Radical Formation and Peroxidative Activity of Phytotoxic Diphenyl Ethers

Abstract

Phenyl-t-butylnitrone can be used to trap light-induced radicals with isolated chloroplasts, measurable by ESR technique. The radical signals are dramatically amplified and their lifetime prolonged in the presence of peroxidizing diphenyl ethers. A para-substitution with -NO2, - Cl-or - I is necessary, as well as an operating photosynthetic electron transport. The nature of radicals is not yet clear; they may be alkyl or linolenic-acid radicals, but their presence indicates peroxidation. Furthermore, the ESR measurements presented strengthen our hypothesis that peroxidative activity of paraquat and diphenyl ethers are not caused by the same mechanism.