An α-D-galactan and a β-D-glucan from the mushroom Amanita muscaria: Structural characterization and antitumor activity against melanoma

Polysaccharides alpha-D-galactan (GAL-Am) and beta-D-glucan (GLC-Am) were obtained from Amanita muscaria fruiting bodies. They were purified using different methodologies, such as Fehling precipitation (for both fractions), freeze-thawing process and ultrafiltration (for GLC-Am). Results showed that the GAL-Am has (1 -> 6)-linked Galp main chain branched at O-2 by terminal Galp units and has not been previously reported. Besides, GLC-Am has (1 -> 3)-linked Glcp in the main chain, substituted at O-6 by (1 -> 6)-linked beta-Glcp units. Both are watersoluble, with 9.0 x 10(3) g/moL and 1.3 x 10(5) g/moL, respectively. GAL-Am and GLC-Am presented a selective proliferation reduction against B16-F10 melanoma cell line, not affecting non tumoral BALB/3T3 fibroblast cell line. Furthermore, both fractions reduced clonogenic capacity of melanoma cell line over an extended period of time. These results were obtained without modulations in B16-F10 cell adhesion, reinforcing the biological activities towards cell proliferation impairment and eliciting these polysaccharides as promising compounds to further exploration of their antimelanoma properties.