Effect of Cecropin–melittin Chimeric Peptide (CM11) on Trophozoite of Giardia lamblia In Vitro

Background and purpose: Antimicrobial peptides (AMP) are one of the most diverse antimicrobial compounds that have received much attention due to the development of drug resistance of pathogens to conventional antibiotics. But, few studies have evaluated anti-parasitic properties of AMP. The present study was conducted to compare the effect of a cecropin–melittin chimeric peptide (CM11) and metronidazole on Giardia lamblia trophozoite. Materials and methods: In this study, using MTT assay, the cytotoxicity of CM-11 peptide (0.5-32 μg/ml) and metronidazole (0.25-25 μg/ml) was investigated on Caco-2 cells and IC50 was calculated. Flow cytometry was used to determine the rate of induction of apoptosis by CM11 and metronidazole. The toxicity of peptide on G. lamblia trophozitis was evaluated in vitro under different conditions. Results: MTT results showed that the highest percentage of cytotoxicity in caco2 cells was seen at 32 μg/ml of CM11 peptide after 24 (84.3±1.2%), 48 (88.7±0.9%) and 72 (87±1.5%) hours. In metronidazole group, the highest cytotoxicity was observed in 20 μg/ml after 24 (35±2.3), 48 (39.3±1.2) and 72 (48.3±1.8%) hours. The highest concentrations of peptide (32 μg/ml) and metronidazole (20 μg/ml) showed 99.8±0.2% and 99±0.6% cytotoxicity effect, respectively. The cytotoxicity effect of peptide and metronidazole on G. lamblia attached to caco2 cells at highest concentrations were 99.7±0.1% and 99.5±0.3%, respectively. Conclusion: This study showed that cecropin-melittin chimeric peptide could be an appropriate candidate for the treatment of giardiasis.