Shahrekord University of Medical Sciences Future Natural Products 2783-4662 3 2 2017 04 30 Comparison anti-giardia activity of Satureja hortensis alcoholic extract and metronidazole in vitro 15 21 EN Jabber Davoodi Saeid Abbasi Maleki Journal Article 2016 05 30 2016 06 26 Background and aims: Giardiasis is known as intestinal infection and created by the flagellate protozoan Giardia lamblia. Some studies showed that phenolic components, present in plant extracts and essential oils, have anti-Giardia activity. The current study was performed to compare anti-Giardia activity of Satureja hortensis (SH) alcoholic extract and metronidazole in vitro. Methods: In this Laboratory-experimental study, it was separated cysts from the feces by Bingham procedure with minor modification. The numbers of cysts were calculated with Hemusytumetr and the purified cysts of Giardia lamblia (500 µl) were exposed with 500 µl of extract at concentrations of 10, 100 and 200 mg/ml and 125 mg/kg of metronidazole for 30, 60 and 120 min. The numbers of dead and live cysts was enumerated with a microscope. Results: Findings in the currnt studyshowed an increase in anti-Giardia activity of extract at high concentrations with increasing time. SH, at 100 mg/ml killed 53% in 30 min, 68% in 60 min and 78% in 120 min. Also, the extract killed by 62% in 30 min, about 88% in 60 minutes and 92% in 120 minutes. The drug had similar effects in 60 and 120 minutes, but it killed 83% in 30 minutes. Conclusion: SH alcoholic extract showed anti-Giardia activity at high rates and more time. Thus, SH extract at 200 mg may be suitable alternative for Metronidazole, without side effects. However, anti-Giardia activity of SH needs to more attentions, especially clinical investigations.