Chapter 3 Noniridoid Bisindole Alkaloids

This chapter discusses that indole is a reactive nucleus prone to dimerization when it is isolated or a part of tryptamine or tryptophan, which themselves are reactive toward many functionalities. For these reasons, bisindoles, the majority of which are of iridoid origin, are frequently isolated in nature. Besides these “dimers,” there exists a growing class of noniridoid bisindoles found in the marine environment, in microorganisms, and in plant species, many of which display interesting biological activities. The chapter tries to promote research on a series of compounds worthy of attention. Marine environments are a rich source of indole and bisindole alkaloids of great structural variety. In the absence of traditional use, the chemical constituents of marine organisms are separated following bioassay-guided fractionation, and, consequently, contrary to compounds from terrestrial sources, many of the structures are associated with significant biological activity.