Purpurins and benzochlorins as sensitizers for photodynamic therapy.

Purpurins and benzochlorins are hydrophobic second generation photosensitizers, which have sizable absorption in the 650-780 nm range and exhibit photodynamic activity against tumors after visible light treatment. This review summarizes the published data regarding these compounds: from the spectroscopic, photophysical and photochemical characteristics to the in vivo and in vitro photodynamic inactivation of tumors and normal tissue effects. Some mechanistic studies using both the Sn-etiopurpurin and/or the Cu-benzochlorin derivatives are also reviewed.