Structural Examination of Water-soluble Glycans from Fruit Body of Lyophyllum ulmarium No.2

Studies on Constituent of Edible Fungi Part IV

Abstract

In the previous paper we obtained three glycan fractions from an ethanol precipitate of a hot-water extracted fraction of Lyophyllum ulmarium by column chromatography using Sephacryl S-400 gel, a proposed possible structure of P-1. This paper describes chemical stuctures of P-2 and P-3. Molecular weights of P-2 and P-3 were about 108000 and 16000 respectively. [a]²⁰_D of P-2 and P-3 were +0.59 and+0.62 (C=1, water), and obvious absorption was detected at 890cm^-1 in their infrared spectra. From these reults, β-dominant bonding were elucidated for both compounds. P-2 was composed of mannose, galactose and glucose in the molar ratio of 1.0:2.3:1.4. And the component of P-3 was mannose and galactose (1.0:3.1). P-2 and p-3 consumed 1.22 and 1.68mol of periodate and produced 0.54 and 0.71mol of formic acid, respectively. SMITH degradation of P-2 provided glycerol and glucitol in the molar ratio of 2.5:1.0, but that of P-3 provided only glycerol. Methylation analysis suggested that P-2 had a branched structure with 1-linked-D-mannopyranosyl, 1, 3-linked-D-glucopyranosyl, 1, 6-1-inked-D-galactopyranosyl, 1, 3, 6-linked-D-glucopyranosyl and l, 2, 6-linked-D-galacte-pyranosyl residues, and P-3 had a highly branched structure with l-linked-D-mannopyranosyl, 1, 6-linked-D-galactopyranosyl, 1, 2, 6-linked-D-galactopy-ranosyl residues. By partial acid hydrolysis of P-2 mannose and galactose were obtained from the dialysate, indicating that a large amount of glucose was present in the core. Partial hydrolysis of P-3 suggested that mannose was presence at or near non-reducing terminals the core of the molecule consisted mainly of galactose.