BIO ACTIVITY-GUIDED ISOLATION OF THE ANTICONVULSANT PRINCIPLES OF METHANOLIC EXTRACT OF THE STEM-BARK OF LONCHOCARPUS SER1CEUS (POIR) FAMILY PAPILIONACEAE

BIO ACTIVITY-GUIDED ISOLATION OF THE ANTICONVULSANT PRINCIPLES OF METHANOLIC EXTRACT OF THE STEM-BARK OF LONCHOCARPUS SER1CEUS (POIR) FAMILY PAPILIONACEAE

Abstract:

The chloroform soluble fraction of methanol extract of stem-bark of Lonchocarpus sericeus, a plant used in ethnomedicine for the treatment of epilepsy and backache among other ailments, was subjected to phytochemical and anticonvulsant screening. The phytochemical techniques employed were column chromatography, gel filtration and preparative thin layer chromatography. The anticonvulsant activity was stud’.ed using maximal electroshock test, pentylenetetrazole and 4-aminopyridine induced seizures. Preliminary phytochemical screening of the crude extract revealed the presence of flavonoids, phenolic compounds, saponins, steroids and tritcrpenes while that of the chloroform soluble fraction re\ealed steroids, tritcrpenoids, phenolic compound and flavonoids. Extensive chromatographic separation of the chloroform soluble fraction using silica gel column chromatography, gel filtration and preparative thin layer chromatography led to the isolation of a tiiteipcnoid, lup-20(29)-ene-3(}-ol (Lupeol) and a chalcone, 2,,4′-dihydroxy-3,-(4-hydroxy-4-methyl pertenyl)-cha!cone. Their structures were determined by spectral analysis including ID and 2D NMR. In the pharmacological screening, 150 mg/kg of the extract protected 50% of test animals against pentylenetetrazole induced seizure in mice whereas sodium valproate a standard anti-epileptic drug offered 100% protection. In 4-aminopyridine induced seizure model, the fraction at doses of 75 and 300 mg/kg protected 33.3% of the animals against mortality, but phenobarbitone (20 mg/kg) protected 100%. There was no activity against maximal electroshock convulsion. The mean l&hal dose was calculated as 1131.3 mg/kg. The results suggest that the chloroform fraction of Lonchocarpus sericeus stem-bark extract possess psychoactive compound that may be useful in the management of petit mal epilepsy.

BIO ACTIVITY-GUIDED ISOLATION OF THE ANTICONVULSANT PRINCIPLES OF METHANOLIC EXTRACT OF THE STEM-BARK OF LONCHOCARPUS SER1CEUS (POIR) FAMILY PAPILIONACEAE