Simple synthesis of (3,5-/sup 125/I)diiodo-L-thyronine and of (3,5-/sup 125/I)L-thyroxine of high specific activity
The customary methods for labeling T/sub 4/ and its analogs, iodination or exchange-labeling, are not applicable to those iodothyronines whose iodine atoms are exclusively in the nonphenolic ring. Therefore, (3,5-/sup 125/I)diiodo-L-thyronine had to be synthesized by a different method. This synthesis involves the coupling of (/sup 125/I)diiodo-L-tyrosine with 4-hydroxy-3,5-diiodophenylpyruvic acid to form L-thyroxine labeled in the nonphenolic ring, followed by removal of the two unlabeled iodine atoms in the phenolic ring. High specific activity, limited only by that of the (/sup 125/I)diiodo-L-tyrosine used as starting material, can be achieved. Radioactivity yields are approximately 36% in the coupling reaction and approximately 86% in the deiodination reaction, amounting to an overall yield of greater than 30%. L-Thyroxine and 3,5-diiodo-L-thyronine were purified by ion-exchange chromatography. Their radiochemical purity was checked by radiochromatography.
- Research Organization:
- National Inst. of Health, Bethesda, MD
- OSTI ID:
- 5335082
- Journal Information:
- Endocrinology; (United States), Journal Name: Endocrinology; (United States) Vol. 101:4; ISSN ENDOA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
62 RADIOLOGY AND NUCLEAR MEDICINE
AMINO ACIDS
BETA DECAY RADIOISOTOPES
BIOSYNTHESIS
CARBOXYLIC ACIDS
CHROMATOGRAPHY
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
HORMONES
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPES
LABELLING
NUCLEI
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
PEPTIDE HORMONES
RADIOACTIVITY
RADIOISOTOPES
SEPARATION PROCESSES
SYNTHESIS
THYROID HORMONES
THYROXINE