文摘
Successive aqueous and alkaline extraction of the thallus of the lichenized fungus Heterodermia obscurata provided a highly branched glucomannan fraction (GM), whose chemical structure was determined. This was based on monosaccharide composition, methylation, partial acid hydrolysis, and NMR spectroscopic analysis. It consisted of a main chain of (1 → 6)-linked α-d-mannopyranosyl units, almost all being substituted at O-2 with α-d-glucopyranosyl, α-d-mannopyranosyl, and 4-O-substituted α-d-mannopyranosyl groups. Intra-peritoneal administration of this GM induced a marked and dose-dependent inhibition of acetic acid-induced visceral pain with an ID50 of 0.6 (0.2-2.0) mg/kg and inhibition of 88 ± 4 % . It also reduced leukocyte migration by 58 ± 4 % , but did not alter plasmatic extravasation to the peritoneal cavity. The results suggest that the glucomannan from the H. obscurata might have potential for antinociceptive and anti-inflammatory utilization.
