Natural products originating from shikimic acid

Natural Products Originating from Acetate and Shikimic Acid Pathways... 

The naturally occurring naphthoquinones such as lawsone and juglone are products of the shikimic acid pathway to aromatic amino-acids but the path which leads to these naphthoquinones branches from the main pathway before the formation of aromatic compounds, probably no later than chorismic acid.It will be most interesting to see whether the biosynthesis of shihunine also follows this route all the other bases of plant origin which arise from products of the shikimic acid pathway derive from aromatic precursors. 

In addition to acetyl-CoA, shikimic acid, mevalonic acid, and deoxyxylulose phosphate, other building blocks based on amino acids are frequently employed in natural product synthesis. Peptides, proteins, alkaloids, and many antibiotics are derived from amino acids, and the origins of the most important amino acid components of these are briefly indicated in Figure 2.1. Intermediates from the glycolytic pathway and the Krebs cycle are used in constructing many of them, but the aromatic amino acids phenylalanine, tyrosine,... 

One of the most fascinating problems in natural product biosynthesis during the last decade was the origin of the C9-10 unit found in Ipecacuanha, indole, and Cinchona alkaloids. In the initial phases of the work it was proved by tracer studies that this unit did not arise from phenylalanine (45), tyrosine (45), shikimic acid (49), malonate (45), acetate (45,50,51), formate (45), or methionine (52). The role of glycine has also been investigated (53). 

Naturally occurring coumarins, which are classified by their benzopyran-2-one nucleus, have been isolated from numerous plants, particularly members of the Apiaceae, Rutaceae, and Fucaceae, as well as from some genera of Leguminosae. A comprehensive collection of stractures has been described for them [3-6]. Plant coumarins originate from the shikimate and general phe-nylpropanoid pathways, yielding cinnamic acid as the immediate product [7,8], which is diverted in various ways. The pattern of coumarins has been proposed as a parameter of taxonomic identification [9-12]. 

---