|
| Fig. 55.4 Molecular structure of furocoumarin from plants of the Psoralea genus. |
Psoralens are a subclass of drugs that belong to a group of compounds called furocoumarins, which are derived from the fusion of a furan with coumarin (Fig. 55-4). Psoralens are natural constituents in a large variety of medicinal plants (e.g., limes, lemons, figs, parsnips). The two psoralens that are used therapeutically in the United States are methoxsalen and trioxsalen. Methoxsalen (8-methoxypsoraIen, 8-MOP) is a naturally occurring photoactive plant substance found in the seeds of
Amnii majus, a plant that grows wild along the Nile delta. Methoxsalen is absorbed from the upper gastrointestinal tract and metabolized by the intestine and liver. Ninety percent is excreted within 24 hours, with the major portion being excreted in the urine. Trioxsalen is a synthetic psoralen usually reserved for the treatment of vitiligo.
