Shikimic acid

(3R, 4S, 5R) -3,4,5 -trihydroxy- 1-cyclohexene carboxylic acid

Colorless acicular crystals

Fixed

190-191 ° C

4.15 ( 14.1 ° C)

180 g · l-1 in water (20 ° C)

Template: Infobox chemical / molecular formula search available

Shikimic acid is an intermediate in biochemical metabolism of plants and micro-organisms in the biosynthesis of aromatic amino acids. This natural product is the (3R, 4S, 5R) - shikimic acid. The other seven possible stereoisomers of shikimic acid have no biological significance.

History

Shikimic acid was first isolated in 1885 by Johan Fredrik Eykman from Japanese star anise ( Illicium anisatum ), which is called in Japanese shikimic (シキミ/樒/櫁/梻).

Production and representation

Shikimic acid is an intermediate in the biosynthesis of aromatic amino acids essential for the human L-tyrosine, L-tryptophan and L-phenylalanine in plants and microorganisms. Its salts are called shikimate.

The shikimic acid is a metabolic intermediate of plants and therefore more popular. It comes in large amounts in the toxic Shikimifrucht as well as in related but non-toxic star anise.

From the shikimic acid occurring in plants, numerous aromatic compounds are derived from, for example, the protocatechuic acid. Another way is to gallic acid, which is part of the hydrolyzable tannins.

Shikimisäureweg

The Shikimisäureweg is an important way for the biogenesis of aromatics dar. However, the Shikimisäureweg not occur in higher animals.

The Shikimisäureweg not actually begins with the shikimic acid. The biosynthesis starts with the reaction of D- erythrose - 4-phosphate to phosphoenolpyruvate (PEP). Not built until further steps dehydroquinic, dehydroshikimic, shikimic acid and chorismate. When chorismate biosynthesis, the then divides into two paths. In which a path is formed of L-tryptophan, in the other via prephenate as an intermediate of L-tyrosine and L -phenylalanine. The Shikimisäureweg is important not only for the construction of protein in plants, based on the formed at Shikimisäureweg α - amino acid, but also for the biosynthesis of the coumarin derivatives and flavonoids.

Application

From shikimic acid is in a nine -step synthesis of oseltamivir, the active ingredient of Tamiflu ® manufactured. The long pathway that leads on hazardous azides, the low overall yield of about 35 percent and the elaborate extraction of the raw material shikimic acid from Chinese star anise make it difficult at present to produce oseltamivir in higher quantities.

Stereoisomers

Shikimic acid has the natural (3R, 4S, 5R ) configuration. The other seven stereoisomers [( 3S, 4R, 5S) -, (3R, 4R, 5S) -, (3S, 4S, 5R) -, (3R, 4S, 5S) -, (3S, 4R, RS) - (3S, 4S, 5S) - and (3R, 4R, 5R) - shikimic acid ] have no practical significance. The racemic mixture of ( 3R, 4S, 5R ) - and ( 3S, 4R, 5S) - shikimic acid has a melting point of 191-192 ° C.