Kenaf xylan – A source of biologically active acidic oligosaccharides

Two xylose-rich hemicellulose fractions were obtained from kenaf wood (Hibiscus cannabinus L.) through a series of sequential extractions which dissociated xylans from other cell wall components. These fractions were subsequently used as substrates for the production of biologically active aldouronic acids. Incubation of the xylans with a family 10 Thermoascus aurantiacus endoxylanase resulted in the isolation of an aldotetrauronic acid as the main acidic oligosaccharide in the hydrolysis products. Enzymic hydrolysis with a family 11 Sporotrichum thermophile endoxylanase instead resulted in the isolation of a aldopentauronic acid as the main acidic oligosaccharide. The identity and purity of both xylans and aldouronic acids were assessed with solid-state FT-IR, solid-state and solution 13C NMR spectroscopy.