Effect of Origanum vulgare Hydroalcoholic Extract on Giardia lamblia Cysts Compared with Metronidazole in Vitro

Giardiasis, an intestinal infection, is made by the flagellate protozoan and on the other hand, positive effects of plants derivatives, especially phenolic derivatives, against giardiasis. The effect of Origanum vulgare (OV) hydroalcoholic extract is still uninvestigated. Thus, this study was conducted to evaluate the effect of OV hydroalcoholic extract on Giardia lamblia cysts compared with metronidazole in vitro. The present experimental study was conduct ed in 2015-2016 in the Laboratory of Department of Parasi tology of Islamic Azad University (Abhar Branch, Abhar, Iran). Cysts separated from feces by Bingham procedure were calculated by using the Hemusytumetr method. Five hundred µl of concentrations of 10, 100 and 200 mg/ml of OV hydroalcoholic extract and also125 mg/kg of metronidazole were added to the purified cysts of giardia. Control group was treated with normal saline. Anti-Giardia activity was calculated by using the light microscope for 30, 60 and 120 min and after exposure to eosin stain. The results indicated anti-Giardia activity of OV hydroalcoholic extract and the best response was achieved at higher levels so that there were no significant differences among OV groups at levels of 200 mg/kg with metronidazole (P>0.05). The anti-Giardia activity of Origanum vulgare extract is may due to the presence of phenolic compounds present in it.