Casuarictin is an ellagitannin, a type of hydrolysable tannin.

It can be found in Casuarina and Stachyurus species.

[1] It is formed from two hexahydroxydiphenic acid units and one gallic acid unit linked to a glucose molecule.

The molecule is formed from tellimagrandin II, itself formed from pentagalloyl glucose via oxidation.

Casuarictin is transformed into pedunculagin via loss of a gallate group, and further into castalagin via glucose pyranose ring opening.