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.

Targeting Nuclear Factor-κB Activation Pathway by Thymoquinone: Role in Suppression of Antiapoptotic Gene Products and Enhancement of Apoptosis

“…Several components of black cumin have been identified, including thymoquione, thymol, thymohydroquinone, and dithymquinone (2,3). Thymoquinone (TQ), the most abundant component of black seed oil, has been reported to exhibit antioxidant (4)(5)(6), antiinflammatory, and chemopreventive (7-9) effects. For instance, TQ has been shown to suppress the proliferation of various tumor cells, including colorectal carcinoma, breast adenocarcinoma, osteosarcoma, ovarian carcinoma, myeloblastic leukemia, and pancreatic carcinoma (7,(10)(11)(12)(13)(14), although it is minimally toxic to normal cells (15).…”

The protective effect of thymoquinone over olanzapine-induced side effects in liver, and metabolic side effects

“…Nevertheless, TQ is known to reduce oxidative stress not only through the direct antioxidant effect but also indirectly. Previous studies reported that TQ acted as a strong reactive oxygen species (ROS) scavenger (45,46).…”

Effect ofNigella sativaOil and Activated Charcoal as Antioxidant on Verrucarin J induced Hepatotoxicity in Male Rats

“…Nigella sativa offered some protection to the liver from verrucarin J induced hepatotoxicity i n mice causing liver damage through lipidperoxidation. The positive effect of Nigella sativa through the thymoquinone, being major component of volatile oil and having pharmacological effect on hepatotoxicity (ElSaleh et al, 2004) as potent superoxide anion (0,) scavenging abilities, inhibiting iron dependent microsomal lipid peroxidation (Badary et al, 2003) and preventing high blood lipids (Badary and Gamal El-Din, 2001). Activated charcoal also had similar effects but to a lesser extent (Table 1, 2).…”