Analgesic Effect of
Methanol Leaf Extract of Alstonia Boonei De Wild
(Apocynaceae)
Loretta O Iniaghe*,
Stephen O Okpo, Jacob E Olung and Agharese A Eguae
Department of Pharmacology &
Toxicology, University of Benin, PMB 1154, Benin City
300001, Nigeria
*For correspondence:
Email:
lo.iniaghe@uniben.edu
Tel: +234 802211 3816
Received: 30
April
2012 Revised
accepted: 12 July 2012
Tropical
Journal of Pharmaceutical Research, October 2012;
11(5): 793-798
http://dx.doi.org/10.4314/tjpr.v11i5.13
Abstract
Purpose:
To evaluate the possible
analgesic properties of the methanol leaf extract of
Alstonia boonei (De Wild, Apocynaceae) a locally
available plant used in traditional medicine for the
management of pain and other conditions.
Methods: Alstonia boonei leaves were extracted with
methanol. Rodent models were employed in screening the
analgesic effect of the extract. Pain indices evaluated
in hot plate and tail flick tests, formalin pain test
and mouse writhing assay were mean reaction time to
latent heat, time spent in licking of injected paw and
abdominal writhes, respectively.
Results: Oral administration of the
extract caused a significant (p < 0.05) dose-dependent
reduction in the number of abdominal writhes (control,
84.67 ± 9.58; 100 mg/kg, 57.86 ± 3.07; 200 mg/kg, 24.40
± 3.92; and 400 mg/kg, 22.50 ± 2.53). The extract also
produced significant (p < 0.05) but non-dose dependent
increase in elevation of pain threshold in the hot plate
(ranging from 27.99 to 42.26 % inhibition) and tail
flick tests (ranging from 34.73 to 81.42 % inhibition)
in mice and rats, respectively. All doses of the extract
used produced significant (p < 0.05) inhibition of both
phases of the formalin-induced pain in mice, with a more
pronounced anti-inflammatory effect on the late (ranging
from 46.96 to 74.12 %) phase than the early anti-neurogenic
(ranging from 49.52 to 51.47 %) phase.
Conclusion:
The results obtained suggest
that the analgesic effect of Alstonia boonei may be
mediated via both central and peripheral mechanisms.
Keywords: Alstonia boonei, Analgesia,
Pain, Methanol extract.
