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).

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.

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

Metabolism

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