Quebracho tree

For many years, most of the leather in the United States was tanned with domestic tannins from hemlock and oak bark and from chestnut wood. Today only a small amount of tannin comes from these and other domestic sources. The most important source of vegetable tannin today is the wood of the quebracho tree, which grows mainly in Paraguay and Argentina. The tannin content of this tree and a few other sources of vegetable tannin are shown in Table 28.10. 

Quebracho (cortex). The bark of the quebracho tree, Aspidosperma quebracho-bianco (Apocynaceae), a large tree (up to 20 m high), indigenous to the west of South America. The bark contains ca. 1% monoter-penoid indole alkaloids such as yohimbine, aspido-spermine, quebrachamine. The Aspidosperma alkaloids are structurally related to the Catharanthus alkaloid vindoline. Quebracho bark contains over 25 different alkaloids of widely differing types. ... 

L-Inositol is found in the free state in the drug Euphorbia pilulifera L. (15), but it is found principally as quebrachitol, 1-0-methyl-L-inositol (7, 16), This methyl ether is named for the quebracho tree, from which it was first isolated (17), It occurs in many other plants (2,18), but its most ready source is the latex of the rubber tree (Hevea broMliensis) (19), Conversion of one of the active inositols into the other requires inversion of the configuration of carbon atoms 4 and 5 only. 

Quebrachitol (lL-2-O-methyl-cA/ro-inositol) is present in several woods the barks of the quebracho tree Aspidosperma quebracho), Haplophyton cimh... 

Beauchemin, K.A., S.M. McGinn, T.F. Martinez and T.A. McAllister, 2007. Use of condensed tannin extract from quebracho trees to reduce methane emissions from cattle. J. Anim. Sci. 85, 1990-1996. 

The tannins are synthesized by plants and are abundantly distributed in many different forms of plant life. Common sources of tannins include for example, the bark, leaves, fruit and roots of many plants most tannins, however, have been and are still derived from the bark of a few trees and shrubs, such as oak, chestnut, hemlock, mangrove, quebracho, and wattle, from which they are generally extracted with water. 

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. 

There are a few minor wood-based chemical industries. After chestnut blight wiped out the American chestnut, U.S. tannin production essentially ceased. The main natural tannins, watde and quebracho, are now imported. High U.S. labor costs and the advent of synthetic tannins make re-establishment of a U.S. tannin industry unlikely. Tannins are used in oil-weU drilling muds. Tree exudates are a continuing wood-based chemical industry. Tree exudates include mbber, tme carbohydrate gums (eg, acacia gum), kinos (eg, the phenolic exudates from eucalyptus), balsams (eg, Storax from l iquidambar spp.), and many different types of oleoresins (mixtures of a soHd resin and a liquid essential oil). The most important oleoresin stiU collected in the United States is pine gum (rosin plus turpentine). 

Condensed tannins constitute more than 90 per cent of the total world production of commercial tannins (200000 tons per year) [11]. Their high reactivity towards aldehydes and other reagents renders them both chemically and economically more interesting for the preparation of adhesives, resins and other applications apart from leather tanning. The main commercial species, such as mimosa and quebracho, also yield excellent heavy duty leather. Condensed tannins and their flavonoid precursors are known for their wide distribution in nature and particularly for their substantial concentration in the wood and bark of various trees. These include various Acacia (wattle or mimosa bark extract), Schinopsis (quebracho wood extract), Tsuga (hemlock bark extract), Rhus (sumach extract) species, and various Pinus bark extract species, from which commercial tannin extracts are manufactured. 

Quebracho Extract. An extract of tannin from the S. American tree Quebracho Colorado. It has found some use, particularly as sodium tannate, as a deflocculant for pottery slips. 

Aspidosperma quebracho bianco (Apocynaceae) is a tall tree that grows wild in Argentina, Brazil, and Chile. The bark is called quebracho bark or white quebracho , and contains tannins and alkaloids. It is used in folk medicine as an antipyretic and diuretic and as a treatment for pertussis and asthma. 

T. are extracted from various parts (wood, bark, fruits, gall apples) of trees (oak, birch, mimosa, quebracho, chestnut) with water and spray-dried. Tannin is a white to yellowish powder. 

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