化学发光法测定几种天然产物的抗自由基活性

为从天然产物中筛选出具有较好抗自由基活性的药物,利用鲁米诺 H2O2 CuSO4化学发光体系,测定了几种天然产物的抗自由基活性.结果表明抗自由基活性顺序为速溶茶>玉米须水提物>大豆异黄酮>Vc>刺槐花>花生壳丙酮提取物>玉米须醇提取物≈怀山药醇提物.     

高效液相色谱法测定怀山药中反式N-p香豆酰酪胺的含量

采用COSMOSIL Packed Column C18-PAQ(4.6 mm×250 mm)色谱柱,在流动相为甲醇-水(35∶65),流速为1 m L/min,柱温为25℃,检测波长为292 nm的条件下,建立了反式N-p香豆酰酪胺(t-CT)含量的高效液相色谱检测方法,并用于怀山药不同部位、不同处理方式所得样品中的t-CT含量测定.结果表明,怀山药皮中的t-CT含量明显高于怀山药去皮块茎中的含量,不同干燥方式对怀山药不同部位中t-CT含量的影响不大.研究结果为怀山药质量标准及药效物质基础研究提供参考.     

芜菁籽不同溶剂提取物体外抗氧化活性研究

通过体外试验初步研究芜菁籽提取物的抗氧化活性。用95%乙醇为溶剂提取芜菁籽,采用有机溶剂萃取法将提取物分为石油醚相,乙酸乙酯相,正丁醇相和水相等4个不同极性部位、同时测定了各相提取物对羟自由基,超氧阴离子自由基,DPPH自由基的清除能力,并与合成抗氧化剂BHT进行对照。结果表明,芜菁籽提取物的不同极性部位均有抗氧化活性,其抗氧化效果随着浓度的增加而增强,乙酸乙酯相和正丁醇相的还原能力及清除O-2.,DPPH和.OH的能力均强于水相和石油醚相,乙酸乙酯相和正丁醇相的抗氧化作用强,是天然抗氧化剂的良好来源,应对其进一步分离纯化。     

无过渡金属体系下C(sp^2)—H键的自由基反应构建C—N键研究进展

C—N键广泛存在于药物分子、天然产物及功能材料中,开发简洁高效的C—N键构建方法具有重要意义.近年来,无过渡金属体系下C(sp^2)—H键的自由基反应构建C—N键取得了诸多进展.该方法反应条件相对温和,反应活性较高,为C—N键构建提供了一条新途径.根据氮源类型的不同,对近年来C(sp^2)—H键的自由基反应构建C—N键的研究进展进行简要论述.     

5-取代阿魏酸衍生物的结构与抗氧化活性研究

利用量子化学中密度泛函理论(DFT)的B3LYP方法对一系列5-取代阿魏酸衍生物的结构与抗氧化活性进行了研究,获得了5-取代阿魏酸衍生物中性分子、自由基、自由基阳离子的稳定构型和能量。研究了两种不同的抗氧化机理—氢原子转移机制和电子伴随质子转移机制,以及表征抗氧化活性的两个最重要的参数—键解离焓和电离势。结果表明,分子平面结构和延伸的共轭链都有利于分散单电子,提高了自由基的稳定性,从而使自由基链式反应减慢或终止;5-位引入吸电子基团使得ArO—H键解离焓和电离势增大,抗氧化活性减弱;引入给电子基团则抗氧化活性增强。HOMO轨道能量与电离势具有较好的线性相关性,高度离域分散的自旋密度分布对于稳定半醌式自由基具有重要意义。通过实验测定了部分化合物的抗氧化活性,实验结果与理论预测结果具有良好的一致性,说明密度泛函对于阿魏酸的结构修饰以及抗氧化剂的筛选具有重要的指导作用。     

异丁酰紫草素衍生物捕获自由基能力的理论研究

利用密度泛函理论研究了异丁酰紫草素及其衍生物的捕获自由基的活性.结果表明,分子内氢键结构对异丁酰紫草素及其衍生物捕获自由基的活性起着重要作用.由于异丁酰紫草素及其衍生物具有高的键离解焓(Bond Dissociation Energy,BDE),H原子转移难于发生.但是,它们容易发生电子转移,分子中引入吸电子取代基(—CN,—NO2,—COCH3)可使阳离子自由基的离子化势(Ionization Potential,IP)值相对于异丁酰紫草素升高,而引入推电子取代基(-OCH3)可使阳离子自由基的IP值相对于异丁酰紫草素降低.所研究的化合物均具有良好的捕获自由基能力,尤其是分子中含有取代基—OCH3化合物.以本体系为例,从理论角度提出了一种研究捕获自由基的活性的方法.     

聚合反应中非等活性初级自由基的终止问题

许多光(热)引发剂能分解成二个非等活性自由基。根据非等活性初级自由基终止的概念,可导出以下方程:以ln(R_p~2/[I][M]对R_p/[M]~2作图,发现在很大的引发剂浓度范围内都较好地反映出非等活性初级自由基终止对聚合反应的贡献。对于安息香和O-酰基-α-酮肟类光引发剂,当它们的浓度大于1.0×10~(-2)(mol·1~(-1)时,聚合反应体系中明显存在非等活性初级自由基终止反应。随着反应体系的温度增加,终止反应程度相对减少,说明E_(prt)—E_i—E_p<0,对于O-酰基酮肟和双(O-酰基)-(α,β-二肟-三乙胺光引发体系,在引发剂浓度很低时,也存在初级自由基终止反应。自由基越稳定,初级自由基终止反应影响越明显。     

亚硫酸盐协助中空Bi2WO6微球的光催化性能

本文利用亚硫酸盐与Bi2WO6协同作用,有效地提升其光催化活性。以甲基橙和抗生素环丙沙星(CIP)作为被降解物对该体系的光催化降解性能和机理进行了研究。结果表明:光催化活性增强主要原因为亚硫酸盐能与Bi2WO6的光生空穴及羟基自由基反应,不仅能生成新的活性物质亚硫酸自由基(SO3^2-),还能促进Bi2WO6光生电子—空穴对的分离。此外,还考察了催化剂的用量、和污染物的浓度对该体系光催化性能的影响。     

Moracin M的简便合成及其生物活性

以4-甲氧基水杨醛和3,5-二甲氧基溴化苄为原料,经取代、缩合和水解等3步反应,以38%的总收率合成了Moracin M。分别采用DPPH自由基清除法、小鼠巨噬细胞RAW264.7模型初步测试了Moracin M的抗氧化活性和体外抗炎活性,结果表明该化合物对DPPH自由基的清除能力很强(IC_(50)=0.0433 mg/mL),优于阳性对照药V_C,且具有一定的抗炎活性。     

Moracin M的简便合成及其生物活性研究

本文以4-甲氧基水杨醛和3,5-二甲氧基溴化苄为原料,经取代、缩合和水解等3步反应,以38%的总收率合成了Moracin M。分别采用DPPH自由基清除法、小鼠巨噬细胞RAW264.7模型初步测试了Moracin M的抗氧化活性和体外抗炎活性,结果表明该化合物对DPPH自由基的清除能力很强（IC₅₀=0.0433mg/mL）,优于阳性对照药V_C,且具有一定的抗炎活性。      

山药多糖的制备及其体外抗氧化活性

提取山药粗多糖并进行精制,分析了山药多糖的单糖组成,并研究了山药多糖的体外抗氧化活性.结果表明,山药精制多糖纯度较高,由鼠李糖、阿拉伯糖、甘露糖、葡萄糖和半乳糖组成.体外抗氧化活性测试结果表明,山药多糖具有一定的还原能力,对羟自由基具有较强的清除能力,并对小鼠肝匀浆自氧化有明显的抑制作用.因此,山药多糖具有较好的抗氧化活性,可作为潜在的抗氧化剂或抗衰老药物进行深入研究和开发.     

鱼腥草中黄酮类成分的高效液相色谱指纹图谱分析

采用均匀实验设计和信息理论评价方法,建立了鱼腥草中黄酮类成分的高效液相色谱(HPLC)指纹图谱的分析方法。采用建立的方法和本研究室提出的指纹图谱评价软件,对同样种植条件下10个批次的鱼腥草指纹图谱进行了相似性评价,相似度均大于0.90;同时测定了芦丁、槲皮甙和槲皮素3个成分在10批鱼腥草药材中的含量分别为0.25%～0.34%、0.27%～0.37%、0.012%～0.016%。另外对不同采收季节和不同部位的鱼腥草药材中的黄酮类成分进行了指纹图谱的测定、主成分分析以及成分含量测定,结果表明,不同季节、不同部位的鱼腥草中黄酮类化合物的指纹图谱及成分含量存在较大的差异,且药用部位的差异大于采收季节的差异。该方法为规范鱼腥草中黄酮类成分在制药和用药的实际应用提供了一些可靠的基础信息。     

怀山药成分的热解气相色谱-质谱分析

采用毛细管气相色谱-质谱仪,考察了怀山药在300、400、450及500℃下的热解反应．对怀山药的热解产物进行了分析,首次发现山药热解产物中含有咖啡因成分．确证咖啡因成分是山药中化学成分裂解所产生的．     

Comparative Study on the Structural and Physicochemical Properties of Flour and Starch from Dioscorea opposita Thunb

The objective of this work was to investigate and compare the structural and physicochemical properties of Dioscorea opposita Thunb. flour(DF), starch(DS) and purified starch(PDS). DS and PDS showed higher total starch and amylose content as compared to DF. Starch granules of DF were oval shape with rough surface while DS and PDS were relatively smooth by SEM. According to XRD measurements, FT-IR spectroscopy and 13 C CP/MAS NMR spectroscopy, all samples displayed C-type crystalline pattern, and PDS displayed the highest relative crystallinity and short-range order structure. However, DF contained the greatest content of the amorphous-phase. DF displayed the absorption peaks at 1730 and 1560 cm~(-1) related to the characteristic groups of lipid and protein using FT-IR spectroscopy. Furthermore, DF exhibited significantly higher pasting temperature while DS displayed the great peak and breakdown viscosity, as well as PDS had the highest setback and final viscosity, presumably due to the chemical composition and structural differences. DF exhibited the highest gelatinization temperature whereas PDS displayed the greatest gelatinization enthalpy. The pasting and gelatinization properties of flour and starch might be related to the relative crystallinity, short-range order structure or the interactions between starch and its associated compounds. The results allow the improvement in the manufacture of Dioscorea opposita Thunb. flour and starch with desirable pasting and gelatinization properties.     

The Crystalline Changes of Starch from Rhizoma Dioscorea by Acid Hydrolysis

Dioscoreae (Chinese name Shanyao), the rhizome of various species of genus Dioscorea opposita Thunb.(Dioscoreaceae), has been used as an important invigorant in traditional Chinese medicine (TCM) for many years1. Starch, the most abundant carbohydrate in …     

Two new constituents from Artemisia capillaris Thunb

Two new compounds, 6'-O-caffeoyl-p-hydroxyacetophenone-4-O-beta-D-glucopyranoside(1) and 6-amino-9-[1-(3,4-dihydroxyphenyl)ethyl]-9H-purine (2) were isolated from the aerial parts of Artemisia capillaris Thunb. The structures were established on the basis of spectral data.     

Analysis of Dioscorea japonica by Hydrophilic Interaction Liquid Chromatography

Dioscorea japonica Thunb., traditionally used in folk medicine in Korea for the treatment of hyperglycemia, is known to have biological activity. However, few analytical methods suitable for rapid assessment of constituents of D. japonica rhizomes have been reported. A high-performance liquid chromatography method coupled with variable wavelength ultraviolet detection was developed for the determination of eight constituents of D. japonica rhizome. The separation was performed efficiently on a hydrophilic interaction liquid chromatography column by gradient elution with acetonitrile and water. Calibration curves showed excellent linear regression correlation levels (R ² > 0.9999) within the range of tested concentrations. Intra- and inter-day variations, evaluated by determining relative standard deviations, were below 1.71%. Constituent recovery rates were 93.37–104.24% with relative standard deviations of 0.55–1.98% for spiked D. japonica samples. The developed method was suitable for the qualitative and quantitative determination of the major components in D. japonica.     

Anthranilic acid derivatives from Inula japonica

Three new anthranilic acid derivatives, N-heneicosanoylanthranilic acid （1b）, N-tricosanoylanthranilic acid （1d）, N-tetracosanoylanthranilic acid （1e）, and two known N-arachidylanthranilic acid （1a） and N-docosanoylanthranilic acid （1c） were isolated from the aerial parts of lnula japonica Thunb. Their structures were established by spectroscopic and chemical methods.     

Evaluation of the nanofibrillar structure of Dioscorea opposite extract for cell attachment

Dioscorea opposite has been widely used in traditional herbal medicine in the Far East, ameliorating symptoms ranging from abdominal swelling to pain. Previous studies have focused on understanding the chemical components that lead to the medicinal effects of the extract. In this study, we examined the nanostructures formed by the soluble and insoluble parts of the sticky excretion from the mucilaginous rhizome of Dioscorea opposite and evaluated their cellular response. Using atomic force microscopy, we found that the soluble extract of the excretion had the capacity to form a nanofibrillar scaffold composed of uniform ～10 nm nanofibers with a typical pore size of ～40 nm, while the insoluble extract formed some nanofibers without specific structure. Cellular response to the two types of nanostructures was tested by seeding with HeLa and MC3T3 cells. The observations suggested that the nanofibrillar scaffold formed from the soluble extract provided an excellent platform for HeLa cell attachment and growth and to a lesser degree for MC3T3 cells, while nanofibers from the insoluble extract displayed no cell attachment and growth. Further analysis by direct incubation of the soluble extract with growing cells indicated that components from the extract preferentially bound to HeLa cells, but not to MC3T3 cells, which might help explain the observed preference of HeLa cells on the nanofibrillar scaffold. The nanofibrillar scaffold created from the Dioscorea opposite extract and its ability to sustain the attachment of specific cell types demonstrate the potential for this natural nanomaterial in tissue engineering applications.     

Phytochemical Characterization,Antioxidant Activity,and Cytotoxicity of Methanolic Leaf Extract of Chlorophytum Comosum (Green Type) (Thunb.) Jacq

Chlorophytum genus has been extensively studied due to its diverse biological activities. We evaluated the methanolic extract of leaves of Chlorophytum comosum (Green type) (Thunb.) Jacques, the species that is less studied compared to C. borivilianum. The aim was to identify phytoconstituents of the methanolic extract of leaves of C. comosum and biological properties of its different fractions. Water fraction was analyzed with matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Nineteen compounds belonging to different chemical classes were identified in the methanolic extract of leaves of C. comosum (Green type) (Thunb.) Jacques. In addition to several fatty acids, isoprenoid and steroid compounds were found among the most abundant constituents. One of the identified compounds, 4′-methylphenyl-1C-sulfonyl-β-d-galactoside, was not detected earlier in Chlorophytum extracts. The water fraction was toxic to HeLa cells but not to Vero cells. Our data demonstrate that methanolic extract of leaves of C. comosum can be a valuable source of bioactive constituents. The water fraction of the extract exhibited promising antitumor potential based on a high ratio of HeLa vs. Vero cytotoxicity.