PRODUCTS

TANNIC ACID

CAS Number: 1401-55-4
EC Number: 215-753-2
Formula: C76H52O46
Average Mass: 1701.19850

Tannic acid is a light yellow to tan solid with a faint odor. Sinks and mixes with water.
Tannic acid is a specific form of tannin, a type of polyphenol.
Tannic acids weak acidity (pKa arou: nd 6) is due to the numerous phenol groups in the structure.
The chemical formula for commercial tannic acid is often given as C76H52O46, 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 parts: Tara pods (Caesalpinia spinosa), gallnuts from Rhus semialata or Quercus infectoria or Sicilian sumac leaves.
According to the definitions provided in external references such as international pharmacopoeia, Food Chemicals Codex and FAO-WHO tannic acid monograph only tannins sourced from the above-mentioned plants can be considered as tannic acid.
Sometimes extracts from chestnut or oak wood are also described as tannic acid but this is an incorrect use of the term.
Tannic acid is a yellow to light brown amorphous 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 Tannic acids inclusion in scholarly articles has compounded the confusion.
This is particularly widespread in relation to green tea and black tea, both of which contain tannin but not tannic acid.
Tannic acid is not an appropriate standard for any type of tannin analysis because of its poorly defined composition.

Quercitannic and gallotannic acids
Quercitannic acid is one of the two forms of tannic acid found in oak bark and leaves.
The other form is called gallotannic acid and is found in oak galls.
The quercitannic acid molecule is also present in quercitron, a yellow dye obtained from the bark of the Eastern black oak (Quercus velutina), a forest tree indigenous in North America.
Tannic acid is described as a yellowish-brown amorphous powder.
In 1838, Jöns Jacob Berzelius wrote that quercitannate is used to dissolve morphine.
In 1865 in the fifth volume of "A dictionary of chemistry", Henry Watts wrote : Tannic acid exhibits with ferric salts the same reactions as gallotannic acid.
Tannic acid differs however from the latter in not being convertible into gallic acid, and not yielding pyrogallic acid by dry distillation.
Tannic acid is precipitated by sulfuric acid in red flocks.
According to Rochleder, the tannic acid of black tea is the same as that of oak-bark.
In 1880, Etti gave for Tannic acid the molecular formula C17H16O9.
He described Tannic acid as an unstable substance, having a tendency to give off water to form anhydrides (called phlobaphenes), one of which is called oak-red (C34H30O17).
For him, it was not a glycoside.

An electrostatic potential map (blue is positive and red is negative charge) of decagalloyl tannic acid, i.e. a tannic acid derived from ten molecules of gallic acid
In Allen's "Commercial Organic Analysis", published in 1912, the formula given was C19H16O10.
Other authors gave other molecular formulas like C28H26O15, while another formula found is C28H24O11.
According to Lowe, two forms of the principle exist - one soluble in water, of the formula C28H28O14, and the other scarcely soluble, C28H24O12. Both are changed by the loss of water into oak red, C28H22O11.
Quercitannic acid was for a time a standard used to assess the phenolic content in spices, given as quercitannic acid equivalent.
In an interesting historical note, the inventor of carborundum, Edward G. Acheson, 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."

Uses
Tannins are a basic ingredient in the chemical staining of wood, and are already present in woods like oak, walnut, and mahogany.
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 redwood (Sequoia) is a strong natural defense against wildfire, decomposition and infestation by certain insects such as termites. It is found in the seeds, bark, cones, and heartwood.
Tannic acid is a common mordant used in the dyeing process for cellulose fibers such as cotton, often combined with alum and/or iron.
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 polyamide.

Tannic acid is also an alternative for fluorcarbon 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.
Tannic acid is, however, used in relatively small quantities for the activation of upholstery flock; this serves as an anti-static 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.
Tannic acid 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.
Tannic acid is also found in commercially available iron/steel corrosion treatments, such as Hammerite Kurust.

Use in food
In many parts of the world, its uses in food are permitted.
In the United States, tannic acid is generally recognized as safe by the Food and Drug Administration for use in baked goods and baking mixes, alcoholic and non-alcoholic beverages, frozen dairy products, soft and hard candy, meat products, and rendered animal fat.
According to EU directive 89/107/EEC, tannic acid cannot be considered as a food additive and consequently does not hold an E number.
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.

Uses as a medication
In conjunction with magnesium and sometimes activated charcoal, tannic acid was once used as a treatment for many toxic substances, such as strychnine, mushroom, and ptomaine poisonings in the late 19th and early 20th centuries.
The introduction of tannic acid treatment of severe burn injuries in the 1920s significantly reduced mortality rates.
During World War I, tannic acid dressings were prescribed to treat "burns, whether caused by incendiary bombs, mustard gas, or lewisite".
After the war this use was abandoned due to the development of more modern treatment regimens.

Hazards
Tannic acid could cause potential health hazards such as damage to the eye, skin, respiratory tract, and gastrointestinal tract.
Tannic acid may cause irritation, redness, pain, blurred vision, and possible eye damage.
When tannic acid is absorbed through the skin in harmful amounts, Tannic acid 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.

Crocodilian coloration
Skin color in Crocodilia (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 blackwater rivers) often produce darker skin in these animals.

Polyphenolic compounds with molecular weights of around 500-3000 daltons and containing enough hydroxyl groups (1-2 per 100 MW) for effective cross linking of other compounds (ASTRINGENTS).
The two main types are HYDROLYZABLE TANNINS and CONDENSED TANNINS. Historically, the term has applied to many compounds and plant extracts able to render skin COLLAGEN impervious to degradation.
The word tannin derives from the Celtic word for OAK TREE which was used for leather processing.

Tannic acid is found in the nutgalls formed by insects on the twigs of certain oak trees.
Purified tannic acid is sometimes used as medicine.

People use tannic acid for conditions such as cold sores, diaper rash, heat rash, and many others, but there is no good scientific evidence to support these uses.

In foods and beverages, tannic acid is used as a flavoring agent.

In manufacturing, tannic acid is used in ointments and suppositories; for tanning hides and manufacturing ink; and to kill dust mites on furniture.

Tannins are polyphenolic biomolecules with carbohydrate backbones that are found in in a wide range of plants.
Tannic acid is a specific tannin that formally contains 10 galloyl (3,4,5-trihydroxyphenyl) units surrounding a glucose center.
Commercial tannic acid, however, consists of molecules with 2-12 galloyl moieties.
Tannic acid contains no carboxyl groups, but is weakly acidic because of the multiplicity of phenolic hydroxyls.
The hydroxyls also cause Tannic acid to be extremely soluble in water.
All regulatory authorities classify it as a nonhazardous substance.
As the name implies, tannins are used in leather tanning.
Other commercial uses are in dyeing, ink manufacture, paper sizing, food and wine processing, and production of gallic acid and pyrogallol.
Early reviews of tannins and tannic acid include The Natural Organic Tannins (M. Nierenstein, 1934) and "Gallotannine und Ellagen-gerbstoffe" (O. Th. Schmidt, 1956).

Abstract
IN OCTOBER 1962, Clysodrast2 in a pre-measured powder dosage form containing 1.5 mg of bisacodyl tannex and 2.5 g of tannic acid was made available to American radiologists for cleansing and barium enemas.
The association of three patient deaths with the use of tannic acid (1) and two with Clysodrast (2) was reported recently.
Although several extenuating circumstances surrounded the association between Clysodrast and the two reported deaths, all shipments of Clysodrast in interstate commerce were voluntarily stopped in July 1964.
This was done in order that the safety level could be re-evaluated.
At that time, many meaningful studies concerning this question were initiated.
More recently a re-evaluation of efficacy was undertaken.
The cooperation and help of numerous scientists in completing these studies is gratefully acknowledged.
Our contributions to this large pool of new knowledge were mainly on the chemistry, analysis, and toxicology of tannic acid.
Tannic acid is these aspects I wish to review.

Chemistry
The chemistry of tannic acid is complicated because Tannic acid is of natural origin and consists of a mixture of complex substances.
Although many plant species contain tannins, commercial tannic acid has Tannic acids origin in Turkish nutgalls gathered from the young twigs of Quercus infectoria.
The powdered galls are extracted with ether, alcohol, and water.
Tannic acid is soluble in water.

A yield of 50 to 70 per cent tannic acid is obtained from the water extract.
Tannic acid may be obtained as an amorphous fluffy or dense powder, yellowish-white to light-brown in color.
Tannic acid is further characterized by having an acid reaction in water, essentially no odor, and a strongly astringent taste.
The powder holds about 10 per cent water.
The commercial tannic acid contains many ester linkages and is hydrolysable in the presence of acids, alkalies, or enzymes.
Hydrolysis yields primarily glucose and gallic acid.
Small amounts of other polyhydric alcohols and other phenolic acids such as m-digallic, ellagic and chebulic acids which are chemically related to gallic acid are also found.
Gallic acid is always found in commercial tannic acid in small amounts.

When purified tannic acid is chromatographed, gallotannin consisting of an isomeric mixture of polygalloylated glucose appears as one spot.
Hydrolysis of purified gallotannin yields glucose and gallic acid.
An average structural approximation for gallotannin can be given as eight or nine gallic acid molecules for each glucose molecule.
The gallic acid is bound to glucose as well as to other gallic acid molecules through ester linkages.
The polyphenolic groups in the tannic acid are responsible for Tannic acids astringent action.
This astringent action is caused by its ability to precipitate protein.
The ability to precipitate protein is partly due to the high molecular weight of gallotannin.
Other noteworthy chemical properties of tannic acid include:Darkens on exposure to air and light.

Tannic acid offers an intermediate surface stability option when compared to the other non-covalently-bound surfaces of citrate and PVP we offer, all of which associate with the particle surface by Van der Waals attraction and metal ligand charge transfer.
The tannic acid molecule is a naturally-occurring polyphenol that is a component of oak bark and leaves often used as a dye or stain.
Tannic acid (~1.7 kDa, depending on source) is a polyphenol that associates with the particle surface more strongly than citrate (192 Da), but is smaller and more displaceable than PVP (40 kDa).
Tannic acid is a common reagent in the fabrication of gold and silver nanoparticles and tannic acid or tannic acid/citrate surfaces are a common stability and surface coating for many colloidal solutions.

Intermediately displaceable as a surface for stabilizing particles in aqueous solutions.
Molecules with thiols or amine will displace tannic acid from the surface.
Useful in situations where the surface needs to be exchanged but a more stable surface than citrate is needed during the initial formulation.
Only a moderate difference between the hydrodynamic and TEM measured diameter is observed.
Negatively charged zeta potential

Tannic acid is found in the nutgalls formed by insects on twigs of certain oak trees (Quercus infectoria and other Quercus species).
Tannic acid is removed and used as medicine.
Historically, tannic acid was used along with activated charcoal and magnesium oxide in the "universal antidote," formerly used for poisoning.
These three ingredients in combination were believed to work better at absorbing poisons than any of the ingredients alone.
Unfortunately, the activated charcoal soaked up the tannic acid, more or less inactivating it.
This made the combination less effective.

These days, people apply tannic acid directly to the affected area to treat cold sores and fever blisters, diaper rash and prickly heat, poison ivy, ingrown toenails, sore throat, sore tonsils, spongy or receding gums, and skin rashes; and to stop bleeding.
Tannic acid is also taken by mouth and applied directly for bleeding, chronic diarrhea, dysentery, bloody urine, painful joints, persistent coughs, and cancer.
Vaginally, tannic acid is used as a douche for white or yellowish discharge (leukorrhea).
In foods and beverages, tannic acid is used as a flavoring agent.
In manufacturing, tannic acid is used in ointments and suppositories for the treatment of hemorrhoids; for tanning hides and manufacturing ink; and to kill dust mites on furniture.

How does Tannic acid work?
Tannic acid contains ingredients that have a protective effect on the skin.

Tannic acid is a chief gallo-tannin belonging to the hydrolysable tannins extracted from gall nuts and other plant sources.
A myriad of pharmaceutical and biological applications in the medical field has been well recognized to tannic acid.
Among these effects, potential anticancer activities against several solid malignancies such as liver, breast, lung, pancreatic, colorectal and ovarian cancers have been reported.
Tannic acid was found to play a maestro-role in tuning several oncological signaling pathways including JAK/STAT, RAS/RAF/mTOR, TGF-β1/TGF-β1R axis, VEGF/VEGFR and CXCL12/CXCR4 axes.
The combinational beneficial effects of tannic acid with other conventional chemotherapeutic drugs have been clearly demonstrated in literature such as a synergistic anticancer effect and enhancement of the chemo-sensitivity in several resistant cases.
Yet, clinical applications of tannic acid have been limited owing to its poor lipid solubility, low bioavailability, off-taste, and short half-life.
To overcome such obstacles, novel drug delivery systems have been employed to deliver tannic acid with the aim of improving its applications and/or efficacy against cancer cells.
Among these drug delivery systems are several types of organic and metallic nanoparticles.

In this review, the authors focus on the molecular mechanisms of tannic acid in tuning several neoplastic diseases as well as novel drug delivery systems that can be used for its clinical applications with an attempt to provide a systemic reference to promote the development of tannic acid as a cheap drug and/or drug delivery system in cancer management.
Tannic acid is a chief gallo-tannin belonging to the hydrolysable tannins extracted from gall nuts and other plant sources.
A myriad of pharmaceutical and biological applications in the medical field has been well recognized to tannic acid.

Among these effects, potential anticancer activities against several solid malignancies such as liver, breast, lung, pancreatic, colorectal and ovarian cancers have been reported.
Tannic acid was found to play a maestro-role in tuning several oncological signaling pathways including JAK/STAT, RAS/RAF/mTOR, TGF-β1/TGF-β1R axis, VEGF/VEGFR and CXCL12/CXCR4 axes.
The combinational beneficial effects of tannic acid with other conventional chemotherapeutic drugs have been clearly demonstrated in literature such as a synergistic anticancer effect and enhancement of the chemo-sensitivity in several resistant cases.
Yet, clinical applications of tannic acid have been limited owing to its poor lipid solubility, low bioavailability, off-taste, and short half-life.
To overcome such obstacles, novel drug delivery systems have been employed to deliver tannic acid with the aim of improving its applications and/or efficacy against cancer cells.
Among these drug delivery systems are several types of organic and metallic nanoparticles.
In this review, the authors focus on the molecular mechanisms of tannic acid in tuning several neoplastic diseases as well as novel drug delivery systems that can be used for its clinical applications with an attempt to provide a systemic reference to promote the development of tannic acid as a cheap drug and/or drug delivery system in cancer management.

IUPAC name: 1,2,3,4,6-penta-O-{3,4-dihydroxy-5-[(3,4,5-trihydroxybenzoyl)oxy]benzoyl}-D-glucopyranose
Systematic IUPAC name: 2,3-dihydroxy-5-({[(2R,3R,4S,5R,6R)-3,4,5,6-tetrakis({3,4-dihydroxy-5-[(3,4,5-trihydroxyphenyl)carbonyloxy]phenyl}carbonyloxy)oxan-2-yl]methoxy}carbonyl)phenyl 3,4,5-trihydroxybenzoate
Formula: C76H52O46
Average Mass: 1701.19850
Monoisotopic Mass: 1700.17297
Density: 2.12g/cm3
Boiling point: 218 ºC
Melting point: decomposes above 200 °C
Solubility in water: 2850 g/L or 250 g/L
Solubility: 100 g/L in ethanol
1 g/L in glycerol and acetone
insoluble in benzene, chloroform, diethyl ether, petroleum, carbon disulfide, carbon tetrachloride.
Acidity (pKa): ca. 6
XLogP3-AA: 6.2
Hydrogen Bond Donor Count: 25
Hydrogen Bond Acceptor Count: 46
Rotatable Bond Count: 31
Topological Polar Surface Area: 778 Å²
Heavy Atom Count: 122
Formal Charge: 0
Complexity: 3570
Isotope Atom Count: 0
Defined Atom Stereocenter Count: 0
Undefined Atom Stereocenter Count: 5
Defined Bond Stereocenter Count: 0
Undefined Bond Stereocenter Count: 0
Covalently-Bonded Unit Count: 1
Compound Is Canonicalized: Yes
InChl: InChl=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
InChlKey: LRBQNJMCXXYXIU-YIILYMKVSA-N
SMILES: Oc1cc(cc(O)c1O)C(=O)Oc1cc(cc(O)c1O)C(=O)OC[C@H]1OC(OC(=O)c2cc(O)c(O)c(OC(=O)c3cc(O)c(O)c(O)c3)c2)[C@H](OC(=O)c2cc(O)c(O)c(OC(=O)c3cc(O)c(O)c(O)c3)c2)[C@@H](OC(=O)c2cc(O)c(O)c(OC(=O)c3cc(O)c(O)c(O)c3)c2)[C@@H]1OC(=O)c1cc(O)c(O)c(OC(=O)c2cc(O)c(O)c(O)c2)c1

Tannic acid (TA), a type of polyphenol, is widely distributed in plants, especially in legumes.
Not only does it possess antimicrobial properties, but Tannic acid also has the ability to bind with proteins.
The fermentation parameters, nitrogen fractions, antioxidant capacity, and bacterial communities present in mulberry leaves and stylo (Stylosanthes guianensis) ensiled with or without 1 and 2% TA per kilogram of fresh matter (FM) were investigated after 75 days' fermentation.
The results showed that 1 and 2% TA both significantly decreased the butyric acid content (4.39 and 7.83 g/kg dry matter (DM), respectively) to an undetectable level in both mulberry leaf and stylo silage.
In addition, 2% TA significantly increased the contents of lactate (24.0-39.0 and 8.50-32.3 g/kg DM), acetate (18.0-74.5 and 9.07-53.3 g/kg DM), and the antioxidant capacity of both mulberry leaf and stylo silage, respectively.
With the addition of 1 and 2% TA, the pH values (5.55-5.04 and 4.87, respectively) and ammonia-N (NH3-N) content (85.5-27.5 and 16.9 g/kg total nitrogen (TN), respectively) were all significantly decreased in stylo silage.
In addition, TA increased the relative abundance of Weissella, Acinetobacter, and Kosakonia spp. and decreased that of undesirable Clostridium spp.
TA can thus be used to improve the silage quality of both mulberry leaf and stylo silage, with 2% TA being the better concentration of additive to use.

Mechanism of action
Pharmaceutical grade tannic acid is generally considered to be pentadigalloylglucose.
Tannic acid has an astringent effect.
When used internally, Tannic acid dehydrates tissues when cause reduction in secretions.
Externally, Tannic acid works through formation of protective layer of harder and constricted cells.
Tannic acid is thought to exert antiviral and antibacterial effects.

Absorption
After ingestion Tannic acid has poor bioavailability, due to large size, high affinity to bound to plasma proteins and low lipid solubility.
Tannic acids main actions are due to local effects.

Other names
Acidum tannicum
Gallotannic acid
Digallic acid
Gallotannin
Tannimum
Quercitannin
Oak bark tannin
Quercotannic acid
Querci-tannic acid
Querco-tannic acid