Structure and conformation of α-glucan extracted from Agaricus blazei Murill by high-speed shearing homogenization

Agaricus blazei Murill is an edible and medicinal mushroom favored in many countries, by virtue of both its delicious taste and its potential health benefits such as its purported anticancer activity. A neutral α-glucan (ABM40-1) with a carbohydrate content of 96% was purified from the high-speed shearing homogenization extracts of A. Blazei Murill by ethanol precipitation and column chromatography. Methylation analysis along with nuclear magnetic resonance spectroscopy revealed that ABM40-1 was an α-(1 → 4)-d-glucopyranan with O-6 position occasionally occupied with α-Glcp-(1 → or α-Glcp-(1 → 6)-β-Glcp-(1 → side chains. A weight-average molecular weight of 7.34 × 106 Da was determined for ABM40-1 and its chain in solution was revealed as a compact sphere by size exclusion chromatography (SEC) coupled with a laser light scattering. This spherical conformation was also further confirmed by Congo red test and using atom force microscopy. These results suggest it would be worthwhile to further study the potential bioactivities of ABM40-1.