Castalagin is an ellagitannin, a type of hydrolyzable tannin, found in oak and chestnut wood
Castalagin is the diastereomer of vescalagin in C-1 of the glycosidic chain.
Sources
Castalagin was first isolated in
Fagaceae family woody species :
Oak (oak) and
Chestnut (chestnut) by Walter Mayer and co-workers (1967).
In some chestnut species, such as
Castanea sativa, heartwood could contain 63 mg of castalagin/ vescalagin per gram of dry wood.
In some
Wine, these two isomers represent about 40 to 70% of total ellagitannins.
Castalagin was isolated in Myrciaria dubia, the Amazonian fruit camu-camu.
Biosynthesis
In some plants including oak and chestnut, the ellagitannins are formed from 1,2,3,4,6-pentagalloyl-glucose and further elaborated via oxidative dehydrogenation (tellimagrandin II and
casuarictin formations). After conversion of
casuarictin to
pedunculagin, the pyranose ring of the
glucose opens and the family of compounds including
casuariin,
casuarinin, castalagin, and
castalin, vescalagin and
vescalin forms.
Castalagin thus forms from a pentagalloyl-glucose structure. Castalagin and vescalagin (1,2,3,5-nonahydroxytriphenoyl-4,6-hexahydroxydiphenoyl-glucoses) can be further polymerized in their corresponding dimers roburin A
Derivatives
Castalagin and other related ellagitanins polymerizes or forms complexes with anthyocyanins and
Flavonoid. The flavono-ellagitannin known as
acutissimin A is created when the oak tannin vescalagin interacts with
catechin a flavan-3-ol found in wine.
is a castalagin glycoside
which forms by binding to the pentose
lyxose.
Chemical hydrolysis of Castalagin/ Vescalagin produces vescalene and vescalin which are potent topoisomerase II inhibitors.
