Abstract
The influence of 1, 2-alkylene-1, 2, 4-triazolidines and 3, 4-alkylene-1, 3, 4-thiadiazolidines on peroxidizing phytotoxicities was investigated using corn etioplast protoporphyrinogen-IX oxidase (Protox), autotrophic Scenedesmus acutus cells and Echinochloa utilis. Both types of compounds inhibited Protox, caused ethane formation, decreased chlorophyll content and inhibited growth of Scenedesmus and root-growth of Echinochloa, like peroxidizing herbicides such as p-nitrodiphenyl ethers and cyclic imides. All compounds were identified as peroxidizing herbicides. Among the 1, 2-alkylene-1, 2, 4-triazolidines, tetramethylene-triazolidines exhibited the strongest peroxidizing phytotoxicity, trimethylene-triazolidines and pentamethylene-triazolidines were found to be less active peroxidizers. The tetramethylene moiety of the triazolidine-type compounds appears to be essential for producing active peroxidizing compounds. Phytotoxicities by triazolidin-one-thiones and triazolidine-dithiones were more than 10 times stronger than those of triazolidine-diones. Replacing carbonyl groups in the five-membered moiety by at least one thiocarbonyl group produces stronger peroxidizing phytotoxities. Although the Protox inhibition of triazolidine-peroxidizers was 10-70 times stronger than that of the corresponding thiadiazolidine-peroxidizers, the level of other phytotoxic activities was quite similar with both types of peroxidizers. This fact may be caused by isomerization of thiadiazolidines to triazolidines.
