Methoxsalen is a naturally occurring photoactive substance found in the seeds of the Ammi majus (Umbelliferae) plant. It belongs to a group of compounds known as psoralens or furocoumarins. The chemical name of methoxsalen is 9-methoxy-7H-furo [3,2-g] [1]-benzopyran7-one. It has an empirical formula of C12H8O4 and a molecular weight of 216.19 g mole−1. Photochemotherapy (PUVA) is...