Biosynthesis of the indole and Colchicum alkaloids.

نویسنده

A R Battersby

چکیده

There has been enormous progress over the past fifteen years or so in our understanding of the ways in which complex natural products are synthesized in living systems. In the field of alkaloids, as elsewhere, research during the initial phase1 pin-pointed those substances which are used as the common building blocks, examples being acetic acid, ornithine and lysine for the reduced systems, and tyrosine, phenylalanine, 3,4-dihydroxyphenylpyruvic acid, and tryptophan for the many bases containing aromatic nuclei. Such knowledge allows the second phase of research to be undertaken; here the intermediates on the pathway are identified and this in turn leads to a study of the mechanism of each step in the biosynthetic sequence. At present a most exciting stage has been reached where hypothesis2—7, tracer experiment8'9, structure determination, and isolation work can be combined in a very powerful way. We can illustrate all these aspects by examining two quite different groups of alkaloids which have held our deep interest for several years. One is the large family of indole alkaloids, exemplified by corynantheine (I), strychnine (II), catharanthine (IV, Figure 1), and vindoline (VII), and the other contains the alkaloids found in Colchicum species of which the ancient poison colchicine (XXXVI) is the best known member. The origins of these groups of alkaloids have remained until very recently the two major unsolved problems in the field. The number of known indole alkaloids has increased sharply over the last few years and there are now about six hundred10"1. A tryptamine

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