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

Islam MH, Ahmad IZ, Salman MT. Neuroprotective effectsof Nigella sativa extracts during germination on central nervous system. Phcog Mag 2015;11:182-9.

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 5th 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 5th 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.

New drug target for epilepsy

Scientists have identified a specific molecular target whose increased activity is linked with seizure disorders- a potassium channel known as the BK channel.

A new anticonvulsant compound that eliminates seizures in a model of epilepsy. The drug works by inhibiting ion channels whose role in epilepsy was only recently discovered. Understanding how these channels work in seizure disorders, and being able to target them with a simple treatment, represents a significant advance in our ability to understand and treat epilepsy. Researchers have found that after a first seizure, BK channel function was markedly enhanced.

Thus, the neurons became overly excitable and were firing with more speed, intensity and spontaneity, which led the researchers to believe that the abnormal increase in the activity of the channels might play a role in causing subsequent seizures and the emergence of epilepsy. In a recent study the researchers tested this theory by blocking the ion channels using a BK-channel antagonist called paxilline.
Using an experimental model for epilepsy, Barth tested whether paxilline could reduce or prevent experimentally induced seizures, as it could normalize aberrant brain activity induced by previous seizures.

And to their surprise, the researchers discovered that the compound was effective at completely blocking subsequent seizures. The drug is orally available, and works in the low nanomolar range.
As the drug is effective in low concentrations and can be taken as a pill, it could turn out to be an especially promising compound for treatment in epilepsy patients.

The findings have been published in the current issue of the journal Epilepsia.