Studies on the porphine labeled with 99mTc-pertechnetate

The aim of this research is to use acetylacetonate as a 99mTc chelating agent label with porphyrin and evaluate its radiochemical and biological characteristics. Stannous chloride was used as a reductant to determine the chemical and biological characterization of 99mTc-complexes from labeling porphine (4',4'',4'''-(2lH,23H-Porphine-5,10,15,20-terayl)tetrakis-(benzoic acid), TPPB) with 99mTc-pertechnetate. Instant thin layer chromatography (ITLC), size exclusion chromatography (SEC), paper electrophoresis, and UV/Vis spectrophotometry were used to evaluate chemical characterization. Finally, biodistribution and liver function tests were applied to evaluate biological characteristics. The results of this study show that the labeling efficiency of 99mTc(acac)-TPPB was nearly 100% when using acetylacetone (acac) as a conjugator. Three major 99mTc(acac)-TPPB complexes were separated by SEC, and all of them were hydrophilic. The UV-Vis spectra of 99mTc(acac)-TPPB complexes closely resembled those of the TPPB, but the wave lengths of their peaks changed 430, 521, 556, 591 and 647 nm after complexation. The biodistribution study selected the liver as the target organ. The 99mTc(acac)-TPPB complex may cause short-term liver injury. However, this injury can be repaired, and the reagent is quickly metabolized. Hence, the toxicity of the 99mTc(acac)-TPPB complex is within an acceptable range, and making it a promising liver imaging agent. (author)