Oxidative and genotoxic effects of Thymoquinone, Nigella sativa active compound, in Balb/c mice

Nigella sativa has been traditionally used for the treatment of many ailments. Experimentally, it has been demonstrated that N. sativa extracts and Thymoquinone (TQ), the main compound of their volatile oil, possess several biological activities such as antioxidant, anti-inflammatory and hepato-protective properties. To further evaluate the oxidative damage and genotoxicological properties of TQ in vivo, this compound was injected with increasing doses by intraperitoneal route to Balb/c mice, and both oxidative and genotoxic effects were tested. Malondialdehyde (MDA) levels and catalase (CAT) activity in liver and kidney were determined as endpoints of oxidative damage, while chromosomal aberrations and the DNA damage index in liver and kidney served as endpoints of genotoxicity. These experiments showed that TQ demonstrated oxidative and genotoxic effects in a concentration dependent manner by inducing significant increase of MDA level and CAT activity from 40 mg/kg body weight (b.w). At high dose (80 mg/kg b.w.), TQ significantly increased chromosomal aberrations and the DNA damage index in liver and kidney. These results contradict the reports indicating antioxidant and anti-genotoxic effects.   Key words: Nigella sativa, Thymoquinone, Malondialdehyde (MDA), catalase, comet test, chromosomic abberations.