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单词 tannin
释义

tannin


tan·nin

T0039000 (tăn′ĭn)n.1. Any of various water-soluble polyphenols found in plant tissues that bind proteins and promote the tanning of leather. Also called tannic acid.2. Any of various other substances that promote the tanning of leather, such as chromium salts.
[French, from tan, crushed oak bark, from Old French, from Medieval Latin tannum; see tan1.]

tannin

(ˈtænɪn) n (Elements & Compounds) any of a class of yellowish or brownish solid compounds found in many plants and used as tanning agents, mordants, medical astringents, etc. Tannins are derivatives of gallic acid with the approximate formula C76H52O46. Also called: tannic acid [C19: from French tanin, from tan1]

tan•nin

(ˈtæn ɪn)

n. any of a group of astringent vegetable principles or compounds, chiefly complex glucosides of catechol and pyrogallol, as the reddish compound that gives tanning properties to oak bark or the whitish compound that occurs in nutgalls. Also called tan′nic ac′id. [earlier tanin < French (1798). See tan1, -in1]
Thesaurus
Noun1.tannin - any of various complex phenolic substances of plant origin; used in tanning and in medicinetannic acidcutch, kutch - tannin extract derived from any of several mangrove barks of Pacific areasphenol - any of a class of weakly acidic organic compounds; molecule contains one or more hydroxyl groupscatechin - a tannic acid that is extracted from black catechu as a white crystalline substance
Translations
tanninoacido tannico

tannin


tannin,

 

tannic acid,

or

gallotannic acid,

astringent vegetable product found in a wide variety of plants. Sources include the bark of oak, hemlock, chestnut, and mangrove; the leaves of certain sumacs; and plant galls. Tannin is also present in tea, coffee, and walnuts. A solution of tannic acid is obtained from one of these natural sources by extraction with hot water; in particular, gallotannic acid is obtained from plant gall. Tannin varies somewhat in composition, having the approximate empirical formula C76H52O46. Tannic acid is a colorless to pale yellow solid; it is believed to be a glucoside in which each of the five hydroxyl groups of the glucose molecule is esterified with a molecule of digallic acid. Tannin is used in tanning animal skins to make leather; it transforms certain proteins of animal tissue into compounds that resist decomposition. It is also used in manufacturing inks, as a mordant in dyeing, and in medicine as an astringent and for treatment of burns.

Tannin

 

any of a group of phenol compounds that are widespread in plants and are capable of forming strong bonds with proteins and certain other natural polymers, such as cellulose and pectins.

Originally (late 18th century), the term “tannin” was applied to a mixture of substances extracted by water from a number of plants that was capable of transforming animal hides into leather. In modern usage, the term includes all naturally occurring compounds having molecular weights from 500 to 3,000 and containing a large number of phenolic hydroxyl groups. (In the Soviet Union, tannins of plant origin are also called tannides.)

Tannins are divided into two classes. The first comprises the tannins formed by a polyhydric alcohol, such as glucose, in which the hydroxyl groups are partially or completely esterified by gallic acid or related compounds. These tannins are referred to as hydrolyzable; an example is seen in structural formula I. The second includes the tannins formed through the condensation of such phenol compounds as catechins. These tannins are described as condensed; an example is seen in structural formula II.

Tannins are contained in galls and in bark, wood, and leaves and/or fruits of tannin plants. They are used in tanning leather, and they also serve as mordants in dyeing cotton fabrics. In medicine they are used as astringents. When used on burns, aqueous solutions of tannins bind the toxic protein products of tissue decomposition and facilitate healing. In the body, tannins can bind bacterial toxins, as well as toxic salts of silver, mercury, and lead.

REFERENCES

Biokhimiia rastenii. Moscow, 1968. Chapter 22. (Translated from English.)
Zaprometov, M. N. Osnovy biokhimii fenol’nykh soedinenii. Moscow, 1974.

tannin

[′tan·ən] (organic chemistry) tannic acid

tannin

any of a class of yellowish or brownish solid compounds found in many plants and used as tanning agents, mordants, medical astringents, etc. Tannins are derivatives of gallic acid with the approximate formula C76H52O46

tannin


tannic acid

 [tan´ik] a substance obtained from nutgalls, oak bark, and other plant parts, formerly used in medicine as an astringent. It is no longer used alone because it can be absorbed through mucous membranes or damaged skin in amounts sufficient to produce hepatic necrosis, although it is still used as a component of dermatological preparations.

tan·nin

(tan'in), Any one of a group of complex nonuniform plant constituents that can be classified into hydrolyzable tannins (esters of a sugar, usually glucose, and one or several trihydroxybenzenecarboxylic acids) and condensed tannins (derivatives of flavonols). Tannins are used in tanning, dyeing, photography, and as clarifying agents for beer and wine. Sometimes used synonymously with tannic acid. Tannins form black stains in the presence of iron.

tannin

Herbal medicine
Any of a family of compounds that react with proteins to produce a leathery coating on animal tissues and give woods their brown, red and yellow hues; tannins are anti-inflammatory, antimicrobial and astringent.

tan·nin

(tan'in) A complex nonuniform plant constituent; used in tanning, dyeing, photography, and as clarifying agents for beer and wine.

tannin

a complex organic compound occurring widely in plant sap, particularly in bark, leaves and unripe fruits, that is used in the production of leather and ink.

tan·nin

(tan'in) Complex nonuniform plant constituent used in tanning, dyeing, photography, and as clarifying agents for beer and wine. Sometimes used synonymously with tannic acid.

tannin


  • noun

Synonyms for tannin

noun any of various complex phenolic substances of plant origin

Synonyms

  • tannic acid

Related Words

  • cutch
  • kutch
  • phenol
  • catechin
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