以啤特果为原料，经水提醇沉、脱色脱脂、除蛋白，DEAE-52阴离子交换柱纯化获得啤特果多糖（PTGP1），利用光谱、色谱和电镜等技术对PTGP1的结构、组成及分子量进行了分析；评价了PTGP1的体外抗氧化性能。结果表明，PTGP1是还原性多糖，不含淀粉、花色苷等物质，表面呈孔洞褶皱纤维状结构，主要由鼠李糖、阿拉伯糖、木糖、甘露糖、葡萄糖和半乳糖组成，摩尔比为3.06:2.32:1.56:4.87:3.28:2.18，含有典型的多糖红外吸收峰，是一种以α-糖苷键为主的吡喃糖；HPSEC-LLS分析结果表明PTGP1是由3种不同组分组成的聚合物构成，主要组分占76%，重均分子量为5.81×105 Da；抗氧化试验结果表明，PTGP1的还原能力是Vc的0.44倍，对羟自由基、超氧阴离子和DPPH自由基清除率呈剂量效应，其IC50分别为1.24 mg/mL，1.05 mg/mL和2.13 mg/mL，能有效抑制羟自由基引起的脂质过氧化和小鼠肝匀浆MDA的生成。

The polysaccharides of Piteguo (PTGP1) extracted by water-extraction and ethanol-precipitation methods were purified by Soxhlet extraction, Sevag method andDEAE-52 anion exchange column chromatography. The structure, composition and molecular weight of PTGP1 were analyzed by ultraviolet-visible spectra (UV-VIS), infrared spectrum (IR), scanning electron microscopy (SEM), gas chromatography tandem mass spectrometer (GC-MS) and high performance size exclusion chromatography multiangle laser light scattering (HPSEC-LLS). The in vitro antioxidant activities of PTGP1 were determined by the total reducing power, DPPH, superoxide radicals, hydroxyl radicals scavenging assays and the inhibition rate of malondialdehyde (MDA) in mice liver homogenate. Results showed that PTGP1 was a reducing sugar without starch and anthocyanins, whose surface was of holes fold fibrous structure. PTGP1was mainly consisted of rhamnose, arabinose, xylose, mannose, glucose and galactose, with the molar ratio of 3.06:2.32:1.56:4.87:3.28:2.18 in the form of pyranose containing α-glycosidic bond. HPSEC-LLS analysis showed that the PTGP1 was composed of three different polymers, whose average molecular weight was 5.81×105 Da and the main composition content was 76%. Oxidation test indicated that the total reduction ability of PTGP1 was 0.45 times compared with VC, the half inhibit concentration (IC50) of PTGP1 for scavenging hydroxyl free radicals, superoxide anion and DPPH free radicals were 1.24 mg/mL, 1.05 mg/mL and 2.13 mg/mL, respectively, which could effectively inhibit lipid peroxidation induced by hydroxyl free radicals, as well as the formation of MDA in mice liver homogenate.

农业行业科研专项：饲草饲料资源开发利用技术研究与示范(201203042)；国家自然基金资助项目(31060041; 51366009)；甘肃省自然基金（1212RJYA008，1212RJYA034）；兰州理工大学“红柳青年教师培养计划”(Q201207)；兰州理工大学教学研究项目（JY2012045）