Metabolism of fungicide 2-allylphenol in Rhizoctonia cerealis

- 2-Allylphenol was metabolized and bio-transformed by Rhizoctonia cerealis.
- Four metabolites were detected by HPLC and MS/MS in R. cerealis cultures.
- Based on the structures of the metabolites determined by NMR, possible degradation pathways of 2-allylphenol were proposed.

2-Allylphenol is a biomimetic synthetic fungicide that mimics the compound ginkgol found in gingko fruit (Gingko biloba L.). This systemic fungicide can effectively suppress a wide range of plant diseases, including wheat sharp eyespot (Rhizoctonia cerealis). However, its degradation in environment after application is still unknown. To understand this fungicide degradation, major metabolites of 2-allylphenol in R. cerealis were examined. The parent and metabolites of 2-allylphenol were detected and quantified in the mycelia and liquid medium. Results showed that 2-allylphenol was metabolized and bio-transformed by R. cerealis, and four metabolites were found, including 2-(2-hydroxyphenyl) acetic acid (M1), 2-(2, 3-dihydroxypropyl) phenol (M2), 2-(2-hydroxypropyl)-phenol (M3) and 2-(3-hydroxypropyl)-phenol (M4). Based on the results, we propose that the biodegradation pathway is that 2-allylphenol is rapidly oxidized into metabolite M2 and hydrolyzed into M3 and M4, which formed M2, and carboxylation of M2 to 2-hydroxy-3-(2׳-hydroxyphenyl) propionic acid which undergo hydrolyzation and decarboxylation to form M1. 2-Allylphenol can be bio-transformed to new compounds by R. cerealis, suggesting the existence of microbe metabolic pathways for 2-allylphenol.

High performance liquid chromatography (HPLC) chromatograms of different chemical fractions after 72 h incubation at 25 °C in the dark. A: extracts of Rhizoctonia cerealis control mycelia; B: 2-allylphenol standard in ethanol; and C: extract of R. cerealis mycelia treated with 2-allylphenol. Metabolites (M1-M3) of 2-allylphenol (P) are labeled.