Studies on polyphenols and lignin of Astronium urundeuva wood

Abstract

An Astronium urundeuva ball-milled wood sample was successively extracted with benzene, benzene-ethanol (2:1, v/v-1), chloroform, and water in a soxhlet apparatus. The extracted wood was air-dried giving the residue A that was then treated with ketone-water (9:1), in a soxhlet apparatus. From the ketone-water extract was precipitated the milled wood lignin (MWL). With exception of MWL, the extract contents summed up 18.19% (o.d.w.). The Klason lignin content of A and the methoxyl content of the MWL were 23.84% and 19.00%, respectively. Another sample of A gave hardly and easily hydrolysable polysaccharide contents of 34.86% and 18.81%, respectively. A second sample of ball-milled wood was submitted to a single extraction with methanol, at room temperature, affording the methanol extract B (23.85% o.d.w.). Liquid and solid state 13C-NMR spectroscopies indicated that B is mainly constituted by proanthocyanidins of profisetinidin and prorobinetidin types.

Keywords

• lignin
• polyphenols
• Astronium urundeuva
• cerrado vegetation