Abstract: Objective To detect the effect of gossypol， praziquantel and artemether on activity of the recombinant lactate dehydrogenase of Schistosoma japonicum （rSjLDH）. Methods Effect of gossypol （0-0.10 mmol/L）， praziquantel （0-0.20 mmol/L） and artemether （0-0.10 mmol/L） on the enzymatic activity of rSjLDH was detected by spectrophotometric method in standard reaction system established before， same solvent of each reagent was used as control. Results were analyzed by SPSS13.0 software. Results Compared with the control， considerable inhibition for both reduction and ox-idation reactions catalyzed by rSjLDH was observed at 0.04 mmol/L of gossypol （P<0.01）. The enzyme activities of rSjLDH for reduction and oxidation reactions were inhibited by 91.3% and 89.1% respectively at 0.1 mmol/L of gossypol， com-pared with the control （P<0.01）. To praziquantel， enzymatic activity inhibition was observed at 0.02 mmol/L for oxidation reaction and at 0.06 mmol/L for reduction reaction （P<0.05）. At 0.2 mmol/L of praziquantel， enzymatic activities were inhibited by 83.8% for reduction reaction and 72.2% for oxidation reaction respectively， than that of the control （P<0.01）. No inhibition for both reduction and oxidation reactions was observed at 0.1 mmol/L of artemether， compared with that of the control （P>0.05）. Conclusion Gossypol and praziquantel show a high inhibition on rSjLDH. SjLDH may be one of the molecular targets of praziquantel.

Key words: Schistosoma japonicum, Lactate dehydrogenase, Recombinant protein, Gossypol, Praziquantel, Artemether