3种分光光度法对天然抗氧化物质抗自由基性能的分析检测

用1,1 二苯基 2 苦基肼(DPPH)自由基捕获、亚硝基R盐 Co3 褪色、连苯三酚红等3种分光光度法对3种野生植物抗氧化剂的对自由基的作用进行了分析检测及方法比较研究。3种分光光度法对自由基的分析检测及抗氧化剂的抗自由基性能检测方法,对于普通实验室检测自由基或相关的研究工作具有很好的实用性。没食子酸丙酯及葡萄籽提取物的抗氧化性要优于灯盏花素提取物。对自由基的清除率可以达到40%～80%,具有很好的抗氧化能力及氧自由基清除作用。     

洋葱色素的提取及抗氧化活性的测定

分别用芬顿（Fenton）反应法和1,1-二苯-2-苦肼基（DPPH）法测定了洋葱色素的抗氧化作用。结果表明,洋葱色素对羟自由基和DPPH自由基均有一定的清除作用,其清除率大小依次为42．4％,58．2％。洋葱色素是十分具有开发利用价值的天然色素。     

锗(Ⅳ)-槲皮素配合物的制备、表征及其抗氧化活性测定

槲皮素(Qu)是一种天然的、具有抗氧化活性的黄酮类化合物。本研究通过优化合成条件,制备了配位比分别为1:1和1:2(Qu/Ge)的QuGe和QuGe2两种配合物,并采用紫外、红外、核磁共振、元素分析、高效液相色谱、电化学等方法对配合物的结构进行表征。结果表明,QuGe中的Ge(Ⅳ)结合在3'位和4'位羟基的氧原子上,而QuGe2除了结合3'位和4'位羟基的位点外,还结合了4位CO和3位羟基。利用Fenton反应与罗丹明B体系,研究了Qu及其配合物的抗氧化活性。结果表明,两种配合物的抗氧化活性均比单独的Qu配体明显增强,并探讨了配合物抗氧化活性的增强机制,对开发具有保健功能的新型锗化合物具有重要意义。     

7-取代三唑硫乙氧基黄酮衍生物的合成及生物活性

7-羟基黄酮与过量1,2-二溴乙烷反应得到7-溴乙氧基黄酮,将其分别与3-取代-4-氨基-1,2,4-三唑-5-硫酮肉桂醛席夫碱、3-取代-4-苯基-5-巯基-1,2,4-三唑、3-(α-萘亚甲基)-5-巯基-1,2,4-三唑及3-巯基-5-氨基-1,2,4-三唑肉桂醛席夫碱反应,得到4类共16个7-三唑硫乙氧基黄酮类衍生物.采用红外光谱(IR)、核磁共振氢谱(1H NMR)、质谱(MS)及元素分析(EA)等方法对化合物的结构进行了确证.测定了目标化合物清除超氧自由基(O-·2)、羟自由基(·OH)和2,2-二苯基-1-苦味酰基自由基(DPPH·)的活性及总还原能力,并测定了其抗菌活性.结果表明,多数化合物在0.5 mg/m L浓度时具有抗DPPH·活性,其中7-(5-苯亚甲基-4-苯基烯丙亚胺基-1,2,4-三唑-3-硫乙氧基)黄酮(1i)活性较强;多数化合物表现了较好的抑菌活性,其中7-(5-苯亚甲基-4-苯基-1,2,4-三唑-3-硫乙氧基)黄酮(2c)对大肠杆菌、金黄色葡萄球菌和黑曲霉均具有较强的抑制作用.     

八元瓜环对氯化矢车菊素溶解性、稳定性及抗氧化性的影响

采用核磁共振氢谱(¹H NMR)、 红外光谱及紫外吸收光谱等方法考察了八元瓜环(Q[8])对氯化矢车菊素(Cy)的包结作用. 结果表明, 在pH=0.8的盐酸介质中, Q[8]可与Cy形成摩尔比为1:1的主客体配合物, 紫外吸收光谱法测得的主-客体结合常数为1.51×10⁶ . 相溶解度研究结果表明, Q[8]能使饱和Cy溶液的溶解度增大, 当Q[8]浓度为100 μmol/L时, 可使Cy的溶解度增大12.21倍. 紫外吸收光谱随时间变化结果表明, 在较为稳定存在形态及相同实验条件下, Q[8]/Cy溶液比Cy溶液的稳定性提高了2.58倍. 抗氧化性实验结果表明, Q[8]/Cy包合物和Cy均表现出较好的抗氧化活性.     

Ultrasound irradiation promoted enzymatic alcoholysis for synthesis of monoglyceryl phenolic acids in a solvent-free system

Monoglyceryl phenolic acids (MPAs) were known as the natural hydrophilic antioxidants which could be used in different fields such as food, pharmaceutical, cosmetic etc. A novel enzymatic route of MPAs synthesis by the alcoholysis of phenolic acid ethyl esters with glycerol under ultrasound irradiation in solvent free system was developed. Optimization of reaction parameters shows that a high conversion of above 97.4% can be obtained under the following conditions: phenolic acid ethyl esters to glycerol molar ratio of 1:10, with 6% catalyst (Novozym 435), at 60 °C and 200 rpm, with ultrasound input of 250 W, at 20 kHz frequency. Compared to the conventional stirring method, the activation energy for phenolic acid ethyl esters conversion was decreased from 65.0 kJ/mol to 32.1 kJ/mol under ultrasound promotion; the apparent kinetic constant (V_m/K_m) increased above 1.2-folds; the lipase amount decreased to 50%; the time required for the maximum conversion reduced up to 3-folds without damaging the lipase activity, which is the fastest report for enzymatic synthesis of MPAs.     

吡喃酮型花色苷衍生物的制备、光谱特性及抗氧化活性研究

吡喃酮型花色苷衍生物是一类具有非氧鎓离子结构和内酯型吡喃环结构的新型多酚类化合物。本研究以植物花色苷为原料,通过羧基吡喃花色苷形成及微氧化等两步反应法,结合柱色谱分离纯化技术,制备高纯度的吡喃酮花色苷衍生物A (Oxovitisin A)标准品;高效液相色谱-光电二极管阵列检测器-串联质谱法(HPLC-DAD-ESI-MS/MS)分析鉴定出纯化后反应产物Oxovitisin A的纯度达99%以上。利用荧光光谱仪、紫外可见光谱仪及超微弱化学发光光谱仪研究了Oxovitisin A及其前体物质花色苷(锦葵素-3-葡萄糖苷,Mv-3-gluc)与羧基吡喃花色苷A(Vitisin A))的光谱特性、色泽稳定性及抗氧化活性。结果表明：Oxovitisin A在440 nm激发波长下有最大荧光峰,最大发射波长490 nm,而具有氧鎓离子结构的两种前体物质无荧光特性。紫外光谱结合LAB色泽空间表征参数显示Oxovitisin A在不同pH值条件下具有不同的结构稳定性和色泽稳定性。Mv-3-gluc,VitisinA和Oxovitisin A在不同体系中均表现出良好的抗氧化活性,清除超氧阴离子自由基的IC₅₀值分别为71.4,30.7和19 μg·mL-1(抗坏血酸28 μg·mL-1),清除羟自由基的IC₅₀值分别为1.68,3.524,2.854 μg·mL-1(抗坏血酸8.441 μg·mL-1),对双氧水清除率的IC₅₀值分别为1.311,0.4098和0.288 μg·mL-1(抗坏血酸3.265 μg·mL-1),表明Oxovitisin A清除自由基和抗氧化的能力均高于反应前体物Mv-3-gluc和VitisinA及抗坏血酸。     

Ni-Mo-B非晶态合金纳米颗粒的抗氧化性能研究

在水溶液体系中用化学还原法制备Ni-B和Ni-Mo-B非晶态合金纳米颗粒.SEM测试表明,样品的颗粒形貌呈球形或类球形,平均粒径约10nm.XPS分析结果表明,Ni-Mo-B非晶态合金中钼元素主要以氧化态形成于合金的表面,并导致合金表面合金化硼原子浓度显著增加,氧化态硼（B3＋）的原子浓度显著减少,氧的原子浓度明显减少,合金化镍的原子浓度显著增加,氧化态镍（Ni3＋）的原子浓度显著减少.因此,Ni-Mo-B合金的抗氧化性能显著高于Ni-B合金.XPS谱图分析还表明,在Ni-B和Ni-Mo-B非晶态合金中,存在Ni和B的合金化物Ni2B,其中B失去部分电子,而Ni则富余电子.Ni2B的氧化产生副产物Ni2O3和B2O3.     

Study on flavonoid and bioactivity features of the pericarp of Citri Reticulatae ‘chachi' during storage

The mature pericarp of Citri Reticulatae 'Chachi' (PCRC) is one of the six traditional Chinese medicinal materials that should be used after long storage, and it was regarded that the longer the medicine was stored, the better. However, the aging mechanism of the medicine is not clear. To further investigate the effect of aging on the main active flavonoids of PCRC, ultra-performance liquid chromatography coupled with triple quadrupole mass spectrometry (UPLC-MS/MS) and metabolomics analysis were used to analyze the flavonoids of PCRC stored for different periods. In the results, 219 flavonoids were detected. 5,7,3′,4′,5′-pentamethoxy dihydroflavone and 2′-hydroxy-3,4,5,3′4′,6′-hexamethoxychalcone were found from PCRC for the first time. According to the clustering analysis of metabolites, aging times of 0 year, 1 year, and 2 year were clustered into one group, and aging times of 3 year, 4 year, and 29 year were clustered into the other group. Quantitative analysis showed that the former group contained a greater amount of 4 flavonoids than the latter group, while the latter group contained a greater amount of 15 polymethoxyflavonoids. The newly harvested PCRC was compared with the other 5 groups of PCRC (stored for 1, 2, 3, 4, and 29 years). Eight flavonoids, tectochrysin, apigenin, 2′-hydroxyisoflavone, luteolin, 6-hydroxyluteolin, gallocatechin, quercetin -O- acetylhexoside and apigenin ?7-O-[β-D-glucuronide (1 → 2) -O-β-D-glucuronide], were used as marker components to discriminate newly harvested PCRC and aging PCRC. In addition, the antioxidant potency composite index (APC) indicated that the PCRC stored for three or four years had stronger antioxidant activity than the PCRC stored for other periods. By means of molecular docking, it was reviewed that the amount of antiviral components against SARS-CoV-2 in freshly harvested PCRC was significantly higher than that in aging PCRC. The results in this study supplied scientific data for quality control, evaluation, and rational utilization of PCRC and basic information for further analysis of the metabolic regulation of the active components of the PCRC.     

流动注射化学发光法及光度法用于巴戟天提取液抗氧化活性的研究

将中药巴戟天提取液加入鲁米诺-H₂O₂-CuSO₄化学发光体系,测量其发光强度, 根据系统化学发光被抑制的程度可以评价巴戟天的抗氧化活性,并将巴戟天与抗坏血酸的抗自由基活性进行了对比实验,实验证明巴戟天提取液具有明显的抗自由基活性;采用分光光度法测定体系吸光度的变化来研究巴戟天对OH·及O₂-·自由基的清除作用,以抗坏血酸作阳性对照,结果发现：巴戟天对OH·及O₂-·自由基均有良好的清除作用,结果较为满意。提示中药巴戟天可作为潜在的具有抗氧化活性的天然药物。