[en] The antibiotic, disodium (+)-(Z)-[[[1-(2-amino-4-[2-¹⁴C]thiazolyl)-2-[[(2S,3S)-2-(carbamoyloxymethyl) -4-oxo-1-sulfonato-3-azetizinyl]amino-2-oxoethylidene]-amino]oxy]acetate([¹⁴C]AMA-1080) was synthesized from [¹⁴C]thiourea. Trisodium(+)-(Z)-[[[1-(2-amino-4-[2-¹⁴C]thiazolyl)-2-[[(1S,2S)-3-carbamoyloxy-1-carboxylato-2-sulfonatoaminopropyl]amino]-2-oxoethylidene]amino]oxy] acetate([¹⁴C]AMA-1294) as the principal metabolite of [¹⁴C]AMA-1080 was also prepared. (author)