Radioiodination of hydroxyphenyl-ethylamine derivatives of some digitalisglycosides and their aglycones

Article abstract of DOI:10.1002/jlcr.2580150127

As potential adrenal gland imaging agents the tyraminyl-(p-hydroxyphenyl-ethylamine) derivatives of the heart-glycosides digitoxin, digoxin, gitoxin and their aglycones digitoxigenin, digoxigenin and gitoxigenin are synthetized and radioiodinated. The aglycones are dehydrated by oxidation to the corresponding ketone and reacted in a regioselective way with tyramine as aminocomponent and NaBH₃CN as reducing agent to the compounds 3-tyraminyl-3-deoxy-digitoxigenin 7, 3-tyraminyl-3-deoxy-digoxigen-12-one 8 and 3-tyraminyl-3-deoxy-gitoxigen-16-one 9. After the oxidative fission of the terminal 3'''-digitoxose to the 3''',4'''-dialdehyde the glycosides are aminated reductively with NaBH₃CN/tyramine to the monotyramine derivatives, forming 4-oxa-perhydroazepine by cyclization, and to the dityramine derivatives: 3'''-monotyraminyldigitoxin 19, 3'''-monotyraminyldigoxin 20, 3'''-monotyraminylgitoxin 21, 3''',4'''-dityraminyl-digitoxin 22, 3''',4'''-dityraminyldigoxin 23, 3''',4'''-dityraminylgitoxin 24. The insertion of tyramine allows a rapid radioiodination of the glycoside and aglycone derivatives. An activity of 250 respectively 450mCi iodinated product / 1mg initial material could be attained with carrier-free ¹³¹J (as Na¹³¹J in NaOH).