CONJUGATED DIENE FORMATION PROMOTED BY TRIPLET ACETONE ACTING UPON ARACHIDONIC ACID

Abstract

Abstract— Triplet acetone, whether generated from the decomposition of tetramethyldioxetane, enzym‐atically or by optical excitation, induces conjugated diene formation from micelle‐solubilized arach‐idonic acid as judged from the increase in A. Especially with optically generated triplet acetone, thiobarbituric acid reactive products could also be detected. When tetramethyldioxetane thermolysis was the source of triplet acetone, the activation energy for diene formation was the same as for thermolysis indicating that the latter is the rate determining step. Stern‐Volmer data indicate that the suppression of triplet acetone by arachidonic acid is diffusion controlled or almost so. Anthracene derivatives which are well known abstractors of energy from triplet acetone, decreased the rate of diene formation. Our results fully support the earlier inference that the observed lipid peroxidation is promoted by an excited species produced when substrates capable of enzymatic excitation are added to appropriate cells or organelles. Since lipid peroxidation efficiently generates excited species, the present results raise the possibility of an amplification mechanism and suggest that the effects produced by triplet carbonyls mimic those of ‘active oxygen species’.