High-molecular-weight polyphenols

Lignin The substance that binds together cellulose fibers in higher plants to stiffen their structures. Wood may contain as much as 50% lignin. It is a high-molecular-weight polyphenolic compound that varies in composition with different plant types. 

Bioactivation of High-Molecular-Weight Polyphenols by the Gut Microbiome... 

BIOACnVATION OF HIGH-MOLECULAR-WEIGHT POLYPHENOLS BY THE GUT MICROBIOME... 

Polyphenols are ubiquitous in all plant organs where they are found as monomers or in polymerised forms (Schofield et al, 2001). In addition to the beneficial effect of poljq)henols, they also bind minerals and precipitate proteins and carbohydrates, in effect reducing the nutritive value of foods. Polyphenols have been classified for nutritional purposes into extractable and non-extractable types (Bravo, 1998). Extractable polyphenols are low-and intermediate-weight phenolics while non-extractable polyphenols have high molecular weight and are insoluble in normal solvents. 

When appreciable amounts of pectin, proteins, lipids, unwanted polyphenols, or other compounds are suspected to be present in anthocyanin-containing extracts, some of them can be precipitated or the anthocyanins may be crystalhzed and separated from the others. Pectin and proteins can be removed by organic solvents such as methanol and acetone in order to reduce their solubility, then precipitated and separated by centrifugation. Gelatin was used to remove proanthocyanidin due to its high molecular weight. Anthocyanins were reported to be precipitated early by lead acetate to achieve isolation from other materials. ... 

Tannins are polyphenolic compounds of high molecular weight that occur naturally and react with proteins. They can form insoluble complexes with proteins, which are responsible for the taste known as astringency that is caused by precipitation of mouth proteins. Tannins are typically classified into three groups (1) the condensed tannins, (2) the hydrolyzable tannins, and (3) the phlorotannins (Figure 11.3.10). 

Hagerman, A.E., Riedl, K.M., Jones, G.A., Sovik, K.N., Ritchard, N T., Hartzfeld, P.W., and Riechel, T.L. 1998. High molecular weight plant polyphenolics (tannins) as biological antioxidants. J. Agric. Food Chem. 46 1887-1892. 

Tannins (Figure 11.3.10) are polyphenolic polymers of high molecular weight that occur naturally and react with proteins. Tannins are... 

Sanguisorba officinalis L. (Rosaceae) is one of the traditional plants whose air-dried roots (Japanese name ziyu ) are used medicinally as hemostatic, antiphlogistic and astringent. The effective constituents of the plant have been shown to be high molecular weight (Mr) polyphenols of... 

Pu-erh tea, highly fermented, possesses a rich flavor and was long recognized as a tribute tea in the imperial court of China. Its major polyphenols are not well characterized, because of their insolubility in most extracting solvents, but are considered to be polymerized catechins of high molecular weight. The aqueous extract of pu-erh tea is active in inhibiting lipopolysaccharide (LPS)-induced inducible nitric oxide synthase activity. ... 

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