Cyclopropanecarboxylic acids complexes

The receptor interaction of the pyrethrums with the sodium channel complex is stereospecific and dependent on the stereochemistry of the carboxylic acid. In the case of the pyrethrolds, the most active isomers are the 1R,3-c/s- and 1 R,3-frans-cyclopropanecarboxylates. The IS-c/ s- and -frans-isomers are inactive and actually are antagonists to the action of the IR-isomers. 

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