Castalagin

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 (33beta)-isomer of vescalagin. During aging of alcohols in oak barrels, vescalagin can be extracted from the wood and can subsequently be transformed into new derivatives by chemical reactions. Vescalagin is one of the most abundant ellagitannins extracted from oak wood using white wine.