Structure and oligomers distribution of commercial Tara (Caesalpina spinosa) hydrolysable tannin

Samuele Giovando (1) , Antonio Pizzi (2, 3) , Harald Pasch (4) , Naomi Pretorius (4)

1 Silvachimica S.r.l.
2 ENSTIB - Ecole Nationale Supérieure des Technologies et Industries du Bois
3 LERMAB - Laboratoire d'Etude et de Recherche sur le Matériau Bois
4 Stellenbosch University

Solvent extracted commercial Tara tannin extract have been examined by Matrix Assisted Laser Desorption/Ionisation Time-of-Flight (MALDI-TOF) mass spectrometry and by High Pressure Liquid Chromatography (HPLC). The Tara extract has been found to be composed of a series of oligomers of polygallic acid attached by an ester link to one quinic acid. They constitute the oligomers in higher proportion in the extract. Other polygallic chains linked to one only or two repeating units such as caffeic acid and methylated quinic, methylated gallic and methylated caffeic acids are also present. Negative ion mode MALDI-TOF showed that some carbohydrate residues appear to still be present, linked to the polyphenolic material of the extract but their proportion is very low as would be expected of a solvent extracted tannin.

Mots clés: wood; MALDI; hydrolysable tannins; HPLC; polygallic oligomers; quinic acid; Caesalpina spinosa; tannin; Tara extract; structure

Domaines: Chimie analytique; Polymères

Samuele Giovando, Antonio Pizzi, Harald Pasch, Naomi Pretorius. Structure and oligomers distribution of commercial Tara (Caesalpina spinosa) hydrolysable tannin. PRO LIGNO - Open Access Scientific Journal in the Field of Wood Engineering, 2013, 9 (1), pp.22-31. ⟨hal-01596680⟩