IUPAC REPORTS ON PESTICIDES .37. CHIRALITY IN SYNTHETIC AGROCHEMICALS- BIOACTIVITY AND SAFETY CONSIDERATION

Most synthetic agrochemicals with chiral structures are marketed as ra cemates even though the desired biological activity may be derived fro m only one enantiopure isomer. However some synthetic agrochemicals su ch as pyrethroid insecticides, aryloxypropanoate herbicides and triazo le fungicides are marketed as the most biologically active enantiopure isomer. Numerous reports describing the relative biological activitie s, preparations and analyses of enantiopure agrochemicals are availabl e. Some examples of how different enantiomers in racemates are selecti vely metabolized have also been reported. When agrochemicals have chir al structures, efforts should be made to define the mode of action, el ucidate metabolic pathways and to define the human and environmental t oxicity of each enantiopure isomer. If there are large differences in the biological activities of individual enantiomers in racemates, it i s desirable to develop and use only the enantiopure isomer with the hi ghest sought-after biological activities.