沙棘黄酮的测定及其抗氧化作用

沙棘(ＨｉｐｐｏｐｈａｅｒｈａｍｎｏｉｄｅｓＬ.)是胡颓子科沙棘属植物,为灌木或乔木。沙棘果实含有多种生物活性物质,是我国古代藏医、蒙医用来治病的常用药[1]。本文采用三氯化铝比色法测定了沙棘根皮、茎皮和叶中黄酮类化合物含量,并考察其对羟自由基和超氧离子自由基的清除作用。1　实验部分1 1　仪器和试剂722型光栅可见分光光度计(上海分析仪器总厂);756ＭＣ型紫外可见分光光度计(上海分析仪器总厂);ｐＨＳ 3ＴＣ型精密数显酸度计(上海天达仪器有限公司)。槲皮素(中国预防医学科学院劳卫所);邻苯三酚(贵州遵义市第二化工厂);三…     

野西瓜中槲皮素提取工艺的研究

以槲皮素提取含量为评价指标,采用HPLC测定槲皮素的含量,选取超声波辅助提取时间、提取温度和甲醇水溶液浓度为考察因素,通过单因素实验和正交实验优选野西瓜中槲皮素的提取工艺.结果显示野西瓜中槲皮素提取工艺条件为:甲醇水溶液的浓度为90%,提取温度80℃,提取时间30 min.该提取方法简单、方便,为野西瓜中槲皮素的进一步研究提供依据.     

槲皮素分子印迹聚合物的制备及固相萃取性能研究

采用分子印迹技术, 以槲皮素为模板分子, 丙烯酰胺为功能单体, 乙二醇二甲基丙烯酸脂为交联剂, 通过热引发聚合, 制备了槲皮素分子印迹聚合物, 并通过装入固相萃取柱试验了聚合物对槲皮素的选择性能. 结果表明, 该分子印迹聚合物对槲皮素具有高度选择性, 为从天然产物中高效分离富集黄酮活性成分槲皮素提供了一种新材料.     

反相高效液相色谱法测定罗布麻叶中槲皮素和山萘酚

采用反相高效液相色谱法(RP-HQLC)测定了罗布麻叶中槲皮素和山萘酚。色谱柱为Nova-pak C18(15cm×4.6mm i.d.),流动相为A.甲醇、B.1%乙酸,流速为0.6mL/min,检测波长为360nm。槲皮素在0.0137~0.136μg、山萘酚在0.0053~0.0265μg范围内与峰面积呈良好的线性关系,相关系数分别为0.9998和0.9980。槲皮素的回收率为99.6%,RSD为0.97%;山萘酚的回收率为98.2%,RSD为2.0%。方法可用于罗布麻叶中槲皮素和山萘酚的测定。     

槲皮素金属配位分子印迹聚合物的识别性能

以槲皮素与Zn(Ⅱ)的配合物为模板,在甲醇溶液中制备金属配位分子印迹聚合物.通过紫外光谱研究了槲皮素与Zn(Ⅱ)的配位方式及配位比,验证了槲皮素、Zn(Ⅱ)和4-乙烯基吡啶之间的三元配位作用.利用红外光谱对产物的结构进行了表征.用平衡结合实验考察了功能单体及交联剂用量对聚合物吸附性能的影响,优化了聚合物的反应配比.同时对系列印迹聚合物的识别体系进行了考察.结果表明,槲皮素-Zn(Ⅱ)模板印迹聚合物对槲皮素-Zn(Ⅱ)的配合物表现出明显的吸附选择性和特异性,对槲皮素结构类似物芦丁和柚皮素的吸附选择性较差,分离因子分别为3.21和1.91.     

种植沙生植物--沙棘改善内蒙古地区生态环境

结合内蒙古地区现状，对沙棘的生物学和生态学特性、沙棘属植物化学成分和微量元素及种植沙生植物——沙棘的重要性和必要性进行了详细的研究和探讨。研究表明，沙棘属植物具有极强的生态适应性并富含多种营养成分和生物活性物质，并以耐干旱、耐瘠薄、萌蘖及固氮能力强等特点被称为治理非宜林地水土流失、改善生态环境的先锋树种。种植沙棘是治理内蒙古脆弱生态环境最经济、最有效的措施，是贫瘠的不毛之地发展经济、增加收入的经济树种。另外．种植沙棘的技术简便，容易掌握，投资少，见效快。     

槲皮素衍生物的合成及生物活性研究进展

综述了槲皮素衍生物的合成及生物活性研究进展,介绍了国内外槲皮素氨基酸类、糖苷类、酯类、醚类衍生物及金属配合物的合成方法及其生物活性研究现状.指出槲皮素是一种从天然植物中提取的黄酮醇类化合物,具有抗氧化,抗菌,扩张血管,抗肿瘤及抗突变等多种生物学活性.然而,槲皮素具有水溶性差、生物利用度较低等缺点,临床应用受到限制.为此,国内外学者对其结构进行修饰改造,开发出了一系列具有新颖结构的槲皮素先导化合物,可望为新型槲皮素衍生物的设计合成提供参考.     

荧光光度法测定槐花中槲皮素

研究了基于槲皮素和铝的络合反应来测定槲皮素的荧光光度法,试验结果表明:铝与槲皮素的配合物在pH 9.15的BR缓冲溶液中进一步与BO3-3形成三元体系,在452 nm激发波长下,于516 nm发射波长处测定其荧光强度,槲皮素浓度在1.0×10-7～6.0×10-6mol·L-1范围内配合物的荧光强度与槲皮素的浓度呈线性关系,检出限(3S/N)为2.1×10-7mol·L-1.该方法用于槐花提取物中槲皮素的测定,并以实样为基体用标准加入法做了回收试验,测得回收率在101.5%～112.5%之间.     

催化动力学荧光法测定洋葱中的槲皮素

研究了稀硫酸介质中,槲皮素催化溴酸钾氧化吖啶红的荧光光谱。在优化实验条件下,确定了荧光强度改变值(ΔIF)与槲皮素质量浓度的关系,建立了催化动力学荧光法测定洋葱中槲皮素的新方法。该方法的线性范围为0.43~18.0μg.L-1,检出限为0.13μg.L-1。方法操作简便,具有较好的灵敏度,用于洋葱中槲皮素含量的测定,结果满意。     

化学浸提-分光光度法测定沙棘叶中不同形态铝

利用KCl、NH4Ac、HCl、NaOH四种浸提液将沙棘叶中的铝浸提溶出,得到沙棘叶中铝的不同化学形态,采用分光光度法定量测定,测定结果:沙棘叶中的Al3+为10.7%,Al(OH)2+和Al(OH)+2为2.1%,胶态Al(OH)03为34.3%,有机铝为53.0%.浸提液中铝的回收率为86.9%～101.0%.     

分子印迹聚合物选择性富集长春碱的研究

分子印迹聚合物(MIPs)是近年来发展起来的一种对特定分子(模板分子)具有高度选择性的合成高分子材料.本文以长春碱(VLB)为模板分子,以甲基丙烯酸(MAA)为功能单体、乙二醇二甲基丙烯酸酯(EGDMA)为交联剂,在偶氮二异丁腈(AIBN)的引发下制备了长春碱印迹聚合物(VLB-MIP).采用紫外光谱对VLB与MAA之间形成的模板-功能单体复合物进行了分析,通过扫描电镜(SEM)对制备的VLB-MIP的表面形态进行了表征,并用BET法对MIP表面的孔径进行了测定.结果表明,VLB-MIP与未加模板分子制备的非印迹聚合物(NIP)相比表面多孔、粗糙,比表面积显著增加.以VLB-MIP作为固相萃取(SPE)的吸附剂,对VLB-MIP的选择性进行了评价,VLB-MIP能特异性地吸附VLB,而对VLB的结构类似物长春新碱(VCR)却没有表现出明显的吸附行为.将长春花提取物上样于填充VLB-MIP的SPE柱上,在最优实验条件下,长春花提取物中的VLB能被高效富集.此外,上样溶剂对MIP柱的吸附容量有影响,长春花提取物溶于非极性溶剂甲苯时,MIP的吸附容量最大为750μg/g,其次是氯仿吸附容量为625μg/g,最小的是甲醇为250μg/g.     

Synthesis of molecularly imprinted polymers for the application of selective clean-up vinblastine from Catharanthus roseus extract

Molecularly imprinted polymers (MIPs) are synthetic tailor-made polymers with high selectivity towards a particular substance (template). An MIP using vinblastine (VLB) as the template molecule was synthesized and characterized. The presence of monomer-template complexes in a non-covalent way was confirmed by UV-vis spectrometry analysis. The polymerization was performed using methacrylic acid (MAA) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linking agent, and toluene as the porogenic solvent by a thermo-polymerization method. The characterization of the obtained MIP was evaluated by scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) analysis. It was observed that the morphology of the MIP was more porous and rough, and the surface area had a significant increase compared with that of the non-imprinted polymer (NIP). This MIP was used as the sorbents of solid-phase extraction (SPE) to assess the selectivity of the MIP after optimization of the SPE protocol. VLB was specifically adsorbed on the MIP cartridge, while to vincristine (VCR), the chemical analog of VLB, almost no selective binding appeared. On the basis of the results, Catharanthus roseus extract was applied to the MIP cartridge for investigating its capability to extract VLB from the plant extract, and the capacity of the MIP cartridge was also evaluated. It was shown that the MIP could effectively enrich VLB from C. roseus extract and the recovery amounted to 93.8%. The solvents dissolving the samples had significant influence on the capacity of the MIP cartridge; it was 750 μg/g in toluene, 625 μg/g in chloroform, and 250 μg/g in methanol.     

Selective extraction of derivates of p-hydroxy-benzoic acid from plant material by using a molecularly imprinted polymer

Selective SPE of derivates of p-hydroxybenzoic acid (pHBA) from plant extract of Melissa officinalis is presented using a molecularly imprinted polymer (MIP) made with protocatechuic acid (PA) as template molecule. MIP was prepared with acrylamide as functional monomer, ethylene glycol dimethacrylate as crosslinking monomer and ACN as porogen. MIP was evaluated towards six phenolic acids: PA, gallic acid, pHBA, vanillic acid (VA), gentisic acid (GeA) and syringic acid (SyrA), and then steps of molecularly imprinted SPE (MISPE) procedure were optimized. The best specific binding capacity of MIP was obtained for PA in ACN (34.7 microg/g of MIP). Other tested acids were also bound on MIP if they were dissolved in this solvent. ACN was chosen as solvent for sample application. M. officinalis was extracted into methanol/water (4:1, v/v), the extract was then evaporated to dryness and dissolved in ACN before application on MIP. Water and ACN were used as washing solvents and elution of benzoic acids was performed by means of a mixture methanol/acetic acid (9:1, v/v). pHBA, GA, PA and VA were extracted with recoveries of 56.3-82.1% using this MISPE method. GeA was not determined in plant extract.     

Molecularly imprinted polymers for the clean-up of a basic drug from environmental and biological samples

A molecularly imprinted polymer (MIP) was synthesized and evaluated to selectively extract an alpha-blocker, i.e. alfuzosin, from human plasma. The synthesis of the MIP was performed in dichloromethane with methacrylic acid as monomer and the target drug as template. A first series of experiments was carried out in dichloromethane to estimate the potential of the MIP in its specific recognition medium, i.e. dichloromethane, by developing a selective procedure and by measuring the capacity of the sorbent. An optimized procedure was developed for the selective extraction of alfuzosin with a recovery close to 100% in this medium and a specific capacity of 1.3 micromol g(-1) of MIP was measured. A study in aqueous media was also carried out by a comprehensive approach of the retention mechanism in order to build a selective procedure of extraction. The effects of the amount and of the charge of cations were studied and an optimal pH value was defined to limit matrix effects. Then, the alfuzosin MIP was then directly used to selectively extract the target drug from human plasma with an extraction recovery of 60%. Lastly, a soil was extracted by a pressurized solvent and the resulting extract was cleaned up on the MIP, showing the possibility to use this selective sorbent for the sample treatment of various complex matrices.     

A (−)‐norephedrine‐based molecularly imprinted polymer for the solid‐phase extraction of psychoactive phenylpropylamino alkaloids from Khat (Catha edulis Vahl. Endl.) chewing leaves

A molecularly imprinted polymer (MIP) was prepared using (?)‐norephedrine as the template, methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross‐linker and chloroform as the porogen. The MIP was used as a selective sorbent in the molecularly imprinted solid‐phase extraction (MIP‐SPE) of the psychoactive phenylpropylamino alkaloids, norephedrine and its analogs, cathinone and cathine, from Khat (Catha edulis Vahl. Endl.) leaf extracts prior to HPLC‐DAD analysis. The MIP was able to selectively extract the alkaloids from the aqueous extracts of Khat. Loading, washing and elution of the alkaloids bound to the MIP were evaluated under different conditions. The clean baseline of the Khat extract obtained after MIP‐SPE confirmed that a selective and efficient sample clean‐up was achieved. Good recoveries (90.0–107%) and precision (RSDs 2.3–3.2%) were obtained in the validation of the MIP‐SPE‐HPLC procedure. The content of the three alkaloids in Khat samples determined after treatment with MIP‐SPE and a commercial Isolute C₁₈ (EC) SPE cartridge were in good agreement. These findings indicate that MIP‐SPE is a reliable method that can be used for sample pre‐treatment for the determination of Khat alkaloids in plant extracts or similar matrices and could be applicable in pharmaceutical, forensic and biomedical laboratories. Copyright © 2015 John Wiley & Sons, Ltd.     

Molecularly imprinted polymer for solid‐phase extraction of ephedrine and analogs from human plasma

A molecularly imprinted polymer (MIP) was synthesized and evaluated to selectively extract ephedrine from human plasma. The MIP synthesis was performed in chloroform with methacrylic acid as a functional monomer and the target alkaloid as a template molecule. The resulting MIP was applied to the selective extraction of ephedrine from a pure aqueous medium. A recovery about 74% was obtained using the MIP with only 7% on the nonimprinted polymer (NIP). A very straightforward selective SPE procedure was then successfully applied to the direct extraction of ephedrine from spiked human plasma with a high extraction recovery (68%) on the MIP with no recovery on the NIP. Moreover, the MIP was used for the selective extraction of catecholamine neurotransmitters, i.e. adrenaline and noradrenaline.     

Selective solid-phase extraction of a triterpene acid from a plant extract by molecularly imprinted polymer

A molecularly imprinted polymer (MIP) has been prepared by a thermal polymerisation method using methacrylic acid as functional monomer, ethylene glycol dimethacrylate as cross-linking agent, chloroform as porogenic solvent and an oleanane triterpene compound (18-beta-glycyrrhetinic acid) as imprinted molecule (template). Equilibrium ligand binding experiments were done to assess the performance of the MIP relative to non-imprinted polymer (NIP). After optimisation of SPE protocol (CHCl3 as washing solvent and MeOH as elution solvent), successful imprinting was confirmed by comparison of the recoveries between NIP (5%) and MIP (97%) cartridges. The binding capacity of the MIP for 18-beta-glycyrrhetinic acid was determined to be 0.94 mg g(-1). Four structurally related oleanane triterpenes (18-alpha-glycyrrhetinic acid, oleanolic acid, echinocystic acid, erythrodiol) were selected to assess the MIP selectivity. Experimental data illustrated the influence of functional groups on the triterpene skeleton. The MIP was applied to the solid-phase extraction of triterpenoids from a plant extract prior HPLC analysis. However, CHCl3 was replaced by ACN during the washing step in order to suppress non-specific interactions due to polar matrix components. A selective extraction of 18-beta-glycyrrhetinic acid from hydrolyzed extract of liquorice roots was achieved with a good extraction yield (98%).     

Selective enrichment of anti-inflammatory drugs from river water samples by solid-phase extraction with a molecularly imprinted polymer

A molecularly imprinted polymer (MIP) is synthesised by a noncovalent protocol in which ibuprofen was used as a template molecule. The polymer was evaluated chromatographically and it was seen that the MIP showed cross-reactivity. Subsequently, when this polymer was used as sorbent in SPE it was possible to selectively extract a mixture of nonsteroidal anti-inflammatory drugs from aqueous samples when a cleanup step with dichloromethane was performed. The performance of the MIP was evaluated with river water and water from a wastewater treatment plant, and compared with the performance of a commercial Isolute ENV+ sorbent.     

Surface-initiated molecularly imprinted polymeric column: In situ synthesis and application for semi-preparative separation by high performance liquid chromatography

In this work, we prepared a monolithic and surface initiated molecularly imprinted polymeric (MIP) column for HPLC and explored its application for template separation from plant extract. The silica beads (40-60 μm) were coupled with initiator on the surface and then packed in to a stainless steel HPLC column. The pre-polymerization mixture (the template, functional monomer and crosslinker were emodin, acrylamide and divinylbenzene, respectively) was injected into the column and polymerized by thermal initiation. The prepared MIP column exhibited excellent retention capability and large imprinted factor for template (the retention time and imprinted factor for emodin on MIP column were 16.26 min and 7.21, respectively). Moreover, the emodin-molecularly imprinted polymeric column could be applied to separate emodin from alcohol extract of Rheum palmatum L. at semi-preparative scale and 1.2 mg of emodin was obtained in 4 h.     

Synthesis of a molecularly imprinted polymer for the selective solid-phase extraction of chloramphenicol from honey

Solid-phase extraction (SPE) with a molecularly imprinted polymer (MIP) as sorbent has been investigated for the clean-up of the broad-spectrum bacteriostatic antibiotic chloramphenicol (CAP) in honey samples. The MIP was prepared by using methacrylic acid (MAA) as functional monomer, ethylene glycol dimethacrylate (EDMA) as cross-linker, chloroform as porogen and CAP as template molecule. The binding behaviour of the template CAP on the MIP was evaluated by high-performance liquid chromatography, and then the MIP was applied as a sorbent in SPE to selectively extract CAP from honey. It was shown that recoveries of nearly 100% of a CAP standard solution and up to 94% from spiked honey samples could be obtained after SPE.