The kinetics of incorporation of111In into m-tetraphenylporphine

Preparation and biological evaluation of a carrier free 90yttrium labelled porphyrin as a possible agent for targeted therapy of tumor

In this research article, 5,10,15,20-tetrakis(phenyl)porphyrin (H2TPP) was produced and characterized. Then, radiolabeling of H2TPP was performed using the carrier free Y-90 which was prepared by the use of a home-made yttrium imprinted sorbent. The radiolabeling procedure was accomplished at 60 [Formula: see text] C during 12 h with a suitable radiochemical purity (95 ± 2% ITLC, 99 ± 0.5% HPLC) and specific activity of (1.0 ± 0.1 GBq/mmol). The obtained radio-labeled H2TPP in final formulation was kept for a week in order to investigate the complex stability. Accordingly, the partition coefficient was calculated as log [Formula: see text] 2.05. Furthermore, the biodistribution of the [Formula: see text]Y–TPP was determined in vital organs of normal wild-type rats using scarification studies. The kidneys could mostly remove the radio-complexes from the blood circulation and in less extends from the liver. As a result it is expected that due to its lipophilicity the higher mitochondrial and thus, tumor cell uptake of this radiolabeled porphyrin happens and therefore [Formula: see text]Y–TPP could act as an efficient potential agent for targeted therapy of tumor.

Development of a (68)Ga-Fluorinated Porphyrin Complex as a Possible PET Imaging Agent

AIM

Due to the interesting pharmacologic properties of porphyrins, the idea of developing a possible tumor imaging agent using PET by incorporating (68)Ga into a suitable porphyrin ligand was investigated.

METHODS

(68)Ga-labeled 5,10,15,20-tetrakis(pentafluoro-13 phenyl) porphyrin ((68)Ga-TFPP) was prepared using freshly eluted [(68)Ga]GaCl3 obtained from a 68Ge/68Ga generator developed in-house and 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin (H2TFPP) for 60 min at 100°C.

RESULTS

The complex was prepared with high radiochemical purity (>99% ITLC, >99% HPLC, specific activity: 13-14 GBq/mmol). Stability of the complex was checked in the final formulation and in human serum for 5 h. The partition coefficient was calculated for the compound (log P = 0.62). The biodistribution of the labeled compound in vital organs of Swiss mice bearing fibrosarcoma tumors was studied using scarification studies and SPECT imaging up to 1 h. The complex was mostly washed out from the circulation through kidneys and liver. The tumor-to-muscle ratio 1 h post injection was 5.13.

CONCLUSION

The radiolabeled porphyrin complex demonstrated potential for further imaging studies in other tumor models.

The biological characteristics of a water soluble porphyrin in rat lymph nodes

The biological characteristics of a radiolabeled metalloporphyrin, 5,10,15,20-tetrakis(4-carboxyphenyl)-porphinato [67Cu]copper (II) [( 67Cu]TCPP), in rat lymph nodes, surrounding muscle, fat, and blood were determined. Lymphatic tissue localized greater amounts of [67Cu]TCPP than did surrounding muscle and fat. Inflamed lymph nodes localized greater amounts of [67Cu]TCPP than did noninflamed lymph nodes. Time course studies suggest that the uptake of [67Cu]TCPP in noninflamed and in inflamed lymph nodes may involve different biological processes. The affinity of [67Cu]TCPP for inflamed lymph nodes may be influenced by the degree of inflammation. If further studies confirm these results, [67Cu]TCPP may be useful as a potential radiopharmaceutical for imaging inflamed lymph nodes.

The biodistribution of radiocopper-labeled compounds

Porphyrins form extremely stable chelates with Cu2+. Two copper radionuclides, 67Cu and 64Cu, have attractive nuclear decay properties for use in nuclear medicine applications. We have investigated the use of radiocopper-labeled porphyrins for localization in inflamed tissue and for attachment to antibodies for tumor imaging and therapy. We have examined the biodistribution of a 67Cu labeled porphyrin, [5, 10, 15, 20-tetrakis(4-carboxyphenyl) porphinato [67Cu] copper (II)], 67 CuTCPP. The 67CuTCPP was intravenously injected into the tail vein of Fischer F344 male rats. The kidneys, liver, and spleen localize the greatest amounts of 67CuTCPP. The elimination of 67CuTCPP from the body is described by a normal exponential decay curve with a biological half-life of 108 hours and an effective half-life of 32 hours. We have also examined the biodistribution of 5-(4-carboxyphenyl)-10, 15,20-tris(4-sulfophenyl) porphinato [67Cu] copper (II) anti-Thy 1.2 antibody conjugates in normal and tumor-bearing male AKR/J mice. The liver, kidney, and tumor have the highest uptake of the 67Cu labeled antibody conjugate. In all 67Cu labeled compounds studied, the blood clearance was rapid and the bone concentration of the radiolabeled species was low.

Copper-67 labeled porphyrin localization in inflamed tissue

A series of experiments compared the uptake of 5,10,15,20 tetrakis(4-carboxyphenyl) porphinato [67Cu] copper (II), 67CuTCPP, by the lymph nodes of inflamed and two sets or control rats. The results demonstrate that 67CuTCPP localizes in greater concentration in inflamed lymph nodes than in noninflamed control lymph nodes. This enhanced uptake of 67CuTCPP by inflamed lymph nodes was 3.6 times greater than was the uptake by control lymph nodes. A time course study demonstrated that the uptake of 67CuTCPP by inflamed lymph nodes reached the maximum level by 24 hours post-injection of 67CuTCPP and remained constant throughout the 96 hours examined. It was also found that the uptake of 67CuTCPP by inflamed lymph nodes was not exclusively dependent upon an increase in the weight of inflamed lymph nodes. These studies show that 67CuTCPP has potential as a lymphoscintigraphy agent.

Synthesis and evaluation of an 111In-labeled porphyrin for lymph node imaging

111In-labeled tetra(4-N-methylpyridyl)porphyrin was investigated as a possible lymph node imaging agent. A clinically feasible method for the preparation of this radioactive pharmaceutical was developed from experiments with the synthesis and characterization of the unlabeled complex. The in vivo distribution of the compound in Wistar rats was determined as a function of time. Favorable lymph node-blood, lymph node-muscle, and specific lymph node-surrounding tissue ratios were obtained.