BACKGROUND: Herbicide safeners mitigate crop damage without reducing herbicide efficacy. Here, the protective effects of phenoxyacetyl oxazolidine derivatives as potential safeners were evaluated with a view toward reducing injury caused by sulfonylurea herbicide nicosulfuron to sensitive maize varieties. RESULTS: Growth indices demonstrated that the bioactivity of compound 9 (N-phenoxyacety-2-methyl-2,4-diethyl-1,3-oxazolidine) was superior to that of R-28725 and all other compounds tested. Compound 9 induced endogenous glutathione and upregulated glutathione-S-transferase (GST) in maize. Thus, it could enhance maize tolerance to nicosulfuron. Compared with the untreated water control group, the maximum reaction rate of GST was increased by 37.62%, while the maximum velocity of GST was decreased by 61.93% after treatment with compound 9. Acetolactate synthase relative activity was significantly enhanced in the case of treatment with compound 9, indicating the excellent protective effects of compound 9 against nicosulfuron in maize. CONCLUSIONS: The present work demonstrates that phenoxyacetyl oxazolidine derivatives are potentially efficacious as herbicide safeners and merit further investigation.

The structure of the title compound (systematic name: N-{[(2-hydroxyphenyl)methylidene]amino}morpholine-4-carbothioamide), C12H15N3O2S, was previously determined (Koo et al., 1977) using multiple-film equi-inclination Weissenberg data, but has been redetermined with higher precision to explore its conformation and the hydrogen-bonding patterns and supramolecular interactions. The molecular structure shows intramolecular O—H...N and C—H...S interactions. The configuration of the C=N bond is E. The molecule is slightly twisted about the central N—N bond. The best planes through the phenyl ring and the morpholino ring make an angle of 43.44 (17)°. In the crystal, the molecules are connected into chains by N—H...O and C—H...O hydrogen bonds, which combine to generate sheets lying parallel to (002). The most prominent contribution to the surface contacts are H...H contacts (51.6%), as concluded from a Hirshfeld surface analysis.

AbstractC14H17NO4, monoclinic, P21/c (no. 14), a = 9.6719(19) Å, b = 13.529(3) Å, c = 11.094(2) Å, β = 112.31(3)°, V = 1342.9(5) Å3, Z = 4, Rgt(F) = 0.0480, wRref(F2) = 0.1422, T = 293(2) K.