Neuroprotective effects of Nigella sativa extracts during germination on central nervous system

Background: Nigella sativa Linn. which has many acclaimed medicinal properties is an indigenous herbaceous plant and belongs to the Ranunculaceae family, which grows in countries bordering the Mediterranean Sea, Pakistan and India. Objective: This study was designed to investigate the effects of N. sativa seed extracts of different germination phases on the central nervous system (CNS) responses in experimental animals. Materials and Methods: Anxiolytic, locomotor activity of extracts (1 g/kg of body weight) was evaluated in both stressed and unstressed animal models and antiepileptic effect was evaluated by maximal electroshock seizure model keeping diazepam (20 mg/kg) as a positive control. Antidepressant effect was evaluated by forced swim test and tail suspension test keeping imipramine (15 mg/kg) as a positive control. Results: All tested extracts of N. sativa during different phases of germination (especially 5 ^th day germination phase) showed significant (P < 0.001) anxiolytic effect in comparison to control. Diazepam reduced locomotor activity in control (unstressed) rats but did not show affect in stressed rats while N. sativa extracts from germination phases significantly (P < 0.001) reduced locomotor activity in unstressed as well as stressed animals. All the extracts of N. sativa from different germination phases exhibited significant (P < 0.001) reduction in various phases of epileptic seizure on comparison with the reference standard (diazepam). During antidepressant test, N. sativa extracts exhibited a slight reduction in the immobility of rats. Conclusion: During germination, especially in 5 ^th day germination extract, N. sativa showed significant CNS depressant activity as compared to whole seeds that possibly may be due higher content of secondary metabolites produced during germination.