title: In vitro and in vivo effect of levopraziquantel, dextropraziquantel versus racemic praziquantel on different developmental stages of Schistosoma japonicum.
abstract: OBJECTIVE
  To compare the antischistosomal effect of racemic praziquantel (Pra) and its enantiomers, levopraziquantel (L-Pra) and dextropraziquantel (D-Pra), on different developmental stages of Schistosoma japonicum.
  
  
  METHODS
  The in vitro effects of the drugs were determined in different stages of schistosomes maintained in RPMI 1640 supplemented with 20% calf serum. In vivo study mice infected with schistosome cercariae were treated intragastrically (ig) with Pra, L-Pra or D-Pra at different intervals after infection. The efficacy of the drugs was evaluated by residual mean worm number.
  
  
  RESULTS
  Based on the degree of tegument damage induced by L-Pra, d28 and d35 schistosomes were most susceptible to L-Pra, while d14 schistosomules being least susceptible. At comparable concentrations of 0.1-1 g/ml, L-Pra was more active than Pra even when the concentration of L-Pra was reduced to one-half of the minimum effective concentration of Pra. At above-mentioned concentrations D-Pra exhibited no apparent in vitro effect on different stages of schistosomes. When infected mice were treated ig with L-Pra, Pra or D-Pra at a single dose of 300 mg/kg or 500 mg/kg, only the former two drugs showed apparent effect on d0, d21, d28 and d35 schistosomes and less or much less effect on d3, d7 and d14 schistosomules. D-Pra only exhibited a negligible effect on d35 adult schistosomes as compared with L-Pra and Pra. When mice infected with d35 adult schistosmes were treated ig with L-Pra 150 mg/kg, the efficacy was similar to that of mice treated with Pra 300 mg/kg.
  
  
  CONCLUSIONS
  L-Pra is the principal active component against schistosomes in racemic Pra.
authors.affiliation: Institute of Parasitic Diseases, Chinese Academy of Preventive Medicine, WHO Collaborating Center for Malaria, Schistosomiasis and Filariasis, Shanghai 200025, China.
authors.forename: S
authors.initials: S
authors.lastname: Xiao
authors.forename: J
authors.initials: J
authors.lastname: You
authors.forename: J
authors.initials: J
authors.lastname: Mei
authors.forename: Y
authors.initials: Y
authors.lastname: Hu
authors.forename: D
authors.initials: D
authors.lastname: Zhou
authors.forename: B A
authors.initials: BA
authors.lastname: Catto
mesh_terms: D000818:Animals; D000871:Anthelmintics / Q000494:pharmacology*; D051379:Mice; D011223:Praziquantel / Q000494:pharmacology*; D012549:Schistosoma japonicum / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D012554:Schistosomiasis japonica / Q000188:drug therapy / Q000469:parasitology; D013237:Stereoisomerism
chemical_list: D000871:Anthelmintics; D011223:Praziquantel