Effects of Trichilia monadelpha (Thonn.) J. J. De Wilde (MELIACEAE) Bark Extracts on Ulcerative Colitis, Colonic Microflora and Wound Healing in Wistar Rats

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Trichilia monadelpha (Thonn.) de Wilde, has been reported to have therapeutic effect against microbes, dysentery, dyspepsia, sores and ulcers. However, no scientific basis is established of such claims. Thus, this study sought to determine the effectiveness of Trichilia monadelpha bark extracts on surface wounds and ulcerative colitis as well as the extent to which it could displace colonic microflora. Generally, Wistar rats of comparable age and weight were housed 5 per cage in 6 groups for each experimental set-up. The excision wound healing and indomethacin/acetic-acid induced animal models of ulcerative colitis were employed in this study. All extracts for the treatment of ulcerative colitis were administered orally, while wound treatment was carried out with topical formulations. In the indomethacin-induced ulcerative colitis, colons of animals treated with the ethanolic extract revealed persistent mucosal ulceration in the disease control and 30 mg/kg but not the 100 mg/kg and 300 mg/kg dose groups. For the acetic acid-induced ulcerative colitis, the aqueous extract significantly restored mucosal integrity in the 100 mg/kg and 300 mg/kg dose treated groups relative to the ulcerated and oedematous mucosae of 30 mg/kg treated group, pointing to a marked response to treatment in a dose dependent fashion. The petroleum ether extract manifested crypt abscesses and globular mucosae in the 100 mg/kg and 300 mg/kg dose treated groups of acetic acid-induced colitic rats, while the ethyl acetate extract showed serrated, crypt and oedematous mucosae among the 100 mg/kg and 300 mg/kg dose groups, evident of persistent disease. The role of Trichilia on colonic microflora in colitic rats suggested a dose dependent activity. There was a 24%, 12% and 8% microbial infestation among animals of the 30 mg/kg, 100 mg/kg and 300 mg/kg treated groups relative to a 32% and 24% occurrence in disease and normal controls respectively. Therefore, Trichilia was found to be detrimental to colonic microflora. In the case of excision wounds, the aqueous extract of Trichilia showed appreciable rate of healing in the 3% and 10% treated groups but not in the 30% dose treated group. On the other hand, rate of wound healing was dose dependent and comparable to the standard treatment among the ethanolic extract treated groups. Most wounds had completely healed by day 13. But the petroleum ether extract showed a relatively poor rate of wound healing with sepsis resulting into chronic wounds. The rate of wound healing in the ethyl acetate extract group was extremely poor, registering 100% mortality in the 30% treated group, characteristic of ineffective treatment. An anti-oxidant assay established the presence of anti-oxidant properties in the aqueous, ethanolic, and ethyl acetate extracts but not the petroleum ether extract. In conclusion, the aqueous extract of Trichilia proved to have a strong anti-oxidant property and was highly effective in the treatment of ulcerative colitis but slightly effective in excision wounds, while the ethanolic extract had appreciable anti-oxidant property and was effective in the treatment of ulcerative colitis but highly effective in the healing of excision wounds. The petroleum ether and ethyl acetate extracts did not prove to be effective treatment options in both cases. Trichilia was also found to displace colonic microfloral balance and could be effective against infectious colitis.
A Thesis submitted to the School of Graduate Studies, Kwame Nkrumah University of Science and Technology, Kumasi, in partial fulfilment of the requirements for the Degree of Master of Philosophy in Pharmacology, March-2011