Shikimic Acid Pathway
The shikimate pathway (shikimic acid pathway) is a seven-step metabolic pathway used by bacteria, fungi, algae, some protozoans, and plants for the biosynthesis of folates and aromatic amino acids (phenylalanine, tyrosine, and tryptophan). This pathway is not found in animals (including humans), who must instead obtain these essential amino acids from their diet. This can be through either the direct consumption of plants or microorganisms, or their indirect consumption via the consumption of other animals; therefore, phenylalanine and tryptophan represent essential amino acids that must be obtained from the animal’s diet. Animals can
synthesize tyrosine from phenylalanine, and therefore is not an essential amino acid except for individuals unable to hydroxylate phenylalanine to tyrosine).
Commonly known as its anionic form shikimate, is a cyclohexene, a cyclitol and a cyclohexanecarboxylic acid. Shikimic acid is a key intermediate from carbohydrate for the biosynthesis of C6 – C3 units (Phenylpropane derivatives). Besides serving as precursor for the biosynthesis of amino acids, it is also an intermediate in production of tannins, flavones, coumarins and vanillin.
Role of Shikimic Acid Pathway:
- Starting material in the biosynthesis of some phenolics
Phenyl alanine and tyrosine are the precursors used in the biosynthesis of phenylpropanoids. The phenylpropanoids are then used to produce the flavonoids, coumarins, tannins and lignin.
· Gallic acid biosynthesis
Gallic acid is formed from 3-dehydroshikimate by the action of the enzyme shikimate dehydrogenase to produce 3,5-didehydroshikimate. The latter compound spontaneously rearranges to gallic acid.
- Shikimic acid is a precursor for indole, indole derivatives and aromatic amino acid tryptophan and tryptophan derivatives such as the psychedelic compound dimethyltryptamine. many alkaloids and other aromatic metabolites.