Phytochemical, antibacterial and anticonvulsant activity of the stem bark of Lannea kerstingii Engl. & K. Krause (Anacadiaceae)

Abstract

The stem bark of Lannea kerstingii Engl. & K. Krause was investigated for its phytochemistry, acute toxicity, antibacterial and anticonvulsant activit ies. Standard methods were used to evaluate phytochemistry while antibacterial activity was determined using agar diffusion and broth dilution method s on Staphylococcus aureus, Salmonella typhii, Pseudomonas aeruginosa, Klebsiella pneumonia, Proteus vulgaris, Escherichia coli and Bacillus subtilis. Maximal electroshock-induced seizures test in chicks and pentylenetetrazole-induced seizures test in mice were used to determine the anticonvulsant activity. Phytochemical studies revealed the presence of flavonoids, tannins, carbohydrates steroids and triterpenes. Ethyl acetate and methanol fractions of the stem bark were found to be active against S. aureus, S. typhi, P. aeruginosa, K. pneumoniae, Proteus sp, E. coli, Bacillus subtilis with zone of inhibition ranging from 20-27.5mm and MIC ranging from 6.25mg/mL to 100mg/mL and MBC from 50mg/mL and above. LD₅₀ was found to be 2154.066 mg/kg. The crude methanol extract of the stem bark afforded dose (150, 300 and 600mg/kg) dependent protection to the laboratory animals against the hind limb tonic extension though not statistically significant (P<0.05) showing the inability of the extract to inhibit seizure discharge within the brainstem seizure substrate. Meanwhile the extract at doses of 300 and 600mg/kg significantly (P<0.05) prolonged the onset of seizure in pentylenetetrazole (PTZ) test showing the potential of this plant in raising seizure threshold in the brain therefore making it beneficial in the treatment of myoclonic and absence seizures. This justifies the use of the plant in treating convulsion.

Keywords: Lannea kerstingii; Anticonvulsant; Phytochemical; Antibacterial; Phytochemistry