Abstract:
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
E2 (PGE2) concentration with the view to shed light on
the mechanism of action.
Methods: The extract was obtained by Soxhlet extrac tion 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 PGE2 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 PGE2 concen tration which was reduced by the extract, indomethacin
and nimesulide. High dose extract and indomethacin
reduced plasma PGE2 concentration to a comparable
extent which was much greater than that of the reduc tion caused by nimesulide.
Conclusion: It was concluded that the extract might
act by non-selective inhibition of cyclooxygenase 1 and
2 to decrease plasma PGE2 concentration.
