Separation, characterization and hypoglycemic activity in vitro evaluation of a low molecular weight heteropolysaccharide from the fruiting body of Phellinus pini.

Edible mushrooms have potential in anti-diabetic phytotherapy. They are rich in natural compounds such as polysaccharides, which have been known to have antihyperlipidemic effects since ancient times. A polysaccharide fraction of PP80 and a contained low molecular-weight (Mw), water-soluble polysaccharide (PPW-1, Mw: 3.2 kDa) were isolated from the fruiting body of Phellinus pini. Both PP80 and PPW-1 possess α-glucosidase inhibition and glucose consumption amelioration in an insulin-resistant HepG2 cell model. The α-glucosidase inhibitory activity of PPW-1 (IC50 = 2.2 ± 0.1 mg mL-1) is significantly (P < 0.01) higher than those of PP80 (IC50 = 13.1 ± 0.5 mg mL-1) and acarbose (IC50 = 4.3 ± 0.2 mg mL-1), behaving in a non-competitive inhibition manner. The structural characterization results indicated that PPW-1 is a homogeneous heteropolysaccharide composed of d-glucose, d-mannose, d-galactose and l-rhamnose. The major backbone of PPW-1 is primarily comprised of 1,6-linked glucopyranose, every third residue of which is branched at the O-3 position by a side chain consisting of 1,3-linked and terminal glucopyranose. In addition, small amounts of 1,2-linked-α-d-Manp, 1,6-linked-3-O-Me-α-d-Galp and rhamnose exist in PPW-1. In summary, PPW-1 is a novel heteropolysaccharide with potent in vitro hypoglycemic activity, and it may be a potential dietary component for improving glucose homeostasis.

Chemical Characterization and In Vitro Antioxidant Activity Evaluation of Polysaccharides from the Fruiting Bodies of the Red Heart Mushroom Phellinus pini (Higher Basidiomycetes).

Phellinus pini is a precious medicinal mushroom. Three water-soluble fractions of crude polysaccharides (PP30, PP60, and PP80) were obtained from the fruiting bodies of Ph. Pini. The basic chemical characterization and in vitro antioxidant activity of these 3 polysaccharides were determined. All 3 crude polysaccharides were heteropolysaccharide complexes with a small amount of protein (1.14-2.55%) and uronic acid (2.06-4.11%). The monosaccharide composition of PP30, PP60, and PP80, as a molar ratio, was mannose (1.00):glucose (18.7):galactose (0.92), fucose (0.47):3-0-Me-Gal (0.51):mannose (1.00):glucose (7.86):galactose (1.10), and rhamnose (0.12):fucose (0.32):xylose (0.17):3-0-Me-Gal (0.26):mannose (1.00):glucose (4.79):galactose (0.53), respectively. The in vitro antioxidant activities of crude polysaccharides were evaluated by 2,2-diphenyl-1-picrylhydrazyl, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt, hydroxyl radical, and ferric-reducing antioxidant power methods. The antioxidant data obtained using these methods were in accordance with each other and decreased in the same order of PP80 > PP60 > PP30 at a concentration of 0.1-2.5 mg/mL.