Abstract:

Objective To evaluate the inhibitory effect of dihydroartemisinine (DHA) on acanthamoeba in vitro. Design Experimental study. Participants Acanthamoeba isolated from patients’ cornea. Methods Culture acanthamoeba in vitro and add different concentrations of dihydroartemisinin (3.2%, 1.6%, 0.8%, 0.4%, 0.2%, 0.1%, 0.05%, 0.025%, and 0.0125%). They were incubated together and used chlorhexidine (CHG) and PHMB as control drugs. The inhibitory effect of drugs on acanthamoeba were observed through turing acanthamoeba medium and LIVE/DEAD staining. Main Outcome Measures Morphological changes of mites under optical microscope after drug action. Activity of acanthamoeba under fluorescence microscope after LIVE/DEAD staining. Measure minimum cysticidal concentration (MCC) and minimum trophozoite amoebicidal concentration (MTAC). The cumulative distribution rate of acanthamoeba under MTAC and MCC levels was MTAC50 and MCC50 or MTAC90 and MCC90. Results The range of MTAC and MCC in DHA group were both 0.05%~0.6%; MTAC50 and MCC50 were 0.4% both, while both MTAC90 and MCC90 were 1.6%. The MTAC range of CHG group was 0.0125%~1.6%; MCC range was 0.0125%~0.8%, MTAC50 and MCC50 were 0.05% and 0.1%; MTAC90 and MCC90 were both 0.8%. The MTAC of PHMB group was 0.00625%~0.4%; MCC range was 0.00625%~0.2%; MTAC50 and MCC50 were both 0.025%; MTAC90 and MCC90 were both 0.2%. There was no statistically significant difference between MCC and MTAC in the three groups for different strains of acanthamoeba (P=0.342, 0.459, 0.469). The difference of the MTAC among DHA, CHG and PHMB group was statistically significant (F=3.813, P=0.035). The MTAC of DHA group was higher than PHMB group(P=0.011). There was no statistically significant difference of the MTAC between the DHA and CHG group as well as CHG and PHMB group (P=0.105, 0.297). The difference of the MCC among DHA, CHG and PHMB group was statistically significant difference (F=6.672, P=0.004). The  MCC of DHA group was higher than CHG group, and DHA group was higher than PHMB group (P=0.017, 0.001). There was no significant difference of the MCC between CHG and PHMB group (P=0.325). Conclusion The inhibitory effect of the dihydroartemisinine on acanthamoeba is observed in vitro, and the effect on acanthamoeba keratitis in clinic remains to be further studied.

Key words: dihydroartemisinine, acanthamoeba, inhibitory effect