麦冬多糖相对分子质量测定方法的研究

Research on the methods for relative molecular weight determination of polysaccharides from Ophiopogon japonicus

目的对麦冬多糖相对分子质量测定的方法进行研究。方法采用高效凝胶渗透色谱联用蒸发光散射检测法(HPGPC-ELSD)、基质辅助激光解吸/电离飞行时间质谱法(MALDI-TOF-MS)和分子排阻色谱联用小角度激光光散射检测、黏度检测法(SEC-LALLS)对麦冬多糖的相对分子质量及其分布进行测定。结果 HPGPC-ELSD法测得麦冬多糖的相对重均分子质量为2 376 g/mol,分散度为1.23;MALDI-TOF-MS法测得麦冬多糖的糖残基单元为己糖,其相对重均分子质量为721 g/mol,分散度为1.49;SEC-LALLS法测得麦冬多糖的相对重均分子质量为3 962 g/moL,分散度为1.49,其流体力学半径为1.3 nm,在水相的构象介于球状和无规卷曲之间。结论 MALDI-TOF-MS法更适用于多糖单元结构等信息的获取;HPGPC-ELSD法是相对测定法,其相对分子质量测定结果与多糖的空间结构有关;SECLALLS法不仅可用于测定多糖的相对分子质量,而且能够提供其结构相关信息,因此是一种较为理想的测定方法。

AIM To study the determination of relative molecular weight of polysaccharides from Ophiopogon japonicus （POJ）. METHODS High performance gel permeation chromatography coupled with evaporative light scattering detection （HPGPC-ELSD）, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry （MALDI-TOF-MS） and molecular exclusion chromatography combined with low-angle laser light scattering detec- tion （SEC-LALLS） were adopted. RESULTS The relative weight-average molecular weight （Mw ） of POJ was a- bout 2 376 g/tool determined by HPGPC-ELSD, while the value was about 721 g/tool and the sugar residue units of POJ were hexoses by using MALDI-TOF-MS. However, the Mw of POJ was about 3 962 g/mol analyzed by SEC- LALLS with fluid mechanics radius of 1.3 nm, and the conformation was between spherical and random coil in the aqueous phase. CONCLUSION As an absolute method for the determination of relative molecular weight, the Mw value of POJ obtained from SEC-LALLS is the most reliable; MALDI-TOF-MS is more suitable for the demon- stration of the unit structure of polysaccharide; HPGPC-ELSD is a relative method for the determination of relative molecular weight, the analytical results are related to the spatial structure of polysaccharide.