Phytochemical Characterization, Compound Isolation, and Anticonvulsant Evaluation of Methanol Stem Bark Extract of Bombax Costatum (Bombacaceae)

Bombax Costatum is a deciduous plant widely distributed in West Africa and the Indian subcontinent. It is used in ethnomedicine for the treatment of oedema, snake bites, malaria, epilepsy, amoebiasis, and birth-related complications. Despite its extensive ethnomedicinal applications, its neuropharmacological properties remain underexplored. This work is aimed at the isolation of compounds and anticonvulsant studies on the methanol stem bark extract of B. costatum evaluate its anticonvulsant potential using established animal models of seizure. The powdered stem bark of B. costatum was extracted by cold maceration in methanol. The resulting crude methanol extract (CME) was suspended in water and fractionated into n-hexane (HF), chloroform (CF), ethyl acetate (EF), and n-butanol (BF) portions. Phytochemical screening and median lethal dose (LD50) were carried out using standard methods. Silica gel Column chromatography was carried out on the chloroform fraction (CF), which yielded 60 sub-fractions, pooled together to give ten main fractions coded as B1 – B10 based on their TLC profile. Fraction B003 and B005 were further purified on an open capillary column in an isocratic manner, leading to the isolation of stigmasterol (compound B5), whose structure was elucidated using IR, 1D, and 2D NMR spectroscopy, respectively. Anticonvulsant activity of the CME was assessed using the maximal electroshock test (MEST) and the pentylenetetrazole test (PTZ) models. Phytochemical screening of the CME revealed the presence of steroids, flavonoids, anthraquinones, terpenoids, glycosides, tannins and carbohydrates, while the chloroform fraction revealed the presence of steroids and triterpenes predominantly. The extract showed no signs of acute toxicity up to 5000 mg/kg. In both MEST and PTZ models, the CME (300 and 600 mg/kg) significantly delayed seizure onset and reduced seizure duration compared to the control group (p < 0.05). Although full protection was not observed, the extract demonstrated dose-dependent anticonvulsant effects. These findings suggest that B. costatum possesses bioactive phytochemicals with significant anticonvulsant activity, supporting its traditional use in the treatment of epilepsy. The isolation of stigmasterol further highlights the plant’s therapeutic potential. Further studies are warranted to elucidate the mechanisms of action and explore its clinical applicability.