In vitro antiprotozoal activity from the roots of Geranium mexicanum and its constituents on Entamoeba histolytica and Giardia lamblia.

This paper examines the antiprotozoal activity of the dichloromethane-MeOH extract, fractions and pure compounds from the roots of Geranium mexicanum on Entamoeba histolytica and Giardia lamblia. The result indicated that the extract, organic fraction and a pure flavonoid were active against both protozoa with IC50 values ranging from 1.9 to 79.2 microg/ml for Entamoeba histolytica and from 1.6 to 100.4 microg/ml in the case of Giardia lamblia. The main active compound was the flavan-3-ol, (-)-epicatechin. In addition, the moderate active compounds (+)-catechin, tyramine and beta-sitosterol 3-O-beta-D-glucopyranoside, also were isolated. These results support the anecdotal reports for the traditional use of Geranium mexicanum roots in the management of diarrhoea and dysentery, illnesses caused in some cases by enteric protozoa.