科研之友
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摘要
In order to prepare a specific melanocortin type 2 receptor (Mc2r) ligand, [18F]-tetracosactide ([18F]-beta 1-24-corticotrophin) was prepared in one-step reaction using [18F]SFB and beta-1-24-corticotrophin pharmaceutical solution (1 mg/ml, pH=6.5). [18F]SFB was prepared in a semi-automated module in two steps with an overall radiochemical yield of 83% (decay corrected to E.O.B.), in 90 minutes. The production of all radiolabeled intermediates and radiolabeled peptide was checked by RTLC and HPLC HPLC and Radio-thin layer chromatography showed overall radiochemical purity of %26gt;95%, 91% yield (decay corrected to [18F]SFB) and 76%(decay corrected to E.O.B.) for final radiolabeled peptide at optimized conditions. Preliminary in vivo studies in normal mice was performed to determine the biodistribution of the radiolabeled peptide up to 150 min. Testes and adipocytes showed to have the major tracer uptake which is consistent with the natural distribution of Mc2r receptors in mammals. Testes/blood, testes/muscle ratios for radioligand at 150 minutes were 184 and 1.56 respectively and adipocyte/blood and adipocyte/muscle ratios at 120 minutes were 221 and 142 respectively. These data support the specific receptor binding of the radiolabeled compound as reported for Mc2r receptor accumulation in adipocytes and testes and demonstrates the retention of biological activity of the ligand. This tracer can be used in detection of Mc2r distribution in malignancies and sex organ diseases.
