PHOTOCHEMISTRY and PHOTOBIOLOGY WITHOUT LIGHT

Abstract—This review covers the literature since 1980 on chemically and enzymatically generated electronically excited species. The emphasis lies on triplet states of carbonyl products that are derived from dioxetanes and dioxetanones as precursors or from suitable enzymatic oxygenations. Singlet oxygen, an important excited state species in biological processes, is not explicitly treated. The utilization of triplet excited carbonyl products to promote photochemical and photobiological transformations by energy transfer are of primordial interest and not the photomechanistic behavior, photophysical properties and inherent photochemical reactions of such excited state species. Thus, the coverage concentrates on photodamage of DNA and RNA, the photochemistry of flavins, vitamin D, tryptophan, arachidonic acid, chlorophyll, lipid peroxidation, urocanase activation, excitation of chlorophlasts, and the aerobic oxidation of Schiff bases derived from amino acids and proteins. The potential perspectives of employing authentic dioxetanes and enzymatically generated dioxetane intermediates as effective photon equivalents in photochemotherapy, phototoxicity, photoaffinity labeling and photogenotoxicity are pointed out, in the hope of stimulating more intensive activity in this emerging and novel bioorganic and photobiological field.