Tannin from plants

Lignin from Wood Tannin from Plant leaves, wax, seeds... 

All the tannins readily react with proteins, forming insoluble, stable compounds when they react with collagen, the main constituent of animal skin, they form leather, a material that is resistant to hydrolysis, oxidation, and biological attack and therefore stable to weathering and resistant to decomposition. Since tannins from different plant sources have different chemical compositions, each tannin used for tanning skin produces a leather having slightly different properties and color. Tannins that have... 

Giner-Chavez BI, Van Soest PJ, Robertson JB et al (1997) A method for isolating condensed tannins from crude plant extracts with trivalent ytterbium. J Sci Food Agric 74 359-368... 

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. 

Tannins are water-soluble phenolic compounds which are usually extracted from plant material by hot water. After lignins, they are the second most abundant group of plant phenolics. Their tanning property is due to their capacity to combine with proteins. However, they can also complex with other polymers such as alkaloids, cellulose, and pectins. 

Wall, M. E., H. Taylor, L. Ambrosio, and K. Davis. Plant Antitumor agents III a convenient separation of tannins from other plant constituents. J Pharm... 

Yoshida, T. et al.. Tannins and related polyphenols of melastomataceous plants. V. Three new complex tannins from Melastoma malabathrician L., Chem. Pharm. Bull, 40, 1727, 1992. 

Trees of the genus Schinopsis. native to the southern part of South America, including southern Brazil, Bolivia and other southern countries are very important source of tannin. These trees are known by the name quebracho, which means ax-breaker, because of their very hard, dense, heavy, dark-red wood, which is cut with difficulty. The heartwood of the tree contains 20-27% tannin, which is obtained by cutting the wood into small chips and extracting with water. Tilts tannin is often used in combination with tannins from other plants. 

Cork, S.J. and Krockenberger, A.K. 1991. Methods and pitfalls of extracting condensed tannins and other phenolics from plants Insights from investigations on Eucalyptus leaves. J. Chem. Ecol. 17 123-134. 

Interest in pine bark as a source of adhesive components began to accelerate following the oil crisis of 1973. Sodium hydroxide extracts of southern pine bark were successfully used in replacing up to 40% of the phenolic resin for bonding of particleboards, oriented strandboards, and composites with a flakeboard core and veneer facing (50f51). Similar results were obtained with extracts from patula pine (52). Encouraged by results of this type, the New Zealand Forest Products Ltd. Corporation expanded their radiata pine bark tannin pilot plant to full-scale operation in 1981 to produce an extract trademarked Tannaphen. This material was crosslinked with paraformaldehyde and used as an adhesive... 

Peng S, Jay-AUemand C (1991) Use of antioxidants in extraction of tannins from walnut plants. J Chem Ecol 17 887-896... 

On the basis of the studies concerning the activity of the hydrolysable tannins from Phyllanthus amarus (Euphorbiaceae), it seems that their effectiveness against common protein kinases is lower than that of condensed tannins. In fact, IC50 values ranged from 0.2 to 1.7 pM for the rat liver PKA-catalytic subunit, and was 26 pM for geraniin (11) and other closely-related compounds against rat brain PKC. Other tannins of the same plant inhibited PKC at the high fixed dose of 167 pM [38]. 

Pyrolysis techniques were applied for the evaluation of catechol content of tannins from different plant materials [1,2], or for the quantitation of tannin content in products such as wine [2]. 

Adsorption and removal of the polyphenols and tannins from tinctures and plant extracts (Section 3.4.6)... 

Many foods obtained from plants contain tannins. These are phenolic compounds that bind proteins, such as mammalian enzymes. It has been shown in vitro that tannic acid significantly reduces the lubricating qualities of human saliva both by decreasing its viscosity and increasing friction [55], This effect depends on the presence of salivary PRPs, which have a high affinity for tannins [56], It has been shown that the introduction of tannins into the diet can stimulate the production of PRPs in the saliva of rats [57], PRPs are a major component of salivary pellicle, and thus it would not be surprising to find that dietary tannins affect the viscosity of pellicle. 

Tannin. Any of a group of complex phenolic compounds derived from plants, characterized by their useful function of precipitating proteins. The chemistry of tannins is complex and variable. 

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