Abstract

Euphorbia hirta (Euphorbiaceae) has been used widely in traditional medicine as a treatment against infectious pathogens. This medicinal plant is also well known for its diverse biological activities. The present study aimed to evaluate the susceptibilities of the clinical isolates of Entamoeba histolytica to E. hirta aqueous extract, methanol fraction, methylene chloride fraction, and hexane fraction. The clinical isolates of E. histolytica grown on polyxenic medium were treated with E. hirta aqueous extract (AE), methanol fraction (MF), methylene chloride fraction (CH₂Cl₂ F), and hexane fraction (HF). Metronidazole (MTZ) was used as the reference drug. Furthermore, the effects of the extract as well as the fractions on the activity of E. histolytica ribonuclease (RNase), aldolase, acid and alkaline phosphatases (ACP and ALP) were evaluated. The methanol fraction of E. hirta inhibits significantly the clinical isolate of E. histolytica growth with the IC₅₀ of 67.18 ± 7.40 µg/ml after 72 h of incubation but remains lowers compared to metronidazole (IC₅₀<10 µg/ml). The aqueous extract and methylene chloride showed moderate activities, whereas no amoebicidal activity was found associated to the hexane fraction. The enzymes activity assay showed that the inhibitory effect of the methanol fraction against E. histolytica RNase, aldolase acid and alkaline phosphatases activities were comparable to that of metronidazole and significantly higher than those of aqueous extract and methylene chloride fraction. According to the above mentioned results, the methanol fraction of E. hirta exhibits antiamoebic activity and inhibition of enzymes involved in the metabolism or survival of E. histolytica.

Key words: Entamoeba histolytica; Euphorbia hirta; Antiamoebic activity.