Flavonoid B-ring chemistry and antioxidant activity: fast reaction kinetics.
Rapid scavenging of the model stable radical cation, ABTS(*+), has been applied to screen for the antioxidant activity of flavonoids. The reaction follows two distinct phases. For compounds with a monophenolic B-ring there is a rapid initial phase of reduction of ABTS(*+) within 0.1 s with no further change in the subsequent 2.9 s. In contrast, compounds with a catechol-containing B ring follow a fast initial scavenging phase with a slow secondary phase. Flavonoids with an unsubstituted B ring do not react within this time scale. The findings suggest that the structure of the B ring is the primary determinant of the antioxidant activity of flavonoids when studied through fast reaction kinetics.
Sekher Pannala
A
A
Wolfson Centre for Age Related Diseases, GKT School of Biomedical Sciences, King's College London, St. Thomas's Street, London, SE1 9RT, United Kingdom.
Chan
T S
TS
O'Brien
P J
PJ
Rice-Evans
C A
CA
D000975:Antioxidants / Q000737:chemistry*; D001578:Benzopyrans / Q000737:chemistry; D052160:Benzothiazoles; D002392:Catechin / Q000031:analogs & derivatives / Q000737:chemistry; D002396:Catechols / Q000737:chemistry; D002839:Chromans / Q000737:chemistry; D003373:Coumaric Acids / Q000737:chemistry; D044950:Flavanones; D005419:Flavonoids / Q000737:chemistry*; D044948:Flavonols; D016166:Free Radical Scavengers / Q000737:chemistry; D007700:Kinetics; D013329:Structure-Activity Relationship; D013451:Sulfonic Acids / Q000737:chemistry
D000975:Antioxidants; D001578:Benzopyrans; D052160:Benzothiazoles; D002396:Catechols; D002839:Chromans; D003373:Coumaric Acids; D044950:Flavanones; D005419:Flavonoids; D044948:Flavonols; D016166:Free Radical Scavengers; D013451:Sulfonic Acids; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; D002392:Catechin; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid; C028610:flavanone