Roburin A is a tannin found in oak wood (''

Quercus robur ''Quercus robur'', commonly known as common oak, pedunculate oak, European oak or English oak, is a species of flowering plant in the beech and oak family, Fagaceae. It is a large tree, native plant, native to most of Europe west of the Caucasus ...

'' and ''

Quercus petraea ''Quercus petraea'', commonly known as the sessile oak, Cornish oak, Irish Oak or durmast oak, is a species of oak tree native to most of Europe and into Anatolia and Iran. The sessile oak is the national tree of Ireland, and an unofficial emble ...

'' or ''

Quercus alba An oak is a tree or shrub in the genus ''Quercus'' (; Latin "oak tree") of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably '' ...

'') or oak cork (''

Quercus suber ''Quercus suber'', commonly called the cork oak, is a medium-sized, evergreen oak tree in the section ''Quercus'' sect. ''Cerris''. It is the primary source of cork for wine bottle stoppers and other uses, such as cork flooring and as the cores ...

''). It is a dimeric compound, composed of two

vescalagin Castalagin is an ellagitannin, a type of hydrolyzable tannin, found in oak and chestnut wood and in the stem barks of '' Anogeissus leiocarpus'' and ''Terminalia avicennoides''. Castalagin is the diastereomer of vescalagin in C-1 of the glycosidi ...

subunits probably linked through an ether bond between the diphenoyl group (

hexahydroxydiphenic acid Hexahydroxydiphenic acid is an organic compound with the formula HO)3C6HCO2Hsub>2. It is the oxidatively coupled derivative of gallic acid It is a white solid, although samples are typically brown owing to oxidation. left, 142px, Ellagic acid. ...

or HHDP) of one subunit and the triphenoyl moiety (

nonahydroxytriphenic acid Nonahydroxytriphenic acid is a moiety found in some ellagitannins such as roburin A, B,C and D, castalagin Castalagin is an ellagitannin, a type of hydrolyzable tannin, found in oak and chestnut wood and in the stem barks of '' Anogeissus leioca ...

) of the other one.

References

Ellagitannins Tannin dimers {{aromatic-stub