Preparation and Biological Evaluation of [111In]-THPP [5, 10, 15, 20-tetrakis (4-Hydroxyphenyl) Porphyrin] Complex in Healthy Rats Via SPECT Imaging

The aim of this research was the synthesis of 111In-THPP, and its evaluation as a new imaging agent. The 111In-THPP radiotracer was synthesized by 111InCl3 and 5, 10, 15, 20-tetrakis (4-hydroxyphenyl) porphyrin) (THPP) in solution for 60 min at 80˚C. In-111 radionuclide was produced from proton bombardment of natCd target using 30MeV protons and 150μA current. Separation was achieved using ion chromatography method with the separation yield of >98%. In order to determine the radiolabeling yield (or metallation) radio thin layer chromatography (RTLC) and high performance liquid chromatography (HPLC) were used (with the radiochemical yield of >99% for both methods). The radiolabeled compound was injected to the healthy rats and the biodistribution studies were performed using scarification. The single photon emission computed tomography (SPECT) imaging within 2-24h shows the accumulation of  111In-THPP in the kidneys, compared to other organs. 111In-THPP is essentially excreted via kidneys. Due to relatively low liver uptake and kidney wash-out, 111In-THPP could be a potential agent for imaging.