Molecular and genetic basis of furocoumarin reactions.

The Presently Known Distribution of Furocoumarins (Psoralens) in Plants

The photophysics, photochemistry, photobiology, and structural analysis of furocoumarin derivatives have been reviewed from molecular and interdisciplinary points of view. The molecular aspects have been clear in the photoreaction of furocoumarins since the mid-1900s. Since furocoumarin derivatives absorb UVA light and act as photosensitizers, they have been used as helpful molecular probes and as skin disease drugs. The versatility of these compounds is entirely due to their optical properties. The photoexcited furocoumarins react with biomolecules, especially with pyrimidine bases in DNA, and form mono- and di-adducts. [2 + 2] Photocycloaddition reactions play an important role in the formation of mono- and di-adducts. The degree of photobinding in furocoumarins depends on the types of coumarin compounds, the DNA base sequences, the UVA light doses, excitation wavelengths, temperatures, solvents, and other factors. Consequently, choosing the appropriate conditions can easily control the photoreaction. Furocoumarins have been widely employed for many purposes, and the development of the understanding of their photobiology is still in progress.

Molecular aspects of furocoumarin reactions: Photophysics, photochemistry, photobiology, and structural analysis

Publisher Summary The contradictory observations on the toxicity of coumarin stimulated the research into closely related coumarin derivatives in biochemical–pharmacological studies. This chapter emphasizes on the biological properties of these compounds. It has been considered important to discuss the chemical structure–biological activity relationship of simple coumarins, coumarin anticoagulants, light sensitisers, aflatoxins, and related isocoumarin derivatives. The coumarin nucleus is the basis of various compounds possessing several pharmacological and physiological activities. Plant extracts containing these compounds have been applied against gastrointestinal diseases, typhus, paralysis, for the therapy of leucoderma, and as anticoagulants. In veterinary medicine, they have been used as diuretics, or against trichomonas infection. Coumarins have also been applied in industry, mainly as food flavors. The chapter discusses the metabolism of coumarins in plants, animals, microorganisms, and metabolism by intestinal microorganisms. The chapter also discusses coumarins effect on plants and algae. Due to its pleasant flavor, coumarin has been widely used as an ingredient in food products and drugs, although early studies have shown the adverse effect of this compound to man.

Herbert Holzen

Papers

Über pflanzliche Fischgifte, V. Mitteil.: Die Konstitution des Imperatorins (aus Imperatoria Ostruthium)

Synthese des Osthols (X. Mitteil. über natürliche Cumarine)