Study on the labeling of paclitaxel with radionuclide 125I

Abstract: The modified Ch-T labeling method has been investigated.. Firstly, the paclitaxel was reacted with non-radioactive NaI. Then the mixtures was radiolabeled with 125I by Ch-T method. The radiolabeling efficiencies were analyzed by thin paper chromatography and HPLC. After purified, the radiochemical purity and stability of the radiolabeled compounds were tested in vitro in different conditions, such as temperature or solvent and the final labeled compound was identified by infrared spectra. The radiolabeled efficiency of the compound produced by the modified Ch-T method was compared with those produced by the nitric acid oxidization method and the common Ch-T method. The radiolabeling efficiency of the labeled compound produced by the modified Ch-T method was about 63.1%±5.7% and the radiochemical purity was about 96.3%±1.3%. After 24 hours stored in NS or alcohol system at 4℃,The radiochemical purity of the product was above 95%, and 90% after 120hours. The labeled product was also stable in serum, after 24h stored at 4℃and 37℃, the radiochemical purities were 92.3%±0.4% and 89.5%±0.6% respectively. The modified Ch-T method was simple and convenient. The radiolabeling efficiency was high and the labeled compound was stable. It was qualified for the isotopic tracing experiment in vivo.