Shahrekord University of Medical Sciences Journal of Herbmed Pharmacology 2345-5004 12 2 2023 04 01 Antiparasitic effect of limonene, a monoterpene compound found in the essential oils against Giardia lamblia 327 330 10.34172/jhp.2023.34 EN Ali Kharazmkia https://orcid.org/0000-0001-9081-8065 Javad Ghasemian Yadegari https://orcid.org/0000-0002-3897-2222 Mohamad Mohamadian https://orcid.org/0000-0002-4877-9143 Rehman Ali https://orcid.org/0000-0002-7464-4453 Hossein Mahmoudvand https://orcid.org/0000-0003-4194-393X Journal Article 10.34172/jhp.2023.34 2022 09 16 2022 11 23 Introduction: The present work aimed to assess the anti-parasitic effects of limonene (LMN) against Giardia lamblia trophozoites and cysts. Methods: Anti-Giardia activities of LMN (25, 50, and 100 µg/mL) were assessed against G. lamblia cysts and trophozoites for 15-360 minutes. The effects of LMN on the apoptosis stimulation G. lamblia parasites were determined by colorimetric protease assay. Results: Giardia trophozoites were more sensitive to LMN than cysts. The best effect of LMN was seen at 100 μg/mL. LMN markedly triggered caspase-3 activity by 10.2%, 25.3%, and 36.1%, respectively (P<0.001). Conclusion: We found the potent in vitro anti-giardia activity of LMN against G. lamblia parasites with the maximum activity at 50 and 100 µg/mL. However, additional surveys are necessary to reveal the specific efficacy, mechanisms, and safety of LMN.