Stereoselective bioactivity, toxicity and degradation of the chiral triazole fungicide bitertanol

Abstract BACKGROUND The chiral pesticide bitertanol has been widely used in the prevention and treatment of fungal diseases on many crops. However, research on bitertanol at the stereoisomer level has not been reported. Here, we study the stereoselective bioactivity, toxicity, and degradation of this pesticide under laboratory and field conditions. RESULT (1 S ,2 R )‐Bitertanol was the most effective stereoisomer, showing 4.3–314.7 times more potent bioactivity than other stereoisomers against eight target pathogenic fungi. (1 S ,2 R )‐Bitertanol showed 10.2 times greater inhibition of Botrytis cinerea spore germination than (1 R ,2 S )‐bitertanol. According to the receptor‐drug docking results, the distances from the nitrogen atom in the heterocycle of (1 S ,2 R )‐, (1 R ,2 S )‐, (1 R ,2 R )‐, and (1 S ,2 S )‐bitertanol to the central Fe + atoms in the ferriporphyrin were 2.5, 3.8, 2.6, and 3.8 Å, respectively. (1 S ,2 S )‐Bitertanol was 1.6–2.7 times more toxic than (1 R ,2 R )‐bitertanol to Chlorella pyrenoidosa . The half‐lives of (1 R ,2 S )‐, (1 S ,2 R )‐, (1 R ,2 R )‐, and (1 S ,2 S )‐bitertanol were 3.7, 4.1, 4.1, and 4.8 d, respectively, in tomato. CONCLUSION The stereoselective bioactivity, toxicity, and degradation for bitertanol were first studied here. (1 S ,2 R )‐Bitertanol was a high efficiency and low toxicity stereoisomer. Moreover, the stereoselective bioactivity among all stereoisomers correlated with the binding distances and calculated energy differences between stereoisomers and the target protein. This study also provides a foundation for a systematic evaluation of bitertanol at the stereoisomer level. © 2019 Society of Chemical Industry