Preparation, molecular modeling and biodistribution of ~(99m)Tc-phytochlorin complex

摘要

Phytochlorin [21H, 23H-Porphine-7-propanoicacid, 3-carboxy-5-(carboxymethyl)13-ethenyl-18-ethyl-7, 8-dihydro-2,8,12,17-tetramethyl-,(7S,8S)] was labeled with ~(99m)Tc and the factors affecting the labeling yield of ~(99m)Tcphytochlorin complex were studied in details. At pH 10, ~(99m)Tc-phytochlorin complex was obtained with a high radiochemical yield of 98.4 ± 0.6 % by adding ~(99m)Tc to 100 mg phytochlorin in the presence of 75 μg SnCl_2·2H_2O after 30 min reaction time. The molecular modeling study showed that the structure of ~(99m)Tc-phytochlorin complex presents nearly linear HO–Tc–OH unit with an angle of 179.27° and a coplanar Tc(N1N2N3N4) unit. Biodistribution of ~(99m)Tc-phytochlorin complex in tumor bearing mice showed high T/NT ratio (T/NT = 3.65 at 90 min post injection). This preclinical study showed that ~(99m)Tc-phytochlorin complex is a potential selective radiotracer for solid tumor imaging and afford it as a new radiopharmaceutical suitable to proceed through the clinical trials for tumor imaging.