Background: Acanthamoebiasis treatment is a major and challenging problem due to
the presence of resistant cyst form. Many herbal extracts and their derivatives have been used
against trophozoites and cysts of Acanthamoeba, but no effective therapeutic agent has yet been discovered.
Therefore, the present study aimed to evaluate the effect of Rumex obtusifolius (R. obtusifolius)
extracts against a clinical strain of Acanthamoeba genotype T4 in vitro.
Methods: In this experimental study, after genotyping the clinical isolate, the hydroalcohlic extracts
of R. obtusifolius seeds and leaves were prepared. Different concentrations (1.25, 2.5, 5 and
10 mg/ml) of extracts were tested in triplicate (24, 48 and 72h) on trophozoites and cysts of Acanthamoeba.
The mortality of the parasite was assessed by trypan blue vital staining and flow cytometry
Results: Results showed that the extract of R. obtusifolius leaves at the concentration of 10 mg/ml
killed 100% of trophozoites and cysts after 72 h. However, the seed extract of R. obtusifolius had
weak inhibitory effects on trophozoites and cysts of Acanthamoeba. In the presence of 10 mg/ml of
hydroalcoholic seed extract of R.obtusifolius in culture medium after 72 h, 28.6% of trophozoites
and 0% of cysts of Acanthamoeba were killed. After analysis by flow cytometry, seeds and leaves
extract indicated apoptosis effect. Seed and leaf extracts caused 2.6% and 0.4% percent apoptosis.
Conclusion: These extracts are not promising candidates for further medicine development on
acanthamoebiasis. Nonetheless, further research is necessary to clarify the effects of effective fractions
of seed and leaf extracts of R. obtusifolius and their mechanisms of action.