【作者】 陈静静；

【导师】 江波；

【作者基本信息】 江南大学 ， 食品科学， 2011， 硕士

【摘要】 银杏是世界上珍贵的药用植物资源,它的叶、果和外种皮等都有药用开发价值。根用银杏叶生产的银杏提取物制剂是畅销国内外的天然药物之一,同时银杏果开发的各种营养食品也较多,但银杏外种皮的开发利用较低。我国银杏种植时间长,规模大,银杏果和银杏叶的年产量较大,但同时每年有大量的银杏外种皮被丢弃,而银杏外种皮具有多种生物活性,因此合理利用银杏外种皮开发相关产品,将对综合利用银杏资源和保护环境产生重要影响。本文主要研究银杏外种皮提取工艺的优化,粗多糖的纯化,初步结构鉴定以及银杏外种皮多糖的抗氧化活性研究。首先,考察温度、料液比、时间以及提取次数对银杏外种皮多糖提取率的影响,确定最佳提取条件。多糖提取的最佳条件为:提取温度100℃,提取时间2h,料液比1:20,提取次数3次。以多糖的损失率和蛋白质的去除率为指标,比较三种方法:三氯乙酸法、Sevage法、酶法去除GBEP中蛋白质的效率。结果表明,用酶法除蛋白时,多糖的损失率最低;Sevage法除蛋白最彻底,重复多次操作后可以得到不含蛋白质的多糖,虽然多糖损失较大,但有利于进一步的实验研究。高效凝胶过滤色谱(HPGFC)分析表明,除蛋白后的银杏外种皮的重均分子量为11179。用离子交换色谱DEAE Sepharose Fast Flow,对除蛋白后的多糖进行分离。去离子水洗脱得到的是中性多糖,0.05mol/L,0.1mol/L,0.15mol/L,0.2mol/L的氯化钠溶液洗脱得到了四种酸性多糖。其中两种用Superdex 200凝胶层析进行进一步纯化。傅立叶红外光谱显示银杏外种皮多糖为含有α-D-半乳吡喃糖。气相色谱分析表明,银杏外种皮多糖中的中性组分有鼠李糖,阿拉伯糖,甘露糖,葡萄糖和半乳糖。其摩尔比为鼠李糖:阿拉伯糖:甘露糖:葡萄糖:半乳糖1.76:2:1.53:1:2。反向高效液相柱前衍生PMP法测定酸性多糖中的单糖组成为:木糖,鼠李糖,阿拉伯糖,半乳糖醛酸,果糖,葡萄糖,甘露糖,半乳糖,葡萄糖醛酸和氨基半乳糖组成,它们的摩尔比11.85 : 15.98 : 1: 5.05 : 1 : 5.98 : 193.52 : 3.34 : 14.56 : 2.67。对银杏外种皮多糖进行体外抗氧化实验,分别测定银杏外种皮多糖的还原力、DPPH自由基的清除率、羟基自由基清除率以及超氧阴离子的清除力。研究表明粗多糖具有一定的抗氧化活性,高浓度的GBEP清除DPPH自由基的能力和还原力与阳性对照抗坏血酸类似,但仍不如抗坏血酸,而对羟基自由基的清除率却高于抗坏血酸。更多还原

【Abstract】 Ginkgo biloba is one of the most ancient and valuable medicinal plant, its leaves, seeds and exocarp are all worthy to be developed for pharmaceutical utilization. There are many Ginkgo biloba leave preparation prevailing in the world market, and many nutritional food made by ginkgo fruit, but no exocarp product are available. China is the main habitat of Ginkgo biloba, large quantity of Ginkgo biloba exocarp were discarded as waste after fruit were collected, whereas this part of the plant have many pharmacological activity, it will bring remarkable ecological and economical benefits if Ginkgo biloba was comprehensively and properly developed.This work focus on the optimization of GBEP extraction, crude polysaccharide purification, primary characterization and GBEP antioxidant activity assay. At first, optimum extracting condition was investigated, which was to extract at 100℃for three times, with material to solvent as 1:20.Three deproteinization methods: trichloroacetic acid treatment, Sevag method, enzyme treatment and were evaluated, with protein removal rate and polysaccharide loss rate as efficiency criteria. Enzymatic method exhibits the minimum polysaccharide loss, while protein could be completely removed by Sevag method.The weight-average molecular weight of deproteinized polysaccharides was determined through high-performance gel-permeation chromatography. The deproteinized GBEP was fractionated by DEAE Sepharose Fast Flow. Five fractions waere obtained, natural polysaccharide (GBEP-N) and four acidic polysaccharide. GBEP-N and GBEP–A3 were further purified on by Superdex 200 chromatography, HPGFC indicated two homogenized polysaccharide were obtained by this method.Gas chromatography analysis indicated natural GBEP are mainly made up of arabinose, galactose, mannose glucose and rhamonse, with the relative ratio of 1.76:2:1.53:1:2. Acidic polysaccharide GBEP-AA was mainly composed of ten monosaccharides, ie. manose, rhammnose, glucuronic acid, galacturonic acid, galactosamine, glucose, galactose, xylose, arabinose, and fructose, with the molar ratio of 11.85:15.98:1:5.05:1:5.98:193.52:3.34:14.56:2.67, indicating GBEP contains more monosaccharide than just glucose, fructose, galactose and rhamnose reported by Song et al.The crude GBEP exhibited certain antioxidant activity. At the concentration of 5mg/mL, GBEP have a stronger scavenging effect of hydroxyl radical than the positive control ascorbic acid.更多还原