Tannin-derivatives

Internal treatment-related problems may take the form of organic material present in deposits of iron oxide corrosion debris and salt scales. The material typically is present as carbonized organic components and may originate from water treatment chemicals such as quebracho, wattle, pymgallol, or other tannin derivatives. Also, acrylates, starches, sulfonated lignins, and other sludge dispersants may be present. 

Tannins derive their name from their ability to tan (i.e. they combine with protein). They render plants less palatable and impair digestion by binding with the buccal mucosa, dietaiy proteins, and digestive enzymes of the animal. Tannins are thought to bind to proteins upon destruction of plant tissue by herbivores. This reduces the nutritive value of the plant to the herbivore. Some tannins such as oak gallotannins, are even toxic to livestock and rabbits (Meyer and Karasov, 1991). However, Martin and Martin (1983) have questioned the role of tannins as plant defense against herbivores. 

The astringency of wine tannin fractions appears to be correlated to the content of flavanol units released after thiolysis regardless of their environment in the original mol-ecules. Anthocyanins contributed neither bitterness nor astringency. Whether incorporation of anthocyanin moieties in tannin-derived structures affects their interactions with proteins and taste properties remains to be investigated. 

Group I includes materials containing tannins derived from pyrocatechol, which give a precipitate with bromine water and a greenish-black coloration with ferric alum. It comprises two sub-groups, with which the precipitate given by copper sulphate (a) redissolves, (6) does not redissolve, in ammonia. 

Group III comprises tanning materials containing tannins derived from pyrogallol, and are not precipitated by bromine water and give a bluish-black coloration with ferric alum. These also are subdivided into (a) those which give the above characteristic reaction with nitrous acid, and (6) those which give no reaction or only a brown colour. 

With respect to the activity of tannins, Momose et al. [157] have demonstrated that gallic acid exhibits higher activity than the tannins derived from it. Gallic acid was found to induce apoptosis in different cell lines this induced cell death was mediated by ROS such as hydrogen peroxide and superoxide anion, as well as by Ca2+. However, the induction of apoptosis depends on the acid s distinctive structural features rather than on its antioxidative activity [158]. In fact, the... 

Caffetannic Acid, ChHibOt, caffetannin, is an example of a tannin derived from protocatechuic acid. It occurs in coffee berries. When fused with potassium hydroxide, it yields protocatechuic acid and acetic acid, and when heated alone it gives pyrocatechol. It is not affected by a solution of gelatin. It does, however, form an insoluble compound with a protein present in milk. It is for this reason that the bitter taste of tea,... 

Le Bourvelleca et al. [17] have investigated the sorption of procyanidins, a polyphenol tannin derivative, on native cellulose fibers and other polysaccharide substrates such as modified pectin and xyloglucan and starch. Through this study, they showed a relatively low affinity of the substrate towards the tested chemical which presented a low adsorbed around 4 mg.g. ... 

FUNATOGAWA, K., HAYASHI, S., SHIMOMURA, H., YOSHIDA, T., HATANO, T., ITO, H., HIRAI, Y., Antibacterial activity of hydrolyzable tannins derived from medicinal plants against Helicobacter pylori, Microbiol. Immunol, 2004, 48, 251-261. 

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). 

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