Porphyrinoid Drug Conjugates

Drawing inspiration from nature today remains a time-honored means of discovering the therapies of tomorrow. Porphyrins, the so-called "pigments of life'' have played a key role in this effort due to their diverse and unique properties. They have seen use in a number of medically relevant applications, including the development of so-called drug conjugates wherein functionalization with other entities is used to improve efficacy while minimizing dose limiting side effects. In this Perspective, we highlight opportunities associated with newer, completely synthetic analogs of porphyrins, commonly referred to as porphyrinoids, as the basis for preparing drug conjugates. Many of the resulting systems show improved medicinal or site-localizing properties. As befits a Perspective of this type, our efforts to develop cancer-targeting, platinum-containing conjugates based on texaphyrins (a class of so-called "expanded porphyrins'') will receive particular emphasis; however, the promise inherent in this readily generalizable approach will also be illustrated briefly using two other common porphyrin analogs, namely the corroles (a "contracted porphyrin'') and porphycene (an "isomeric porphyrin'').