title: Thymoquinone is a potent superoxide anion scavenger.
abstract: The antioxidant and pro-oxidant effects of thymoquinone (TQ), a natural main constituent of the volatile oil of Nigella saliva seeds, and a synthetic structurally-related tert-butylhydroquinone (TBHQ), were examined in vitro. Both TQ and TBHQ efficiently inhibited iron-dependent microsomal lipid peroxidation in a concentration-dependent manner with median inhibitory concentration (IC50) values of 16.8 and 14.9 microM, respectively. TBHQ was stronger than TQ as a scavenger of 2,2'-diphenyl-p-picrylhydrazyl radical (DPPH) (IC50 = 5 microM, 200 times more active than TQ) and as a scavenger of hydroxyl radical (OH*) with an IC50 of 4.6 microM (approximately 10 times more active than TQ). TQ was more active than TBHQ as a superoxide anion scavenger with IC50 of 3.35 microM compared to 18.1 microM for TBHQ. Only TBHQ significantly promoted DNA damage in the bleomycin-Fe(III) system. The results suggest that both TQ and TBHQ have strong antioxidant potentials through scavenging ability of different free radicals. Moreover, the data indicate that TQ is acting mainly as a potent superoxide anion scavenger.
authors.affiliation: Department of Pharmacology & Toxicology, College of Pharmacy, Al-Azhar University, Nasr City, Cairo, Egypt. oabadary@hotmail.com
authors.forename: Osama A
authors.initials: OA
authors.lastname: Badary
authors.forename: Ragia A
authors.initials: RA
authors.lastname: Taha
authors.forename: Ayman M
authors.initials: AM
authors.lastname: Gamal el-Din
authors.forename: Mohamed H
authors.initials: MH
authors.lastname: Abdel-Wahab
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000737:chemistry / Q000494:pharmacology / Q000633:toxicity; D016227:Benzoquinones / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity; D001713:Biphenyl Compounds; D001761:Bleomycin / Q000633:toxicity; D004249:DNA Damage / Q000187:drug effects; D016166:Free Radical Scavengers / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity; D006873:Hydroquinones / Q000737:chemistry / Q000494:pharmacology / Q000633:toxicity; D066298:In Vitro Techniques; D015227:Lipid Peroxidation / Q000187:drug effects; D008297:Male; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism; D031881:Nigella sativa; D010084:Oxidation-Reduction; D010851:Picrates / Q000737:chemistry; D010938:Plant Oils; D051381:Rats; D017208:Rats, Wistar; D013481:Superoxides / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D016227:Benzoquinones; D001713:Biphenyl Compounds; D016166:Free Radical Scavengers; D006873:Hydroquinones; D010851:Picrates; D010938:Plant Oils; D001761:Bleomycin; D013481:Superoxides; C018855:2-tert-butylhydroquinone; C004931:1,1-diphenyl-2-picrylhydrazyl; C003466:thymoquinone