THE ANTITHYROXINE ACTIVITY OF THYROXINE ANALOGS

SINCE the discovery of the inhibitory action of para-aminobenzoic acid on the sulfonamides, the concept of antagonistic action between compounds closely related structurally has been applied to many fields of biologic activity, as reviewed recently by Woolley (1947 (1)). In 1946 (2) Woolley reported on the synthesis of a series of compounds which were antagonistic to thyroxine. Using as a criterion of such activity the ability of the compounds to protect tadpoles against lethal doses of thyroxine, he found that several ethers of N-acetyl-diiodotyrosine possessed the property of inhibiting the activity of thyroxine. Some of these compounds exhibited in addition a weak thyroxine-like effect. To explore further the possibility of antagonizing the action of thyroxine by compounds related to it structurally, a series of substituted thyronine compounds were examined for their antithyroxine activity. These compounds were more closely related structurally to thyroxine than the compounds studied by Woolley. They w...