Asian Journal of Advances in Medical Science

Background: Amoebiasis, caused by Entamoeba histolytica, remains an important intestinal parasitic infection, particularly in areas with poor sanitation and limited access to safe water.

Aim: This study assessed the phytochemical constituents and in vitro antiprotozoal activity of the methanolic leaf extract of Chromolaena odorata against E. histolytica detected in stool specimens.

Methodology: Fresh leaves of C. odorata were collected, authenticated, air-dried, pulverised and extracted by cold maceration using methanol. Qualitative phytochemical screening was carried out using standard methods. Fifty stool specimens were examined microscopically, and specimens showing Entamoeba morphology were subjected to E. histolytica-specific antigen detection using ELISA. Antigen-positive specimens were used for the in vitro antiprotozoal assay. The extract was tested at concentrations of 6.25, 12.5, 25, 50 and 100 mg/mL, with metronidazole as the positive control. Percentage inhibition and minimum inhibitory concentration (MIC) were determined.

Results: The extract contained alkaloids, flavonoids, tannins, saponins, glycosides, terpenoids, phenolic compounds and steroids, while anthraquinones were not detected. Eighteen (36.0%) of the 50 stool specimens were positive for E. histolytica antigen. The extract produced inhibition of 20.0%, 37.5%, 59.2%, 80.0% and 93.3% at 6.25, 12.5, 25, 50 and 100 mg/mL, respectively. Metronidazole produced 96.7% inhibition at 17 µg/mL. The MIC of the extract was 100 mg/mL within the concentration range tested.

Conclusion: The methanolic leaf extract of C. odorata showed in vitro antiprotozoal activity against E. histolytica, with inhibition increasing with the concentrations tested. Further studies are required to identify the active constituents and assess their safety and activity under in vivo conditions.