PREPARATION AND STRUCTURE OFFIVE DERIVATIVES OFβ-(1→3)-D-GLUCAN ISOLATED FROM PORIA COCOS SCLEROTIUM*

A new solvent of cellulose (1.5 mol/L NaOH/0.5 mol/L urea aqueous solution) was used as one of the homogeneous reaction media of polysaccharides for methylation, hydroxyethylation and hydroxypropylation. A water insoluble β-(1→3)-D-glucan, sample PCS3-Ⅱ, isolated from fresh sclerotium of Poria cocos was sulfated in dimethyl sulfoxide (Me2SO), carboxymethylated in NaOH, isopropanol solution, as well as methylated, hydroxyethylated and hydroxypropylated in the new solvent system, respectively, to obtain five water-soluble derivatives coded as S-PCS3-Ⅱ, C-PCS3-Ⅱ, M-PCS3-Ⅱ, HE-PCS3-Ⅱand HP-PCS3-Ⅱ. Their chemical structure and distribution of substitution were characterized by infrared spectroscopy (IR), elementary analysis (EA), ^1H-NMR, ^13C-NMR, 2D-COSY, 2D-TOCSY and 2D-^1H-detected ^1H ^13C HMQC spectra. The results reveal that the relative reactivity of hydroxyl groups of the β(1→3)-D-glucan is in the order C-6 ＞ C-4 ＞ C-2 on the whole. The substitution of the samples S-PCS3-Ⅱ, C-PCS3-Ⅱ and M-PCS3-Ⅱ occurred mainly at C-6 position and secondly at C-4 and C-2 positions, and that of HE-PCS3-Ⅱ occurred at C-6 and C-4 positions and of HP-PCS3-Ⅱ almost completely occurred at C-6 position. The degrees of substitution (DS) obtained from ^13C-NMR range from 0.23 to 1.27. The water solubility of the derivatives is in the order S-PCS3-Ⅱ ＞ C-PCS3-Ⅱ ＞ M-PCS3-Ⅱ ＞ HE-PCS3-Ⅱ ＞ HP-PCS3-Ⅱ. This work provides a novel and nonpolluting process for the methylation, hydroxyethylation and hydroxypropylation of β-(1→3)-D-glucan.

PREPARATION AND STRUCTURE OFFIVE DERIVATIVES OFβ-(1→3)-D-GLUCAN ISOLATED FROM PORIA COCOS SCLEROTIUM*

 A new solvent of cellulose (1.5 mol/L NaOH/0.5 mol/L urea aqueous solution) was used as one of the homogeneous reaction media of polysaccharides for methylation, hydroxyethylation and hydroxypropylation. A water insoluble β-(1→3)-D-glucan, sample PCS3-Ⅱisolated from fresh sclerotium of Poria cocos was sulfated in dimethyl sulfoxide (Me₂SO), carboxymethylated in NaOH, isopropanol solution, as well as methylated, hydroxyethylated and hydroxypropylated in the new solvent system, respectively, to obtain five water-soluble derivatives coded as S-PCS3-ⅡC-PCS3-Ⅱ,M-PCS3-Ⅱ,HE-PCS3-Ⅱand HP-PCS3-Ⅱ.Their chemical structure and distribution of substitution were characterized by infrared spectroscopy (IR), elementary analysis (EA),¹H-NMR,¹³C-NMR, 2D-COSY, 2D-TOCSY and 2D-¹H-detected ¹H¹³C HMQC spectra. The results reveal that the relative reactivity of hydroxyl groups of the β -(1→3)-D-glucan is in the order C-6 > C-4 > C-2 on the whole. The substitution of the samples S-PCS3-Ⅱ,C-PCS3-Ⅱ and M-PCS3-Ⅱoccurred mainly at C-6 position and secondly at C-4 and C-2 positions, and that of HE-PCS3- Ⅱoccurred at C-6 and C-4 positions and of HP-PCS3-Ⅱalmost completely occurred at C-6 position. The degrees of substitution (DS) obtained from ¹³ C-NMR range from 0.23 to 1.27. The water solubility of the derivatives is in the order S-PCS3-Ⅱ>C-PCS3-Ⅱ>M-PCS3-Ⅱ>HE-PCS3-Ⅱ>HP-PCS3-Ⅱ. This work provides a novel and nonpolluting process for the methylation, hydroxyethylation and hydroxypropylation of β-(1→3)-D-glucan.