Photochemical and Photophysical Processes in Photochemotherapy, Search for New Drugs

The data on the structure, photochemical and photophysical properties of furocoumarins (psoralens) and their analogs are collected and systemized in this review. Current points of view about the role of triplet states and reactions of [2+2]-photocycloaddition in the coupling of these compounds with biomacromolecules (DNA, proteins, lipids) upon photoexcitation by the light of the UV-A range (320‒400 nm), as well as electron transfer and reactions of the furocoumarin triplets with oxygen to afford active oxygen structures, are presented. The interaction of furocoumarin triplets with biomacromolecules is a basis of photochemotherapy (PUVA therapy). The use of furocoumarins of natural origin in the PUVA therapy has revealed a series of unwanted side effects. Therefore, in recent years, attempts have been made to synthesize new compounds for photochemotherapy. The current state of the art in these studies is considered in the review: these are modified psoralens, derivatives of angular furocoumarins, angelicine and allopsoralen, and nitrogen-containing psoralen isosteres, furoquinolinones and furodihydroquinolines.