丹贝异黄酮生物活性增强的机理研究

以少孢根霉RT-3孢子接种在含高浓度的大豆异黄酮提取物制成的发酵基质中，发酵36h后大豆异黄酮被部分水解成相应的苷元．用从丹贝中分离的β-葡萄糖苷酶与标准品染料木素糖苷和大豆苷元的糖苷作用10min，染料木素糖苷和大豆苷元的糖苷被水解成相应的苷元．结果表明：丹贝异黄酮生物活性增强是发酵剂RT-3孢子分泌的β-葡萄糖苷酶将异黄酮由糖苷水解成苷元，而苷元比糖苷有更强的活性．     

大豆异黄酮糖苷和苷元免疫功能研究

用大豆异黄酮糖苷和大豆异黄酮苷元喂养小鼠后,其鸡红细胞作免疫原的溶血素光密度值比在相同环境下空白对照组明显增加,这表明大豆异黄酮糖苷和苷元都能有效提高小鼠体液免疫功能;同时发现小鼠对大豆异黄酮苷元吸收效果强于大豆异黄酮糖苷,说明大豆异黄酮苷元免疫功能优于大豆异黄酮糖苷。     

豆制品中大豆异黄酮转化与富集的研究进展

大豆异黄酮属于黄酮类化合物,主要分为结合型大豆异黄酮糖苷和游离型大豆异黄酮苷元。游离型大豆异黄酮苷元具有比结合型大豆异黄酮糖苷更高的生理活性,如预防骨质疏松和女性更年期综合症,抗氧化和抗癌抑癌等。大豆异黄酮在食品保健方面应用前景广阔,国内外研究者对大豆异黄酮研究越发深入。该文主要综述豆制品中大豆异黄酮的转化和富集方法,旨在为生产富含大豆异黄酮苷元的功能性豆制品研究提供参考。     

大豆异黄酮糖苷及其苷元调节免疫功能的比较研究

目的:比较大豆异黄酮糖苷及游离型大豆苷元对小鼠免疫功能能力的影响。方法:将实验室提取大豆异黄酮糖苷和苷元(纯度为41%左右)的产品按照40～100mg/kg,连续灌胃21d后,与对照组相比能显著提高小鼠腹腔巨噬细胞的吞噬能力及小鼠脾重。结果:大豆异黄酮糖苷和苷元具有较强的调节小鼠腹腔巨噬细胞的吞噬能力,能刺激小鼠脾脏和胸腺器官的发育;同一剂量的大豆异黄酮糖苷和苷元雌鼠的效果要好于雄鼠,游离型大豆苷元的吸收效果明显好于糖苷。     

纤维素酶水解大豆异黄酮糖苷混合物的抗氧化活性

大豆异黄酮主要以糖苷类型的分子形式存在于大豆中,但是其具有生物活性的部分主要是苷元.为了建立一种体外生物转化大豆异黄酮糖苷为大豆异黄酮苷元的新方法,采用纤维素酶水解70%乙醇提取脱脂大豆粕得到的异黄酮粗提物,对比了水解前后两样品的异黄酮组成差异,并测定了其清除DPPH自由基的能力.结果表明:纤维素酶能完全水解大豆苷和染料木苷为大豆素和染料木素;而不能水解丙二酰基染料木苷和丙二酰基大豆苷.纤维素酶处理以后的大豆异黄酮糖苷混合物达到DPPH自由基50%清除率所需要的异黄酮浓度是未处理的大豆异黄酮糖苷混合物的1/2.56.     

C18柱层析法提取大豆胚轴中异黄酮苷元

从大豆胚轴提取总糖苷后，采用C18反相柱层析法分离大豆异黄酮糖苷，再将其水解制各成异黄酮苷元。产品经薄层色谱法(TLC)和高效液相色谱法(HPLC)分析异黄酮苷元纯度和含量。     

青方腐乳发酵过程中大豆异黄酮的转化研究

本文比较了青方、红方、白方和低盐红腐乳中大豆异黄酮组成和含量差异,并对青方腐乳发酵过程中大豆异黄酮含量和构型变化规律进行研究。结果表明,四种类型腐乳中大豆异黄酮基本以苷元形式存在,青方腐乳大豆异黄酮含量明显低于其他类型腐乳,仅为红方腐乳的33.01%,从单一异黄酮来看,大豆苷元和染料木素在四种类型腐乳中的含量明显高于黄豆黄素;青方腐乳发酵过程中大豆异黄酮转化研究发现,白坯中大豆异黄酮以糖苷型为主,染料木苷含量高于大豆苷和黄豆黄苷,前酵过程中糖苷型大豆异黄酮转化为苷元型大豆异黄酮,盐腌过程中糖苷型大豆异黄酮含量有轻微降低,发酵过程中苷元型大豆异黄酮总量在后酵前30 d显著下降,其中大豆苷元可能部分转化为雌马酚,导致青方腐乳大豆异黄酮含量明显低于其他类型腐乳,对其转化物质需进一步鉴定。     

纤维素酶对黑大豆和葛根异黄酮糖苷不同组分的水解活性

异黄酮主要以糖苷的分子形式存在于黑大豆和葛根中,但是其具有生物活性的部分主要是苷元.为了建立一种体外生物转化异黄酮糖苷为异黄酮苷元的新方法,采用70%乙醇提取黑大豆和葛根异黄酮,用高效液相色谱分析了纤维素酶水解前后两粗提物的异黄酮组成.结果表明:纤维素酶对于不同种类的异黄酮糖苷具有不同的水解专一性、基团专一性和键专一性,能完全水解大豆苷和染料木苷为大豆素和染料木素,而不能水解丙二酰基染料木苷、丙二酰基大豆苷和葛根素.     

大豆异黄酮苷元的提取及其抗血浆脂蛋白氧化作用

从大豆胚轴提取总糖苷后,采用C18反相柱层析法分离大豆异黄酮糖苷,再将其水解制备成异黄酮苷元,并对大豆异黄酮苷元的抗脂蛋白氧化作用进行了实验研究.12名健康受试者空腹食用大豆异黄酮苷元前后抽取静脉血制备血浆脂蛋白,观察血浆脂蛋白过氧化程度及氧化易感性的变化.结果表明,大豆异黄酮苷元食用后受试者血浆VLDL、LDL和HDL过氧化脂质水平明显降低;在体外进行氧化修饰时,LDL氧化延滞时间明显延长,LDL氧化易感性下降.大豆异黄酮苷元可增强血浆抗氧化能力,尤其增强LDL抗氧化修饰能力,因此能够起到防治心血管疾病的积极作用.     

纤维素酶催化大豆异黄酮的水解

为充分发挥大豆异黄酮生物价值,采用纤维素酶催化糖苷型大豆异黄酮水解制备游离苷元型大豆异黄酮。通过考察10种纤维素酶对糖苷型大豆异黄酮总水解率和苷元型大豆异黄酮总转化率的影响,筛选得到一种成本较低且水解效果较好的纤维素酶,用于催化水解糖苷型大豆异黄酮,优化了该纤维素酶在水解工艺中底物质量浓度、酶添加量、反应体系pH、酶解温度、酶解时间等参数。结果表明：选择来源于Trichoderma viride的纤维素酶作为大豆异黄酮水解用酶;底物质量浓度0.8～2.0 mg/mL、酶添加量7%～11%、反应体系pH 5.0、酶解温度55℃、酶解时间5～6 h是较经济有效的水解工艺参数,实验优化过程中,大豆异黄酮总水解率超过90%,总转化率接近60%。因此,采用纤维素酶催化水解大豆异黄酮可显著增加游离苷元含量,提高大豆异黄酮利用价值。     

Effect of soybean varieties on the content and composition of isoflavone in rice-koji miso

To clarify the effect of soybean varieties on isoflavone, a useful component for human health, in soybean products, we investigated changes in the isoflavone content and composition in rice-koji miso, after fermentation/aging for 6 or 12 months using varieties of soybeans (Tohoku-126, Tohoku-135, Tohoku-139, Suzuyutaka and Chinese soybeans), by high performance liquid chromatography. In soybeans, the total isoflavone content in Tohoku-126 was 444 mg/100 g, which was 1.2–2.0 times the content in the other soybean varieties. The malonyl glycosides and aglycones in soybeans accounted for more than 60% and only a few percent, respectively. As for rice-koji miso, the total isoflavone and aglycone contents were the highest in miso prepared from Tohoku-126. The ratios of glycosides to aglycones (80.1–92.6%) in miso were higher than those in the original soybeans. The time course of the isoflavone composition during the fermentation/aging process of rice-koji miso indicated that glycosides decreased from 86.4% to 44.9% after 6 months but aglycones increased from 9.6% to 53.3%.     

Hydrolysis of soybean isoflavone glycosides by a thermostable β-glucosidase from Paecilomycesthermophila

The β-glucosidase from Paecilomyces thermophila J18 was found to be capable of hydrolysing daidzin and genistin in a previous study. This report further evaluated the thermostability and hydrolysis of soybean isoflavone glycosides. The enzyme was found to be very stable at 50 °C, and retained more than 95% of its initial activity after 8 h at 50 °C. It converted isoflavone glycosides, in soybean flour extract and soybean embryo extract, to their aglycones, resulting in more than 93% of hydrolysis of three isoflavone glycosides (namely, daidzin, genistin and glycitin) after 4 h of incubation. Also, addition of the β-glucosidase greatly increased the contents of isoflavone aglycones in the suspended soybean flour and soymilk. The results indicate that the thermostable β-glucosidase may be used to increase the isoflavone aglycones in soy products. This is the first report on the potential application of fungal β-glucosidases for converting isoflavone glycosides to their aglycones in soy products.     

大豆异黄酮提取及其生物转化的研究进展

大豆异黄酮是大豆生长过程中形成的一种次级代谢产物,主要以糖苷和游离苷元的形式分布于大豆的子叶和胚轴中。研究表明,游离型大豆异黄酮具有许多重要的生理功能,诸如抗氧化、抗癌抑癌、保护心血管、预防骨质疏松及女性更年期综合症等。随着科学技术的进步,大豆异黄酮的应用日趋广泛。对国内外大豆中异黄酮的提取方法及其优缺点,以及由糖苷型大豆异黄酮转化为游离苷元的方法进行综述,以期为大豆异黄酮的应用研究提供帮助。     

大豆异黄酮及其苷元的研究进展

大豆异黄酮是一种天然的雌激素,是大豆生长过程中的次级代谢产物,其主要位于大豆种子的子叶和胚轴中。其中97%左右以糖苷形式存在,其余以苷元形式存在,大豆异黄酮苷元是其发挥主要功能活性的形式。目前大豆异黄酮的常规提取方法包括有机溶剂萃取法、超声波辅助提取法、微波辅助提取法、超临界流体萃取法、亚临界水法等。研究表明,大豆异黄酮及其苷元具有一定的生理功效,包括预防心血管疾病,预防骨质疏松,抗肿瘤和神经保护等。本文在介绍大豆异黄酮及其苷元的组成、化学结构特性的基础上,详细综述了大豆异黄酮及其苷元的研究概况、提取工艺和主要功能活性,并展望了该领域今后的发展趋势和有待加强的研究方向,旨在为大豆异黄酮及其苷元产业化开发和深入研究其临床应用价值提供参考依据。     

The influence of isoflavone glycosides on the taste of subterranean clover leaves

Four variants of subterranean clover cultivar Geraldton were fed to sheep. One variant, whose flavonoid glycosides were stable due to absence of glucosidase activity in the leaves, was more distasteful to the sheep than were the other clovers. These results suggest that flavonoid glycosides may be unpalatable to the sheep whilst the products of hydrolysis (glucose and aglycone) are not. Taste testing by human subjects of seven purified isoflavone glycosides indicated a slight but distinctive astringent–bitter taste in contrast to the lack of taste of the aglycones.     

Relative antioxidant activity of soybean isoflavones and their glycosides

The present study compared the antioxidant potency of genistein and daidzein with their corresponding glycosides isolated from soybean seeds. The antioxidant activity was assessed using three methods, namely human low-density lipoprotein (LDL) oxidation, the ferric reducing-antioxidant power (FRAP) and the anti-DPPH free radical assays. It was found that soybean was rich in genistein and daidzein but they were present mainly in form of glycosides. Both the FRAP and the anti-DPPH assays demonstrated that these glycosides, as well as genistin, daidzein, glycitin, malonyl glycitin and malonyl genistein possessed similar antioxidant activities to their corresponding aglycones, genistein and daidzein. In contrast, the antioxidant potency of these glycosides was much weaker than their corresponding aglycones, genistein and daidzein, in the LDL oxidation assay. The present results demonstrate that genistein and daidzein were less effective, as antioxiants in the three assays, than two well-defined antioxidants, green tea epicatechin and -tocopherol. It is concluded that soybean isoflavones and their glycosides possess antioxidant activity but they are ineffective antioxidants compared with tea epicatechins and -tocopherol.     

不同大豆种质种皮黄酮类色素的差异分析

为探究大豆种皮中黄酮类色素的含量和分布规律,选取167份大豆种质资源为实验材料,利用高效液相色谱(HPLC)法对大豆种皮黄酮类色素含量进行测定。结果表明：大豆种皮花色苷组分中矢车菊素-3-O-葡萄糖苷含量最多,异黄酮组分中大豆苷含量最高。花色苷组分在野生和半野生大豆种皮中高于栽培大豆。异黄酮组分中染料木苷在野生大豆中最高,黄豆黄苷在半野生大豆中最高,其他组分在栽培大豆中最高。栽培大豆黑色种皮花色苷组分、染料木苷和大豆苷元含量最高,青色种皮大豆苷和黄豆黄苷含量最高,双色种皮黄豆黄素含量最高。相关分析表明3类结合型糖苷内部、3类游离型苷元内部、3种花色苷组分内部两两相关极显著。大豆苷与游离型苷元、矢车菊素-3-O-葡萄糖苷相关显著。聚类分析将大豆材料划分为三大类群,第一类群除黄豆黄苷和飞燕草素-3-O-葡萄糖苷外,其他色素组分含量均最高,为黄酮类色素的研究和利用提供参考。