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PO3-10-23

Anti-inflammatory activity of the methanol extract of Waltheria indica leaves

[Speaker] Stephen O. Okpo:1
[Co-author] Olukayode O. Tugbobo:2, Buniyamin A. Ayinde:3, Chijioke C. Micah:2
1:Pharmacolology and Toxicology, University of Benin, Benin City, Nigeria, 2:Pharmacology, Therapeutics and Toxicology, University of Lagos, Nigeria, 3:Pharmacognosy, University of Benin, Benin City, Nigeria

Background: Waltheria indica L. (Sterculiaceae) is a plant widespread in subtropical and tropical regions of the world. Commonly known as Sleepy morning in English, the plant is widely used in African traditional medicine for the treatment of diarrhoea, dysentery, conjunctivitis, abscesses, convulsions, anaemia, bladder ailments, erectile dysfunction and impotence, asthma, pain, rheumatism and other inflammatory disorders. Based on its acclaimed use for the treatment of inflammation, the present study was designed to investigate the effects of the methanol extract of Waltheria indica leaves (MEWIL) on different animal models of inflammation.
Methods: Acute toxicity study on the plant extract was determined in mice and rats via oral and intraperitoneal routes. Anti-inflammatory activity was evaluated using acute (carrageenan-, histamine- serotonin-induced paw oedema and croton oil-induced ear oedema) and chronic (cotton pellet granuloma test and adjuvant-induced arthritis) rodent models of inflammation.
Results: Acute toxicity studies revealed oral LD50 greater than 2g/kg in rats and mice and intraperitoneal LD50 of 747.60 mg/kg in mice. The administration of MEWIL, one hour before carrageenan showed significant, dose-dependent suppression of paw swelling at the 4th hour of oedema response. The highest inhibition (56.80 %) was achieved at the highest dose of the extract and this was comparable to that produced by the standard anti-inflammatory drug-indomethacin (55.98 %). Pre-treatment of rats with MEWIL (100-400mg/kg) caused a non-dose-dependent suppression of paw swelling in the histamine-induced paw oedema model, with the highest inhibition at 200mg/kg, but with no effect on serotonin-induced oedema. MEWIL also caused significant (p<0.01) dose-dependent inhibitions of croton oil-induce ear oedema in mice and granuloma tissue growth in rats. Prophylactic treatment with MEWIL (20 mg/kg/day) for 28 days significantly suppressed paw and ankle swelling, attenuated body weight loss and decreased leucocyte count. However, there were no significant alterations in arthritis score, paw or spleen weight indices, as well as other haematological parameters.
Conclusions: The results obtained indicate that the methanol extract of Waltheria indica leaves possesses therapeutic potential in the treatment of acute and chronic types of inflammatory response and provides a rationale for its traditional use in the treatment of inflammatory disorders.

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