Wei Wei, Feng Lei, Bao Wan-Rong, Ma Dik-Lung, Leung Chung-Hang, Nie Shao-Ping, Han Quan-Bin
School of Chinese Medicine, Hong Kong Baptist University , Hong Kong, China.
State Key Laboratory of Food Science and Technology, Nanchang University , Nanchang, Jiangxi, China.
J Agric Food Chem. 2016 Feb 3;64(4):881-9. doi: 10.1021/acs.jafc.5b05180. Epub 2016 Jan 20.
A crude polysaccharide fraction (cDOP) has been determined to be the characteristic marker of Dendrobium officinale, an expensive tea material in Asia, but its chemistry and bioactivity have not been studied. In work reported here, cDOP was destarched (DOP, 90% yield) and separated into two subfraction polysaccharides, DOPa and DOPb, which were characterized by monosaccharide composition and methylation analyses and spectral analyses (FT-IR and (1)H and (13)C NMR). Both are composed of mannose and glucose at similar ratios and have a similar structure with a backbone of 1,4-linked β-D-mannopyranosyl and β-D-glucopyranosyl residues. Significant differences were observed only in their molecular weights. Bioassay using mouse macrophage cell line RAW264.7 indicated that DOP and its two subfractions enhance cell proliferation, TNF-α secretion, and phagocytosis in a dose-dependent manner. They also induced the proliferation of lymphocytes alone and with mitogens. DOPa and DOPb are thus proven to be major, active polysaccharide markers of D. officinale.
粗多糖组分（cDOP）已被确定为铁皮石斛的特征性标志物，铁皮石斛是亚洲一种昂贵的茶饮原料，但其化学性质和生物活性尚未得到研究。在本文报道的研究中，对cDOP进行了脱淀粉处理（得到DOP，产率为90%），并将其分离为两个亚组分多糖DOPa和DOPb，通过单糖组成分析、甲基化分析以及光谱分析（傅里叶变换红外光谱（FT-IR）、氢核磁共振（1H NMR）和碳核磁共振（13C NMR））对它们进行了表征。二者均由比例相近的甘露糖和葡萄糖组成，且具有相似的结构，主链由1,4-连接的β-D-甘露吡喃糖基和β-D-葡萄糖吡喃糖基残基构成。仅在分子量方面观察到显著差异。使用小鼠巨噬细胞系RAW264.7进行的生物测定表明，DOP及其两个亚组分以剂量依赖的方式增强细胞增殖、肿瘤坏死因子-α（TNF-α）分泌和吞噬作用。它们还能单独或与有丝分裂原一起诱导淋巴细胞增殖。因此，DOPa和DOPb被证明是铁皮石斛的主要活性多糖标志物。
