In vitro activity of organic leaf/stem extracts from Marrubium vulgare and Mentha spicata against Entamoeba histolytica and Giardia lamblia

Entamoeba histolytica and Giardia lamblia, the causal agents of Amebiasis and Giardiasis are worldwide distributed. The aim of this study was to determine the in vitro activity against Entamoeba histolytica and Giardia lamblia of four plants used popularly against intestinal disorders. The concentration of aqueous and organic leaf and stem extracts from Marrubium vulgare, Mentha spicata, Chenopodium ambrosioides and Artemisia ludoviciana producing 50% growth inhibition (IC50) of E. histolytica and G. lamblia axenic cultures was determined. Acetone and methanol extracts from M. vulgare were very active against E. histolytica (IC50 = 7 and 12 μg/mL, respectively) and slightly to moderately toxic to G. lamblia (IC50 = 90 and 34 μg/mL, respectively). Hexane, acetone, and methanol extracts from Mentha spicata were also very potent against E. histolytica (17, 13, and 8 μg/mL), while only the acetone extract was slightly active against G. lamblia (IC50 = 98 μg/mL). Hexane and acetic C. ambrosioides extracts were moderately active only against E. histolytica (IC50 = 57 and 58 μg/mL); while A. ludoviciana was inactive against both protozoan species (IC50 > 100 μg/mL). Organic extract from M. vulgare and M. spicata were the most active; being E. histolytica strickingly more susceptible than G. lamblia. None of the aqueous extracts was active. Further studies to isolate and characterize the active principles against both protozoa species are justified.