PURPOSE: The present experimental study seeks to evaluate the in vitro and in vivo effects, as well as the potential mechanisms of action, of Rhanterium epapposum essential oil (REE) and its main constituents against Giardia lamblia infection. METHODS: The analysis of REE was performed using the Gas Chromatography-Mass Spectrometry (GC-MS) detector. The in vitro effects of REE and its main constituents on viability of G. lamblia cysts and the human intestinal epithelial cell line, as well as their effects on plasma membrane permeability, the reactive oxygen species (ROS) generation, and trophozoite adherence were assessed by MTT assay. Effects of oral administration of REE and its main constituents at doses 10 and 20 mg/kg on the number of Giardia cysts, the serum level of electrolytes of sodium (Na+) and potassium (K+), as well as the gene expression of inflammatory genes of TNF-α, IL-1β, IL-10, NF-κB p65, and Toll-like receptor 4 (TLR4)) were assessed. RESULTS: The 50% inhibitory concentrations (IC50) value of REE, MC, CP, LN and MTZ against G. lamblia cysts was 26.7, 32.1, 35.3, 45.1, and 42.1 µg/mL, respectively
indicated that REE, MC, and CP displayed high antigiardial effects in comparison with MTZ. The obtained 50% cytotoxic concentration (CC50) value of REE, MC, CP, LN, and MTZ on HIEC-6 cells was 279.1, 363.4, 394.2, 478.3, and 422.1 µg/mL, respectively. REE and its main compounds significantly (p <
0.002) increased the plasma membrane permeability and ROS generation in Giardia trophozoites, while, reduced the Giardia trophozoites adherence. In vivo, REE, MC, CP, and LN mainly at the dose of 20 mg/kg considerably reduced the number and viability of Giardia cysts, modulated the serum level of electrolytes Na and K in the infected mice compared with the mice treated with MTZ (P <
0.01)
whereas inhibited the inflammation cytokines in the infected mice compared with the mice treated with MTZ (p <
0.002). CONCLUSION: The current investigation showed that R. epapposum essential oil and its main compounds controlled the Giardia infection in mice by inhibiting inflammation, and serum electrolyte imbalance. After confirmation in further studies, these compounds may be considered for development as a novel therapeutic option for the treatment of giardiasis.