Wirksamkeit schilddrüsenhemmender Stoffe auf die Xenopusmetamorphose

Abstract

A number of the compounds which had been shown byAstwood, in experiments on the rat, to have an action on the thyroid, were investigated for their inhibitory effect on the metamorphosis of Xenopus. The same compounds which had been proved to be active in the rat, were also shown, with few exceptions (e. g. p-amino-benzoic acid), to be active in Xenopus. On the other hand several substances which were not active in the rat (e. g. ammonium thiocyanate, thioacetamide) were active in Xenopus. Several of the compounds whichAstwood had described as not especially active or even inactive, proved to be particularly active. N-allylthiourea is about 10–20 times, and N-benzoylthiourea up to 200 times more active than thiourea or thiouracil. Ammonium thiocyanate and thioacetamide, which were found byAstwood to be inactive, showed a higher activity in Xenopus than potassium thiocyanate, which is active in the rat. The possible reasons for these big differences in activity in the rat and in Xenopus are discussed.