Synthesis of functionalised HP-DO3A chelating agents for conjugation to biomolecules

Two novel bifunctional chelating agents (BFCAs) based on the structure of 10-(2-hydroxypropyl)-1,4,7-tetraazacyclododecane-1,4,7-triacetic acid (HP-DO3A) have been designed and synthesized. BFCAs are able to strongly coordinate metals (e.g. Gd(iii)) and radiometals (e.g.(90)Y(iii), (177)Lu(iii) and (111)In(iii)), and find applications in the synthesis of products for the imaging and treatment of several cancer types. Indeed, these two BFCAs have been employed in solid-phase peptide synthesis (SPPS) and coupled to well-known peptides such as bombesin and RGD analogues in order to target tumor cells. We also report here the conjugation of one of them to Lys(8)-oxytocin and radiolabeling with (111)In(iii) to obtain a new radiopharmaceutical product with potential applications in the diagnosis of tumors over-expressing oxytocin receptors.