Quinic acids

Quinic acid, a carboxylated tetrahydroxycyclohexane, is a secondary plant substance formed from dehydroquinic acid, an intermediate in the shikimic acid pathway, the metabolic pathway leading to aromatic compounds. It, therefore, is ubiquitous in living plant cells. It has been isolated from cinchona bark and detected in the cambial sap of conifers (114). 

The burden of the proof of configuration of quinic acid rests on a series of reactions involving the acetone derivative and its lactone (quinide) [84), The following scheme illustrates the reactions involved  

It had been previously established that quinic acid readily forms a lactone, called quinide. Quinide was shown to have a 7-lactone structure by conversion of the trimethyl ether to 3-hydroxy-4-methoxybenzoic acid (isovanillic acid). At the same time, this reaction established that the hydroxyl at carbon 6 and the carboxyl must be on the same side of the ring. Since the hydroxyl derivative obtained through the Grignard reaction consumes one mole of lead tetraacetate and from the results of the Curtius degradation, it follows that carbon 2 must have both a carboxyl and hydroxyl attached. Furthermore, since the resultant ketone cannot form an osazone, carbons 1 and 3 must be free of hydroxyl groups. By elimination, therefore, the remaining two hydroxyls must be at carbons 4 and 5. Finally, these must 

2 Deoxy-D-ara6o-hexonic acid (2-Deoxygluconic acid) 

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Biochemical Routes. Enzymatic oxidation of benzene or phenol leading to dilute solution of dihydroxybenzenes is known (62). Glucose can be converted into quinic acid [77-95-2] by fermentation. The quinic acid is subsequently oxidized to hydroquinone and -benzoquinone with manganese dioxide (63). 

These useful compounds have played a central role in both theoretical and practical organic chemistry since the 1840s. In 1838 quinic acid [36413-60-2] (1) was oxidized to 1,4-benzoquinone (2) with manganese dioxide (1). 

Soybeans contain only 1—25 ppm of phenofic acids (33) whereas defatted sunflower meal contains 2.7% chlorogenic acid, 0.38% quinic acid, and 0.2% caffeic acid (34). Chlorogenic acid turns from yellow to green and finally to brown as the pH is raised from 7 to 11. Interaction of chlorogenic acid... 

Other Phenolic Compounds. There are several phenolic acids important to tea chemistry. GaUic acid (3) and its quinic acid ester, theogallin (4), have been identified in tea (17,18) and have been detected by hplc (19,20). 

Of these, the CGA isomers are the principal acids and result from the esterification of the 3, 4, and 5 position hydroxyls of quinic acid with the carboxyls of several phenoHc acids, including caffeic acid (C) [331-39-5], ferruHc acid (F) [1135-24-6], andT -coumaric acid (Cm) [501 -98 ]. 

Quinhydrone [106-34-3] M 218.2, m 168 . Crystd from H2O at 65°, then dried in a vac desiccator. 1R,3R,4R,5R-Quinic acid (1,3,4,5-tetrahydroxy-cyciohexane-carboxylic acid) [77-95-2] M... 

The present method is adapted from that of Loven. The resolution has been carried out with d-a-bromocamphor-TT-sulfonic acid (f-form) 2.3 with /-and d/-malic acids (d- and /-forms) with /-quinic acid and d-tartaric acid (d- and /-forms) and with d- and /-6,6 -dinitrodiphenic acids (d- and /-forms). Methods employing d-benzyimethylacetyl chloride, d-oxymeth-ylenecamphor, /-quinic acid, and d-camphoric anhydride are of theoretical interest only. The d/-amine is not resolved by the active camphor-lo-sulfonic acids or mandelic acids. ... 

China-ol, n. baleam of Peru, rindet/. cinchona bark, Peruvian bark. rindensauret /. quinic acid, -rot, n. cinchona red. 

China-saure, /. quinic acid, -seide, /. China silk Chinese silk, -silber, n. China silver (a plated alloy). 

Quinic acid, 1,3,4,5-tetrahydroxycyclohexane-carboxylic acid [(HO)4C6H7COOH]... 

C jHijO 77-95-2) see Oseltamivir quinic acid y-lactone (C7H,oO, 27783-00-2) see Cynarine quinine... 

ROBERTS E A H and MYERS M (1958) Theogallin, a polyphenol occurring in tea. 11. Identification as a gaUoyl quinic acid , J Sci Food Agric, 9, 701-5. 

Gallic acid is present in tea leaf and is a known reactant during the complex enzymatic and organochemical reactions that occur when tea components are oxidized.51 The gallic and quinic acids originate via the shikimate/arogenate pathway. The key enzymes in shikimic acid biosyn-... 

The treatment and environment of green coffee beans affects the concentrations of both caffeoyl- and feruloyl quinic acids,52 and several decomposition products have been recognized. Some of these products, in this case from steam-treated green coffee beans, are given in Figure 5.53... 

Chlorogenic acid loss is also correlated with its incorporation in browning products.3 During roasting, the diphenols, 4-ethylpyrocatechol and pyrocatechol are formed from the caffeic acid moiety and the quinic acid moiety yields phenol and benzoic acid as well as all the di- and trihydroxybenzenes.39... 

Chlorogenic acid lactones are produced in roasted coffee and range from 1.5 to 3.5 g/kg in commercial roasted coffee samples. Two lactones that have been identified in roasted coffee are 3-caffeoyl- and 4-caffeoyl-quinic acid-y-lactone.60... 

The Quinic Acid Content of Increasingly Roasted Coffee Beans58... 

Roast style in order of increasing roast Quinic acid (%)... 

Green coffee beans, as expected, contain storage polysaccharides such as starch, and structural support compounds such as cellulose and lignin. Mono- and di-saccharides are represented, as well as the related compounds quinic acid and myo inositol. 

Scholtz-Boettcher, B. M., Maier, H. G., Isomers of quinic acid and quinides in roasted coffee indicators for the degree of roast Colloq. Sci. Int. Cafe, 14th, 220, 1991 (publ. 1992). (CA117 89128c)... 

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