Abstract

The inhibitory activity of the leaf extract of Morinda lucida on Escherichia coli was investigated both in vitro and in vivo. The effect of the extract in vivo was obtained by feeding albino rats with the extract. The in vitro experiment was carried out using the agar well diffusion method and results showed that 25 mg/ml of the extract inhibited E. coli with a zone of inhibition measuring 5 mm. Immunological indices observed in the albino rats showed that the extract was able to eliminate and control symptoms of E. coli infection in the experimental rats. Results of haematological indices in group A rats infected with E. coli revealed an increase in WBC (4900 to 5600 mm³⁾ and neutrophil count (46 - 68%), while a decrease occurred in PCV (41 - 27%) and Hb (13.7 - 9.0 g). However, result for group B (rats infected with E. coli but treated with extract) showed a decrease in WBC (5800 – 3600 mm³) PCV (31 - 29%), Hb (10.4 - 9.7 g) and neutrophil count (52 - 49%). At the same time, group C (rats fed with the extract alone) gave results as follow; WBC (5700 – 4200 mm³), PCV (42 - 36%), neutrophil (58 - 63%) while group D, (Placebo administered with normal saline) had their WBC increased (5200 – 5400 mm³); PCV (37 - 38%) and neutrophil count (52 - 54%). Results on urinalysis showed fluctuation in pH values for rats in groups A, C and D from before infection to after infection. These results have indicated that the extract has been able to control the establishment of E. coli infection in the rats. This has given a clue that the extract can be of use in the treatment of the symptoms of infections caused by enteropathogenic E. coli.

Key words: Antimicrobial activity, immunological indices, urinalysis, Escherihia coli, phytochemical screening, infection, albino rats.