Tannic acid

Absorption

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

Toxicity

LD50 is 2.26 g/Kg in rats.

Description

Tannic acid is a naturally occurring plant polyphenol and can be found in practically all aerial plant tissues. Tannic acid was historically used for the treatment of diarrhea, topically to dress skin burns and rectally for treatment of unspecified rectal disorders. Pharmaceutical use of tannic acid is discontinued due to safer and better alternatives.
An unusually high incidence of esophageal cancer has been noted in areas of South Africa, where a sorghum rich in tannins is consumed. A positive relation has been observed between the tannin content of the sorghum and the incidence of esophageal cancer.

Description

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 it 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).

Chemical properties

Tannic acid, C₁₄H₁₀O₉, also known as digallic acid, tannin, and gallotannin, is a yellowish powder that decomposes at 210°C (410°F). Tannic acid is derived from nutgalls. It is soluble in water and alcohol,and is insoluble in acetone and ether. Tannic acid is used in tanning,textiles, and as an alcohol denaturant. An amorphous form of tannic acid, also known as pentadigalloylglucose, exists with the formula C₇₆H₅₂O₄₆. It is a yellowish to brownish powder that is very soluble in alcohol and ether.It also decomposes between 210 and 215°C (410 and 419 °F). This form is used to clarify wine or beer, as a reagent,and as a mordant in dyeing.

Chemical properties

Quebracho, an evergreen tree 15 to 18 m (49 to 59 ft) tall, grows abundantly throughout South America (Argentina, in particular). The Argentine variety is characterized by its bright-red bark, rich in tannin, used for dyeing. The part used is the bark (from either the trunk or branches). Quebracho is tonic, aromatic.

Chemical properties

Tannic acid or hydrolysable gallotannin is a complex polyphenolic organic structure that yields gallic acid and either glucose or quinic acid as hydrolysis products. Tannic acid is odorless or has a faint, characteristic odor and an astringent taste.

Occurrence

Reported found in Quercus oliver and related species; Tara (Caesalpinia spinosa); and various sumac species, including Rhus semialata, R. coriaria, R. glabra and R. typhia.

The Uses of Tannic acid

Tannic Acid is a sequestrant that refers to a mixture of hydrolyzable tannins of a more complex structure than gallic acid. it is used in clarifying beer and wine. see tannins.

The Uses of Tannic acid

nonspecific enzyme/receptor blocker

The Uses of Tannic acid

Clarifying agent; pH control

The Uses of Tannic acid

Tannic acids are phenolic compounds that have several hydrolyzable groups. They are classified as (a) hydrolyzable, yielding phenols such as gallic acid in the presence of acid and heat; and (b) condensed, obtained from the extract of oak trees and not hydrolyzable. Tannic acids are used for taste and chemical properties and as a sequestrant. They affect the color and flavor of fruits and vegetables. They are used in fruits, wine, and beer to remove undesirable material by forming insoluble complexes with the proteins.

The Uses of Tannic acid

Tannic acid is a powder extracted from gall nuts that is soluble in water but less so in alcohol. Tannic acid was used by Major Russell in the mid-1850s for the tannin process of preparing dry collodion plates. The collodion plate was coated and sensitized as usual but the excess silver was then washed completely from the surface. A solution of tannic acid was then poured on and off the plate and the collodion film allowed to dry completely in the dark. The tannin plate could be preserved for months prior to exposure. The exposed plate was developed in pyrogallic acid, citric acid, and silver nitrate to replace that which was washed off during the initial preparation. The exposures required for tannin plates were as much as five times longer than wet collodion plates, which made them suitable only for landscape work.

Indications

Tannic acid is indicated for cold sores, fever blisters, diaper rash, minor burn or sunburn and prickly heat. Vaginally, tannic acid is used as a douche for leukorrhea. It has been also indicated for sore throat, inflamed tonsils, spongy or receding gums, and acute dermatitis.

Background

Tannic acid is a polyphenolic compound. It is a type of the commercially available tannins. It acts as a weak acid. Tannic acid is found in the nutgalls formed by insects on twigs of certain oak trees (Quercus infectoria and other Quercus species). It is removed and used as medicine. In the old days it was used as antidote against different poisons. Nowadays, tannic acid is applied topically for the treatment of cold sores, diaper rash, fever blisters and poison ivy. Tannic acid is also taken by mouth and applied directly for bleeding, chronic diarrhea, dysentery, bloody urine, painful joints, persistent coughs, and cancer.

What are the applications of Application

Gallotannin is an inhibitor of NOS3 and a weak inhibitor of NOS2 and NOS1

Definition

ChEBI: A gallotannin obtained by acylation of the five hydroxy groups of D-glucose by 3,4-dihydroxy-5-[(3,4,5-trihydroxybenzoyl)oxy]benzoic acid (a gallic acid dimer).

Definition

tannic acid: A yellowish complexorganic compound present in certainplants. It is used in dyeing as a mordant.

Preparation

Tannic acid is obtained by solvent extraction from the nutgalls or the excrescences that form on the young twigs of Quercus olivier and allied species of Quercus L.; from the seed pods of Tara (Caesalpinia spinosa); or from the nutgalls of various sumac species, including Rhus semialata, R. coriaria, R. glabra and R. typhia.

Composition

Main constituents include three crystalline alkaloids—aspidospermine, quebrachine and quebrachamine (chemically identical to yohimbine)—responsible for the tonic and antispasmodic physiological action. A. quebrachoblanco bark contains 0.3 to 1.5% alkaloids (aspidospermine 30%, quebrachine 10%, deacetylaspidospermine 5%, aspidospermatidine 3%, 1-methylaspidospermatidine 0.5%, quebrachimine and quebrachit). Leaves contain rhazinilam (lactam).

General Description

Light yellow to tan solid with a faint odor. Sinks and mixes with water.

Air & Water Reactions

Water soluble. Gradually darkens on exposure to air and/or light

Reactivity Profile

Glycerite decomposes at 210° to carbon dioxide and pyrogallol, which can form irritating vapors [USCG, 1999]. Incompatible with salts of heavy metals, alkaloids, gelatin, albumin, starch, oxidizing substances-e.g., permanganates, chlorates; lime water [Merck].

Hazard

Toxic by ingestion and inhalation. Questionable carcinogen.

Health Hazard

Inhalation causes irritation of nose and throat, coughing, and sneezing. Ingestion may cause gastric disturbance. Contact with eyes causes irritation.

Fire Hazard

Special Hazards of Combustion Products: Decomposes at 210° to carbon dioxide and pyrogallol, which can form irritating vapors.

Industrial uses

Quebracho is the most common tannic acid derivative widely used in flotation. The main phenolic nuclei present in Quebracho are resorcinol/phloroglucinol and catechol/pyrogallol.
Quebracho is commercially available in the following three forms: (a) standard Quebracho, a direct hot-water extract from the heart-wood with adjusted pH (Qu–O), (b) sulfited Quebracho, in which sulfonic acid groups have been introduced (Qu–S) and (c) aminated Quebracho (Qu–A), where amine groups are introduced to ordinary Quebracho, rendering the polymer amphoteric (iso-electric point at pH 7). Each of these types of Quebracho has a different depressing effect.

Anticancer Research

Tannins, an astringent organic compound, are toxic to many microorganisms due toinhibition of oxidative phosphorylation (Scalbert 1991). It is responsible for thepuckering feeling in the human mouth following the consumption of unripe fruits ortea (Vidal et al. 2004). Pomegranates (Punica granatum) have been widely studiedfor their potent antioxidants, which include ellegitannin, elegiac acid, and punicalagin,which are commonly known for their anti-proliferative and apoptotic effects oncolon cancer cell lines (Seeram et al. 2005). Herbs such as cloves (Syzygium aromaticum)can also play important role in preventing and treating some cancers.Cervical, breast, prostate, and oesophageal cancer cells were killed within 24 h afterthe application of clove oil (Dwivedi et al. 2011). It was also found effective in treatinglung cancer by means of in situ cell proliferation (Banerjee et al. 2006). Tarragon(Artemisia dracunculus) extract is indicated as cytotoxic to breast cancer thoughregulation of certain proteins that induce apoptosis (Obolskiy et al. 2011). Tarragonalso contains potent compounds such as sakuranetin and 6-methoxycapilliarisin thatappear to have anticancer effects on oesophageal cancer by inducing DNA damagein the cancerous cells (Hong and Ying 2015). Cumin (Cuminum cyminum) has beenused since ancient times, and some studies have shown it to have a cytotoxic effectto colorectal cancer cell lines (Prakash and Gupta 2014; Al-Snafi 2016). Thyme(Thymus vulgaris) essential oil has been claimed to demonstrate cytotoxic activity on head and neck squamous cell carcinomas by interrupting reproduction at the transcriptionallevel of cancer cells, with effects such as interfering in N-glycan biosynthesisand extracellular signal-regulated kinase 5 signalling (Sertel et al. 2011).Cinnamon (Cinnamomum sp.) is most commonly known as culinary spice, yet it isalso used for its medicinal properties in treating gastrointestinal sickness. Cinnamonbark extract was evaluated for anticancer ability, and it was found to induce apoptosisin HepG2 cells (liver cancer cells) after 24 h at certain dosages (Varalakshmiet al. 2014). An extract of cinnamon, 2′-hydroxycinnamaldehyde, shows severalantitumour effects on oral cancer cell lines; this is demonstrated by anti-proliferativeactivity of apoptotic cells and inhibition of tumour mass growth (Kim et al. 2010).

Safety Profile

Poison by intravenous and intraperitoneal routes. Questionable carcinogen with experimental tumorigenic data. When heated to decomposition it emits acrid smoke and irritating fumes.

Synthesis

Tannic acid is synthesized by extraction from Nutgalls (Chinese or Turkish), Myrobalans (Terminalia SP.), Oakbark, etc. It is also synthesized by esterification of Glucose with meta-galloylgallic acid.

Environmental Fate

Tannins and tannic acid occur naturally in plants. Essentially all wood and plant tissue contain tannins. Therefore, biodegradation is expected to be the major environmental fate process for tannic acid.

Metabolism

Orally administered Tannic acid is hydrolysable tannin which releases gallic acid and other compounds upon decomposition.

Toxicity evaluation

Tannic acid causes centrilobular liver necrosis following absorption from gastrointestinal tract, mucus membranes, or denuded skin surfaces. Liver metabolism of tannic acid requires methyl-group donors. Therefore, methyl-group donors can be depleted following excessive tannic acid absorption.