Comparative study of potent anti-amoebic and anti-inflammatory activities of different extracts from Sida rhombifolia (L)

Background: Sida rhombifolia (L) is a medicinal plant from tropical regions belonging to the Malvaceae family and the plantea kingdom. It is known for its multiple pharmacological properties. The aim of this work was to evaluate the anti-amoebic, and anti-inflammatory potential of Sida rhombifolia aqueous and ethanolic leaf and stem extracts harvested in two localities of Cameroon (Yaoundé and Massangam in the Centre and West regions, respectively). Methods: The anti-amoebic activity was evaluated on a polyxenic culture of Entamoeba histolytica. A primary macrophage culture activated by Saccharomyces cereviseae (SC) was used to evaluate anti-inflammatory potential of the plant extracts. Macrophages were treated with different concentrations (1; 10; 100 and 500 μg/mL) of the extracts for the inhibition of nitric oxide (NO) production and 5-lipoxygenase activity. Methods: The anti-amoebic activity was evaluated on a polyxenic culture of Entamoeba histolytica. A primary macrophage culture activated by Saccharomyces cereviseae (SC) was used to evaluate the anti-inflammatory potential of the plant extracts. Macrophages were treated with different concentrations (1; 10; 100 and 500 μg/mL) of the extracts for the inhibition of nitric oxide (NO) production and 5-lipoxygenase activity. Results: No significant difference was found between the anti-amoebic activity of the ethanolic extract of Yaoundé (Centre region, IC50 = 7.71 μg/mL) and that of ethanolic leaf extract from Massagam (West region IC50 = 7.77 μg/mL) after 72 hours. Among the extracts, ethanolic leaf extracts exhibited the highest anti-amoebic activity after 72 hours of treatment. Metronidazole showed better activity (IC50 = 5.96 µg/mL) in the same periods of time. Phenolic compounds and flavonoid contents were higher in Yaoundé (Centre region) ethanolic leaf extract, proving that these extracts can prevent certain damages linked to a state of oxidative stress. The ethanolic extracts of the leaves significantly inhibited NO production and 5-lipoxygenase activity in macrophages (IC50 of 3.85 µg/mL; 3.99 µg/mL and 36.64 µg/mL; 73.22 µg/mL respectively). Conclusion: This preliminary study shows that the ethanolic extract of S. rhombifolia possesses better anti-amoebic properties and can act at the level of the intestinal mucosa in order to fight against the damage linked to the dysfunction of the inflammatory cells.