An Arabinogalactan Isolated from the Medicinal Plant Maytenus ilicifolia

Abstract

An arabinogalactan was obtained from the leaves of Maytenus ilicifolia by hot aqueous 2% KOH extraction, followed by a freezing-thawing process and anion-exchange chromatography. It consisted of arabinose, galactose, galacturonic acid, and rhamnose in a 69:20:6:5 molar ratio. Methylation analysis, partial acid hydrolysis, and (13)C NMR spectroscopy indicated that it was an arabinogalactan containing a (1-->4)-linked beta-Galp main chain, substituted at O-6 with Ara units, which were in turn substituted at O-5 (Araf) and/or O-4 (Arap), O-3, O-3,5, and O-2,5. This arabinogalactan is probably linked to O-4 of some Rhap units of a type I rhamnogalacturonan, formed by repeating (1-->4)-alpha-D-GalpA-(1-->2)-alpha-L-Rhap groups.