体外模拟消化过程中果胶对竹叶黄酮生物可及性的影响

目的:为提高竹叶黄酮化合物在消化过程中的生物可及性,采用体外模拟消化模型,探究果胶的加入对竹叶黄酮生物可及性的影响。方法:采用超高效液相色谱分析有、无果胶存在的条件下,竹叶提取物中4种竹叶黄酮(异荭草苷、荭草苷、异牡荆素、牡荆素)在不同模拟消化阶段的质量浓度。结果:与未经消化的样品相比,直接消化(未添加果胶)显著降低了竹叶黄酮提取物溶液中4种竹叶黄酮的质量浓度(P0.05),且口腔、胃、肠道模拟消化对竹叶黄酮质量浓度产生不同的影响。与直接消化(未添加果胶组)相比,添加果胶显著提高了竹叶黄酮的生物可及性(P0.05),特别是异牡荆素和牡荆素经肠道消化后的生物可及性分别提高了75.1%和80.2%。研究中通过主成分分析和聚类分析阐明了不同处理后4种竹叶黄酮含量存在不同的聚类趋势。结论:果胶显著影响竹叶黄酮的生物可及性,添加果胶有助于提升竹叶黄酮在消化过程中的稳定性。本研究结果有助于竹叶黄酮类功能食品的开发。     

箬叶中4种黄酮苷的同步HPLC检测

箬叶中含有丰富的黄酮类化合物,具有多种生物活性。采摘国内箬叶主产区浙江松阳、武义,以及安徽黄山、福建光泽、江西宁都的样品。样品经体积分数50%乙醇提取,随后利用高效液相色谱法(HPLC)快速检测其中异荭草素、荭草素、牡荆素、异牡荆素含量,方法简单准确。结果显示,不同产地的箬叶均含有较丰富的黄酮苷。该结果揭示了国内不同产地的箬叶中异荭草素、荭草素、牡荆素、异牡荆素的含量差异,为全面深入研发箬叶提供采收情况和质量评价参考。     

芹菜素黄酮氧苷、黄酮碳苷同分异构体抗炎活性评价

目的:评价2种芹菜素黄酮氧苷（芹菜素-7-O-β-D-吡喃葡萄糖苷和5-O-β-D-吡喃葡萄糖苷芹菜甙元）和2种芹菜素黄酮碳苷（牡荆素和异牡荆素）的抗炎活性。方法:采用Western Blot法测定芹菜素黄酮苷在炎性细胞THP-1中的蛋白变化,采用酶联免疫法和实时荧光定量聚合酶链式反应法分析细胞中细胞因子变化。结果:4种芹菜素黄酮苷均能极显著抑制IL-10 mRNA的上升（P<0.01）,且牡荆素、异牡荆素能够极显著地抑制环氧合酶-2酶活力（P<0.01）,此外,异牡荆素还通过极显著抑制白细胞介素1β（P<0.01）和白细胞介素6（P<0.01）发挥了更有效的抗炎作用,而芹菜素-7-O-β-D-吡喃葡萄糖苷极显著抑制了肿瘤怀素因子TNF-α的表达（P<0.01）,5-O-β-D-吡喃葡萄糖苷芹菜甙元则对除IL-10外的其余几种细胞因子无抑制作用;进一步的研究发现,8位碳苷取代形成的芹菜素黄酮苷（即异牡荆素）对核转录因子P65（核转录因子κB（nuclear factor κB,NF-κB）亚基之一）的核移位抑制作用显著强于其余3种芹菜素黄酮苷的抑制作用(P<0.01)。但异牡荆素未通过抑制上游调控蛋白IκBα（α Inhibitor of κB,κB抑制因子α亚基）、IKKβ（IκB Kinase β,IκB激酶β亚基）而抑制NF-κB蛋白家族P65蛋白。结论:芹菜素黄酮碳苷尤其是异牡荆素在THP-1炎性细胞模型中具有更好的抗炎活性作用,但异牡荆素的抗炎作用并非通过IκBα依赖型的NF-κB信号通路实现。     

木犀草素-Zn（Ⅱ）配位温敏分子印迹聚合物的制备及其性能

以木犀草素-Zn（Ⅱ）配合物为模板分子，丙烯酰胺为功能单体，N-异丙基丙烯酰胺为温敏单体，N,N′-亚甲基双丙烯酰胺为交联剂制备木犀草素-Zn（Ⅱ）配位温敏分子印迹聚合物（thermo-sensitive molecularly imprinted polymers,TMIPs），分离箬叶黄酮碳苷。结果表明，TMIPs最佳制备工艺为模板分子、功能单体、温敏单体、交联剂摩尔比1∶4∶16∶30，其低临界溶解温度约为32℃，吸附性能符合Langmuir吸附模型和准一级动力学模型，TMIPs对木犀草素吸附量为36.06μmol/g，印迹因子为3.18，相对于芹菜素和芦丁，对木犀草素选择系数分别达到1.83和2.18，对温度响应灵敏，易于控制解吸。TMIPs用于分离箬叶黄酮碳苷，对牡荆苷、异牡荆苷、荭草苷、异荭草苷吸附量分别为32.99、27.73、35.16、36.05μmol/g。     

高效液相色谱法测定粽子中的黄酮类化合物及其迁移规律

建立天然包装材料箬叶及粽米中荭草苷、异荭草苷、牡荆苷、异牡荆苷、对香豆酸5 种黄酮类化合物的高效液相色谱的分析方法。通过测定一次蒸煮、二次蒸煮、不同保存条件等因素对箬叶及粽米中黄酮类化合物含量变化的影响,阐明了不同条件下箬叶中黄酮类化合物在粽子中的迁移规律。结果表明：一次蒸煮后,荭草苷、异荭草苷、牡荆苷、异牡荆苷、对香豆酸5 种黄酮化合物从箬叶迁移到粽米的迁移率为7.41%～45.18%;二次蒸煮时,在120 min内箬叶中5 种黄酮类化合物的迁移率为18.07%～65.94%,特别是在前30 min中,箬叶中黄酮类化合物降低明显,分别占120 min总减少量的51.61%～72.48%,并且二次蒸煮的迁移率大于一次蒸煮。在30 d的保存时间内,箬叶中黄酮类化合物在前15 d减少明显,占总减少量的68.60%～85.50%（除异牡荆苷为0外）;第15天后迁出缓慢;30 d内总迁移率分别为25.90%～64.84%（除异牡荆苷为0外）。随着二次蒸煮时间与保存时间的变化,荭草苷与异荭草苷较迁移缓慢。新鲜保存的方式最有利于异牡荆苷在粽子中迁移,速冻保存最有利于荭草苷、异荭草苷、牡荆苷、对香豆酸的迁移。异牡荆苷在真空保存和速冻保存时短时间内不发生迁移。     

谷物植物化学物中α-葡萄糖苷酶抑制剂的筛选及其分子机制

目的：从谷物植物化学物中筛选潜在的人源α-葡萄糖苷酶抑制剂。方法：构建小分子数据库,采用分子对接结合ADME和Lipinski性质从265 种中筛选出了10 种具有人源α-葡萄糖苷酶抑制潜力的植物化学物。结果：体外抑制活性实验结果显示牡荆素和异牡荆素两种常见碳苷黄酮及其苷元芹菜素抑制酵母源α-葡萄糖苷酶活力的能力为芹菜素＞牡荆素＞异牡荆素,与分子对接打分结果不一致。进一步的分子动力学和弱相互作用分析结果表明,虽然上述3 种植物化学物都能与关键氨基酸残基稳定结合,但可能是结构中的糖苷取代增大了立体位阻效应,使后两者在活性口袋中的运动轨迹范围不同于芹菜素,导致三者产生活性差异。结论：研究可为从谷物植物化学物中筛选人源α-葡萄糖苷酶抑制剂及结构改造提供依据。     

超声波辅助提取RP-HPLC法测定藜麦中的3种碳苷黄酮

基于超声波辅助提取藜麦中碳苷黄酮类化合物的工艺研究,建立了反相高效液相色谱法同时检测荭草素、异荭草素和牡荆素的方法。藜麦种子打粉过筛后,以90%的甲醇为提取溶剂,采用3因素3水平正交试验考察,得出超声波提取的最佳工艺条件为:超声功率80 W,超声时间30 min,超声温度55℃;在Diamonsil-C_(18)分离柱,酸性甲醇-水流动相体系,合适梯度洗脱程序下以恒流速1.0 mL/min,35℃柱温条件分离测定藜麦样品中的荭草素、异荭草素和牡荆素;结果显示,3种碳苷黄酮类物质分别在5.6~90μg/mL、2.66~42.5μg/mL和3.28~52.5μg/mL的范围内线性关系良好,定量限分别为0.519,0.416和0.322μg/mL,精密度和重复性的RSD分别为0.76%~1.63%、0.57%~1.78%,加样平均回收率为93.73%~101.68%,RSD为0.51%~2.55%;该方法精密度、重复性和稳定性良好,可用于藜麦样品中3种碳苷黄酮的分离检测。     

不同方法比较黄酮类化合物抗氧化性及其构效关系分析

通过三种化学抗氧化方法(DPPH、FRAP和ORAC法)以及细胞抗氧化方法(CAA法)对芹菜素、山奈酚、木犀草素、槲皮素4种黄酮甙元及它们的糖苷化合物抗氧化活性进行比较研究,结果表明DPPH和FRAP法基本一致,芹菜素、牡荆素和异牡荆素这类C环上无羟基且B环只有一个羟基的黄酮抗氧化性极低;在C环上的羟基相同时,B环有3',4'-邻二羟基的木犀草素和槲皮素的抗氧化活性显著高于仅含4'-OH的芹菜素和山奈酚;而ORAC法的结果与此相反。化学抗氧化测定结果均表明,当C环羟基被取代形成3-O-连黄酮苷时其抗氧化活性减小;而A环上6、8号位的氢被取代形成C-连黄酮苷时其抗氧化性反而会增加。CAA法结果显示,当C环无羟基时,B环只有一个4-OH的芹菜素及其黄酮苷无细胞抗氧化性,但B环有两个羟基的木犀草素及其糖苷却显示出较强的氧化性。与化学抗氧化性不同,A环上C-连黄酮苷的抗氧化性低于其苷元,而C环O-连糖苷的影响则较为复杂。     

体外模拟胃肠消化中山楂多酚及抗氧化活性的变化

本实验研究了山楂多酚、黄酮及抗氧化活性在体外模拟胃肠道环境下的变化规律,并利用高效液相色谱法测定了胃肠消化对山楂中5 种主要单体酚类化合物的影响。结果表明：山楂多酚在模拟胃液消化中稳定性较好,总多酚、黄酮含量及抗氧化能力均无显著性变化（P＞0.05）;而在模拟肠液消化中山楂多酚易发生降解,总多酚、黄酮含量在0.5 h内分别降低16.26%和7.46%,抗氧化能力也随之降低10.25%。高效液相色谱测定结果显示,5 种单体酚类化合物含量在胃液消化中无显著性变化（P＞0.05）;而在肠液消化中变化情况不相一致,其中金丝桃苷和异槲皮苷含量无显著性变化（P＞0.05）,表儿茶素在0.5 h内完全降解,绿原酸和原花青素B2在0.5 h内分别显著下降40.78%和28.99%（P＜0.05）。     

食品胶对豆浆中活性成分异黄酮苷元热稳定性的影响

研究了羧甲基纤维素钠(CMC)、海藻酸钠、黄原胶等食品添加剂对豆浆热处理过程中活性成分异黄酮苷元热稳定性的影响.高效液相色谱分析表明,CMC、黄原胶、海藻酸钠都能减少黄豆苷元、大豆黄素、染料木黄酮三种异黄酮苷元的热损失,其中CMC效果最理想,海藻酸钠次之,黄原胶最差.食品胶的复配能够减少豆浆中异黄酮苷元热损失.CMC/海藻酸钠组合明显好于CMC/黄原胶和黄原胶/海藻酸钠两种组合,当CMC/海藻酸钠=3:2时,在热处理条件为95℃,lOmin条件下,各异黄酮苷元热损失最少,黄豆苷元含量提高9.83%,大豆黄素12.67%,染料木黄酮18.63%.在三种食品胶共同复配组合中,CMC/黄原胶/海藻酸钠(4:3:3)组合的效果最好,黄豆苷元含量提高9.3%,大豆黄素10.13%,染料木黄酮18.26%.     

Effects of different types and concentrations of thickeners on yoghurt protein bioaccessibility by an in vitro dynamic gastrointestinal digestive model

This study analysed the protein bioaccessibility of yoghurt containing different concentrations of pectin, acid-resistant carboxymethylcellulose (CMC), guar gum and xanthan gum before and during in vitro gastrointestinal digestion, respectively. Soluble protein contents and protein digestion rates of yoghurt with 0.2% (m/v) guar gum, CMC and xanthan gum were significantly higher and faster, whereas other thickeners had slower rates than control yoghurt during gastric digestion phase. In addition, the contents of small peptides and amino acids were higher in yoghurt with 0.2% (m/v) thickeners than those with 1.0% (m/v) thickeners during simulated intestinal digestion in most of the samples.     

Isolation and purification of four flavone C-glycosides from antioxidant of bamboo leaves by macroporous resin column chromatography and preparative high-performance liquid chromatography

The present study investigated a robust method for the preparation of four flavone C-glycosides, i.e. orientin, homoorientin, vitexin and isovitexin, which were prepared from an ethanol aqueous extract, i.e. antioxidant of bamboo leaves (AOB), by AB-8 resin-based column chromatography and preparative high-performance liquid chromatography (HPLC) using a mobile phase consisting of 10% and 15% (v/v) of acetonitrile and 1% acetic acid. These flavone C-glycosides were further purified by the drowning-out crystallization method using methanol and water as drowning-out anti-solvents and salting-out agents, respectively. The purity was assessed by analytical HPLC and the confirmation of chemical structures was performed by IR, MS, NMR and UV spectroscopy. Orientin (49 mg), homoorientin (142 mg), vitexin (15 mg) and isovitexin (62 mg) were prepared from 6.5 g of crude column chromatography fraction obtained from 5 L of AOB concentrated solution. The present method is robust and suitable for preparing available quantities of pure flavone C-glycosides and the quantification of orientin, homoorientin, vitexin and isovitexin in bamboo leaves.     

Stability of lactobacilli encapsulated in various microbial polymers

Various microbial polymers, namely xanthan gum, gellan gum, pullulan gum and jamilan, were tested as a suitable encapsulating material for Lactobacillus plantarum CRL 1815 and Lactobacillus rhamnosus ATCC 53103. Resulting capsules were also studied for their pH and simulated gastrointestinal conditions tolerance. The morphology of the microcapsules was studied using scanning electron microscopy. pH tolerance was tested at pH 2.0, 3.5, 5.0 and 6.5 over a 6h incubation period. Simulated gastrointestinal conditions were assayed with simulated gastric and pancreatic juices and simulated bile over a 24h incubation period. Suspensions of probiotic organisms were used as a control. The results from encapsulation with microbial polymers indicate that mixtures of 1% xanthan gum with 0.75% gellan gum and 1% jamilan with 1% gellan gum were the most suitable for microencapsulation. Results for the pH tolerance tests showed no improvement in the viability of cells in relation to the control, except for pH 2.0 where lactobacilli encapsulated in xanthan:gellan gum (1%:0.75%) prolonged their viability by 6h exposure. Xanthan:gellan gum (1%:0.75%) was the most effective of the encapsulating materials tested in protecting L. plantarum and L. rhamnosus against simulated bile, improving its viability in 1-2 logCFU when compared with control. The results of this study suggest that microbial polymers are an interesting source of encapsulating material that should be taken into account for prospective studies of probiotic encapsulation for oral delivery applications.     

Antioxidant Properties of Flavone C-Glycosides from Atractylodes japonica Leaves in Human Low-density Lipoprotein Oxidation

ABSTRACT: Three antioxidant flavone C -glucosides, isoorientin, vitexin, and isovitexin, were identified for the 1st time from Atractylodes japonica leaves by an activity-guided fractionation with various analytical techniques including column chromatography, high-performance liquid chromatography (HPLC), fast atom bombardment mass spectrometry (FAB-MS), and nuclear magnetic resonance (NMR). Hydroxyl and superoxide anion radicals scavenging activities of these compounds were examined using electron spin resonance (ESR). Inhibitory activities of these compounds on human low-density lipoprotein (LDL) oxidation were evaluated by malondialdehyde (MDA) and thiobarbituric acid-reactive substances (TBARS), both representing intermediates of lipid peroxidation. These flavone C -glucosides displayed about 50% of scavenging activity against hydroxyl radicals at the concentrations below 10 μ M . The superoxide dismutase (SOD)-equivalent activities of isoorientin, vitexin, and isovitexin at 1 m M were 31.37, 2.71, and 2.63 unit/mL, respectively. Isoorientin at 1 μ M exhibited over 60% inhibition of MDA formed during copper-mediated human LDL oxidation. Amounts of free MDA in LDL treated with isoorientin, vitexin, isovitexin, and control were 20.06, 40.73, 34.08, and 48.03 n M /mg protein, respectively. These compounds also prolonged the lag phase time of the conjugated diene formation. There was a positive correlation between the free radical scavenging activities and the inhibitory effects on the LDL oxidation of these compounds. These results suggest that the flavone C -glucosides isolated from the leaves of A japonica possess beneficial antioxidant properties against free radicals as well as LDL oxidation.     

Influence of anionic dietary fibers (xanthan gum and pectin) on oxidative stability and lipid digestibility of wheat protein-stabilized fish oil-in-water emulsion

The influence of two anionic dietary fibers (xanthan gum and pectin) on the oxidative stability and lipid digestibility of fish oil emulsions stabilized by wheat protein (gliadin) was investigated. Lipid oxidation was determined by measuring lipid hydroperoxides and TBARS of the emulsions during storage, while protein oxidation was measured using fluorescence spectroscopy. Lipid and protein oxidation was faster at pH 3.5 than at pH 7, which may have been due to increased iron solubility under acidic conditions. Xanthan gum inhibited lipid and protein oxidation, which was attributed to its ability to bind iron ions. Conversely, pectin promoted oxidation, which was attributed to the presence of endogenous transition metals in the polysaccharide ingredient. In vitro digestion was carried out to evaluate the digestibility of oil droplets in emulsions with or without polysaccharides. Both xanthan gum and pectin significantly increased the rate of lipid digestion, which was attributed to their ability to inhibit droplet aggregation under gastrointestinal conditions. These results have important implications for designing emulsion-based functional foods with improved oxidative stability and lipid digestibility.     

体外模拟消化过程中胡萝卜中新烟碱类杀虫剂的生物可及性研究

摘 要: 目的 利用体外胃肠道模型研究胡萝卜中啶虫脒、噻虫胺、吡虫啉、噻虫嗪4种新烟碱类农药(neonicotinoid insecticides, NNIs)的生物可及性, 为其风险评估提供依据。方法 基于3种体外模型和胡萝卜在消化液中对NNIs的吸附过程, 采用液相色谱质谱联用仪分析4种NNIs的含量, 计算胡萝卜中NNIs的生物可及性和吸附量。结果 油脂的添加会增加胡萝卜中噻虫胺、噻虫嗪、吡虫啉的生物可及性, 分别从(63.3±5.9)%、(60.7±4.5)%、(81.1±9.9)%增加到(79.3±6.1)%、(79.7±7.5)%、(94.3±2.7)%; 而消化液中低浓度胆盐和胰酶的存在会降低NNIs的生物可及性。当胰酶质量浓度为0.25 g/L时, 降幅可达4.1%(噻虫胺)~26.7%(噻虫嗪)。吸附实验结果表明, 模拟肠液中4种NNIs的吸附亲和性系数KF值高于背景溶液。这表明胡萝卜在模拟肠液中有更高的吸附量, 胆盐的加入增强了胡萝卜与NNIs的相互作用, 降低了其生物可及性。结论 胡萝卜在不同体外消化模型中NNIs生物可及性存在差异, 胃肠道中胆盐和胰酶含量的升高在一定程度上会降低NNIs的生物可及性。     

Synergistic interaction of xanthan gum with glucomannans and galactomannans

Xanthan gum forms thermoreversible gels when mixed with konjac mannan or locust bean gum. The stronger gels are formed with konjac mannan and the maximum gel strength for the mixed systems in the absence of electrolyte occurs at a xanthan-konjac mannan or xanthan-locust bean gum mixing ratio of about 1:1. In the presence of 0.04 mol/dm³ NaCl the optimum mixing ratio is unchanged for xanthan-locust bean gum blends but changes to about 2:1 for xanthan-konjac mannan blends. These observations support differential scanning calorimetric data which are able to monitor both gelation and the conformational transition of the xanthan molecules and indicates that (i) in the absence of electrolyte konjac mannan interacts with disordered xanthan chains whilst in the presence of 0.04 mol/dm³ NaCl it interacts with ordered xanthan chains, and (ii) locust bean gum interacts with ordered xanthan chains both in the presence and absence of electrolyte.     

Antioxidants of therapeutic relevance in COPD from the neotropical blueberry Anthopterus wardii

Four flavone C-glycosides, isoorientin (1), orientin (2), vitexin (3), and isovitexin (4), were isolated from the neotropical blueberry of Anthopterus wardii, a so-called “superfruit”, using antioxidant activity-guided fractionation. A dose-response relationship of compounds 1-4 was determined for their anti-inflammatory activity against interleukin-8 (IL-8) and for the inhibition of matrix metalloproteinase-1 (MMP-1) expression, an inflammatory marker for chronic obstructive pulmonary disease. The four flavone C-glycosides exhibited inhibitory activity against IL-8 production and MMP-1 expression, with compounds 1, 3, and 4 having the most potent inhibitory activities in both assays at 100 μg/ml. The structures of compounds 1-4 were determined by spectroscopic methods. These flavone C-glycosides are reported for the first time in the Anthopterus genus.     

黄原胶的特性、生产及应用进展

黄原胶是Xanthomnas.sp分泌的胞外水溶性多糖,由于其有突出的高粘性和水溶性、独特的流变特性、优良的温度稳定性和pH稳定性、极好的兼容性以及安全环保等特性,已被广泛于石油开采、食品工业、纺织和化妆品等诸多行业。主要综述了黄原胶的分子结构、分子特性、生产以及应用的研究进展。     

食品级黄原胶酶法脱蛋白及其主要性能的研究

黄原胶发酵液在适宜的条件下经碱性蛋白酶处理,并用酒精沉淀可制得黄原胶粉剂。测定结果表明,碱性蛋白酶处理能使黄原胶产品含氮量降低41.8％,且有良好的增粘性、触变性和冷热稳定性,与槐豆胶协同使用有显著的增粘性,可作为食品添加剂。