Environmental degradation of the insect growth regulator methoprene (isopropyl (2E,4E) 11 methoxy 3,7,11 trimethyl 2,4 dodecadienoate). I. Metabolism by alfalfa and rice

Article abstract of DOI:10.1021/jf60194a022

The metabolic fate of isopropyl (2E, 4E) 11 methoxy 3,7,11 trimethyl 2,4 dodecadienoate, a new insect growth regulator (common name, methoprene; trademark Altosid), was studied in alfalfa and rice as a function of time. The major metabolic pathways involved ester hydrolysis, O demethylation, and oxidative scission of the 4 ene double bond. The principal nonpolar metabolite was 7 methoxycitronellal which was isolated from vapors evolved from the plants. Chromatographic evidence strongly suggests the incorporation of radiolabel from the extensively degraded (2E) [5 ¹⁴C]methoprene molecule into carotenoids, chlorophylls, and other higher molecular weight plant constituents. Yields of primary metabolites were grossly inflated (10x too high) unless thin layer chromatography was accompanied by prior purification by gel permeation chromatography, because much radioactivity was attributed to coeluting natural products. Rapid metabolism of methoprene to biologically inocuous derivatives was characteristic of both rice and alfalfa.