Chapter 2 Marine Alkaloids

Abstract

Publisher Summary This chapter describes guanidine alkaloids, indole alkaloids, pyrrole alkaloids, and miscellaneous alkaloids. Tetrodotoxin and saxitoxin of this group of alkaloids are among the best known marine natural products. Tetrodotoxin is present in a variety of puffer species of the family Tetraodontidae, many of which are used for food in Japan. A very complex mixture of polyhalogenated indoles from the red alga Rhodophyllis membranacea Harvey is studied . Partial separation is affected by column chromatography, yielding six crystalline fractions, and further purification of three of these fractions by GLC gives samples suited for NMR analysis. Because of the instability and separation problems encountered, many alkaloids are isolated as acetyl derivatives. Studies of trideuterioacetylated samples demonstrate that the alkaloids occur in the sponge in their free phenolic forms. There is a growing interest in the ecological role of marine natural products. At present, only few chemical–ecological relationships are adequately investigated. The near future will undoubtedly add more detailed knowledge to this interesting and important field.