Semisynthesis of Selenoauraptene.

Selenium-containing compounds are gaining more and more interest due to their valuable and promising pharmacological properties, mainly as anticancer and antioxidant agents. Ebselen, the up to now only approved drugs, is well known to possess very good glutathione peroxidase mimicking effects. To date, the most of efforts have been directed to build pure synthetic Se containing molecules, while less attention have been devoted to Se-based semisynthetic products resembling natural compounds like terpenes, polyphenols, and alkaloids. The aim of this short communication is to report the synthesis of the first example of a Se-phenylpropanoids, namely selenoauraptene, containing a selenogeranyl side chain in position 7 of the umbelliferone core. The key step was the Newman-Kwart rearrangement to obtain a selenocarbamate in which the Se atom was directly attached to umbelliferone (replacing its 7-OH function) followed by hydrolysis to get diumbelliferyl diselenide, which was finally easily converted to the desired Se-geranyl derivative in quite a good overall yield (28.5%). The synthesized adduct displayed a greater antioxidant and a radical scavenger in vitro activity than parent auraptene. The procedure we describe herein, to the best of our knowledge for the first time in the literature, represents an easy-to-handle method for the synthesis of a wide array of seleno analogues of naturally occurring biologically active oxyprenylated secondary metabolites.

7-Isopentenyloxycoumarin: What Is New across the Last Decade.

7-Isopentenyloxycoumarin is among the most widespread naturally occurring prenyloxy umbelliferone derivatives. This secondary metabolite of mixed biosynthetic origin has been typically isolated from plants belonging to several genera of the Rutaceae and Apiaceae families, comprising widely used medicinal plants and in general plants with beneficial effects on human welfare, as well as edible fruits and vegetables. Although known for quite a long time (more than 50 years), only in the last two decades has this natural compound been revealed to exert powerful and promising pharmacological properties, such as active cancer chemopreventive, antibacterial, antiprotozoal, antifungal, anti-inflammatory, neuroprotective, and antioxidant properties, among the activities best outlined in the recent literature. The aim of this comprehensive miniature review article is to detail the novel natural sources and the effects described during the last decade for 7-isopentenyloxycoumarin and what has been reported on the mechanisms of action underlying the observed biological activities of this oxyprenylated secondary metabolite. In view of the herein described data, suggestions on how to address future research on the abovementioned natural product and structurally related derivatives in the best ways according to the authors will be also provided.