Chlorogenic acid structure

Each patent has somewhat different features and claims. We select one patent for more detailed discussion to highlight certain technical facets of the process. First we explain the (often misunderstood) effect of water on the extractability of caffeine by selective supercritical carbon dioxide. A number of references report that dry carbon dioxide cannot extract caffeine from dry coffee, either green or roasted, but moist carbon dioxide can. The inability of dry carbon dioxide to extract caffeine from coffee should not be misconstrued to mean that dry carbon dioxide cannot dissolve neat caffeine. This same moist-versus-dry effect is experienced if, for example, methylene chloride is used to extract caffeine from coffee. Dry methylene chloride cannot decaffein-ate dry coffee but moistened coffee can be decaffeinated. It is thought that the caffeine is chemically bound in a chlorogenic acid structure present in the coffee bean. Thus, water somehow acts as a chemical agent it frees caffeine from its bound form in the coffee matrix in both the carbon dioxide and the methylene chloride processes. 

Duenas, M., et al., UV-visible spectroscopic investigation of the 8,8-methylmethine catechin-malvidin-3-glucoside pigments in aqueous solutions structural transformations and molecular complexations with chlorogenic acid, J. Agric. Food. Chem., 54, 189, 2006. 

Hydroxy cinnamic acids are included in the phenylpropanoid group (C6-C3). They are formed with an aromatic ring and a three-carbon chain. There are four basic structures the coumaric acids, caffeic acids, ferulic acids, and sinapic acids. In nature, they are usually associated with other compounds such as chlorogenic acid, which is the link between caffeic acid and quinic acid. 

The remaining shlklmates in Table III also are relatively simple, well known compounds. The phenolic structures of vanillin (125) and gallic acid (127) and the prephenolic structures of the common quinic acid (128) and chlorogenic acid (129) make them candidates for physiological activity. Gallic acid is the monomer for tannins, biological polymers found in the cotton plant (15, 37). 

Rawel, H.M., Rohn, S., Kruse, H.P., and Kroll, J., Structural changes induced in bovine serum albumin by covalent attachment of chlorogenic acid. Food Chem., 78, 443, 2002. 

Figure 14.6 Structure of chlorogenic acid, rutin and kukoamine A.

Chlorogenic acids occur ubiquitously in plants. They are esters of hydroxycinnamic acids with quinic acid. The structures of chlorogenic... 

Figure 6-1. Oxidation of chlorogenic acid (6.4) by polyphenoloxidase (PPO), resulting in chlorogenoquinone (6.5), which can react with nucleophilic groups in proteins (6.6) to give the cross-linked compound 6.7, which can react with another protein molecule to yield 6.8. The quinate residue in structures 6.5, 6.7 and 6.8 is represented by R, whereas Ri and R2 indicate different amino acid residues.

Figure 2.3 Example of chemical structure of a chlorogenic acid 5-O-caffeoylquinic acid (with ITJPAC numbering).

The TPA-induced conversion of xanthine dehydrogenase to XO is reduced by curcumin to the basal level noted in untreated cells. The activity of XO is remarkably inhibited by curcumin in vitro but not by its structurally related compounds caffeic acids, chlorogenic acid, and ferulic acid. When Colo205 colorectal carcinoma cells... 

The flavonols and their glycosides contribute to specific taste characteristics such as bitterness and astringency in berry fruits and their products (Shahidi and Naczk, 1995). The molecular structure of flavonols lacks the conjugated double bonds of the anthocyanins, and they are thereby colorless. They may, however, contribute to discoloration of berry fruits, as they are readily oxidized by O-phenoloxidase in the presence of catechin and chlorogenic acid. Discoloration may also occur as a consequence of complex formation with metallic ions. On the other hand, the flavonol glycoside rutin is known to form complexes with anthocyanins, thus stabilizing the color of these compounds. 

FIGURE 3.4 Structures of (a) chlorogenic acid, (b) caftaric acid, (c) ellagic acid and (d) resveratrol. [Source Adapted from Spanos and Wrolstad (1992) and Macheix and Fleuriet (1998).]... 

Non-volatile multifunctional acids present in green coffee are not mentioned here. Their contribution to the flavor and taste qualities essentially concerns the roasted coffee beverage. Their structures and properties are partly discussed in Section 5.E. Similarly, free acid-phenols present in small amounts, mainly decomposition products of chlorogenic acids and depsides, will be discussed in Section 5.H. 

Figure 2 Chemical structures of selected plant polyphenols. Structures include a flavonol (quercetin), isoflavone (daidzein), cinnamic acid (chlorogenic acid), flavan-3-ol (catechin), a lignan microbial metabolite (enterodiol), and a stilbene (resveratrol).

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