拐枣不同部位多糖的结构特征及活性分析

Structural Features and Activity Analyses of Polysaccharides from Different Parts of Hovenia dulcis

为明确拐枣不同部位多糖的结构及生理活性的差异,采用水提醇沉法制备了三种拐枣多糖(HDP)-全果多糖(HDPW)、籽多糖(HDPS)和果梗多糖(HDPP)。通过紫外-可见光谱、高效尺寸排阻色谱、离子色谱、傅里叶红外光谱和扫描电子显微镜对其结构进行对比,研究结果表明,三种HDP均为酸性多糖,由不同摩尔比例的岩藻糖、鼠李糖、阿拉伯糖、半乳糖、葡萄糖、甘露糖、半乳糖醛酸和葡萄糖醛酸组成,HDPW、HDPS和HDPP的分子量均有三个色谱峰,其中HDPS的中、低分子量值(45.72×10^(4)~165.75×10^(4)u)要高于HDPW(0.34×10^(4)~12.53×10^(4)u)和HDPP(0.51×10^(4)~21.26×10^(4)u),红外光谱表明HDPW及HDPP含有α-糖苷键,而HDPS是一种含有β-糖苷键的多糖。HDP对DPPH自由基、ABTS自由基和α-葡萄糖苷酶的半数抑制浓度范围分别为0.015~0.043 mg/mL、0.47~1.21 mg/mL和0.13~9.99 mg/mL,当HDPW和HDPP的质量浓度在0.1 mg/mL及以上时,可显著提升胰岛素抵抗HepG2细胞(IR-HepG2)的葡萄糖消耗率,较模型组最高可提高7.66%。较HDPS而言,HDPW和HDPP结构相似且显示出了更好的抗氧化及α-葡萄糖苷酶抑制活性,更强的IR-HepG2葡萄糖摄取促进能力,研究为拐枣的综合利用提供一定的理论依据和数据支持。

To identify structures and differences in physiological activity of polysaccharides from different Hovenia dulcis tissues,three populations of H.dulcis polysaccharides(HDP),including whole fruit polysaccharides(HDPW),seed polysaccharides(HDPS)and peduncle polysaccharides(HDPP),were prepared using water extraction and alcohol precipitation.Their structures were analyzed using UV-Vis spectroscopy,high-performance size exclusion chromatography,ion exchange chromatography,Fourier transform infrared spectrometry,and scanning electron microscopy.All three HDP preparations comprised the acidic polysaccharides fucose,rhamnose,arabinose,galactose,glucose,mannose,galacturonic acid,and glucuronic acid in different molar ratios.HDPW,HDPS,and HDPP each eluted in size exclusion chromatography with three chromatographic peaks,and the low and medium molecular weight HDPS peaks(45.72×10^(4)~165.75×10^(4)u)displayed higher molecular weights than those of HDPW(0.34×10^(4)~12.53×10^(4)u)and HDPP(0.51×10^(4)~21.26×10^(4)u).Infrared spectra showed that HDPW and HDPP containedα-glycosidic bonds,while HDPS containedβ-glycosidic linked polysaccharides.The respective median inhibitory concentrations of HDP for DPPH free radicals,ABTS free radicals,andα-glucosidase were 0.015~0.043,0.47~1.21,and 0.13~9.99 mg/mL.When the mass/volume concentrations of HDPW and HDPP were 0.1 mg/mL or above,the glucose consumption rate of insulin-resistant HepG2 cells(IR-HepG2)was significantly increased,with the highest increase compared with the model group being 7.66%.Compared with HDPS,HDPW was similar to HDPP in structure,and both showed better antioxidant andα-glucosidase inhibitory activity and stronger IR-HepG2 glucose uptake promotion ability.This study provides a theoretical basis and data supporting the comprehensive utilization of H.dulcis.