Abstract: Objective To investigate in vitro anti-hydatid efficacy on Echinococcus granulosus protoscolex （EgPSC） by using albendazole sulfoxide （ASOX） and its two enantiomeric antipodes， L-ASOX and D-ASOX. Methods Eg protoscoleces were divided into eight groups and cultured in the DMEM culture media under two concentrations（50 μg/ml and 100 μg/ml） of ASOX， L-ASOX and D-ASOX respectively. The appropriate controls included （i） a culture containing an equal amount of DMSO and （ii） a culture medium alone. The mortality of EgPSC in each group was daily counted until 100% EgPSC death in some groups. Results Significant difference of EgPSC mortality was found among the three drugs with various concentrations compared to control group （P<0.01）, and a significant difference between L-ASOX group and D-ASOX group （P<0.05）. There were no statistical difference between ASOX group and D-ASOX group （P>0.05）， but between ASOX group and L-ASOX group （P<0.05）. On the 9th day of culture, the mortality of protoscleces with the concentration of 50 μg/ml was 93.6%, 56.2% and 99.0% in ASOX, L-ASOX and D-ASOX groups respectively, and those under the concentration of 100 μg/ml were 100%, 74.5% and 100% respectively. The mortality was 19.1% and 22.5% respectively in the control and solvent groups. Conclusion ASOX，L-ASOX and D?-ASOX demonstrate significant effect of anti-Eg protoscolex in vitro. D-ASOX shows stronger effect than L-ASOX.

Key words: Echinococcus granulosus, Protoscolex, Albendazole sulfoxide, Enantiomeric antipode, In vitro