Radiosynthesis and biological evaluation of [sup.166]Ho labeled methoxylated porphyrins as possible therapeutic agents

[sup.166]Ho labeled 5,10,15,20-tetrakis(3,4-dimethoxyphenyl) porphyrin, and 5,10,15,20-tetrakis(3,4,5-trimethoxyphenyl) porphyrin ([[sup.166]Ho]-TDMPP and [[sup.166]Ho]-TTMPP respectively) were prepared with acceptable radiochemical purity and specific activities. Stability and partition coefficient of the complexes were determined in the final formulations and biodistribution studies in mouse demonstrated high accumulation of [[sup.166]Ho]-TDMPP in the lung and liver and less excretion through the kidney while [[sup.166]Ho]-TTMPP was mostly excreted into intestines and kidneys while lungs were a minor accumulation site. In contrast to other reported radiolanthanide labeled porphyrins these two complexes showed less liver accumulation. Further investigation of their potential therapeutic properties is of interest. Keywords Methoxylated porphyrins * [sup.166]Ho * Biodistribution * Cancer therapy