Digallic acid is a polyphenolic compound found in ''
Pistacia lentiscus''. Digallic acid is also present in the molecule of
tannic acid
Tannic acid is a specific form of tannin, a type of polyphenol. Its weak acidity ( pKa around 6) is due to the numerous phenol groups in the structure. The chemical formula for commercial tannic acid is often given as C76H52O46, which correspon ...
. Digalloyl esters involve either ''-meta'' or ''-para''
depside
A depside is a type of polyphenolic compound composed of two or more monocyclic aromatic units linked by an ester bond. Depsides are most often found in lichens, but have also been isolated from higher plants, including species of the Ericaceae, L ...
bonds.
Tannase
The enzyme tannase (EC 3.1.1.20) catalyzes the following reaction:
: digallate + H2O = 2 gallate
It is a key enzyme in the degradation of gallotannins and ellagicitannins, two types of hydrolysable tannins. Specifically, tannase catalyzes the ...
is an enzyme that uses digallate to produce
gallic acid
Gallic acid (also known as 3,4,5-trihydroxybenzoic acid) is a trihydroxybenzoic acid with the formula C6 H2( OH)3CO2H. It is classified as a phenolic acid. It is found in gallnuts, sumac, witch hazel, tea leaves, oak bark, and other plants. It i ...
. This enzyme can also be used to produce digallic acid from
gallotannin A gallotannin is any of a class of molecules belonging to the hydrolysable tannins. Gallotannins are polymers formed when gallic acid, a polyphenol monomer, esterifies and binds with the hydroxyl group of a polyol carbohydrate such as glucose.
Meta ...
s.
References
Gallotannins
Trihydroxybenzoic acids
Pyrogallols
Benzoate esters
Vinylogous carboxylic acids
{{aromatic-stub