title: Synthetic carotenoids, novel polyene polyketones and new capsorubin isomers as efficient quenchers of singlet molecular oxygen.
abstract: Novel synthetic polyene polyketones and new synthetic capsorubin isomers were examined for their ability to quench singlet molecular oxygen (1O2) generated by the thermodissociation of the endoperoxide of 3,3'-(1,4-naphthylene) dipropionate (NDPO2). C28-polyene-tetrone (1) exhibits the highest physical quenching rate constant with 1O2 (kq = 16 x 10(9) M-1 s-1). For comparison, the rate constant for the most efficient biological carotenoid, lycopene (3) is kq = 9 x 10(9) M-1 s-1 and that of beta-carotene (5) kq = 5 x 10(9) M-1 s-1. The presence of two oxalyl chromophores at the ends of the polyene chain seems to enhance the 1O2 quenching ability in the C28-polyene-tetrone (1). C28-polyene-tetrone-diacetal (2) (kq = 9 x 10(9) M-1 s-1) and C40-epiisocapsorubin (4) (kq = 8 x 10(9) M-1 s-1) also have high 1O2 quenching abilities. Two carotenoids from plants, phytoene and phytofluene, were much less efficient, kq values being below 10(7) M-1 s-1. Due to the very high singlet oxygen quenching abilities, C28-polyene-tetrone (1), C28-polyene-tetrone-diacetal (2) and C40-epiisocapsorubin (4) may have potential use in preventing 1O2-induced damage in biological and non-biological systems.
authors.affiliation: Institut für Physiologische Chemie I, Universität Düsseldorf, Fed. Rep. Germany.
authors.forename: T P
authors.initials: TP
authors.lastname: Devasagayam
authors.forename: T
authors.initials: T
authors.lastname: Werner
authors.forename: H
authors.initials: H
authors.lastname: Ippendorf
authors.forename: H D
authors.initials: HD
authors.lastname: Martin
authors.forename: H
authors.initials: H
authors.lastname: Sies
mesh_terms: D002338:Carotenoids / Q000031:analogs & derivatives* / Q000737:chemistry*; D007536:Isomerism; D007659:Ketones; D010100:Oxygen; D010777:Photochemistry; D026082:Singlet Oxygen; D013329:Structure-Activity Relationship; D024341:Xanthophylls
chemical_list: D007659:Ketones; D024341:Xanthophylls; D026082:Singlet Oxygen; D002338:Carotenoids; C035624:capsorubin; D010100:Oxygen