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{{short description|Chemical compound}}
{{chembox {{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 408795684
| ImageFile = Tannic acid.svg | ImageFile = Tannic acid.svg
| ImageSize = | ImageSize = 200px
| ImageCaption = Chemical structure of penta(digalloyl)glucose, a representative component of tannic acid
| IUPACName =
| ImageFile2 = Tannic acid STICK model decagalloyl.png
| OtherNames = Acidum tannicum<br>Gallotannic acid<br>Digallic acid<br>Gallotannin<br>Tannimum<br>Quercitannin<br>Oak bark tannin<br>Quercotannic acid<br>Querci-tannic acid<br>Querco-tannic acid
| ImageSize2 = 200px
| Section1 = {{Chembox Identifiers
| IUPACName = 1,2,3,4,6-penta-''O''-{3,4-dihydroxy-5-benzoyl}-<small>D</small>-glucopyranose
| SystematicName = 2,3-dihydroxy-5-({phenyl}carbonyloxy)oxan-2-yl]methoxy}carbonyl)phenyl 3,4,5-trihydroxybenzoate
| OtherNames = {{Unbulleted list|Acidum tannicum|Gallotannic acid|Digallic acid|Gallotannin|Tannimum|Quercitannin|Oak bark tannin|Quercotannic acid|Querci-tannic acid|Querco-tannic acid}}
|Section1={{Chembox Identifiers
| IUPHAR_ligand = 4319
| Abbreviations = | Abbreviations =
| CASNo_Ref = {{cascite|correct|??}}
| CASNo = 1401-55-4 | CASNo = 1401-55-4
| UNII_Ref = {{fdacite|changed|FDA}}
| UNII = 28F9E0DJY6
| Beilstein = 8186386 | Beilstein = 8186386
| EINECS = | EINECS =
| ChEMBL_Ref = {{ebicite|changed|EBI}}
| ChEMBL = 506247
| PubChem = 16129878 | PubChem = 16129878
| ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}}
| SMILES =
| ChemSpiderID = 17286569
| InChI =
| InChI = 1/C76H52O46/c77-32-1-22(2-33(78)53(32)92)67(103)113-47-16-27(11-42(87)58(47)97)66(102)112-21-52-63(119-72(108)28-12-43(88)59(98)48(17-28)114-68(104)23-3-34(79)54(93)35(80)4-23)64(120-73(109)29-13-44(89)60(99)49(18-29)115-69(105)24-5-36(81)55(94)37(82)6-24)65(121-74(110)30-14-45(90)61(100)50(19-30)116-70(106)25-7-38(83)56(95)39(84)8-25)76(118-52)122-75(111)31-15-46(91)62(101)51(20-31)117-71(107)26-9-40(85)57(96)41(86)10-26/h1-20,52,63-65,76-101H,21H2/t52-,63-,64+,65-,76+/m1/s1
| InChIKey = LRBQNJMCXXYXIU-PPKXGCFTBB
| StdInChI_Ref = {{stdinchicite|changed|chemspider}}
| StdInChI = 1S/C76H52O46/c77-32-1-22(2-33(78)53(32)92)67(103)113-47-16-27(11-42(87)58(47)97)66(102)112-21-52-63(119-72(108)28-12-43(88)59(98)48(17-28)114-68(104)23-3-34(79)54(93)35(80)4-23)64(120-73(109)29-13-44(89)60(99)49(18-29)115-69(105)24-5-36(81)55(94)37(82)6-24)65(121-74(110)30-14-45(90)61(100)50(19-30)116-70(106)25-7-38(83)56(95)39(84)8-25)76(118-52)122-75(111)31-15-46(91)62(101)51(20-31)117-71(107)26-9-40(85)57(96)41(86)10-26/h1-20,52,63-65,76-101H,21H2/t52-,63-,64+,65-,76+/m1/s1
| StdInChIKey_Ref = {{stdinchicite|changed|chemspider}}
| StdInChIKey = LRBQNJMCXXYXIU-PPKXGCFTSA-N
| SMILES = Oc1cc(cc(O)c1O)C(=O)Oc1cc(cc(O)c1O)C(=O)OC1O(OC(=O)c2cc(O)c(O)c(OC(=O)c3cc(O)c(O)c(O)c3)c2)(OC(=O)c2cc(O)c(O)c(OC(=O)c3cc(O)c(O)c(O)c3)c2)(OC(=O)c2cc(O)c(O)c(OC(=O)c3cc(O)c(O)c(O)c3)c2)1OC(=O)c1cc(O)c(O)c(OC(=O)c2cc(O)c(O)c(O)c2)c1
| RTECS = | RTECS =
| MeSHName = | MeSHName =
| ChEBI_Ref = {{ebicite|changed|EBI}}
| ChEBI =
| KEGG = | ChEBI = 75211
| KEGG_Ref = {{keggcite|changed|kegg}}
| ATCvet =
| KEGG = C13452
| ATCCode_prefix =
}}
| ATCCode_suffix =
|Section2={{Chembox Properties
| ATC_Supplemental =}}
| Formula =
| Section2 = {{Chembox Properties
| Formula = |C=76|H=52|O=46| | C=76 | H=52 | O=46
| MolarMass = 1701.19 g/mol | MolarMass = 1701.19 g/mol
| ExactMass = 1700.172974
| Appearance = | Appearance =
| Density = | Density = 2.12g/cm<sup>3</sup>
| MeltingPt = decomposes above 200°C | MeltingPt = decomposes above 200&nbsp;°C
| Melting_notes = | MeltingPt_notes =
| BoilingPt = | BoilingPt =
| Boiling_notes = | BoilingPt_notes =
| Solubility = 2850 g/L or 250 g/L<ref>{{cite web |title=Tannic acid |url=https://www.acs.org/content/acs/en/molecule-of-the-week/archive/t/tannic-acid.html |website=American Chemical Society |access-date=|date = 15 January 2018}}</ref><ref>{{cite web |title=Tannic acid |url=https://www.chemicalbook.com/ProductChemicalPropertiesCB3116328_EN.htm |website=Chemical Book}}</ref>
| Solubility = 2850 g/L
| SolubleOther = 100 g/L in ethanol<br> 1 g/L in glycerol and acetone<br> insoluble in benzene, chloroform, diethyl ether, petroleum, carbon disulfide, carbon tetrachloride.
| SolubleOther =
| pKa = ca. 6
| Solvent = acetone, methanol, ethanol, glycerol, ethyl acetate
| pKa = ca. 10
| pKb = }} | pKb = }}
| Section7 = {{Chembox Hazards |Section7={{Chembox Hazards
| ExternalMSDS = | ExternalSDS =
| EUClass =
| EUIndex =
| MainHazards = | MainHazards =
| NFPA-H = | NFPA-H =
| NFPA-F = | NFPA-F =
| NFPA-R = | NFPA-R =
| NFPA-O = | NFPA-S =
| RPhrases = | HPhrases =
| SPhrases = | PPhrases =
| RSPhrases = | GHS_ref =
| FlashPt = | FlashPt =
| Autoignition = | AutoignitionPt =
| ExploLimits = | ExploLimits =
| PEL = }} | PEL =
}}
}} }}
] ].]]


'''Tannic acid''' is a specific commercial form of ], a type of ]. Its weak ] (] around 6) is due to the numerous ] groups in the structure. The ] for commercial tannic acid is often given as C<sub>76</sub>H<sub>52</sub>O<sub>46</sub>, which corresponds with decagalloyl glucose, but in fact it is a mixture of polygalloyl glucoses or polygalloyl quinic acid esters with the number of galloyl moieties per molecule ranging from 2 up to 12 depending on the plant source used to extract the tannic acid. Commercial tannic acid is usually extracted from any of the following plant part: Tara pods ('']''), gallnuts from '']'' or '']'' or Sicilian Sumac leaves ('']''). '''Tannic acid''' is a specific form of ], a type of ]. Its weak ] (] around 6) is due to the numerous ] groups in the structure. The ] for commercial tannic acid is often given as C<sub>76</sub>H<sub>52</sub>O<sub>46</sub>, which corresponds with decagalloyl glucose, but in fact it is a mixture of polygalloyl glucoses or polygalloyl quinic acid esters with the number of ] moieties per molecule ranging from 2 up to 12 depending on the plant source used to extract the tannic acid. Commercial tannic acid is usually extracted from any of the following plant parts: Tara pods ('']''), gallnuts from '']'' or '']'' or Sicilian sumac leaves ('']'').


According to the definitions provided in external references such as international pharmacopoeia, Food Chemical Codex and FAO-WHO tannic acid monograph only tannins sourced from the above mentioned plants can be considered as tannic acid. Sometimes extracts from ] or ] wood are also described as tannic acid but this is an incorrect use of the term. It is a yellow to light brown ] powder which is highly soluble in water; one ] dissolves in 0.35 ] of water. According to the definitions provided in external references such as international pharmacopoeia, ] and FAO-WHO tannic acid monograph only tannins obtained from the above-mentioned plants can be considered as tannic acid. Sometimes extracts from ] or ] wood are also described as tannic acid but this is an incorrect use of the term. It is a yellow to light brown ] powder.


While 'tannic acid' is a specific type of 'tannin' (plant polyphenol), the two terms are sometimes (incorrectly) used interchangeably. The long standing misuse of the terms, and its inclusion in scholarly articles have compounded the confusion. This is particularly widespread in relation to green tea and black tea. Although tea contains tannin and various types of polyphenols, "contrary to widespread belief, tea does not contain tannic acid." <ref>{{cite journal |author=Hamilton-Miller JM |title=Antimicrobial properties of tea (''Camellia sinensis L.'') |journal=Antimicrob. Agents Chemother. |volume=39 |issue=11 |pages=2375–7 |date=1 November 1995|pmid=8585711 |pmc=162950 |url=http://aac.asm.org/cgi/pmidlookup?view=long&pmid=8585711 }}</ref> While tannic acid is a specific type of tannin (plant polyphenol), the two terms are sometimes (incorrectly) used interchangeably. The long-standing misuse of the terms, and its inclusion in scholarly articles has compounded the confusion. This is particularly widespread in relation to green tea and black tea, both of which contain many different types of tannins not just exclusively tannic acid.<ref>{{cite journal |doi=10.1126/science.432625 |title=Darvon safety |year=1979 |last1=Pettinga |first1=C. |journal=Science |volume=204 |issue=4388 |pages=6 |pmid=432625 |bibcode=1979Sci...204....6P}}</ref>

Tannic acid is not an appropriate standard for any type of tannin analysis because of its poorly defined composition.


== Quercitannic and gallotannic acids == == Quercitannic and gallotannic acids ==
'''Quercitannic acid''' is one of the two forms of tannic acid<ref></ref> found in ] and leaves<ref></ref>. The other form is called gallotannic acid and is found in oak galls.


] is one of the two forms of tannic acid<ref>{{cite book|title=L'Energie Homo-Hydrogne |url=https://books.google.com/books?id=HVoi7qnjYMQC&pg=PA248|year=2004|publisher=Editions Publibook |isbn=978-2-7483-0811-2|pages=248–}}</ref> found in ] and leaves.<ref>{{cite web|url = http://www.henriettes-herb.com/eclectic/bpc1911/quercus.html |title = Quercus Cortex. Oak Bark.|website = Henriette's Herbal Homepage}}</ref> The other form is called ] and is found in oak galls.
The quercitannic acid molecule is also present in ], a yellow dye obtained from the bark of the Eastern black oak (''Quercus velutina''), a forest tree indigenous in North America. It is described as as a yellowish brown amorphous substance<ref></ref>.

The quercitannic acid molecule is also present in ], a yellow dye obtained from the bark of the Eastern black oak (''Quercus velutina''), a forest tree indigenous in North America. It is described as a yellowish-brown amorphous powder.


In 1838, ] wrote that quercitannate is used to dissolve morphine.<ref>Traité de chimie, Volume 2. Jöns Jakob Berzelius (friherre) and Olof Gustaf Öngren, A. Wahlen et Cie., 1838</ref> In 1838, ] wrote that quercitannate is used to dissolve morphine.<ref>Traité de chimie, Volume 2. Jöns Jakob Berzelius (friherre) and Olof Gustaf Öngren, A. Wahlen et Cie., 1838{{page needed|date=December 2013}}</ref>


In 1865 in the fifth volume of "A dictionary of chemistry", ] wrote : In 1865 in the fifth volume of "A dictionary of chemistry", ] wrote :
<blockquote>It exhibits with ferric salts the same reactions as gallotannic acid. It differs however from the latter in not being convertible into ], and not yielding ] by dry distillation. It is precipitated by sulfuric acid in red flocks. (], Ann. Ch. Pharm. xlv. 16.) <blockquote>It exhibits with ferric salts the same reactions as gallotannic acid. It differs however from the latter in not being convertible into ], and not yielding ] by dry distillation. It is precipitated by ] in red flocks. (], Ann. Ch. Pharm. xlv. 16.)
<br>According to Rochleder (ibid lxiii. 202), the tannic acid of black tea is the same as that of oak-bark.<ref>A dictionary of chemistry, Volume 5, by Henry Watts, 1865</ref></blockquote> <br>According to Rochleder (ibid lxiii. 202), the tannic acid of black tea is the same as that of oak-bark.<ref>{{cite book|url = https://books.google.com/books?id=J9fokzIF4NMC&pg=PA6 |title = A Dictionary of chemistry and the allied branches of other sciences|volume= 5|first = Henry|last = Watts|date = 1868|publisher = Longmans, Green, and Company|page = 6}}</ref></blockquote>


In 1880, Etti gave for it the molecular formula C<sub>17</sub>H<sub>16</sub>O<sub>9</sub>. He described it as an unstable substance, having a tendency to give off water to form ]s (called ]s), one of which is called ''oak-red'' (C<sub>34</sub>H<sub>30</sub>O<sub>17</sub>). For him, it was not a glycoside.<ref>Über die Gerbsäure der Eichenrinde. C. Etti, Monatshefte für Chemie, Volume 1, Number 1, 262-278, 1880 {{doi|10.1007/BF01517069}} (German)</ref><ref>Zur Geschichte der Eichenrindegerbsäuren. C. Etti, Monatshefte für Chemie, Volume 4, Number 1, 512-530, 1883 {{doi|10.1007/BF01517990}} (German)</ref> In 1880, Etti gave for it the molecular formula C<sub>17</sub>H<sub>16</sub>O<sub>9</sub>. He described it as an unstable substance, having a tendency to give off water to form ]s (called ]s), one of which is called ''oak-red'' (C<sub>34</sub>H<sub>30</sub>O<sub>17</sub>). For him, it was not a glycoside.<ref>{{cite journal |doi=10.1007/BF01517069 |title=Über die Gerbsäure der Eichenrinde |trans-title=About the tannic acid from oak bark |language=de |year=1880 |last1=Etti |first1=C. |journal=Monatshefte für Chemie |volume=1 |issue=1 |pages=262–78|s2cid=94578197 |url=https://zenodo.org/record/1938533 }}</ref><ref>{{cite journal |doi=10.1007/BF01517990 |title=Zur Geschichte der Eichenrindegerbsäuren |trans-title=On the history of oak bark tannins |language=de |year=1883 |last1=Etti |first1=C. |journal=Monatshefte für Chemie |volume=4 |issue=1 |pages=512–30|s2cid=105109992 |url=https://zenodo.org/record/2518525 }}</ref>


]
In Allen’s "Commercial Organic Analysis", published in 1912, the formula given was C<sub>19</sub>H<sub>16</sub>O<sub>10</sub>.<ref>The nature of tea infusions. Henry L. Smith, The Lancet, Volume 181, Issue 4673, 22 March 1913, Page 846, {{doi|10.1016/S0140-6736(01)03766-7}}</ref>


In Allen's "Commercial Organic Analysis", published in 1912, the formula given was C<sub>19</sub>H<sub>16</sub>O<sub>10</sub>.<ref>{{cite journal |doi=10.1016/S0140-6736(01)03766-7 |title=The Nature of Tea Infusions |year=1913 |last1=Smith |first1=Henryl. |journal=The Lancet |volume=181 |issue=4673 |pages=846|url=https://zenodo.org/record/1911379 }}</ref>
Other authors gave other molecular formulas like C<sub>28</sub>H<sub>26</sub>O<sub>15</sub>, while another formula found is C<sub>28</sub>H<sub>24</sub>O<sub>11</sub>.<ref></ref>


According to Lowe, two forms of the principle exist - one soluble in water, of the formula C<sub>28</sub>H<sub>28</sub>O<sub>14</sub>, and the other scarcely soluble, C<sub>28</sub>H<sub>24</sub>O<sub>12</sub>. Both are changed by the loss of water into oak red, C<sub>28</sub>H<sub>22</sub>O<sub>11</sub>.<ref></ref> Other authors gave other molecular formulas like C<sub>28</sub>H<sub>26</sub>O<sub>15</sub>, while another formula found is C<sub>28</sub>H<sub>24</sub>O<sub>11</sub>.<ref>{{cite book |url=http://envstudies.brown.edu/theses/98RECKORD.pdf |title=What are the historic and contemporary ethnobotanical uses of native Rhode Island wetlands plants? |first=Courtney |last=Reckford |year=1997 |type=MA Thesis |oclc=549678548}}{{page needed|date=December 2013}}</ref>


According to Lowe, two forms of the principle exist – "one soluble in water, of the formula C<sub>28</sub>H<sub>28</sub>O<sub>14</sub>, and the other scarcely soluble, C<sub>28</sub>H<sub>24</sub>O<sub>12</sub>. Both are changed by the loss of water into oak red, C<sub>28</sub>H<sub>22</sub>O<sub>11</sub>."<ref>{{cite book|url =http://www.swsbm.com/SayreMM/Sayre's_Materia_Medica-1.pdf|title = A manual of organic materia medica and pharmacognosy: An introduction to the study of the vegetable Kingdom and the vegetable and animal drugs |edition = Fourth|first = Lucius E|last = Sayre|page = 95|date = }}</ref>
Quercitannic acid was for a time a standard used to assess the phenolic content in ]s, given as ''quercitannic acid equivalent''.<ref>Government standards for spices. Journal of the American Pharmaceutical Association, Volume 12, Issue 12, pages 1091–1094,December 1923, {{doi|10.1002/jps.3080121212}}</ref>

Quercitannic acid was for a time a standard used to assess the phenolic content in ]s, given as ''quercitannic acid equivalent''.<ref>{{cite journal |doi=10.1002/jps.3080121212 |title=Government standards for spices |year=2006 |journal=Journal of the American Pharmaceutical Association |volume=12 |issue=12 |pages=1091–4|last1=Putt |first1=Earl B. |last2=Seil |first2=Harvey A. }}</ref>

In an interesting historical note, the inventor of ], ], discovered that gallotannic acid greatly improved the plasticity of clay. In his report of this discovery in 1904 he noted that the only known historical reference to the use of organic material added to clay is the use of straw mixed with clay described in the Bible, Exodus 1:11 and that the Egyptians must have been aware of his (re-)discovery. He stated "This explains why the straw was used and why the children of Israel were successful in substituting stubble for straw, a course that would hardly be possible, were the fibre of the straw depended upon as a bond feasible for the clay, but quite reasonable where the extract of the plant was used."<ref>Acheson, Edward G. (1904) "Egyptianized Clay" in ''Transactions of the American Ceramic Society''. pp. 31–65.</ref>


==Uses== ==Uses==
{{More citations needed section|date=July 2016}}
Tannins are a basic ingredient in the chemical staining of ], and are already present in woods like ], ], and ]. Tannic acid can be applied to woods low in tannin so chemical stains that require tannin content will react. The presence of tannins in the bark of ] is a strong natural defense against ], ] and infestation by certain insects such as ]s. It is found in the ], ], ], and ].
Tannins are a basic ingredient in the chemical staining of ], and are already present in woods like ], ], and ]. Tannic acid can be applied to woods low in tannin so chemical stains that require tannin content will react. The presence of tannins in the bark of ] is a strong natural defense against ], ] and infestation by certain insects such as ]s. It is found in the ], ], ], and ].


Tannic acid is a common ] used in the dyeing process for ] fibers such as ], often combined with ] and/or ]. The tannin mordant should be done first as metal mordants combine well with the fiber-tannin complex. However this use has lost considerable interest. Tannic acid is a common ] used in the dyeing process for ] fibers such as ], often combined with ] and/or ]. The tannin mordant should be done first as metal mordants combine well with the fiber-tannin complex. However this use has lost considerable interest.


Similarly tannic acid can also be used as an aftertreatment to improve wash fastness properties of acid dyed ]. It is also an alternative for fluorcarbon aftertreatments to impart anti-staining properties to polyamide yarn or carpets. Similarly tannic acid can also be used as an aftertreatment to improve wash fastness properties of acid dyed ]. It is also an alternative for ] aftertreatments to impart anti-staining properties to polyamide yarn or carpets.
However, due to economic considerations currently the only widespread use as textile auxiliary is the use as an agent to improve chlorine fastness (i.e. resistance against dye bleaching due to cleaning with hypochlorite solutions in high-end polyamide 6,6-based carpets and swimwear. However, due to economic considerations currently the only widespread use as textile auxiliary is the use as an agent to improve chlorine fastness, i.e. resistance against dye bleaching due to cleaning with hypochlorite solutions in high-end polyamide 6,6-based carpets and swimwear. It is, however, used in relatively small quantities for the activation of ] flock; this serves as an anti-] treatment.


Tannic acid is used in the conservation of ferrous (iron based) metal objects to passivate and inhibit corrosion. Tannic acid reacts with the corrosion products to form a more stable compound, thus preventing further corrosion from taking place. After treatment the tannic acid residue is generally left on the object so that if moisture reaches the surface the tannic acid will be rehydrated and prevent or slow any corrosion. Tannic acid treatment for conservation is very effective and widely used but it does have a significant visual effect on the object, turning the corrosion products black and any exposed metal dark blue. It should also be used with care on objects with copper alloy components as the tannic acid can have a slight etching effect on these metals.
A particular and unique nich textile application of tannic acid is the activation of flock, which is basically an anti-static aftertreatment.


Tannic acid is also found in commercially available iron/steel ], such as Hammerite Kurust.
Tannic acid is also used in the restoration of objects made of metal like ]s recovered from the sea and often extensively damaged from exposure to salt water. Because of this, electrolytic reduction treatment is required to forestall the process of corrosion. The cannon is then washed in deionized water to remove the electrolyte, and is treated in tannic acid, which prevents further ] and gives the metal a bluish-black color.


==Use in food== ===Use in food===
In many parts of the world, its uses in food are permitted. In the ], tannic acid is ] by the ] for use in baked goods and baking mixes, alcoholic and non-alcoholic beverages, frozen dairy products, soft and hard candy, meat products, and ] animal fat.<ref name="fda-gras">{{cite web |title=Food Additive Status List (GRAS); listing for tannic acid |url=https://www.fda.gov/food/food-additives-petitions/food-additive-status-list#ftnT |publisher=US Food and Drug Administration |access-date=6 November 2020 |date=24 October 2019}}</ref>
Use of tannic acid in food applications is far more widespread and significant amounts are used as process aids in beer clarification, aroma compound in soft drinks and juices. Equally important are applications in the wine industry, where it finds use as a natural clarifying agent, colour stabilizer and taste enhancer.


According to ] 89/107/EEC, tannic acid cannot be considered as a ] and consequently does not hold an ].<ref name="efsa">{{cite journal |date=2014-10-01 |title=Scientific Opinion on the safety and efficacy of tannic acid when used as feed flavouring for all animal species|journal=EFSA Journal|volume= 12|issue=10|doi=10.2903/j.efsa.2014.3828|author=EFSA Panel on Additives and Products or Substances used in Animal Feed|page=3828 |doi-access=free}}</ref> Under directive 89/107/EEC, tannic acid can be referred to as a food ingredient. The E-number E181 is sometimes incorrectly used to refer to tannic acid; this in fact refers to the ] assigned to tannic acid under the FAO-WHO Codex Alimentarius system.<ref name=efsa/>
In many parts of the world such uses are permitted. In the ], tannic acid is classified as ] by the ].


===Uses as a medication===
According to ] 89/107/EEC tannic acid cannot be considered as a ] and consequently does not hold an ]. Under directive 89/107/EEC tannic acid can be referred to as a food ingredient. The E-number E181 is sometimes incorrectly used to refer to tannic acid; this in fact refers to the INS number assigned to tannic acid under the FAO-WHO Codex Alimentarius system.


In conjunction with magnesium and sometimes activated charcoal, tannic acid was once used as a treatment for many toxic substances, such as ], mushroom, and ptomaine poisonings in the late 19th and early 20th centuries.<ref>{{cite journal |last=Sturmer |first=J. W. |date=April 13, 1899 |title=Pharmaceutical Toxicology |url=https://books.google.com/books?id=dcvmAAAAMAAJ&pg=PA472 |pages=472–4 |journal=The Pharmaceutical Era |volume=21 |issn=0096-9125}}</ref>
==Uses as a medication==
Tannic acid was once used as a treatment for many toxic substances, such as ], mushroom, and ptomaine poisonings in the late 19th and early 20th centuries.<ref>Sturmer, J.W., and . "Pharmaceutical Toxicity." The Pharmaceutical Era. Vol 21. New York: D.O. Haynes & Co., 1899,pg 511-13.</ref>


The introduction of tannic acid treatment of severe burn injuries in the 1920's significantly reduced mortality rates<ref> S.B.A. Halkens et al., "The use of tannic acid in the local treatment of burn wounds: intriguing old and new perspectives.", Wounds, 2001, 13(4), p 144-158.</ref> During ], tannic acid dressings were prescribed to treat "burns, whether caused by incendiary bombs, ] or ]... Where tannic acid is not available, strong, lukewarm tea is a good substitute."<ref>{{cite |title=Medicine: War Wounds |magazine=TIME |date=18 September 1939|url=http://www.time.com/time/magazine/article/0,9171,762600-2,00.html}}</ref> After the war this use was abandoned due to the development of more modern treatment regimes. The introduction of tannic acid treatment of severe burn injuries in the 1920s significantly reduced mortality rates.<ref>{{cite journal |last1= |title=The use of tannic acid in the local treatment of burn wounds: intriguing old and new perspectives |journal=Wounds |year=2001 |volume=13 |issue=4 |pages=144–58 |url=http://taninos.tripod.com/usotaninos.htm}}</ref> During ], tannic acid dressings were prescribed to treat "burns, whether caused by incendiary bombs, ], or ]".<ref>{{cite news |title=Medicine: War Wounds |magazine=TIME |date=18 September 1939|url=http://www.time.com/time/magazine/article/0,9171,762600-2,00.html |archive-url= https://web.archive.org/web/20080530022321/http://www.time.com/time/magazine/article/0,9171,762600-2,00.html |url-status=dead |archive-date=May 30, 2008 }}</ref> After the war this use was abandoned due to the development of more modern treatment regimens.


== Hazards ==
Today tannic acid is still used in pharmaceutical applications to produce ] which is used as an anti-diarrhea agent. Tannic acid is also used to produce tannate salts of certain anti-histamins and anti-tussives to impart increased stability or slow release properties to the API (active pharmaceutical ingredient).
Tannic acid could cause potential health hazards such as damage to the eye, skin, respiratory tract, and gastrointestinal tract. It may cause irritation, redness, pain, blurred vision, and possible eye damage. When tannic acid is absorbed through the skin in harmful amounts, it may cause irritation, redness, and pain. Nausea, vomiting and diarrhoea are symptoms of tannic acid ingestion and prolonged exposure may cause liver damage. Upon inhalation, tannic acid may cause respiratory tract irritation.<ref>{{cite web |title=Material Safety Data Sheet: Tannic Acid |url=https://fscimage.fishersci.com/msds/22410.htm |website=fscimage.fishersci.com |access-date=10 September 2019}}</ref>


==Crocodilian coloration==
There are many unverified and/or dubious claims about tannic acid, such as that soaking feet in tannic acid (or strong tea) can treat or prevent blisters; foot odor; and rough, dry feet<ref>Buck. "Medicine Man". Backpacker August 2003: 63. </ref><ref>Cox, L., & Cox, J. (2009). Ecobeauty: Scrubs, rubs, masks, and bath bombs for you and your friends. Berkeley : Ten Speed Press, pg 219.</ref>. Other claims about tannic acid seem to either add to, or have been created by the confusion between tannic acid and tannin. One example is that "A popular home remedy to stop the bleeding after wisdom tooth extraction is applying tea bags in the back of the jaws and biting down, given that the tannic acid in tea helps to clot blood."


Skin color in ] (crocodiles and alligators) is very dependent on water quality. Algae-laden waters produce greener skin, while tannic acid in the water from decay of leaves from overhanging trees (which produces some types of ]s) often produce darker skin in these animals.<ref>{{cite web|url=https://www.nps.gov/ever/learn/nature/alligator.htm|title=American Alligator: Species Profile|website=National Park Service|date=17 October 2017|access-date=1 November 2018}}</ref>
Tannic acid ] is used for local application<ref></ref>.

==Trivia==
Skin color in ] (crocodiles and alligators) is very dependent on water quality. Algae-laden waters produce greener skin, while tannic acid from overhanging trees often produce darker skin.


==References== ==References==
{{Reflist}} {{reflist|30em}}


==General references== ==General references==
''The Merck Index'', 9th edition, Merck & Co., Rahway, New Jersey, 1976. ''The Merck Index'', 9th edition, Merck & Co., Rahway, New Jersey, 1976.


{{Gallotannin}}
==External links==
* at TIME.com
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{{Hydrolysable tannin}}


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