Further Studies on Anti-Thyroxine Effects of Various Compounds. ∗

Abstract

Summary

(1) The study of compouds inhibiting the peripheral metabolic action of thyroxine in thyroidectomized rats has been extended to such substances as vit. A, vit. B₁₂, cholesterol and a series of aliphatics and aromatics carrying the 3,5-diiodo-4-hydroxyphenyl grouping. (2) The compounds found capable of producing approximately 50% inhibition were vit. A, β-carotene, cholesterol, butyl-3,5-diiodo-4-hydroxybenzoic acid, and x-methyl-β-(3,5-diiodo-4-hydroxyphenyl) -propionic acid. Several other substances were found to be less active than these. No compound tested was found clearly active as a thyroxine antagonist at an inhibitor: thyroxine ratio of less than 300.