Résumé
A pectic arabinogalactan was obtained from the leaves of Andrographis paniculata by aqueous extraction followed by a-amylase treatment, deproteination, and anion exchange chromatography. Methylation analysis, Smith degradation, and NMR spectroscopy indicated that it was a highly branched arabinogalactan containing a (1 -> 3)-linked beta-D-Galp main chain, substituted at 0-6 by (1 -> 6)-linked beta-D-Galp side chains. The latter residues were substituted at 0-3 by (1 -> 5)- and (1 -> 3)-linked alpha-L-Araf chains, and non reducing end-units of alpha-L-Araf and beta-D-Galp. This homogeneous arabinogalactan (36 kDa), which contained phenolic acids, showed dose-dependent anti-oxidative properties. The phenolic acid moieties might be the functional sites. This arabinogalactan can form a complex with bovine serum albumin having binding constant K=6.48 x 10(6)/M. Thus, this study is an important step forward to investigate the involvement of arabinogalactan in processes including interaction with biologically important transport proteins. (C) 2013 Elsevier Ltd. All rights reserved.