ABSTRACT
A number of sensitizers have been developed and proposed as alternatives to hematoporphyrin derivative for use in photodynamic therapy. Since hematoporphyrin derivative results from the oligomerization of the porphyrin hematoporphyrin, it is not too surprising that many of these “second-generation” sensitizers are themselves based on the porphyrin nucleus. The majority of chlorins have been generated through two different approaches. One method involves the modification of a preformed porphyrin to generate a chlorin, whereas the second uses chlorophyll as the starting material for the synthesis of other chlorins. One approach that has led to the synthesis of a new series of sensitizer utilized a vinyl-substituted porphyrin as the diene component of a Diels-Adler addition with an electron-deficient dienophile. The development of new photosensitizers for photodynamic therapy remains a rapidly expanding area. However, despite the wealth of knowledge available on in vitro and in vivo effects of such sensitizers, little comparative data exist.
