Evaluation of tetraphenyl-2,3-dihydroxychlorins as potential photosensitizers

A series of beta,beta-dihydroxychlorins derived from meso-tetraphenylporphyrins (TPPs) have been synthesized. Their in vitro cytotoxicity has been measured and compared to BPDMA (verteporfin). Under the assay conditions BPDMA had an LD50 (lethal dose to kill 50% of cells) value of 0.007 muM (5 ng/mL). The LD50 values for the TPP derivatives varied from 1.7 x 10(-2) to 9.9 muM depending upon the substituents and their position on the phenyl groups. One example of the dihydroxychlorin prepared from unsubstituted 5,15-diphenylporphyrin was examined and this exhibited an LD50 of 2.4 x 10(-3) muM! Copyright (C) 2002 Society of Porphyrins & Phthalocyanines.