A substance in broad beans (Vicia faba) is protective against experimentally induced convulsions in mice

Vicia faba (VF, broad beans) constitutes a major food item for the River Nile populations. Contrary to tropical Africa, the prevalence rate of epilepsy (0.9-1 per 1000) among schoolchildren of Khartoum Province, Sudan, is lower compared with the rates in Europe and North America. To explore whether broad beans contain any anticonvulsant that can explain this observation, Balb/c mice were either treated with VF extract (0.01 mL/g) or kept as a control. Various doses of strychnine and picrotoxin were used to explore the effect of VF extract on strychnine-sensitive glycine receptors and GABA(A) receptors. Diazepam (DIZ) was used as anticonvulsant. Thin-layer chromatography was run for the extract against phenobarbital, DIZ, and/or glycine. VF extract demonstrated a clear protective effect against strychnine-induced convulsions and death in Balb/c mice. Diazepam (20 mg/kg, intraperitoneally), administered 20 minutes prior to strychnine (0.112 mg/kg, intraperitoneally), increased the survival rate to 66.7% and, when given with VF extract (0.01 mL/g), to 100%. Various doses of DIZ protected against picrotoxin-induced convulsions (40 mg/kg, intraperitoneally) and deaths. Pretreatment of mice with VF extract was not protective. On chromatography, VF extract separated in a manner similar to the glycine spot, and revealed one peak coinciding with, but not identical to that of glycine. The extract of broad beans (VF) protects against convulsions probably through the inhibitory glycine receptors, and may contain a substance that is intimately related to glycine. Further research is needed to substantiate this by directly assessing the binding of the VF extract to the glycine receptors or a change in receptor physiology.