Partial Characterization of Glycans from Daedalea quercina (L) Fr.

Abstract

Heteroglycans were extracted and isolated from the fruiting bodies of wild mushroom Daedalea quercina (L) Fr. These were obtained from sequential extraction with hot water, 1% Ammonium oxalate then 5% Sodium hydroxide solution followed by ethanol or acidic precipitation affording crude extracts which were further purified by dialysis membrane (MWCO 12 400). Separation by charge and size were done using DEAE-cellulose column and Sephadex G-100 or Sepharose CL-4B. This resulted to water soluble neutral (W1P-1A) and acidic (W1P-2A) glycan isolates, ammonium oxalate soluble (A1P-1) and two alkali soluble (N1P-1 and N1P-2) glycan isolates. Characterization of the hydrolyzed isolates using HPAEC-PAD and MALDI TOF MS showed glucan-rich heteroglycans (W1P-1A and W1P-2A); glucan and mannan rich heteroglycan, (N1P-1) and galactan-rich heteroglycan (A1P-1). The latter being the first reported galactan-rich glycan found in ammonium oxalate mushroom extract. The hydrolysates had approximately 4-5 degree of polymerization with molecular weights ranging from 689.680 to 851.788 Da. The hydrolysate of isolate N1P-2 is a glucan-rich heteroglycan which also contain N-acetyl glucosamine units. It is composed of polymers with 4-5 hexose units as well as N-acetyl glucosamine containing polymers of 6-8 hexose units with molecular weight range of 689.799 to 851.915 Da and 1055.718 to 1379.584 Da, respectively.