Catechins phenolic acids

The sugars attached to the anthocyanin molecule are in order of relative abundance glucose, rhamnose, galactose, xylose, arabinose, and glucuronic acid. The molecule may also contain one or more of the acyl acids p-coumaric, caffeic, and ferulic or the aliphatic acids malonic and acetic esterified to the sugar molecules. Extracts of anthocyanins invariably contain flavonoids, phenolic acids, catechins and polyphenols. The net result is that it is impossible to express the chemical composition accurately. Specifications usually present tinctorial power, acidity, per cent solids, per cent ash and other physical properties. 

Torronen, R. et al., Flavonoids and phenolic acids in selected berries. Cancer Lett., 114, 191, 1997. Arts, I.C.W., van de Putte, B., and Hollman, P.C.H., Catechin contents of foods commonly consumed in The Netherlands. 2. Tea, wine, fruit juices, and chocolate milk, J. Agric. Food Chem., 48, 1752, 2000. 

Figure 11.3.11 Sample UV spectra from various polyphenolics classes (A) cinnamic acid (a phenolic acid), (B) cyanidin (an anthocyanidin), (C) catechin (a flavan-3-ol), and (D) quercetin (a flavonol). AU, absorbance units.

For the red wines (82-84), which were injected directly into the HPLC without sample preparation, a ternary-gradient system using aqueous acetic acid (1% and 5% or 6%), and acidified acetonitrile (acetonitrile-acetic acid-water, 30 5 6) was used for cinnamic acid derivatives, catechins, flavonols, flavonol glycosides, and proanthocyanidins. Due to the large number of peaks, the gradient was extended to 150 min for the resolution of many peaks of important phenolics. This direct injection method was able to separate phenolic acids and esters, catechins, proanthocyanidins, flavonols, flavonol glycosides, and other compounds (such as tyrosol, and rrans-resveratrol) in wine in a single analysis. However, use of acetic acid did not permit the detector (PDA) to be used to record the UV spectra of phenolics below 240 nm (84). 

Inflammation is now recognized as a key process in atherogenesis [Libby, 2002]. The potential for dietary flavonoids to inhibit inflammatory activities is of particular interest. A potential anti-inflammatory feature of the flavonoids is the ability to inhibit the biosynthesis of eicosanoids. Selected phenolic acids and some flavonoids have been shown to inhibit both cyclooxygenase (COX) and 5-lipoxygenase (5-LO) pathways [Nijveldt et al., 2001 Takano-Ishikawa et al., 2006], Epicatechin and related flavonoids have been shown to inhibit the synthesis of pro-inflammatory cytokines in vitro [Sanbongi et al., 1997], and plasma metabolites of catechin and quercetin inhibit the adhesion of monocytes to cultured endothelial cells [Koga and Meydani, 2001]. Silymarin has been shown to inhibit the production of inflammatory cytokines, such as interleukin-1, interferon-, and tumor necrosis factor-a (TNFa), from macrophages and T-cells [Matsuda et al., 2005], Some flavonoids can inhibit neutrophil... 

Typical flavonol, anthocyanidine (anthocyanin is a sugar-binding anthocyanidine), catechin, uric acid, and tannin are shown in Figure 1.9. All these compounds bear phenolic hydroxy groups which can function as anti-oxidants [3, 4]. Green tea contains high levels of tannin and catechin, and red wine contains a high level of anthocyanidine. 

Among polyphenolic compounds, two types of flavonoids, the anthocyanins and flavanols (i.e., catechins, proanthocyanidins, condensed tannins), are particularly relevant to the quality of red wines, as they are key compounds for color definition and astringency. Other flavonoids such as flavonols may have some influence on color and bitterness, although they are present in red wines in much lower amounts. Phenolic acids and hydrolysable tannins, released from barrel wood, may also have an influence on wine taste and color, and hydroxycinnamoyl derivatives from grape must are involved in the oxidative browning of white wines together with flavanols. Besides, some of these perceptions may be modified by other sensory characteristics (e.g. sourness, sweetness) related to other wine components (Preys et al. 2006). 

Green tea is made by steaming or frying fresh tea leaves at elevated temperatures to prevent polyphenol oxidation. The chemical composition of green tea is similar to that of the fresh leaves regarding the major components. It contains polyphenols, which include flavanols, flavandiols, flavonoids, and phenolic acids. Flavanols are the most abundant constituents and are commonly known as catechins. The major catechins present in green tea are (-)-epicatechin (EC), (-)-epicatechin-3-gallate... 

Fig. 3 HPLC analysis of phenolic acids using (a) Separon SGX Cig column and (b) Symmetry Cig column and gradient elution. Conditions (A) column Separon SGX Cig (250 x 4.6 mm, 7 pm), mobile phase methanol-water (pH = 2.5, adjusted with formic acid), linear gradient from 15% methanol to 75% methanol in 40 min, flow-rate 0.5 mL/min (B) column Symmetry Cig (150 x 3.9 nm, 5 pm), mobile phase and flow-rate same as in (a). Peaks 1) gallic acid, 2) protocatechuic acid, 3) catechin, 4) caffeic acid, 5) sinapic acid, 6) rosmarinic acid.

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