Shikimic acid

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Shikimic acid

Chemical name	(3R,4S,5R)-3,4,5-Trihydroxy- 1-cyclohexenecarboxylic acid
Chemical formula	C₇H₁₀O₅
Molecular mass	174.15 g/mol
Melting point	185–187 °C
CAS number	[138-59-0]
EINECS number	205-334-2
[Chemical infoboxDisclaimer and references]

Shikimic acid, more commonly known as its anionic form shikimate, is an important biochemical intermediate in plants and microorganisms. Its name comes from the Japanese flower shikimi (シキミ, Illicium anisatum), from which it was first isolated.

Shikimic acid is a precursor for:

the aromatic amino acids phenylalanine and tyrosine,
indole, indole derivatives and tryptophan,
many alkaloids and other aromatic metabolites,
tannins, and
lignin.

In pharmaceutical industry, shikimic acid from chinese star anise is used as a base material for production of Tamiflu (oseltamivir). Although shikimic acid is present in most autotrophic organisms, it is a biosynthetic intermediate and generally found in very low concentrations. The low isolation yield of shikimic acid from chinese star anise is blamed for the 2005 shortage of oseltamivir. Shikimic acid can also be extracted from the seeds of the sweetgum fruit, which is abundant in North America, in yields of around 1.5%, so just 4 kg of sweetgum seeds are enough for fourteen packages of Tamiflu. By comparison star anise has been reported to yield 3 to 7% shikimic acid. Recently biosynthetic pathways in E. coli have been enhanced to allow the organism to accumulate enough material to be used commercially.

Biosynthesis

Phosphoenol pyruvate and erythrose-4-phosphate react to form 3-deoxy-arabinoheptulsonate-7-phosphate(DAHP), in a reaction catalysed by the enzyme DAHP synthase. DAHP is then transformed to 3-dehydroquinate(DHQ), in a reaction catalysed by DHQ synthase. Although this reaction requires NAD as a cofactor, the enzymic mechanism regenerates it, resulting in the net use of no NAD (note diagram is incorrect).

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DHQ is dehydrated to 3-dehydroshikimate by the enzyme dehydroquinase, which is reduced by to shikimic acid by the enzyme shikimate dehydrogenase, which uses NADPH as a cofactor.

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External links

[Shikimate and chorismate biosynthesis]

For a full list of external links to MSDSs, spectroscopic data, commercial chemicals suppliers etc. for this compound, see [Chemical sources].

Suppliers

[Sigma-Aldrich Co.] ([product page])

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