亳芍多糖的积累规律及其单糖组成GC-MS分析

目的：揭示亳芍多糖的动态积累规律，为亳芍的科学采收、质量评价及临床用药提供依据。方法：采用蒽酮比色法，以葡萄糖为标准对照品，检测波长628 nm，测定亳芍多糖的含量；亳芍多糖溶于0.5 mol·L^-1盐酸甲醇溶液，80℃水浴酸解16 h，氮气吹干后加入吡啶-六甲基二硅胺烷-三甲基氯硅烷（10：2：1），80℃水浴反应30 min，氮气吹干，残渣溶于正己烷，采用TG-5熔融石英毛细管柱、1.0 mL·min^-1氦气为载气、电子电离离子源（EI）、质量扫描范围为50～350 amu、三甲基硅烷（TMS）柱前衍生化-GC-MS分析法测定单糖组成及其含量。结果：栽培年限影响亳芍多糖积累，1～7年亳芍中多糖的含量分别为（2.7±0.03）%、（3.1±0.23）%、（4.1±0.10）%、（2.2±0.33）%、（1.5±0.23）%、（1.6±0.10）%和（1.6±0.07）%；栽培1～7年亳芍多糖均为葡萄糖、果糖、甘露糖、半乳糖、半乳糖醛酸、木糖、阿拉伯糖、鼠李糖组成的杂多糖，但比例随栽培年限不同而变化。结论：从多糖含量角度，栽培3年的亳芍多糖含量最高，品质最佳；栽培年限对亳芍多糖的单糖种类没有影响，但对单糖比例及含量产生明显影响，提示不同株龄的亳芍多糖的结构可能不同。

Objective: To reveal the accumulation of polysaccharide in Bozhou Peony P. lactiflora and provide references for its scientific harvesting,quality evaluating and clinical medication. Methods: The contents of the total polysaccharide in different ages of Bozhou Peony P. lactiflora were determined by an anthrone-sulfuric acid colorimetric method at 628 nm using glucose as standard. The polysaccharide of each Dendrobium sample was treated with methanolysis reagent (MeOH containing HCl 0.5 mol·L^-1) in nitrogen atmosphere at 80℃ for 16 h to hydrolyze them to their corresponding methyl monosaccharides,and thereafter the excess of reagent was removed using a stream of nitrogen gas. The conversion of the methyl glycosides to their trimethylsilyl (TMS) derivatives was performed by adding a mixed pyridine-hexamethyldisilazane-trimethylclorosilane (10:2:1,v/v) to the dried material. The reaction was carried out at 80℃ for 30 min and the reagent removed using a stream of nitrogen gas and the derived residues were extracted with hexane. The trimethylsilyl-ester O-methyl monosaccharides were separated with Trace 1300 Gas chromatograph coupled to ISQ mass spectrometerseries equipments including a TriPLUS RSH autosampler on a TG-5 fused-silica capillary column. The carrier gas was Helium,1.0 mL·min^-1. The MS transfer line and ion source were at 250℃ and 280℃,respectively. The MS mode was electron ionization (EI). The mass range scanned was 50-350 amu. Different standard carbohydrates were also converted to their corresponding TMS derivatives and analyzed by GC-MS in order to obtain patterns for identification and the standard calibration curves. Results: The accumulation of polysaccharide varied remarkably as their ages increased. The polysaccharide contents in 1-7 cultivated-years of Bozhou Peony P. lactiflora were (2.7±0.03)%,(3.1±0.23)%,(4.1±0.10)%,(2.2±0.33)%,(1.5±0.23)%,(1.6±0.10)% and (1.6±0.07)%,respectively. The polysaccharides in different ages of Bozhou Peony P. lactiflora were all heteropolysaccharides composed of glucose,fructose,mannose,galactose,galacturonic acid,xylose,arabinose and rhamnose while the ratios of the mono-saccharides changed remarkable as the age varied. Conclusion: The kinds of the mono-saccharides were the same while the ratios of them were quite different in the plants at 1-7 ages. This suggested that the structure of polysaccharide in Bozhou Peony P. lactiflora might be varied as the plant ages changes.