Psoralens bioactivity

Benzofuran is the core of many complex natural products such as psoralens, a family of natural products that exhibits a wide range of bioactivities. Indoles are also found in many natural and organic compounds such as tryptophan and indole alkaloids. These core structures, 459 and 461, have been synthesized through the Rh-catalyzed cycloisomerizations of alkynylphenols 458 and alkynylanilines 460, respectively (Scheme 2-52). 

The acetylenes and linear furanocoumarins (psoralens) are examples of bioactive secondary metabolites that have been considered undesirable in plant foods due to their toxic effects. Some acetylenes are known to be potent skin sensitizers and irritants, and neurotoxic in high concentrations, but have also been shown to have a pronounced selective cytotoxic activity against various cancer cells. Due to their role in plant defence many acetylenes and psoralens are considered natural pesticides or in some cases phytoalexins since their formation is often induced in plants as a response to external stimuh. Psoralens are photoactivated secondary metabolites that have been used since ancient times to treat human skin disorders. However, the use of these furanocoumarins in medicine has been associated with increased incidence of skin cancer, and a number of studies have also demonstrated that the furanocoumarins can be carcinogenic, mutagenic, photodermatitic and to have reproductive toxicity. 

This chapter highlights the present state of knowledge on naturally occurring acetylenes and psoralens in the edible parts of more or less common food plants, including their biochemistry, bioactivity and possible relevance for human health. 

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