Cell wall polysaccharides from shoots of woody bamboo species. Quantification of uronic acids by GC-MS

P.V. FERNANDEZ; VICTOR MARTIN ZELAYA; ANDREA SUSANA VEGA; MARINA CIANCIA

Villa General Belgrano

Simposio; 2º Simposio Argentino de Glicobiología; 2016

Cell wall polysaccharides from shoots of woody bamboo species. Quantification of uronic acids by GC-MS Fernández, PV, Zelaya, VM, Vega, AS, Ciancia, M vfernand@agro.uba.arWoody bamboos are perennial evergreen plants with very high rates of growth. Bamboo shoots are the new culms, valorized by their nutritional properties. 10 Extracts were obtained by sequential extraction of cell wall polysaccharides from shoots of Phyllostachys aurea and Guadua chacoensis (Poaceae), which comprise 29 and 23 % of their dry weight, respectively. The major extracts were those obtained with 1M KOH (10 and 14%), mainly composed by glucuronoarabinoxylans (GAXs), comprising a backbone of 4-linked β-D-xylopyranose units, partially substituted on C3 by α-L-arabinofuranose non-reducing end units or short chains of 5-linked units. Also, small amounts of terminal α-D-galactopyranose and (4-O-methyl)-α-D-glucuronic acid were present. The degree of ramification was much higher for GAXs from P. aurea than for those of G. chacoensis. For both species, small amounts of mixed linkage glucans were found, concentrated in the extracts obtained with 4M KOH, while arabinogalactan structures were present mostly in the first hot water extract, which also contains GAXs of low molecular weight. A method for determination and quantification of the different uronic acids present was adapted from previously developed techniques, which comprises hydrolysis with TFA 2M at 135ºC and derivatization to the corresponding N-propylaldonamide acetates. The mass spectrum of 4-O-methyl-D-glucuronic acid was analyzed.