Synthesis and bioactivities of novel 2-(thioether/sulfone)-5-pyrazolyl-1,3,4-oxadiazole derivatives

By introducing the pyrazole moiety into the 5-position of 1,3,4-oxadiazole,a series of novel 2-(thioether/sulfone)-5-pyrazolyl-l,3,4-oxadiazole derivatives were synthesized.Preliminary bioassays suggested that target compounds exhibited appreciable activity against pathogenic bacteria Xanthomonas oryzae pv.oryzae(Xoo) and five phytopathogenic fungi in vitro.Among them,the half-maximal effective concentration(EC_(50)) values of 6c,7a,7b and 7c against Xoo were within 16.6 μg/mL and 65.7 μg/mL,which were better than those of commercial agricultural antibacterial bismerthiazol(92.6 μg/mL) and thiodiazole copper(121.8 μg/mL).While compounds 7a,7b,and 7c exerted comprehensive antifungal activity toward five plant fungi,which were comparable with that of hymexazol.The results demonstrated that this kind of compounds can be further studied and developed as promising antifungal and antibacterial agents.     

Novel 1,3,5-thiadiazine-2-thione derivatives containing a hydrazide moiety: Design,synthesis and bioactive evaluation against phytopathogenic fungi in vitro and in vivo

A series of novel 1,3,5-thiadiazine-2-thione derivatives bearing a hydrazide moiety were designed, synthesized and evaluated for their biological activities against phytopathogenic fungi. The antifungal bioassays indicated that the title compound 5b impressively displayed the obvious selectivity and specificity aganist Rhizoctonia solani (Rs) in vitro and in vivo. The above researches provide a significant reference for the further structural optimization of 1,3,5-thiadiazine-2-thione derivatives bearing a hydrazide moiety as potential fungicides.     

Preparation and in vitro antiproliferative effect of tocotrienol loaded lipid nanoparticles

The primary objective of this study was to prepare nanostructured lipid carriers loaded with tocotrienol-rich-fraction of palm oil (TRF-NLCs) and to evaluate their antiproliferative effects against neoplastic +SA mammary epithelial cells. This necessitated optimizing the ultrasonic homogenization process parameters and the surfactant to lipid ratio within the NLCs. Therefore, sonication time and pulsar rate were initially evaluated for their effect on the size and polydispersity of the nanoparticles using a full factorial design. Also, varying the surfactant to lipid ratio from 0.25:1 to 3:1 was evaluated for its effect on the same responses. Optimal nanoparticles were obtained when dispersions containing a surfactant to lipid ratio of 0.5:1, with a total lipid concentration of 0.25 (w/v), were sonicated at 60% pulsar rate for 10 min. These parameters were subsequently used to prepare TRF-NLCs. TRF was loaded into the nanoparticles by substituting 10% (TRF-10-NLC) or 50% (TRF-50-NLC) of the lipid phase with TRF. In an extended stability study, no significant change in particle size of the TRF-NLCs was observed over 6 months of storage. In the cell culture studies, TRF-NLCs were shown to exhibit potent antiproliferative effect against neoplastic +SA mammary epithelial cells. The IC₅₀ values of TRF-10-NLCs were 2-fold lower than the IC₅₀ value of the reference TRF/BSA solution. In contrast, TRF-50-NLCs had comparable IC₅₀ values as the TRF/BSA solution, which signified the importance of TRF encapsulation within NLCs on their activity. Furthermore, these findings suggested that TRF-NLCs may have potential value in the treatment of breast cancer.     

以锌试剂显色法测定蛋白质的研究

有关蛋白质染色测定的分光光度研究已有不少报道,其中有些已用于蛋白质的分析测定［１～４］．锌试剂常用于金属离子的分光光度法测定,但作为生物大分子分析试剂的研究,目前还未见报道．实验表明,在ｐＨ４左右的缓冲溶液中,锌试剂与ＢＳＡ反应生成有色复合物,吸收光...     

功能性CdS纳米荧光探针荧光增敏法测定人血清白蛋白

目前 ,以荧光分析法对蛋白质进行研究主要采用有机荧光探针[1～ 3 ] .与传统的有机染料 (如罗丹明 )探针相比 ,半导体纳米晶体探针的光强度要高 2 0倍 ,光稳定性要高 1 0 0倍 ,谱线宽度只是有机染料谱线宽度的 1 /3 [4 ] .将半导体纳米晶体作为探针用于测定生物分子 ,将大大提高分析的灵敏度和选择性 ,而目前其应用于生物染色、医疗诊断、DNA序列测定和免疫分析等方面的研究很少 [4 ,5] .本文合成了胶态纳米粒子 Cd S,并在其外表面修饰一层巯基乙酸 ,使其具有水溶性 ,并能与生物分子作用 ,从而可利用其外表面的功能性基团对人血清白蛋白进…     

胰蛋白酶与DNA相互作用的共振瑞利散射光谱及其分析应用研究

当胰蛋白酶与鲱鱼精DNA(hsDNA)、 鲑鱼精DNA(sDNA)以及小牛胸腺DNA(ctDNA)之间发生相互作用时,共振瑞利散射(RRS)会显著增强,并产生新的RRS光谱. 三者有近似的光谱特征,其最大RRS峰分别位于307 nm(hsDNA和sDNA体系)和290 nm处(ctDNA体系),另一散射峰位于350 nm处,其散射强度(ΔI)与DNA或者胰蛋白酶的浓度成正比,因此可用于蛋白质和DNA的相互测定. 当用胰蛋白酶测定DNA时,hsDNA,sDNA和ctDNA的检测范围分别为1.4×10^-3～2.3, 2.1×10^-3～2.5和3.5×10^-3～1.9 μg/mL(ctDNA),它们的检出限分别为0.4,0.7和1.1 ng/mL. 当用hsDNA测定胰蛋白酶时,其线性范围为0.1～30.0 μg/mL,检出限为39.0 ng/mL. 研究了最佳的反应条件、 影响因素和结合产物的化学性质,考察了胰蛋白酶与DNA的结合比,推测了它们的结合方式,并以胰蛋白酶作RRS探针,发展了一种高灵敏、 简便和快速测定痕量DNA的新方法.     

Synthesis,in vitro antibacterial and antifungal evaluation of novel 1,3,4-oxadiazole thioether derivatives bearing the 6-fluoroquinazolinylpiperidinyl moiety

A series of structurally novel 1,3,4-oxadiazole thioether derivatives(6a-6z) containing a 6-fluoroquinazolinylpiperidinyl moiety were designed and synthesized using pharmacophore hybrid approach,and their structures were fully characterized by ^1H NMR,¹³C NMR and HRMS spectra.Among them,the structure of compound 6 d was further corroborated via single-crystal X-ray diffraction analysis.In vitro antibacterial bioassays showed that compounds 6 a,6 g,6 u and 6 v possessed EC₅₀ values of 30.4,30.6,27.5 and 26.0 μg/mL against phytopathogenic bacterium Xanthomonas oryzae pv.oryzae,respectively,which were significantly superior to that of commercially-available bactericide Bismerthiazol(85.1 μg/mL).Moreover,in vitro antifungal bioassays indicated that seven compounds demonstrated broad-spectrum fungicidal acitivties against six types of phytopathogenic fungi at 50 μg/mL.The present work showed the potential of 1,3,4-oxadiazole thioether derivatives carrying a 6-fluoroquinazolinylpiperidinyl moiety as effective antimicrobial agents for crop protection,deserving further investigations in the future.     

Homogenous electrogenerated chemiluminescence immunoassay for human immunoglobulin G using N-(aminobutyl)-N-ethylisoluminol as luminescence label at gold nanoparticles modified paraffin-impregnated graphite electrode

A homogeneous electrogenerated chemiluminescence (ECL) immunoassay for human immunoglobulin G (hIgG) has been developed using a N-(aminobutyl)-N-ethylisoluminol (ABEI) as luminescence label at gold nanoparticles modified paraffin-impregnated graphite electrode (PIGE). ECL emission was electrochemically generated from the ABEI-labeled anti-hIgG antibody and markedly increased in the presence of hIgG antigen due to forming a more rigid structure of the ABEI moiety. The concentration of hIgG antigen was determined by the increase of ECL intensity at a gold nanoparticles modified PIGE. It was found that the ECL intensity of ABEI in presence of hydrogen peroxide was dramatically enhanced at gold nanoparticles modified PIGE in neutral aqueous solution and the detection limit of ABEI was 2 x 10(-14)mol/L (S/N=3). The integral ECL intensity was linearly related to the concentration of hIgG antigen from 3.0 x 10(-11) to 1.0 x 10(-9)g/mL with a detection limit of 1 x 10(-11)g/mL (S/N=3). The relative standard deviation was 3.1% at 1.0 x 10(-10)g/mL (n=11). This work demonstrates that the enhancement of the sensitivity of ECL and ECL immunoassay at a nanoparticles modified electrode is a promising strategy.     

The effect of carboxymethyl-chitosan nanoparticles on proliferation of keloid fibroblast

In this study, different molecular weight (MW) carboxymethyl chitosans (CM-chitosan) nanoparticles were prepared by ionic gelification. The particle size of nanoparticles was around 180–250 nm by dynamic light scattering (DLS) and transmission electron microscope (TEM). With the increase of CM-chitosan nanoparticles concentration from 2 to 200 μg/mL, the growth inhibition effects on the keloid fibroblast increased. At the concentration of 100 μg/mL, CM-chitosan nanoparticles with MW6.3 kDa had a significant inhibitory effect (inhibition ratio 48.79%) of the proliferation of keloid fibroblast. Compared with CM-chitosan solution, the inhibition of CM-chitosan nanoparticles were lower in prior period and similar in later period. By analyzing the different effects of chitosan, CM-chitosan solution and CM-chitosan nanoparticles on proliferation of keloid fibroblast, we have found that the carboxylmethyl groups of CM-chitosan play an important role in inhibition of proliferation of keloid fibroblast.     

Microwave-assisted synthesis of water-soluble styrylpyridine dye-capped zinc oxide nanoparticles for antibacterial applications

ZnO nanoparticles were successfully synthesized using a microwave method, whose surface was modified with {4-[(E)-2-(furan-2-yl)ethenyl]pyridin-1-ium-1-yl}acetate as a capping agent (1 and 3%). Their structural properties were investigated using FTIR, XRD, SEM, EDS, and UV–visible spectroscopy. XRD confirmed the Wurtzite structure for all compounds, a size of 30.6 nm for uncapped and 22.9 nm for 3% dye-capped nanoparticles were calculated from Scherer's equation. Hexagonal wurtzite shape of nanoparticles can be clearly seen in the SEM images. The DFT calculations were carried out using quantum espresso. These dye-capped ZnO nanoparticles were proved to be potential antibacterial agents, the minimum concentrations of dye-capped ZnO nanoparticles that inhibit the growth of bacteria are 1.5 mg/mL for Escherichia coli and 0.78 mg/mL for Bacillus subtilis, which are much lower than those of uncapped ZnO. The bioactivity data suggest these organic–inorganic hybrid nanoparticles emerged as a new class of antibacterial agents.     

Self-aggregated nanoparticles from methoxy poly(ethylene glycol)-modified chitosan: synthesis; characterization; aggregation and methotrexate release in vitro

Methoxy poly(ethylene glycol)-grafted-chitosan (mPEG-g-CS) conjugates were synthesized by formaldehyde linking method and characterized by Fourier transform infrared (FT-IR) and proton nuclear magnetic resonance (¹H-NMR). The degree of substitution (DS) of methoxy poly (ethylene glycol) (mPEG) in the mPEG-g-CS molecules determined by ¹H-NMR ranged from 19% to 42%. The critical aggregation concentration (CAC) was determined by fluorescence spectroscopy using pyrene as fluorescence probe and its value was 0.07 mg/mL in water. mPEG-g-CS formed monodisperse self-aggregated nanoparticles with a roughly spherical shape and a mean diameter of 261.9 nm were prepared by the dialysis method. mPEG-g-CS self-aggregated nanoparticles were used as carriers of poorly water-soluble anticancer drug methotrexate (MTX). MTX was physically entrapped inside mPEG-g-CS self-aggregated nanoparticles by dialysis method and the characteristics of MTX-loaded mPEG-g-CS self-aggregated nanoparticles were analyzed using dynamic laser light scattering (DLLS), transmission electron microscopy (TEM). Moreover, in vitro release behavior of MTX was also investigated and the results showed that MTX was continuously released more than 50% in 48 h.     

Study of the synthesis,antiviral bioactivity and interaction mechanisms of novel chalcone derivatives that contain the 1,1-dichloropropene moiety

A series of novel chalcone derivatives that contain the 1,1-dichloropropene moiety was designed and synthesized. Bioactivity assays showed that most of the target compounds exhibited moderate to good antiviral activity against tobacco mosaic virus (TMV) at 500 μg/mL. Among the target compounds, compound 7h showed the highest in vivo inactivation activity against TMV with the EC₅₀ and EC₉₀ value of 45.6 and 327.5 μg/mL, respectively, which was similar to that of Ningnanmycin (46.9 and 329.4 μg/mL) and superior to that of Ribavirin (145.1 and 793.1 μg/mL). Meanwhile, the microscale thermophoresis and fluorescence spectroscopy experiments showed that the compound 7h had a strong interaction with the tobacco mosaic virus coat protein.     

Synthesis and biological activities of(E)-β-farnesene analogues containing 1,2,3-thiadiazole

In order to discover novel compounds with high-activity to control aphid,a series of novel(E)-β-farnesene analogues containing 1,2,3-thiadiazole were designed and synthesized,and their structures were confirmed by IR,~1H NMR,~(13)C NMR,and HRMS(ESI).The stability of representative compounds was studied by HPLC and ~1H NMR techniques.Repellent activity results indicated that compounds 8h and 8j displayed 60.3%and 62.0%repellent rates,respectively.The aphicidal bioassay results showed that most analogues exhibited considerable aphicidal activity against Myzus persicae.Especially,analogues 81,8s and 8t exhibited high activity with LC_(50) values of 33.4 μg/mL,50.2 μg/mL and 61.8 μg/mL,respectively,which were higher than the lead compound(E)-β-farnesene,but lower than commercial insecticide pymetrozine with a LC_(50) of 7.1 μg/mL     

Self-aggregated nanoparticles of cholesterol-modified glycol chitosan conjugate: Preparation, characterization, and preliminary assessment as a new drug delivery carrier

Cholesterol-modified glycol chitosan (CHGC) conjugate was synthesized and characterized by FTIR and ¹H NMR. The degree of substitution (DS) was 6.7 cholesterol groups per 100 sugar residues of glycol chitosan. CHGC formed self-aggregated nanoparticles with a roughly spherical shape and a mean diameter of 228 nm by probe sonication in aqueous medium. The physicochemical properties of the self-aggregated nanoparticles were studied using dynamic light scattering (DLS), transmission electron microscopy (TEM) and fluorescence spectroscopy. The critical aggregation concentration (CAC) of self-aggregated nanoparticles in aqueous solution was 0.1223 mg/mL. Indomethacin (IND), as a model drug, was physically entrapped into the CHGC nanoparticles by dialysis method. The characteristics of IND-loaded CHGC (IND-CHGC) nanoparticles was analyzed using DLS, TEM and high performance liquid chromatography (HPLC). The IND-CHGC nanoparticles were almost spherical in shape and their size increased from 275 to 384 nm with the IND-loading content increasing from 7.14% to 16.2%. The in vitro release behavior of IND from CHGC nanoparticles was studied by a dialysis method in phosphate buffered saline (PBS, pH 7.4). IND was released in a biphasic way. The initial rapid release in 2 h and slower release for up to 12 h were observed. The results indicated that CHGC nanoparticles had a potential as a drug delivery carrier.     

Encapsulation of L-dopa and catechol in bovine serum albumin nanocarrier using desolvation method and their in vitro release studies

In the current study, the interaction between L-dopa and bovine serum albumin (BSA) as well as catechol and BSA is investigated separately. In order to achieve the optimum values for encapsulated efficiency (EE), the content of crosslinker/BSA, organic/aqueous phase, drug/BSA, stirring rate, and pH were closely studied taking the advantage of Taguchi method. Particle characterization was carried out using transmission electron microscopy and dynamic light scattering techniques. The most appropriate catechol and L-dopa nanoparticles in the size range of 100 nm and 65 nm, respectively, and at optimized conditions of drug/BSA = 0.1, pH = 7.4, crosslinker/BSA = 0.084, organic/aqueous phase = 4 and stirring rate 400 rpm were obtained. The most favorable EE (encapsulation efficiency) and LC (loading capacity) for L-dopa and catechol was estimated to be 88.1% and 83.6%, respectively, and the calculated LC% was achieved 93.4% and 89.7% for L-dopa and catechol, respectively. The chromatographic analyses results were also found to be in a good agreement with the obtained data for the calculated EE% and LC% values. in vitro release of loaded drugs from nanoparticles in phosphate-buffered saline (pH = 7.4, incubated at 37 ± 0.5°C under stirring rate of 100 rpm) showed the release of 78% catechol and 89% L-dopa during 480 min and 510 min, respectively.     

金纳米粒子修饰的手性毛细管电色谱固定相的制备及性能表征

制备了粒径为15 nm的金纳米粒子(GNPs)并将其修饰到氨基衍生化的硅胶整体柱内,通过化学键合法将牛血清白蛋白(BSA)固载到GNPs的表面作为手性固定相。通过透射电子显微镜、扫描电子显微镜等方法进行表征,结果表明,GNPs分散性良好,并被成功地修饰到毛细管柱内,含量高达17.18%。优化了BSA手性柱的制备条件,最终确定了体积分数为10%的3-氨丙基三乙氧基硅烷(APTES)和15 g/L BSA为最佳反应条件。在毛细管电色谱分离模式下,对缓冲液pH值、电压等分离条件进行了考察,最终选择了10 mmol/L pH 7.4的磷酸缓冲液和15 kV运行电压作为最佳分离条件。手性柱对3种手性化合物(色氨酸、阿替洛尔和麻黄碱)有拆分效果,对色氨酸能实现基线分离。与物理吸附法相比,化学键合法制备的手性柱拆分效果好,分析物无需柱前衍生化,且色谱柱稳定性良好。该文的制备方法也为其他类型手性选择剂的引入提供了良好的思路。     

高效液相色谱-荧光检测法同时测定体外循环下狗血浆中的阿曲库铵和劳丹碱

建立了测定体外循环下狗血浆中阿曲库铵及其代谢产物劳丹碱的高效液相色谱-荧光检测(HPLC-FLD)分析方法。使用Agilent Eclipse Plus C18色谱柱分离,以0.03 mol/L磷酸氢二钾(pH 5.0)-乙腈(72:28, v/v)为流动相,流速1.0 mL/min。以维拉帕米为内标,样品经二氯甲烷萃取、浓缩后以流动相溶解进样,荧光检测的激发波长和发射波长分别为240和320 nm。结果表明,阿曲库铵和劳丹碱分别在25~5000 μ g/L和25~6000 μ g/L范围内线性关系良好(r=0.9990和r=0.9984);方法回收率在92.1%~109.5%之间;检出限分别为3 μ g/L和1 μ g/L;日内和日间精密度(以RSD计)均小于10%;稳定性试验结果显示样品在不同存储条件下的稳定性良好。该方法选择性好,灵敏度高,结果准确,重现性好,可用于阿曲库铵和劳丹碱的血药浓度测定及其药代动力学研究。     

Preparation, characterization and in vitro release study of carvacrol-loaded chitosan nanoparticles

The fabrication of carvacrol-loaded chitosan nanoparticles was achieved by a two-step method, i.e., oil-in-water emulsion and ionic gelation of chitosan with pentasodium tripolyphosphate. The obtained particles possessed encapsulation efficiency (EE) and loading capacity (LC) in the ranges of 14-31% and 3-21%, respectively, when the initial carvacrol content was 0.25-1.25 g/g of chitosan. The individual particles exhibited a spherical shape with an average diameter of 40-80 nm, and a positively charged surface with a zeta potential value of 25-29 mV. The increment of initial carvacrol content caused a reduction of surface charge. Carvacrol-loaded chitosan nanoparticles showed antimicrobial activity against Staphylococcus aureus, Bacillus cereus and Escherichia coli with an MIC of 0.257 mg/mL. The release of carvacrol from chitosan nanoparticles reached plateau level on day 30, with release amounts of 53% in acetate buffer solution with pH of 3, and 23% and 33% in phosphate buffer solutions with pH of 7 and 11, respectively. The release mechanism followed a Fickian behavior. The release rate was superior in an acidic medium to either alkaline or neutral media, respectively.     

Binding of chloroquine-conjugated gold nanoparticles with bovine serum albumin

We have conjugated chloroquine, an anti-malarial, antiviral and anti-tumor drug, with thiol-functionalized gold nanoparticles and studied their binding interaction with bovine serum albumin (BSA) protein. Gold nanoparticles have been synthesized using sodium borohydride as reducing agent and 11-mercaptoundecanoic acid as thiol functionalizing ligand in aqueous medium. The formation of gold nanoparticles was confirmed from the characteristic surface plasmon absorption band at 522 nm and transmission electron microscopy revealed the average particle size to be ~7 nm. Chloroquine was conjugated to thiolated gold nanoparticles by using EDC/NHS chemistry and the binding was analyzed using optical density measurement and Fourier transform infrared spectroscopy. The chloroquine-conjugated gold nanoparticles (GNP-Chl) were found to interact efficiently with BSA. Thermodynamic parameters suggest that the binding is driven by both enthalpy and entropy, accompanied with only a minor alteration in protein's structure. Competitive drug binding assay revealed that the GNP-Chl bind at warfarin binding site I in subdomain IIA of BSA and was further supported by Trp212 fluorescence quenching measurements. Unraveling the nature of interactions of GNP-Chl with BSA would pave the way for the design of nanotherapeutic agents with improved functionality, enriching the field of nanomedicine.     

高效液相色谱法分离和测定小麦中的5种内源激素

建立了高效液相色谱法(HPLC)用于分离和测定小麦中的吲哚乙酸(IAA)、脱落酸(ABA)、赤霉素(GA₃)、玉米素(ZT)和水杨酸(SA)5种植物内源激素。经过条件优化,选用甲醇作为样品提取溶剂。然后,经石油醚和乙酸乙酯萃取,经Sep-Pak C18小柱纯化。液相色谱的分离采用Eclipse XDB-C₁₈ (250 mm×4.6 mm, 5 μm)反相色谱柱;流速为1 mL/min;进样量10 μL。检测器波长设置为254 nm; 14.5 min时切换到240 nm; SA洗脱后即18 min时切换回254 nm。流动相A为甲醇,B为乙酸溶液(pH 3.6)。梯度条件为0~7 min, 20%A; 7~10 min, 20%A~28%A; 10~17 min, 28%A; 17~19 min, 28%A~40%A; 19~35 min, 40%A。结果表明,小麦中各激素的分离效果理想,加标回收率达96.9%~98%,相对标准偏差在1.54%~2.29%之间。因此,该方法的建立为快速、准确地分离和测定小麦内源激素提供了可靠的方法。