Abstract: Objective   To compare the effect and acted target of auranofin on juvenile and adult Schistosoma japonicum， and detect the cytotoxicity of auranofin against host cells. Methods  Effect of auranofin on the recombinant SjTrx-1 enzyme activity was investigated with dithiothreitol（DTT）/insulin reduction method. Female Kunming mice（4-6 weeks old） were infected（10 mice with 600-800 cercariae per mice for schistosomula and other 10 mice with 80-100 cercariae per mice for adult worms） and sacrificed after 15 d and 35 d post-infection for worm collection. The perfused worms were washed with sterile saline thoroughly and transformed into 12-well Falcon plate containing 4 ml medium each well. Auranofin or praziquantel was added with different final concentrations（1, 5 and 10 μg/ml）. The morphological alternations and number of death worms were observed microscopically at the defined time points of 2， 24， 48 and 72 h， respectively. CCK-8 kit was used to analyze the cytotoxicity of auranofin against 3 different host cells (Hep G2, 293T and Hela).  Results  10 μg/ml auranofin reduced the recombinant SjTrx-1 activity by 54.5% in 40 min. 5 μg/ml auranofin resulted in 75% mortality of adult worms after 24 h， but no schistosomulum was dead in the same period. Although the auranofin concentration increased to 10 μg/ml resulted in the death of all worms in 72 h， the death of schistosomula was delayed in comparison to that of the adults. When treated with auranofin or praziquantel， the worms contracted， convoluted and became gloomy under optical microscope while scanning electron microscopy showed that the tegument structure was severely damaged for both of them. Cytotoxicity analysis showed that 5 μg/ml auranofin reduced the relative activity by 85% than the control group and nearly 100% cell death when the concentration increased to 10 μg/ml.  Conclusion   SjTrx-1 is one of auranofin acting targets. Auranofin exhibits strong cytotoxicity against host cells， with more significant effect on adults than juveniles.

Key words: Auranofin, Schistosoma japonicum, Target, Cytotoxicity