The anticonvulsant effects of thymoquinone, the major constituent of Nigella sativa seeds, were investigated using pentylenetetrazole (PTZ)- and maximal electroshock (MES)-induced seizure models. We also studied the effect of thymoquinone on pentobarbital-induced hypnosis, locomotor activity, and motor coordination. In PTZ-induced seizure, the intraperitoneally injection of thymoquinone with doses of 40 and 80 mg/kg, prolonged the onset of seizures and reduced the duration of myoclonic seizures. The protective effect of thymoquinone against mortality was 71.4% and 100% in the mentioned doses, respectively. In MES model, thymoquinone failed to reduce the duration of seizure, whereas exhibited a complete protection against mortality. In PTZ model, flumazenil (10 mg/kg, i.p.), an antagonist of benzodiazepine (BZD) site in the GABAA-BZD receptor complex, inhibited the prolongation of seizurelatency, but did not show any effect on the duration of myoclonic seizures. Also, pretreatment with naloxone (0.1 and 03 mg/kg, i.p.) inhibited the prolongation of myoclonic seizure latency and antagonized the reduction of myoclonic seizure duration induced by thymoquinone (40 and 80 mg/kg) in the PTZ model. Moreover, thymoquinone (40 and 80 mg/kg) did not have any hypnosis effect in the pentobarbital-induced hypnosis, but impaired the motor coordination and reduced the locomotor activity. These results indicate that thymoquinone may have anticonvulsant activity in the petit mal epilepsy probably through an opioid receptor-mediated increase in GABAergic tone.

BACKGROUND:

Recently we investigated some neuropharmacological aspects of thymoquinone, such as anticonvulsant, muscle relaxant, and hypnotic effects, as well as its effect on motor coordination and locomotor activity. In this study, we evaluated the effect and mechanism(s) of the action of thymoquinone more precisely via intracerebroventricular (i.c.v.) injection.

MATERIAL/METHODS:

The anticonvulsant effects of thymoquinone, the major constituent of Nigella sativa seeds, were investigated using the pentylenetetrazole (PTZ)-induced seizure model. The animals were placed individually in plastic boxes and observed immediately after PTZ injection for a period of 30 min. The latency to and the duration of tonic-clonic seizures were recorded, as well as the percentages of protection against the incidence of seizure and mortality.

RESULTS:

In PTZ-induced epileptic seizures, the i.c.v. injection of thymoquinone at doses of 200 and 400 microM prolonged the time until onset and reduced the duration of tonic-clonic seizures. The protective effect of thymoquinone against lethality was 45% and 50% in the respective doses. In this study, flumazenil (1 nM, i.c.v.) reversed the anticonvulsant activity of thymoquinone. Also, pretreatment with naloxone (10 microM, i.c.v.) antagonized the prolongation of tonic-clonic seizure latency as well as the reduction in seizure duration induced by thymoquinone (200 microM, i.c.v.).

CONCLUSIONS:

These results indicate that thymoquinone may have anticonvulsant activity, probably through an opioid receptor-mediated increase in GABAergic tone.

BACKGROUND:

Despite the availability and use of numerous antiepileptic drugs (AEDs), nearly 15% of childhood epilepsy cases are resistant to treatment. However, in traditional medicine, Nigella SativaL. (“black cumin seed“) has been known for its anticonvulsant effects. This plant is naturally distributed in Iran and has been widely used as a natural remedy for a long time. In this study the efficacy of this agent in reducing the frequency of seizures in childhood refractory epilepsy was assessed.

MATERIAL/METHODS:

In this double-blinded crossover clinical trial conducted on children with refractory epilepsy, the aqueous extract of black seed was administered as an adjunct therapy and the effects were compared with those of a placebo. Twenty-three children were entered in the study and 20 remained in the study (13 months to 13 years old, 10 boys and 10 girls). All patients were receiving constant treatment for at least one month before the study. They received extract (40 mg/kg/8 h) or placebo for a period of four weeks and between these periods for two weeks they received only their pre-existing anti-epileptic drugs (AEDs).

RESULTS:

The mean frequency of seizures decreased significantly during treatment with extract (p<0.05).

CONCLUSIONS:

It can be concluded that the water extract of Nigella sativa L. has antiepileptic effects in children with refractory seizures.

This study investigated antiepileptic effects of the main constituents of Nigella sativa (NS) seed (i.e. aqueous extract (AE), fixed oil (FO), volatile oil (VO)) and the main components of its VO (i.e. thymoquinone, α-pinene and p-cymene) using pentylenetetrazole (PTZ) and maximal electroshock (MES)-induced convulsions. The potential of these constituents to induce minimal neurological deficit (MND) was also evaluated by using chimney test.Except for the FO, all of the NS seed constituents protected mice effectively against PTZ-induced convulsions. The activity of the VO in this model maybe attributed mainly to its content of thymoquinone and p-cymene and to a lesser extent, α-pinene. VO and its component p-cymene effectively suppressed convulsions induced by MES. The contents of p-cymene present in the effective dose of the VO maybe partially responsible for its anti-seizureeffects.All of the NS seed constituents induced varying degrees of MND in the chimney test. MND induced by VO may pertain to its contents of thymoquinone (63%), p-cymene (23%) and α-pinene (<14%). Protective indices of p-cymene and thymoquinone were closer to one, but only in PTZ model. Exploration on the role of receptors suggests that picrotoxin and bicuculline-sensitive GABA receptors, most probably GABAA receptors, mediate an increase in GABAergic response. In the part dealing with the interaction of valproate with thymoquinone, it can be mentioned that thymoquinone increased the potency of valproate in both PTZ and MES models.

AIM:

To evaluate the effect of black seed oil, as add-on treatment to antiepileptic drugs (AEDs), on seizure frequency and severity as well as oxidative stress in intractable epilepsy patients.

METHODS:

A prospective, randomised, single-blinded, controlled, crossover pilot study. Five healthy children were included as controls. Thirty intractable epileptic children were randomly assigned to either Group I or II. Group I received placebo for four weeks, followed by a two-week washout period, and subsequently black seed oil for four weeks. Group II received the same intervention but in the reverse order. All patients received AEDs throughout the study period. Prior to allocation, all patients underwent a neurological assessment and evaluation of oxidative stress markers; total antioxidant capacity (TAC) and malondialehyde (MDA). Patients were assessed at Weeks 4 and 10 for oxidative stress markers and seizure frequency and severity.

RESULTS:

At baseline, both groups (I, II) had significantly lower serum TAC levels relative to healthy controls (p=0.007), while MDA levels were unchanged. After the 4-week period of black seed oil administration, there was no significant difference between the two groups with regards to seizurefrequency, severity, or oxidative stress markers (TAC and MDA; p>0.05). Eight patients had >50% reduction in seizure frequency/severity after black seed oil versus placebo.

CONCLUSION:

Children with intractable epilepsy show evidence of oxidative stress. Administration of 40-80 mg/kg/day of black seed oil as add-on therapy did not alter either oxidative stress markers orseizure frequency or severity in intractable epileptic patients.