Chemical Characterization of the Diboa-Glc/Atrazine Reaction.

Naturally occurring phytochemicals of the 1,4-benzoxazin-3-one (Bx) class exhibit broad chemical reactivity that includes detoxification of chlorotriazine herbicides. Recently, the Bx compound, 2-β-d-glucopyranosyloxy-4-hydroxy-1,4-benzoxazin-3-one (DIBOA-Glc), was identified as the reactive compound in Eastern gamagrass (Tripsacum dactyloides) roots capable of degrading atrazine. Using radiolabeled atrazine in combination with various chromatographic techniques (HPLC-UV, HPLC-MS-MS, and IC), we have further characterized the DIBOA-Glc/atrazine reaction. Studies included determination of reaction kinetics, identification of intermediates and products, pH effects, and soil dissipation of atrazine. Findings from these studies demonstrated that DIBOA-Glc was consumed in the reaction and was not acting catalytically, as previously proposed. A stable reaction intermediate was identified and shown to be DIBOA-Glc and atrazine linked via the hydroxamic acid moiety at the C-2 position of the triazine ring. Identification of this intermediate supported previous work conducted with model compounds. Additionally, the formation of hydroxyatrazine and Cl^- as products confirmed that the mechanism was a nucleophilic attack and refuted previous speculation regarding the fate of Bx compounds in this reaction. To complete the reaction characterization, on-going studies will attempt to identify the reaction product(s) of DIBOA-Glc. Characterization of the DIBOA-Glc/atrazine reaction will help determine the potential of using DIBOA-Glc as an atrazine mitigation and remediation tool, as well as contribute to the larger body of knowledge regarding Bx reactivity.