| dc.description.abstract | Convulsion is a chronic neurological disorder that develops in up to 5% of the world’s
population with prevalence of nearly 88% occurring in Sub-Saharan Africa, prompting serious
medical, social, health related stigma and discrimination. Although a number of antiepileptic
drugs (AED) are available for patients, most of the drugs have been associated with adverse side
effects, dose-related neurotoxicity and teratogenic effects besides the AED therapy failures
reported in approximately 20% of the patients. Since AED therapies have draw backs restricting
their clinical utility, herbal medicines may offer therapeutic options due to their accessibility, and
less or no side effects. Maytenus heterophylla is one such plant that has been in use by the Teso
communities in western Kenya to manage convulsions. However, there is no scientific evidence
to validate the application. Therefore, the current study was intended to screen the extracts for
anticonvulsant activity, isolate the pure compounds and test them for anticonvulsant activity. A
bioassay-guided isolation and characterization was designed to evaluate the antiepileptic
potential of the various parts of M. heterophylla. Solvent extraction followed by
chromatographic separation and spectroscopic techniques were used to isolate and characterize
the compounds from the active fractions. Picrotoxin-induced convulsion assays in white albino
Swiss mice was used to evaluate the in-vivo anticonvulsion potential of the extracts and
compounds. Stem bark methanol extract (200 mg/kg b.w) significantly (P<0.05) decreased
convulsions compared to control animals against Picrotoxin–induced seizure and relatively better
than the leaf and root extract. The stem bark extract also offered up to 62.5% protection against
seizure at 200 mg/kg which was significant (P<0.05) compared to diazepam (87.5%). Two new
triterpenes; 3-methoxy-4-decarboxydihydrozeylasterone (55) and 3,4˗seco-1-hydroxy-21-oxoolean-
3,11-olide (56) together with three known compounds; 3-acetoxy-28-hydroxylupe-20(29)-
ene (54), Oleanolic acid (58) and a monoterpene, 3,5-dihydroxycamphanoate (57) were isolated
from the stem bark of M. heterophylla. The isolates showed weak to moderate activities with
compounds 55 and 56 showing the highest activities at 62.5% (P<0.05) and 75% (P<0.05)
protection respectively, against convulsion compared to the distilled water (Negative control) at
concentrations of 50 mg/Kg b.w. The results suggest that Maytenus heterophylla contains
bioactive compounds against Picrotoxin-induced convulsion and the plant’s stem bark may be
beneficial in management of epilepsy. Compounds 55 and 56 should therefore be explored
further for potential to manage convulsions. These results lend credence to the ethno-medical
claim for the use of the plant in traditional medicine. | en_US |
