Tannin water soluble polyphenols

Tannins are naturally occurring water-soluble polyphenolic compoimds, and it has been reported that they show their anti-HIV activity by inhibiting polymerase and ribonuclease activities of HIV-1 RT. Phlorotannins are tannin derivatives which contain several phloroglucinol imits linked to each other in different ways and formed by the polymerization of phloroglucinol (1,3,5-trihydroxybenzene) monomer units and biosynthesis through the acetate-malonate pathway. So far, phlorotannins mostly have been isolated from red and brown alga. Numerous bioactivities of phlorotannins have been reported up to date such as antioxidant, antiinflammatory, antibacterial, and anti-MMP activities (Kim et al., 2006 Nagayama et al., 2002). 

Tannins are defined as water soluble polyphenols which differ from noost other natural pol3rphenolic compounds in their ability to precipitate proteins, such as gelatin [3]. Tannins are the most abundant plant constituents, following celltilose, hemiceUulose, and lignin [4]. In tribal pulse Bauhinia malabarica Roxb.), tannins have been found to be one of the antinutritional factors, in addition to phenols, L-DOPA, and... 

Tannins are water soluble polyphenols of relatively high molecular mass and have capacity to form complexes mainly with proteins, to a lesser extent with carbohydrates due to the presence of a large number of phenolic hydroxyl groups. They are usually classified into two major gronps hydrolysable tannins (HT) and condensed tannins (CT). 

The conversion of animal hides into leather by treatment with water-soluble plant extractives has been practiced since antiquity. This process became known as tanning and obviously involved the reaction of a naturally occurring extractive, tannin, with the protein in the hide. We now know, of course, that tannins comprise a whole spectrum of chemical compounds, but generally they are polyphenolic and polymeric. Tannins have been isolated from a wide variety of raw materials, including insect galls, fruit skins, seed hulls, leaves, bark, and heartwood. Indeed, tannins are of nearly ubiquitous occurrence in higher orders... 

Wood often contains tannins, and higher levels of tannins are commonly associated with oak. Tannins are water-soluble phenolic and polyphenolic compounds, which can form dark color complexes with iron salts (ferric salts). That is why some WPG deck... 

Catechins, polyphenols, and tannins in tea Catechins and related flavanols are water soluble, and can be extracted by boiling with water, or by shaking with aqueous acetone. 

The ability of tannins to precipitate water-soluble proteins is the main activity by which various naturally occurring polyphenols are defined as tannins. Several methods for measurement of tannins based on these activities have been developed (Bate-Smith 1973 Porter and Woodruffe 1984 Hagerman 1989). Methods for the assay of relative astringency (RA) and relative affinity to methylene blue (RMB) have been used frequently in pharmacological studies for the measurement of the tannin content of plant extracts (Okuda et al. 1985). 

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