A Dose Response Analysis of Purpurin Derivatives Used as Photosensitizers for the Photodynamic Treatment of Transplantable Fanft Induced Urothelial Tumors

Abstract

Rats engrafted with transplantable N-[4-(5-nitro-2-furyl)-2-thiazolyl] formamide (FANFT) induced urothelial tumors were treated with purpurin derivatives and red light (> 590 nm., 360 joules/cm2). Treated and control tumors were harvested 12 days after treatment and dry weights compared. At doses of 5.0 .mu.g/gm. and 2.5 .mu.g/gm body weight, the purpurins designated NT1 and NT2, when combined with light, caused statistically significant (p < 0.02) tumor regression when compared to light shielded controls. At 1.0 .mu.g/gm body weight, NT1 and light also induced significant tumor regression (p < 0.02). Purpurins, which have strong absorption bands above 650 nm and can be synthesized with a high degree of purity, appear to have potential as photosensitizers for photodynamic therapy.