Experimental bases and primary trials of photochemotherapy of psoriasis by a non-cancerigenic monofunctional furocoumarin, 3-carbethoxypsoralen]

The carcinogenic risk of the photochemotherapy (PUVA) with bifunctional furocoumarins such as 8-methoxypsoralen (8-MOP) forming cross-links in cellular DNA has initiated a search for active but less dangerous psoralens. The 3-carbethoxypsoralen (3-CPs), studied in the yeast Saccharomyces cerevisiae, has been very photoactive on DNA forming only monoadditions to DNA. In Mice it was demonstrated that after local or intra-peritoneal administration, 3-CPs is non toxic, non erythematogenic and non carcinogenic in contrast to 8-MOP. A limited study on ten psoriatic patients has shown that after local application 3-CPs exhibits about the same therapeutic activity as 8-MOP.