A 3-O-methylated mannogalactan from Pleurotus pulmonarius: Structure and antinociceptive effect

A polysaccharide (M-w 2.39 x 10(4) g/mol) was extracted with cold water from the basidiomycete Pleurotus pulmonarius, and its antinociceptive and anti-inflammatory properties were evaluated. It was a mannogalactan (MG), whose structure was characterized using mono- and two-dimensional NMR spectroscopy, methylation analysis, and a controlled Smith degradation. It had a main chain of (1 -> 6)-linked alpha-D-galactopyranosyl and 3-O-methyl-alpha-D-galactopyranosyl units, both of which are partially substituted at O-2 by beta-D-mannopyranosyl non-reducing ends. The MG was tested for its effects on the acetic acid-induced writhing reaction in mice, a typical model for inflammatory pain, causing a marked and dose-dependent inhibition of the nociceptive response, with ID50 of 16.2 (14.7-17.7) mg/kg and inhibition of 93 +/- 3% at a dose of 30 mg/kg. An inflammatory response was not inhibited. (C) 2008 Elsevier Ltd. All rights reserved.