Shikimic acid

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 tyrosine,
• tryptophan,
• many metabolites,
• flavonoids, and lignin.

In the pharmaceutical industry, shikimic acid from the Chinese 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.^[1]

Biosynthesis

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).

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.

References

1. ^ Bradley, David (2005-12). "Star role for bacteria in controlling flu pandemic?" (html). Nature Reviews Drug Discovery 4: 945-946. Retrieved on 2007-03-07.