Detoxification Mechanism of Hinokitiol by Alternaria alternata and Its Application in Agricultural Antifungal Control.

Alternaria alternata is a common plant pathogen that can infect crops and reduce their production. In this work, an antagonism experiment between A. alternata and the essential oil of arborvitae ( Platycladus orientalis ) was performed, and it was proven that A. alternata had developed resistance to this plant-derived fungicide. A. alternata facilitated the biotransformation of hinokitiol ( 1 ), the main antifungal compound in the essential oil of arborvitae, into ( R )-2-hydroxy-β-methylbenzeneethanol ( 2 ), which does not have antifungal activity against A. alternata . This biotransformation is an unusual ring-contraction reaction that was verified to be catalyzed by P450 enzyme hydroxylation and Baeyer-Villiger oxidation. In addition, the P450 enzyme inhibitors 1-aminobenzotriazole and piperonyl butoxide effectively prevented the destruction of the hinokitiol structure by A. alternata , and the combined use of these P450 enzyme inhibitors significantly increased the antifungal activity of hinokitiol. This work provides a theoretical reference for the further development of botanical fungicides.