Study on the composition and structure of commercial chestnut tanning agent.

Current research has focused on the composition of commercially used chestnut tannin extracts so as to provide a quantitative basis for studies of reactions, structure-property relationships, and applications of chestnut tannin extract. Two chestnut tannins, vescalagin and castalagin, have been isolated using chromatography on Sephadex LH-20 and cellulose. The structures of these compounds have been established by means of nuclear magnetic resonance and fast atom bombardment mass spectroscopy. Some other components have been found and analyzed by chromatography and spectroscopy, but their structures have not as yet been completely defined. These structural features, together with quantitative results for each component, provide a better understanding of the mode of action of complex commercial chestnut tannin extracts.