CAROTENOHEMATOPORPHYRIN ACIDS AS TUMOR LOCALIZING AND VISUALIZING AGENTS

A new class of molecules consisting of two carotenoid polyenes covalently linked to free-carboxylic-acid-containing derivatives of naturally occurring heme (exemplified by structure1) have been synthesized for use as tumor localizing, visualizing and diagnostic agents. These carotenohematoporphyrin acids are designed to be administered by injection or other means, to localize preferentially in neoplastic tumor tissue, to absorb visible light and thereupon to fluoresce red light that can be detected by eye or by instrumental methods, thus identifying and delineating the tumor tissue. Furthermore, these compounds are designed to quench porphyrin triplet states by triplet tripletenergy transfer to an attached carotenoid. This will prevent formation of singlet oxygen by energy transfer from porphyrin triplet states, and thus prevent tissue damage to healthy tissue caused by the singlet oxygen.