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
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Date
2012-09
Authors
ABDULLAHI, SAKYNAH MUSA
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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.
Description
A THESIS SUBMITTED TO THE
SCHOOL OF POSTGRADUATE STUDIES
AHMADU BELLO UNIVERSITY, ZARIA-NIGERIA
IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF
MASTER OF SCIENCE DEGREE
IN
PHARMACEUTICAL AND MEDICINAL CHEMISTRY
DEPARTMENT OF PHARMACEUTICAL AND MEDICINAL
CHEMISTRY
AHMADU BELLO UNIVERSITY, ZARIA-NIGERIA
Keywords
BIO ACTIVITY,, ACTIVITY-GUIDED,, ISOLATION,, ANTICONVULSANT,, METHANOLIC EXTRACT,, STEM-BARK,, LONCHOCARPUS SERICEUS,, FAMILY PAPILIONACEAE