Catechins chemical structures

Suzuki, M., Sano, M., Yoshida, R., Degawa, M., Miyase, T., and Maeda-Yamamoto, M., Epimerization of tea catechins and 0-methylated derivatives of (—)-epigallocatechin-3-0-gallate relationship between epimerization and chemical structure, J. Agric. Food Chem., 51, 510, 2003. 

Figure 7.1 Chemical structures of major green tea catechins.

Flavonoids are divided into many classes and subclasses, each with a slightly different chemical structure and function. Classes of flavonoids include flavanols, flavanones, catechins, anthocyanins, and isoflavones. 

Figure 6.1 Chemical structures of flavanoids including catechins and theaflavins. These tiavanoids consisted of two major groups flavanones, including naringenin, taxifolin, and fustin, and flavanols including green tea polyphenols (EC, ECG, EGC, EGCG), black tea polyphenols (TF-1, TF-2a, TF-2b, TF-3), and oolong tea polyphenol (TSA).

The majority of the biological functions of teas may be attributed to their poly-phenolic components (see figures 9.1 and 9.2) the chemical structures of the main polyphenols isolated from green, black, oolong, and pu-erh teas are structurally related but not identical. The monomeric catechins from green tea may be considered the precursors of the more complex polyphenols found in other teas as a result of fermentation. 

The reaction kinetic of the vanillin assay depends on the chemical structure. For (+)-catechin the reaction was terminated after 7 minutes,... 

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).

Overexpression of P-glycoprotein associated with multidrug resistance represents a serious problem in cancer treatment. Evaluation of catechins, fla-vonoids, isoflavonoids, and anthocyanins effects on multidrug-resistant human epidermal carcinoma cells has demonstrated that catechins and antho-cyanidins are most effective inhibitors of P-gp overexpression. It was observed that hydrophobicity enhances planar flavonoids inhibitory effects without affecting nonplanar flavanols activity that significantly depended on their chemical structure [119]. 

Fig. 2 Chemical structures of catechin, epicatechin, and procyanidin oligomers.

The most important members of the flavonoid family include anthocyanidins (e.g., cyanidin, delphinidin, malvidin), flavonols (e.g., quercetin, kaempferol), flavones (e.g., luteolin, apigenin), flavanones (e.g., myricetin, naringin, hesperetin, naringenin), flavan-3-ols (e.g., catechin, epicatechin, gallocatechin) and, although sometimes classified separately, the isoflavones (e.g., genistein, daidzein). For chemical structures see Figure 1. All these phytochemical are frequently referred to as bioflavonoids due to well established effects in human health maintenance. 

Watanabe H. The chemical structure of the intermediate metabolites of catechin I-IV. Bull Agric Chem Soc Jpn 1959 23(25) 257-271. 

FIGURE 53.9. Chemical structures of catechin and epicatechin enantiomers. 

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