Rational herbicide design by synthesis of inhibitors for the peroxidase catalysed oxidation of indolyl‐3‐acetic acid

An attempt has been made to design a herbicide by synthesising active site directed irreversible inhibitors for the peroxidase‐catalysed oxidation of indolyl‐3‐acetic acid (IAA). A variety of substituted indoles were prepared and found to bind reversibly to the enzyme, but none produced any progressive inhibition, nor showed any herbicidal activity. This may be related to the fact that the inhibitors can be degraded by peroxidase in vitro since, if this occurred in the plant, the compounds could not then interfere with IAA oxidation.