling Springer Berlin Heidelberg 21/8(2015-08-01), 1-11 1610-2940 21:8<1 2015 21 894 https://doi.org/10.1007/s00894-015-2758-2 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00894-015-2758-2 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Pérez-González Adriana Departamento de Física y Química Teórica, Facultad de Química, Universidad Nacional Autónoma de México, 04510, México, DF, Mexico aut NATIONALLICENCE 700 1- Alvarez-Idaboy Juan Departamento de Física y Química Teórica, Facultad de Química, Universidad Nacional Autónoma de México, 04510, México, DF, Mexico aut NATIONALLICENCE 700 1- Galano Annia Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, Col. Vicentina. Iztapalapa, C. P. 09340, México, DF, Mexico aut NATIONALLICENCE 773 0- Journal of Molecular Modeling Springer Berlin Heidelberg 21/8(2015-08-01), 1-11 1610-2940 21:8<1 2015 21 894