title: Prooxidant and antioxidant action of 4-(4-phenoxybenzoyl)benzoic acid derivatives.
abstract: 4-(4-Phenoxybenzoyl)benzoic acid derivatives (PBADs) were found to inhibit rat and human alpha-reductase isozymes 1 and 2 in vitro. Chemiluminescence (CL), electron spin resonance, spin trapping techniques, and spectrophotometry were used to examine the effect of PBADs on reactive oxygen species (superoxide radical, O(2)(.-); hydroxyl radical, HO(*); singlet oxygen, (1)O(2)) generating systems. All test compounds at a concentration of 0.5 mM enhanced the CL from O(2)(.-) up to fivefold, which was recorded as the light sums during 1 min. At 0.38 mM PBAD enhanced production of HO(*) from H(2)O(2) in the presence of Co(II) up to 90%, as measured by a deoxyribose assay. Using the spin trap agent 5,5-dimethyl-1-pyrroline-N-oxide, it was found that the amplitude of the signal arising from the Fenton-like reaction [Co(II)/H(2)O(2)] was significantly diminished by the test compounds. The compounds also inhibited the (1)O(2) dependent 2,2,6,6-tetramethylpiperidine-N-oxide radical, which is generated in the acetonitrile/H(2)O(2) system. The measured rate constants of (1)O(2)-dimol quenching by PBAD were in the range of (0.8-2.6) x 10(8) M(-1) s(-1). The interaction between PBAD and (1)O(2) was also checked using a spectrophotometry method based on bleaching of p-nitrosodimethylaniline. These results indicate that PBAD may directly scavenge HO(*) and (1)O(2), but not O(2)(.-). However, the compounds that were examined had prooxidant ability under some reaction conditions.
authors.affiliation: Biological and Medical Research Department, MBC-03-65, King Faisal Specialist Hospital and Research Centre, P. O. Box 3354, Riyadh 11211, Saudi Arabia. enein@kfshrc.edu.sa
authors.forename: Hassan Y
authors.initials: HY
authors.lastname: Aboul-Enein
authors.forename: Alexandra
authors.initials: A
authors.lastname: Kladna
authors.forename: Irena
authors.initials: I
authors.lastname: Kruk
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Lichszteld
authors.forename: Mariola
authors.initials: M
authors.lastname: Marchlewicz
authors.forename: Teresa
authors.initials: T
authors.lastname: Michalska
authors.forename: Ola I A
authors.initials: OI
authors.lastname: Salem
authors.forename: Rolf W
authors.initials: RW
authors.lastname: Hartmann
mesh_terms: D000975:Antioxidants / Q000138:chemical synthesis / Q000737:chemistry; D001565:Benzoates / Q000138:chemical synthesis* / Q000737:chemistry; D016166:Free Radical Scavengers / Q000138:chemical synthesis* / Q000737:chemistry; D007700:Kinetics; D016877:Oxidants / Q000138:chemical synthesis / Q000737:chemistry; D010647:Phenyl Ethers / Q000138:chemical synthesis* / Q000737:chemistry; D013329:Structure-Activity Relationship; D013481:Superoxides / Q000737:chemistry
chemical_list: D000975:Antioxidants; D001565:Benzoates; D016166:Free Radical Scavengers; D016877:Oxidants; D010647:Phenyl Ethers; D013481:Superoxides; C065921:4-carboxybiphenyl ether