Enantioselective Toxic Effects of Prothioconazole toward Scenedesmus obliquus

Prothioconazole (PTC) is a broad-spectrum triazole fungicide with one asymmetric center and consists of two enantiomers, -(-)-PTC and -(+)-PTC. To address the concern of its environmental safety, the enantioselective toxic effects of PTC on ( ) were investigated. PTC racemates ( -PTC) and enantiomers exhibited dose-dependent acute toxicity effects against at a concentration from 1 to 10 mg·L . The 72 h-EC50 value of -, -(-)-, and -(+)-PTC is 8.15, 16.53, and 7.85 mg·L , respectively. The growth ratios and photosynthetic pigment contents of the -(-)-PTC treatment groups were higher than the - and -(+)-PTC treatment groups. Both catalase (CAT) activities and esterase activities were inhibited in the - and -(+)-PTC treatment groups at high concentrations of 5 and 10 mg·L , and the levels of malondialdehyde (MDA) were elevated, which exceeded the levels in algal cells for the -(-)-PTC treatment groups. PTC could disrupt the cell morphology of and induce cell membrane damage, following the order of -(+)-PTC ≈ -PTC > -(-)-PTC. The enantioselective toxic effects of PTC on provide essential information for its ecological risk assessment.