ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Chemical evaluation of Fallopia species leaves and antioxidant properties of their non-cellulosic polysaccharides

Zdenka Hromádková, Ján Hirsch, and Anna Ebringerová

Institute of Chemistry, Center for Glycomics, Slovak Academy of Sciences, Dúbravská cesta 9, SK-845 38 Bratislava, Slovakia

E-mail: chemhrom@savba.sk

Abstract: Utilization of biomass from forest or agricultural crops for the production of energy or chemical products provides environmental advantages. Leaves of the knotweeds Fallopia japonica, Fallopia sachalinensis, and Fallopia × bohemica are rich sources of phenolics and polysaccharides. In view of their potential utilization before the disposal of these invasive plants, their gross composition was investigated. The content of extractives was the highest in F. sachalinensis. Extractive-free leaves of all species showed similar chemical composition. The content of ash, protein, lignin, uronic acids, and α-cellulose in the leaves of F. sachalinensis, F. × bohemica, and F. japonica was 63.3 %, 64.1 %, and 63.4 %, respectively. The rest comprised hemicelluloses and neutral carbohydrate components of pectic polysaccharides. Sequential extraction of F. sachalinensis with water, EDTA, DMSO, 1 % NaOH, and 5 % NaOH yielded fractions accounting together for 27.6 % of polysaccharides. Pectic polysaccharides predominated in the first three fractions, whereas the hemicellulose components — xylan and xyloglucan, prevailed in the two alkaline fractions. The polysaccharides displayed significant radical scavenging activities in the 1,1-diphenyl-2-picrylhydrazyl free radical assay thus indicating their potential application as novel natural antioxidants.

Keywords: Fallopia species - leaves - composition - non-cellulosic polysaccharides - phenolics - flavonoids - radical scavenging activity

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-010-0054-2

Chemical Papers 64 (5) 663–672 (2010)