An acetylated galactomannoglucan from the stems of Dendrobium nobile Lindl

A water-soluble polysaccharide DNP-W2 composed of glucose. mannose. and galactose in the molar ratio of 6.1:2.9.2 0 had been isolated from the stems of Dendrobium nobile Its molecular weight was 1 8 x 10(4) Da determined by HPGPC Structural features of DNP-W2 were investigated by a combination of chemical and instrumental analysis. including FTIR, GC, GC-MS, periodate oxidation-Smith degradation, methylation analysis, partial acid hydrolysis, and NMR spectroscopy The results showed that DNP-W2 is a 2-O-acetylgalactomannoglucan and has a backbone consisting of (1 -> 4)-linked beta-D-Glcp, (1 6)-linked beta-D-Glcp, and (1 -> 4)-linked beta-D-Manp, with branches at O-6 of (1 -> 4)-linked beta-D-Glcp and beta-D-Manp The branches are composed of alpha-D-Galp The acetyl groups are substituted at O-2 of (1 -> 4)-linked Manp. Preliminary tests in vitro reveals that DNP-W2 can stimulate ConA- and LPS-incluced land B lymphocyte proliferation. (C) 2010 Elsevier Ltd All rights reserved.