Thyronine structure

Thyroid hormones and their structural analogs showed lower DPPH-scavenging activity in comparison with butylated hydroxytoluene (BHT) as a standard compound. 3,5,3, 5 -tetraiodothyroacetic acid, 3,3,5 -triiodo-L-thyronine, and thyroxine showed the highest antioxidant activity measured by DPPH reduction, 3,5,3 5 -tetraiodothyroacetic acid having over 20% of the activity of BHT (05). 

In the first report on phenolic PCB metabolites in blood from rats after exposure to Aroclor 1254, and from environmentally exposed Baltic grey seals and humans only a few OH-PCBs were structurally identified [39]. Since then, additional metabolites have been identified and are shown in the chromatogram of a human blood sample taken from a Faeroe Island woman (Fig. 6A). All the identified metabolites have chlorine atoms attached to the carbons ortho to the oxidized carbon. With a few exceptions, the hydroxy-group is attached to one of the two para-positions of the PCB molecule. These structural elements are also found in 3,3, 4, 5-tetraiodo-L-thyronine, or thyroxine, the natural substrate of TTR [44]. The affinities of the retained OH-PCB congeners are up to 10 times greater than for thyroxine [44,134]. The structural similarity to thyroxine was... 

Figure 6.18. Receptor site of thyroid receptor beta filled with spheres (for sake of clarity, sphere centers are depicted actual size of spheres is larger, so that spheres overlap) and thyronine. Crystal structure taken from the PDB (ID Ibsx).

Degradative studies suggested the presence of two benzene rings, a phenolic oxygen, an ether oxygen, and an alanine side chain. Of the possible structures, that now accepted for thyronine was considered most likely and was proved by synthesis (350). The position of the iodine... 

The basic structure of T3 and T4 is that of thyronine, a substituted tyrosine [0-(4-hydroxyphenyl)tyrosine] (Figure 33-1). Iodine residues at positions 3 and 5 of the inner phenolic ring confer on the outer ring a preferred orientation approximately 120° to the plane of the inner ring (Figure 33-2). Hormonal activity is maximal when the following requirements are met ... 

Structure of 3,3, 5,5 -tetraiodo-L-thyronine (T4). T4 is a substituted tyrosine or a diphenylether derivative of alanine. Positions in the outer phenolic ring have prime designations, in contrast to those in the inner ring. T4 is iodinated at positions 3 and 5 in both rings. [Modified and reproduced with permission from V. Cody, Thyroid hormone interactions molecular conformation, protein binding, and hormone action. Endocr. Rev. 1,140 (1980). (c)1980by the Endocrine Society.]... 

Leeson, P.D., Ellis, D., Emmett, J.C., Shah, V.P., Showell. G.A., and Underwood, A.H., Thyroid hormone analogues. Synthesis of 3 -substituted 3,5-diiodo-L-thyronines and quantitative structure-activity studies of in vivo thyromimetic activities in rat liver and heart, J. Med. Chem., 31, 37, 1988. 

Jorgensen EC, Reid JAW. Thyroxine analogues. XI. Structural isomers of 3,5,3 -triiodo-DL-thyronine. J Med Chem 1964 7 701-705. 

Further st udy of the effect of various analogs of thyroxine on the swelling of mitochondria in vitro (Shaw el al., 19,59) has revealed that thyronine derivatives la( king a halogen substitution in cither ring of the diphenyl ether have little or no activity there is a similar structural requirement for... 

Thyroxine and Triiodothyronine. Thyroxine is one of the earliest recognized hormones (isolation in 1915 by Kendall determination of structure and synthesis in 1925 by Harington). It is an iodine-containing aromatic amino acid. The non-iodinated parent compound of thyroxine is called thyronine. The unusual structural feature is the diphenyl ether group. Iodine atoms may be substituted at the positions 3, 5, 3, 5. A few diiodo- and triiodothyronines have physiological significance, especially 3,5,S -triiodothyronine, which is about five times as active as thyroxine itself. 

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