Synthesis and photodynamic activity of some tetraazoporphyrin derivatives

Summary Photodynamic therapy (PDT) is a treatment modality for a number of human neoplasms. The drug preparation most widely used in current clinical trials is photofrin. Photofrin lacks definite structure and as a result the interpretation of its pharmacokinetic data is difficult. Thus the development of new sensitizers of known structure such as the phthalocyanines and naphthalocyanines has been proposed. In our approach, we have studied the use of tetraazaporphyrins (porphyrazines) as sensitizers. This class of sensitizers has received very little attention. A number of porphyrazines were synthesized via the cyclization of tricyanovinyl amines and dinitrile amines in pentanol solution of magnesium oxide. These porphyrazines were converted to their respective zinc chelates and tested for their stability in acidic media and for their ability to photoinactivate cells in culture. Results indicate that these porphyrazines show promise and must be investigated further for applications in PDT.