Tannin activity tannins

Tannins are typically used in BW at 150 to 200 ppm active tannin product, but perhaps only a third of this is related to its polymeric sludge conditioning functionality. 

Figure 4. Binding of a protein (hemoglobin) to several tannin extracts (tannic acid, sugar maple tannins, yellow birch tannins, quebracho tannins see 29) at various pH values. Ranges of microbial chitinase activity, NPV activity, and Bt toxicity are given. See text for discussion and references.

However, the immediate prospect of tannin activation via facile ring isomerization and without introduction of solubilizing sulfonic groups, is the reduction of resorcinol requirements in those cold-set mimosa-resorcinol-formaldehyde... 

In the same manner, not all ellagitannins are hydrolyzable as those with a C-glycosidic bond will not break down with tannin-active enzymes or hot dilute acids to produce free ellagic acid. 

The leaves of M. oleifera have neghgible amounts of tannins and total phenolics (6). Condensed tannins, activity of tiypsin inhibitors and lectins have not been detected in M oleifera. Therefore, these antinutritional factors are considered not to be able to produce any adverse effects in animals. However, lectins have been reported in aqueous extracts at pH 4.5 (43). The saponins are observed to be at comparable contents as in soyabean meal. Phytates are found... 

In chemical terms, tannins are relatively bulky phenol molecules, produced by the polymerization of elementary molecules with phenolic functions. Their configuration affects their reactivity (Section 6.3.4). They must be sufficiently bulky to produce stable combinations with proteins, but if they are too bulky, they are likely to be too far from the active protein sites. The molecular weights of active tannins range approximately from 600 to... 

Tannins are a broad class of complex phenolic compounds that are comprised of two chemical groups the hydrolyzable tannins (gallotannins) and the condensed tannins (proanthocyanidins). Tannins bind to and precipitate proteins, producing the astringent activity of tannin-containing herbs. Tannins are natural components of many herbs and common foods, and some tannins are used in the processing of foods, alcoholic beverages, and medicines. 

Rapeseed meals frequently contain tannins. These are polyphenolic compounds that complex with proteins and carbohydrates to form enzyme-resistant substrates with a consequent lowering of digestibility. This may also result from the combination of the tannins with digestive enzymes, with a consequent loss of activity. Tannins may cause damage to the intestinal mucosa and are known to interfere with iron absorption. 

Phenolic compounds are widely distributed in plant parts from the roots to the seeds and include phenolic acids, flavo-noids and tannins. The tannins may reduce protein digestibility (Ford and Hewitt, 1979) and perhaps the bioavailability of other nutrients. The flavonoids have been reported to have a number of nutritional and pharmacological activities (Kuhnau, 1976). Phenolic acids include benzoic and cinnamic acid derivatives. The benzoic acid derivatives include p-hydroxy-benzoic, protochate-chuic, vanillic, gallic and syringic acids. The cinnamic acids, p-coumaric, caffeic, ferulic and sinapic are found in most oilseeds used to prepare protein concentrates and frequently occur in the form of esters with quinic acid or sugars. Chlorogenic acid for example is an ester of caffeic acid and quinic acid and is found in several isomeric and derivatized forms. 

Okuda T, Yoshida T, Hatano T (1992) Pharmacologically active tannins isolated from medicinal plants. In Hemingway RW, Laks PE (eds) Plant polyphenols. Plenum Press, New York... 

Almond emulsin is prepared from defatted crushed almonds by extraction with water and precipitation of the extracts with alcohol. The dried powder is known as almond emulsin. A preparation of considerably more activity is obtained by treatment of the almond meal with zinc sulfate solution and precipitation of the enzymes from solution by the addition of tannin. The tannin is separated from the enzyme by extraction of the precipitate with acetone, and the solid residue is the Rohferment of Helferich 23) which has been used for many of the studies of the specificities of the enzyme components of almond emulsin. The Rohferment usually has a /S-gluco-sidase value of about 1. 

Antioxidant Activity of Tannins and Tannin-Protein Complexes Assessment In Vitro and In Vivo... 

Plants and microorganisms produce unique and diverse chemical stmctures, some of which act as immunomodulators (18—28). Of specimens used in traditional medicine, approximately 450 plant species have shown antiviral activity out of 4000 plants screened (19). Several tannins (20) exhibit strong inhibition of tumor promotion experimentally. Pretreatment of mice with small amounts of tannins for several days strongly rejected transplanted tumors. This activity has been claimed to be effected through enhancement of host-mediated antitumor activity. 

This needs to be taken into aceount particularly with drugs containing essential oils, tannins, and bitter substanees [I, 2]. Herbal drugs with these active constituents should not be. stocked in the powdered state. 

Tannin blend concentrates primarily intended for oxygen-scavenging duty in steam boilers. They generally are offered as dark-brown to black, blended products of 25 to 50% active strength. Here, tannins provide an additional benefit of sludge conditioning at no extra cost. 

There are few, if any, specific inhibitors of lipase activity. Instead, reported inhibition of lipase by saponins (Han et al., 2002), polysaccharides and tannins (Longstaff and McNab, 1991) is probably due to the non-specific interactions these phytochemicals have with proteins. 

LONGSTAFF M, MCNAB J M (1991) The inhibitory effects of hull polysaccharides and tannins of field beans (Vida faba L.) on the digestion of amino acids, starch and hpid and on digestive enzyme activities in young chicks. Br. TNutr. 65 199-216. 

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