| Shikimic acid | |
|---|---|
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(3R,4S,5R)-3,4,5-trihydroxycyclohex-1-ene-1-carboxylic acid |
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| Identifiers | |
| CAS number | 138-59-0 |
| PubChem | 8742 |
| ChemSpider | 8412 |
| EC number | 205-334-2 |
| ChEBI | CHEBI:16119 |
| ChEMBL | CHEMBL290345 |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | C7H10O5 |
| Molar mass | 174.15 g mol−1 |
| Melting point |
185–187 °C |
| (verify) (what is: /?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Shikimic acid, more commonly known as its anionic form shikimate, is an important biochemical metabolite 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:
In the pharmaceutical industry, shikimic acid from the Chinese star anise is used as a base material for production of oseltamivir (Tamiflu). Although shikimic acid is present in most autotrophic organisms, it is a biosynthetic intermediate and in general found in very low concentrations. The low isolation yield of shikimic acid from the 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%. For example, 4 kg of sweetgum seeds is needed for fourteen packages of Tamiflu. By comparison, star anise has been reported to yield 3 to 7% shikimic acid. Biosynthetic pathways in E. coli have recently been enhanced to allow the organism to accumulate enough material to be used commercially.[1][2][3]
A 2010 study released by the University of Maine showed that shikimic acid can also be readily harvested from the needles of several varieties of pine tree.[4]
Phosphoenolpyruvate and erythrose-4-phosphate react to form 3-deoxy-D-arabinoheptulosonate-7-phosphate (DAHP), in a reaction catalyzed by the enzyme DAHP synthase. DAHP is then transformed to 3-dehydroquinate (DHQ), in a reaction catalyzed by DHQ synthase. Although this reaction requires nicotinamide adenine dinucleotide (NAD) as a cofactor, the enzymic mechanism regenerates it, resulting in the net use of no NAD.
DHQ is dehydrated to 3-dehydroshikimic acid by the enzyme dehydroquinase, which is reduced to shikimic acid by the enzyme shikimate dehydrogenase, which uses nicotinamide adenine dinucleotide phosphate (NADPH) as a cofactor.