Anticonvulsant activity of butanol fraction of methanol root bark extract of Securinega virosa Roxb (ex Willd) Baill. in laboratory animals

Securinega virosa is a commonly used medicinal plant in African traditional medicine in the management of epilepsy. In an attempt to isolate and characterize the bioactive principles responsible for the anticonvulsant property, the crude methanol root bark extract of the plant was exhaustively partitioned into petroleum ether, chloroform, ethyl acetate and n-butanol. The anticonvulsant potential of the n-butanol fraction (75, 150 and 300 mg/kg) was evaluated using maximal electroshock (MES) test in chicks, strychnine, picrotoxin, 4-aminopyridine and pentylenetetrazole-induced seizures in mice. The fraction did not protect the chicks against tonic-hind limb extension due to MES. Similarly, the fraction did not afford significant protection against seizures induced by strychnine, aminopyridine and picrotoxin contrary to the observations of protections in the crude extract, against pentylenetetrazole-induced seizure, the fraction afforded 66.67% protection and significantly (P<0.01) delayed the onset of seizure in unprotected animals. Column chromatographic separation of the n-butanol fraction yielded three major sub-fractions which were subjected to anticonvulsant screening using pentylenetetrazol (PTZ)-induced seizure. The anticonvulsant potential of the n-butanol fraction was retained in the more polar sub-fractions. The findings of this study suggest that the n-butanol fraction Securinega virosa root bark contains bioactive principle(s) that possess anticonvulsant activities which may be beneficial against absence seizure. This lends further credence to the ethnomedicinal claim of the use of the root of S. virosa in the management of epilepsy.   Key words: Securinega virosa, epilepsy, seizure, maximal electroshock, pentyleneterazole, picrotoxin, 4-aminopyridine, strychnine.