In vivo inhibition of prostaglandin e(2) production by crude aqueous extract of the root bark of zanthoxylum xanthoxyloides.
BACKGROUND
Crude aqueous extract of the root bark of Zanthoxylum xanthoxyloides is used in folklore medicine for its anti-inflammatory activity. Although it shares the analgesic and anti-inflammatory property of non-steroidal anti-inflammatory drugs (NSAIDs), its mechanism of action has not been well elucidated.


OBJECTIVE
To ascertain whether the extract decreases carrageenin-induced increase in plasma prostaglandin E(2) (PGE(2)) concentration with the view to shed light on the mechanism of action.


METHODS
The extract was obtained by Soxhlet extraction and rotatory evaporation, followed by freeze-drying. Forty Wistar rats (150g - 200g) were assigned to 8 groups of 5 rats each. The rats were given four different treatments orally: 0.9% saline (two groups of control); two groups received indomethacin, 20mg/kg and 40mg/kg respectively; another two groups received the extract, 2000mg/kg and 4000mg/kg respectively; and the remaining two groups, 50mg/kg and 100mg/kg nimesulide respectively. Inflammation was induced with carrageenin in one of the two groups of control. Enzyme-linked immunospecific assay was used to measure plasma PGE(2) concentration in the control and treated groups of rats. Analysis of variance was used as the statistical test. Differences in means at p<0.05 were considered significant.


RESULTS
Carrageenin increased plasma PGE(2) concentration which was reduced by the extract, indomethacin and nimesulide. High dose extract and indomethacin reduced plasma PGE(2) concentration to a comparable extent which was much greater than that of the reduction caused by nimesulide.


CONCLUSIONS
It was concluded that the extract might act by non-selective inhibition of cyclooxygenase 1 and 2 to decrease plasma PGE(2) concentration.
Prempeh
Aba
A
Department of Pharmacology, University of Ghana Medical School, College of Health Sciences, P. O. Box 4236, Accra, Ghana.
Mensah-Attipoe
J
J