Anticonvulsant properties of saponins from Ficus platyphylla stem bark

Preparations of Ficus platyphylla have been used in Nigerian traditional medicine for the management of epilepsy for many years and their efficacy is widely acclaimed among the Hausa communities of northern Nigeria. The anticonvulsant properties of the saponin rich fraction (SFG) obtained from the methanol extract of F. platyphylla stem bark were studied on pentylenetetrazole-, strychnine- and maximal electroshock seizures in mice. Effects of SFG were also examined in murine models for neurological disease and on relevant in vitro targets for anticonvulsant drugs. SFG protected mice against pentylenetetrazole- and strychnine-induced seizures; and significantly delayed the onset of myoclonic jerks and tonic seizures. SFG failed to protect mice against maximal electroshock seizures at doses tested. SFG neither abolished the spontaneous discharges induced by 4-aminopyridine in a neonatal rat brain slice model of tonic–clonic epilepsy nor could it modulate chloride currents through GABAA receptor channel complex in cultured cortical cells. However, it was able to non-selectively suppress excitatory and inhibitory synaptic traffic, blocked sustained repetitive firing (SRF) and spontaneous action potential firing in these cultured cells. Our results provide scientific evidence that F. platyphylla stem bark may contain psychoactive principles with potential anticonvulsant properties. SFG impaired membrane excitability; a property shared by most anticonvulsants particularly the voltage-gated sodium channel (VGSC) blocking drugs, thus supporting the isolation and development of the saponin components of this plant as anticonvulsant agents.