Hemicelluloses from shoots and shells of the Woody bamboo Guadua chacoensis obtained in different conditions

PAULA VIRGINIA FERNÁNDEZ; MARÍA EVELINA CAPARRÓS FRENTZEL; LUCILA COBELLO; VICTOR MARTIN ZELAYA; ANDREA SUSANA VEGA; MARINA CIANCIA

Barcelona

Simposio; 19th European Carbohydrate Symposium; 2017

European Carbohydrate Association

HEMICELLULOSES FROM SHOOTS AND SHELLS OF THE WOODYBAMBOO GUADUA CHACOENSIS OBTAINED IN DIFFERENTCONDITIONSPaula Virginia Fernández1,2, María Evelina Caparrós Frentzel1, Lucila Cobello1, VíctorMartín Zelaya1,2, Andrea Susana Vega1, Marina Ciancia1,21 Universidad de Buenos Aires, Facultad de Agronomía, Buenos Aires, Argentina2CONICET-UBA. CIHIDECAR, Buenos Aires, Argentinae-mail: ciancia@agro.uba.arWoody bamboos are perennial evergreen plants belonging to Poaceae with very high rates ofgrowth. Bamboo shoots are the new culms that arise from the rhizomes, containing nodes andinternodes in a vertically miniaturized form, they are protected by culm leaves (shells). Recently,chemical characterization of cell wall polysaccharides from leaves of Guadua chacoensis wascarried out, and their use as forage was proposed [1]. In a project devoted to study possible uses forthis natural resource, native from the Americas, we studied the structure of cell wallpolysaccharides obtained from shoots and shells in different extraction conditions.The classic alkaline extraction of hemicelluloses showed huge differences in composition regardstheir yield and structure. While extracts obtained with 1M KOH from shoots, which represent10.3% of AIR, were mostly glucuronoarabinoxylans (GAX), those obtained from shells, whichrepresented 23.0% of AIR, had major quantities of mixed linkage glucans (MLG) (88%GAX and9% MLG, and 42%GAX and 58% MLG, respectively). This pattern was repeated in all the alkalineextracts, their structure was investigated by methylation analysis and NMR spectroscopy. In bothresources, terminal α-D-galactose, α-D-glucuronic, and 4-O-methyl-α-D-glucuronic acids (veryclear in the NMR spectra) constitute, along with α-L-arabinofuranose, the ramifications of the xylanbackbone, although GAX from shoots had less degree of ramification than those from shells.Extracts from shells were further purified by aqueous solubilization of GAX and fractions enrichedin MLG were obtained. The ratio (1→3)/ (1→4)-linkages was determined.On the other hand, extraction of hemicelluloses from shoots with DMSO (twice) alloweddetermination of the substitution pattern respect to acetyl groups and ferulic acid, which were lost,when these polysaccharides were obtained by alkaline extraction. However, yields were lower, andthe GAX obtained in this conditions were very different, not only respect to those substituents, butalso regards the carbohydrates ramification pattern (which was much higher), showing the greatimportance of these conditions determining the characteristic of the product for further applications.Although considerable amounts of phenolics were present in these extracts (100.6 and 48.8 μg/g,respectively), these compounds were not clearly detected in the NMR spectra. Conversely, it waspossible to determine substitution with acetyl groups.In conclusion, in this work the structural features of hemicelluloses from shoots and shells from G.chacoensis were determined, showing that it is possible to obtain GAX with different substitutionpatterns, depending which part of the plant is utilized, and the extraction conditions. Besides, shells,a material usually considered as waist, appear as a potential source of MLG.[1] Panizzo, C.C., Fernández, P.V., Colombatto, D., Ciancia M., Vega, A.S. Anatomy, nutritional value, andcell wall chemical analysis of foliage leaves in Guadua chacoensis (Poaceae, Bambusoideae, Bambuseae), apromising source of forage. J Sci Food Agric 2017, 97 1349?1358