Quinic acid
Quinic acid is 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.The compound is obtained from cinchona bark, coffee beans, the bark of Eucalyptus globulus. It is a constituent of the tara tannins.
Urtica dioica is another common source.
It is made synthetically by hydrolysis of chlorogenic acid. Quinic acid is also implicated in the perceived acidity of coffee.This substance was isolated for the first time in 1806 by French pharmacist Nicolas Vauquelin and its transformation into hippuric acid by animal metabolism was studied by German chemist Eduard Lautemann in 1863.
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 by the action of a synthase. Two subsequent steps involving dehydroquinic acid synthase and a dehydrogenase afford the compound.
Derived bicyclic lactones are called quinides. One example is 4-caffeoyl-1,5-quinide.
Dehydrogenation and oxidation of quinic acid affords gallic acid.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 preparation of the treatment of influenza A and B strains called Tamiflu.
Quinic acid is also thought to displace binding of the μ-opioid receptor antagonist naltrexone.
