Polyhydroxylated 2-styrylchromones as potent antioxidants.
Four polyhydroxylated 2-styrylchromones, structurally related to flavones and cinnamic acid, have been studied. An SC derivative with OH groups only at positions 3' and 4' on the styryl moiety and another SC bearing an additional OH group at position 5 on the benzopyrone ring were more potent inhibitors of the Cu2+-induced peroxidation of LDL than the flavonoid quercetin. Fluorescence and absorption spectroscopies suggested that one LDL particle may bind 40 SC molecules. A pulse radiolysis study in pH 7 buffered micellar solutions of neutral TX100 and positively charged CTAB demonstrated that one-electron oxidation by *Br2-, *O2- and tryptophan radicals (8Trp) depends strongly on the micellar microenvironment. All SCs were readily oxidized by *O2- in CTAB micelles (rate constants: 6-18 x 10(6) M(-1) s(-1)). In TX100 micelles only the SC derivative with OH groups in position 3' and 4' reacted with *O2- (rate constant: 1.1 x 10(6) M(-1)s(-1)). In CTAB, electron transfer to *Trp radicals was observed for all SCs with rate constants > or =3.2 x 10(7) M(-1) s(-1). In TX100 micelles, this reaction occurred solely with the derivative bearing OH groups only at positions 3' and 4'.
Filipe
Paulo
P
Department of Chemistry, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
Silva
Artur M S
AM
Morlière
Patrice
P
Brito
Cristela M
CM
Patterson
Larry K
LK
Hug
Gordon L
GL
Silva
João N
JN
Cavaleiro
José A S
JA
Mazière
Jean-Claude
JC
Freitas
João P
JP
Santus
René
R
D000975:Antioxidants / Q000494:pharmacology*; D002867:Chromones / Q000737:chemistry / Q000494:pharmacology*; D003300:Copper / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D015227:Lipid Peroxidation / Q000187:drug effects; D008077:Lipoproteins, LDL / Q000378:metabolism; D008823:Micelles; D010084:Oxidation-Reduction / Q000187:drug effects; D011675:Pulse Radiolysis; D011794:Quercetin / Q000494:pharmacology; D013228:Stearates / Q000737:chemistry / Q000494:pharmacology*; D013481:Superoxides / Q000378:metabolism / Q000494:pharmacology; D014364:Tryptophan / Q000378:metabolism
D000975:Antioxidants; D002867:Chromones; D008077:Lipoproteins, LDL; D008823:Micelles; D013228:Stearates; D013481:Superoxides; D003300:Copper; D014364:Tryptophan; D011794:Quercetin