Quinic acid

 ( Cyclohexanecarboxylic Acids ) 

Quinic acid is an organic compound with the formula . The compound is classified as a cyclitol, a cyclic polyol, and a cyclohexanecarboxylic acid. It is a colorless solid that can be extracted from plant sources. Quinic acid is implicated in the perceived acidity of coffee, where it occurs around 13% by weight.

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Occurrence and preparation The compound is obtained from cinchona, coffee, and the bark of Eucalyptus globulus. It is a constituent of the tara tannins.

Urtica dioica, the European stinging nettle, is another common source.

It is made synthetically by hydrolysis of chlorogenic acid. Quinic acid is also implicated in the perceived acidity of coffee.

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History and biosynthesis , biosynthetic precursor to aromatic amino acids, is a close relative of quinic acid.]]This substance was isolated for the first time in 1790 by Germany pharmacist Friedrich Christian Hofmann in Leer from Cinchona.Hofmann: Crell's chemische Annal. 1790, II, p. 314, cited in S. Baup: Über die Chinasäure und einige ihrer Verbindungen. In: Annalen der Physik und Chemie 1833, p. 64–70 (). Its transformation into hippuric acid by animal metabolism was studied by German chemist Eduard Lautemann in 1863.Lautemann, E. (1863) "Ueber die Reduction der Chinasäure zu Benzoësäure und die Verwandlung derselben in Hippursäure im thierischen Organismus" (On the reduction of quinic acid to benzoic acid and its transformation into hippuric acid in the animal organism), Annalen der Chemie, 125 : 9–13.

Its biosynthesis begins with the transformation of glucose into erythrose 4-phosphate. This four-carbon substrate is condensed with phosphoenol pyruvate to give the seven-carbon 3-deoxy-D-arabinoheptulosonate 7-phosphate (DAHP) by the action of a synthase. Two subsequent steps involving dehydroquinic acid synthase and a dehydrogenase afford the compound.

Derived bicyclic are called quinides. One example is 4-caffeoyl-1,5-quinide.

Dehydrogenation and oxidation of quinic acid affords gallic acid.

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Applications and medicinal activity Quinic acid is used as an astringent.

This acid is a versatile chiral starting material for the synthesis of pharmaceuticals. It is a building block in the synthesis of oseltamivir, which is used to treat influenza and influenza.

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