Search

Reaction kinetics have been theoretically examined to ascertain the potency of quercetin (Q) and flavonoid catecholic metabolites 1–5 in the inactivation of HOO•, CH3OO•, and O2•− under physiological conditions. In lipidic media, the k overall TST / Eck rate constants for the proton-coupled electron transfer (PCET) mechanism indicate the catecholic moiety of Q and 1–5 as the most important in HOO• and CH3OO• scavenging. 5-(3,4-Dihydroxyphenyl)-γ-valerolactone (1) and alphitonin (5) are the most potent scavengers of HOO• and CH3OO•, respectively. The k overall Mf rate constants, representing actual behavior in aqueous media, reveal Q as more potent in the inactivation of HOO• and CH3OO• via single electron transfer (SET). SET from 3-O− phenoxide anion of Q, a structural motif absent in 1–5, represents the most contributing reaction path to overall activity. All studied polyphenolics have a potency of O2•− inactivation via a concerted two-proton–coupled electron transfer (2PCET) mechanism. The obtained results indicate that metabolites with notable radical scavenging potency, and more bioavailability than ingested flavonoids, may contribute to human health-promoting effects ascribed to parent molecules. [ABSTRACT FROM AUTHOR]

Reaction kinetics have been theoretically examined to ascertain the potency of quercetin ( Q ) and flavonoid catecholic metabolites 1 - 5 in the inactivation of HOO • , CH 3 OO • , and O 2 •- under physiological conditions. In lipidic media, the koverallTST/Eck rate constants for the proton-coupled electron transfer (PCET) mechanism indicate the catecholic moiety of Q and 1 - 5 as the most important in HOO • and CH 3 OO • scavenging. 5-(3,4-Dihydroxyphenyl)-γ-valerolactone ( 1 ) and alphitonin ( 5 ) are the most potent scavengers of HOO • and CH 3 OO • , respectively. The koverallMf rate constants, representing actual behavior in aqueous media, reveal Q as more potent in the inactivation of HOO • and CH 3 OO • via single electron transfer (SET). SET from 3-O - phenoxide anion of Q , a structural motif absent in 1 - 5 , represents the most contributing reaction path to overall activity. All studied polyphenolics have a potency of O 2 •- inactivation via a concerted two-proton-coupled electron transfer (2PCET) mechanism. The obtained results indicate that metabolites with notable radical scavenging potency, and more bioavailability than ingested flavonoids, may contribute to human health-promoting effects ascribed to parent molecules.