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1.
Cao Y  Zhang X  Fang Y  Ye J 《The Analyst》2001,126(9):1524-1528
A simple, reliable and reproducible method, based on capillary electrophoresis (CE) with electrochemical detection (ED), for the determination of five active ingredients and three carbohydrates in extracts of Gastrodia rhizoma is described in this work. The main active ingredients are gastrodin, 4-hydroxybenzyl alcohol, vanillyl alcohol, 4-hydroxybenzylaldehyde and vanillin. Operated in a wall-jet configuration, a 300 microm diameter carbon disc electrode was used as a working electrode, with a good response at +1000 mV (vs. SCE) for 4-hydroxybenzyl alcohol, vanillyl alcohol, 4-hydroxybenzylaldehyde and vanillin; a 300 microm diameter copper disc electrode exhibits a good response at +650 mV (vs. SCE) for gastrodin, sucrose, glucose and fructose. Under optimum conditions, 4-hydroxybenzyl alcohol, vanillyl alcohol, 4-hydroxybenzylaldehyde and vanillin in 100 mmol l(-1) borate buffer (pH 9.2) and gastrodin, sucrose, glucose and fructose in 50 mmol l(-1) sodium hydroxide buffer were baseline separated within 18 min. The response was linear over two orders of magnitude with a detection limit (S/N = 3) in the range 3 x 10(-7)-1.8 x 10(-6) mol l(-1) for all eight analytes. This method was successfully used in the analysis of traditional Chinese medicine, and the assay results were satisfactory.  相似文献   

2.
牟祥  牟祥  王立军 《应用化学》2009,26(7):854-856
对比研究了三氯化铕,三氯化镧,三氯化铈和三氯化镨四种镧系盐催化剂化学选择酯化香草醇收率的影响。以三氯化镧为化学选择催化剂,且香草醇与三氯化镧物质的量比为1:0.005时,癸酸香草醇酯的收率最高为85%,并用该法合成辛酸香草醇酯和月桂酸香草醇酯,其收率分别为87%和71%。  相似文献   

3.
Glycosylation of vanilloids such as vanillin and 8-nordihydrocapsaicin by cultured plant cells of Eucalyptus perriniana was studied. Vanillin was converted into vanillin 4-O-β-D-glucopyranoside, vanillyl alcohol, and 4-O-β-D-glucopyranosylvanillyl alcohol by E. perriniana cells. Incubation of cultured E. perriniana cells with 8-nordihydrocapsaicin gave 8-nordihydrocapsaicin 4-O-β-D-glucopyranoside and 8-nordihydrocapsaicin 4-O-β-D-gentiobioside.  相似文献   

4.
The potent herbicide paraquat and three other analogues MPP+, MPDP+ and MPTP have a known toxicological profile linked to the ability to damage dopaminergic neurons. Other biological effects were recently addressed to this class of compounds, including the ability to interact with enzymatic targets involved in the Central Nervous System, such as the acetylcholinesterase (AChE) and the butyrylcholinesterase (BuChE). A combined molecular modelling and enzymatic study focusing onto their interaction against the AChE and BuChE is reported. The former study was performed by docking techniques using target known co-crystallographic models. The latter study was carried out by the widely adopted Ellman's method. In both studies the anti-Alzheimer FDA approved drug tacrine was used as reference inhibitor. Our results indicate that paraquat, MPTP, MPDP+ and MPP+ recognize both enzymatic cleft in a similar fashion compared to the reference inhibitor. A structure-activity correlation was found with the net charge of the ligands, indicating a major role of the electrostatic term in the recognition and inhibition of these compounds. Our data completed their enzymatic profile, added new information on the molecular mechanisms underlying their neurotoxicity useful for the rational design of new cholinesterase inhibitors.  相似文献   

5.
Abstract

The anti- and syn-diethyleneoxy bridged cryptophanes (3a and 3b) were prepared by the direct trimerization of 1,5-bis[(4-hydroxymethyl)-2-methoxyphenoxy]-3-oxapentane, which was obtained by the reaction of diethyleneglycol ditosylate with vanillyl alcohol and/or by stepwise methods from vanillyl alcohol. The syn isomer (3b) showed highly selective complexing abilities for cesium, and the tetraethylammonium and triethylmethylammonium cations as compared with those of the anti isomer (3a).  相似文献   

6.
The potent herbicide paraquat and three other analogues MPP+, MPDP+ and MPTP have a known toxicological profile linked to the ability to damage dopaminergic neurons. Other biological effects were recently addressed to this class of compounds, including the ability to interact with enzymatic targets involved in the Central Nervous System, such as the acetylcholinesterase (AChE) and the butyrylcholinesterase (BuChE). A combined molecular modelling and enzymatic study focusing onto their interaction against the AChE and BuChE is reported. The former study was performed by docking techniques using target known co-crystallographic models. The latter study was carried out by the widely adopted Ellman's method. In both studies the anti-Alzheimer FDA approved drug tacrine was used as reference inhibitor. Our results indicate that paraquat, MPTP, MPDP+ and MPP+ recognize both enzymatic cleft in a similar fashion compared to the reference inhibitor. A structure-activity correlation was found with the net charge of the ligands, indicating a major role of the electrostatic term in the recognition and inhibition of these compounds. Our data completed their enzymatic profile, added new information on the molecular mechanisms underlying their neurotoxicity useful for the rational design of new cholinesterase inhibitors.  相似文献   

7.
为提高苯甲酰胺类衍生物(S)-N-(1-乙基-2-吡咯烷基)甲基-4-氨基-2-甲氧基苯酰胺(ABZM)的入脑量,对其结构进行改造,得到了新的化合物(S)-4-二甲氨基-N-(1-乙基-2-吡咯烷基)甲基-2-甲氧基苯酰胺(DMABZM).通过Idogen法对DMABZM进行标记得到标记化合物125I-DMAIBZM,标记率为74%,放化纯度达到99%. 体外放射配基结合实验测得DMABZM的IC50为2.9589×10-7 mol?L-1,表明它与能与多巴胺D2受体特异性结合且具有较高的亲和力,在小鼠体内的分布实验中,该标记物纹状体/小脑的比值可达6.5左右,说明了该标记化合物与纹状体的结合有较高的特异性和亲和力.125I-DMAIBZM的脂溶性显著大于125I-AIBZM,入脑量有较大的提高.结论:125I(123I)-DMAIBZM有望用于多巴胺D2受体的显像.  相似文献   

8.
One of the next challenges in the use of biocatalysts (enzyme or microbial cells) is the upgrading of biological reactions of oxidoreduction. The oxidoreductases need cofactors that must be regenerated. Practical experience shows that this is most readily achieved by using living cells of microorganisms. Living cells ofSaccharomyces cerevisiae are able to bioconvert vanillin to vanillyl alcohol (1). By working with a two-phase reactor (dodecanol—feeding medium) it has been possible to use higher vanillin concentrations without inhibiting the bioconversion (2).  相似文献   

9.
Fanconi anaemia (FA) is a rare genetic chromosomal instability syndrome caused by impairment of DNA repair and reactive oxygen species (ROS) imbalance. This disease is also related to bone marrow failure and cancer. Treatment of these complications with radiation and alkylating agents may enhance chromosomal breakage. We have evaluated the effect of amifostine (AMF) on basal and mitomycin C (MMC)-induced chromosomal breakage in FA blood cells using the micronucleus assay. The basal micronuclei count was higher among FA patients than healthy subjects. Pre-treatment with AMF significantly inhibited micronucleation induced by MMC in healthy subjects (23.4 +/- 4.0 - MMC vs 12.3 2.9 - AMF --> MMC) MN/1000CB, p < 0.01, one way ANOVA) as well as in FA patients (80.0 +/- 5.8 - MMC vs 40.1 +/- 5.8 - AMF --> MMC) MN/1000CB, p < 0.01, ANOVA). Release of ROS by peripheral blood mononuclear cells treated with AMF -> MMC and measured by chemoluminometry showed that AMF-protection was statistically higher among FA patients than in healthy individuals. Based on these results we suggest that AMF prevents chromosomal breakage induced by MMC, probably by its antioxidant effect.  相似文献   

10.
Ginseng(Panax ginseng C. A. Mey.) is a traditional medicinal herb in Asia. Studies have shown that ginsenosides significantly affect immunoregulation and rare ginsenosides have anti-allergic effects. In this research, a high temperature and high pressure method was utilized to increase the contents of rare ginsenosides in the ginseng extract(GE). The anti-allergic effects of this extract were investigated in vivo. Water was used as the extraction solvent in extracting the rare ginsenosides via the high temperature and high pressure method. Extraction time and temperature were investigated in order to increase the contents of rare ginsenosides. Rare ginsenosides were qualitatively analyzed by HPLC-ESI-MS and quantitatively analyzed by HPLC-UV. Anti-allergic effects of the extracts were assessed using the ovalbumin(OVA)-induced allergic asthma model in vivo. An extraction temperature of 145℃ and extraction time of 2.0 h were chosen as the optimal conditions. Compared with traditional method, the contents of total rare ginsenosides extracted were considerably higher using the new method, that is, 14.74 times that extracted by the traditional method. In our in vivo experiments, treatment with high concentration GE may have anti-allergic effects in decreasing the total amount of IgE in serum and IL-4 in bronchoalveolar lavage fluid(BALF), and in improving the ratio of CD4+ to CD8+ T cells. The high temperature and high pressure method was an effective method to obtain GE containing more rare ginsenosides, which maybe become anti-allergic agents.  相似文献   

11.
Mahanimbine (MN) is a carbazole alkaloid present in the leaves of Murraya koenigii, which is an integral part of medicinal and culinary practices in Asia. In the present study, the anticancer, apoptotic and anti-invasive potential of MN has been delineated in vitro. Apoptosis cells determination was carried out utilizing the acridine orange/propidium iodide double fluorescence test. During treatment, caspase-3/7,-8, and-9 enzymes and mitochondrial membrane potentials (Δψm) were evaluated. Anti-invasive properties were tested utilizing a wound-healing scratch test. Protein and gene expression studies were used to measure Bax, Bcl2, MMP-2, and -9 levels. The results show that MN could induce apoptosis in MCF-7 cells at 14 µM concentration IC50. MN-induced mitochondria-mediated apoptosis, with loss in Δψm, regulation of Bcl2/Bax, and accumulation of ROS (p ≤ 0.05). Caspase-3/7 and -9 enzyme activity were detected in MCF-7 cells after 24 and 48 h of treatment with MN. The anti-invasive property of MN was shown by inhibition of wound healing at the dose-dependent level and significantly suppressed mRNA and protein expression on MMP-2 and -9 in MCF-7 cells treated with a sub-cytotoxic dose of MN. The overall results indicate MN is a potential therapeutic compound against breast cancer as an apoptosis inducer and anti-invasive agent.  相似文献   

12.
In order to understand the role of iron (Fe) in the oxidative stress underlying the pathogenesis of Parkinson's disease (PD) and parkinsonism–dementia complex (PDC), we investigate distributions and chemical states of Fe within a single neuron of the two disease cases, using synchrotron radiation (SR) micro beam. In the X-ray fluorescence (XRF) spectroscopic study, an excessive accumulation of Fe can be seen in the melanized neurons and free-neuromelanin (MN) aggregates in the substantia nigra tissue of both PD and PDC midbrains. X-ray absorption near-edge structure (XANES) analyses of PD revealed that the chemical state of Fe in the melanized neurons and free-MN aggregates shifted toward Fe3+ with a pre-edge peak at Fe K-edge due to a 1s 3d transition, indicating a breaking of the inversion symmetry around the Fe site. In PDC, however, the melanized neurons and free-MN aggregates showed mixed states of Fe2+ and Fe3+ without any pre-edge peak in the spectra. This tendency was also observed in the control case. These results suggest that the changes in distributions and chemical states of Fe may endogenously play a crucial role in the oxidative damage of the melanized neurons in PD, but through a different mechanism other than PDC.  相似文献   

13.
Some metal-ion-complexing properties of the ligand 2-(pyrid-2'-yl)-1,10-phenanthroline (MPP) are reported. MPP is of interest in that it is a more preorganized version of 2,2';6,2'-terpyridine (tpy). Protonation constants (pK(1) = 4.60; pK(2) = 3.35) for MPP were determined by monitoring the intense π-π* transitions of 2 × 10(-5) M solutions of the ligand as a function of the pH at an ionic strength of 0 and 25 °C. Formation constants (log K(1)) at an ionic strength of 0 and 25 °C were obtained by monitoring the π-π* transitions of MPP titrated with solutions of the metal ion, or 1:1 solutions of MPP and the metal ion were titrated with acid. Large metal ions such as Ca(II) or La(III) showed increases of log K(1) of about 1.5 log units compared to that of tpy. Small metal ions such as Zn(II) and Ni(II) showed little increase in log K(1) for MPP compared to the tpy complexes, which is attributed to the presence of five-membered chelate rings in the MPP complexes, which favor large metal ions. The structure of [Cd(MPP)(H(2)O)(NO(3))(2)] (1) is reported: monoclinic, P2(1)/c, a = 7.4940(13) ?, b = 12.165(2) ?, c = 20.557(4) ?, β = 96.271(7)°, V = 1864.67(9) ?(3), Z = 4, and final R = 0.0786. The Cd in 1 is seven-coordinate, comprising the three donor atoms of MPP, a coordinated water, a monodentate, and a bidentate NO(3)(-). Cd(II) is a fairly large metal ion, with r(+) = 0.96 ?, slightly too small for coordination with MPP. The effect of this size matching in terms of the structure is discussed. Fluorescence spectra of 2 × 10(-7) M MPP in aqueous solution are reported. The nonprotonated MPP ligand fluoresces only weakly, which is attributed to a photoinduced-electron-transfer effect. The chelation-enhanced-fluorescence (CHEF) effect induced by some metal ions is presented, and the trend of the CHEF effect, which is Ca(II) > Zn(II) > Cd(II) ~ La(III) > Hg(II), is discussed in terms of factors that control the CHEF effect, such as the heavy-atom effect.  相似文献   

14.
Both steady state and time resolved spectroscopic measurements reveal that the prime process involved in quenching mechanism of the lowest excited singlet (S1) and triplet (T1) states of the well known electron acceptor 9-Cyanoanthracene (9CNA) in presence of 5,6,7,8-tetrahydro-1-naphthol (TH1N) or 5,6,7,8-tetrahydro-2-naphthol (TH2N) is H-bonding interaction. It has been confirmed that the fluorescence of 9CNA is not at all affected in presence of 5,6,7,8-tetrahydro-2-methoxy naphthalene (TH2MN) both in non-polar n-heptane (NH) and highly polar acetonitrile (ACN) media. This indicates that the H-bonding interaction is crucial for the occurrence of the quenching phenomenon observed in the present investigations with TH1N (or TH2N) donors and 9CNA acceptor. In ACN solvent both contact ion-pair (CIP) and solvent-separated (or dissociated) ions are formed due to intermolecular H-bonding interactions in the excited electronic states (both singlet and triplet). In NH environment due to stronger H-bonding interactions, the large proton shift within excited charge transfer (CT) or ion-pair complex, 1 or 3(D+-H...A-), causes the formation of the neutral radical, 3(D+H-A)*, due to the complete detachment of the H-atom. It is hinted that both TH1N and TH2N due to their excellent H-bonding ability could be used as antioxidants.  相似文献   

15.
Vanillyl alcohol,which is made up of an aromatic ring,an alcoholic hydroxyl group,a phenolic hydroxyl group and a methoxy group,was selected as the model molecule of lignin.Various carbon materials supported Pd catalysts were chosen to catalyze the HDO of vanillyl alcohol.The catalysts were characterized via TEM,TPD,XRD,XPS and CO-chemisorption.It was found that different carbon materials could obviously influence the particle sizes,dispersion and distribution of Pd or Pd O particles.Palladium and carbon can synergistically catalyze the room-temperature HDO of vanillyl alcohol even at room temperature,and the carboxyl group was found to be the effective active acid site during the reaction.Possible reaction mechanism was also proposed.The existence of the effective active acid sites on the carbon supports could obviously lower the reaction temperature without decreasing the selectivity,as a result,making the production of renewable fuels by HDO much more economically feasible,which is of much importance.  相似文献   

16.
中相微乳液;盐度扫描;助表面活性剂对阴/阳离子表面活性剂复配形成微乳液的影响  相似文献   

17.
Nanomaterials with enzyme‐like activities (nanozymes) attracts significant interest due to their therapeutic potential for the treatment of various diseases. Herein, we report that a Mn3O4 nanozyme functionally mimics three major antioxidant enzymes, that is, superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) and the multienzyme activity is size as well as morphology‐dependent. The redox modulatory effect of Mn3O4 plays a crucial role in protecting the cells from MPP+ induced cytotoxicity in a Parkinson disease (PD)‐like cellular model, indicating that manganese‐based nanomaterials having multi‐enzyme activity can robustly rescue the cells from oxidative damage and thereby possess therapeutic potential to prevent ROS‐mediated neurological disorders.  相似文献   

18.
The present work confirms the high separation ability of purified Cyanex 301 towards trivalent americium over europium in liquid-liquid extraction. Solvent 2-nitrophenyl octyl ether (NPOE) lowered the partitioning of Am3+ but remained the separation ability over europium. Solvent toluene and 3-octanone lowered the separation factor to 1000. It is feasible to separate Am3+ from Eu3+ by Cyanex 301 which was immobilized in the macro porous polymer (MPP). 3-Octanone is a suitable solvent for dissolving NH4OH-saponified Cyanex 301 and MPP is a suitable solid supported material for column operation. A five-step column experiment demonstrated the feasibility to separate Am3+ from Eu3+ in column which was packed with Cyanex 301-impregnated MPP.  相似文献   

19.
Dual-functional monomers consist of two distinctly different functional groups that enable chemical versatility. The most readily available epoxy-methacrylate dual-functional monomer is glycidyl methacrylate (GMA). In an effort to produce bio-based, aromatic complements to GMA, asymmetric phenolic diols (vanillyl alcohol, syringyl alcohol, gastrodigenin, and tyrosol) were identified and selectively epoxidized at the aromatic hydroxyl followed by subsequent esterification at the aliphatic hydroxyl to prepare dual functional monomers, vanillyl alcohol epoxy-methacrylate (VAEM), syringyl alcohol epoxy-methacrylate (SAEM), gastrodigenin epoxy-methacrylate (GDEM), and tyrosol epoxy-methacrylate (TEM). These monomers are viable platforms for a multitude of applications due to their unique chemical functionalities. VAEM, SAEM, GDEM, and TEM were homopolymerized individually to produce aromatic, bio-based epoxy-functional thermoplastics analogous to poly(GMA). The molecular weight distributions and thermal properties of each polymer were evaluated, as were the surface characteristics of flow-coated thin films from these polymers. Most of the newly prepared epoxy-functional thermoplastics exhibited increased thermal stability (initial decomposition temperatures >260 °C in air) relative to poly(GMA), while retaining similar glass transition temperatures (~ 65 °C) and surface energies (~ 53 mJ m−2); thus, these materials could be substituted for poly(GMA) and enable use in higher-temperature applications. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58, 673–682  相似文献   

20.
High ambient Ca2+ at bone resorption sites have been implicated to play an important role in the regulation of bone remodeling. The present study was performed to clarify the mode of high extracellular Ca2+ (Ca2+(e))-induced modulation of osteoclastogenesis and the expression of receptor activator of nuclear factor-kappaB ligand (RANKL) and osteoprotegerin (OPG), thereby to define its role in osteoclast formation. Mouse bone marrow cells were cocultured with osteoblastic cells in the absence or presence of osteoclastogenic factors such as 1,25-dihydroxyvitaminD3 (1,25-(OH)2vitD3)and macrophage colony-stimulating factor/soluble RANKL. Ca2+ concentration in media (1.8 mM) was adjusted to 3, 5, 7 or 10 mM. Osteoclast formation was confirmed by the appearance of tartrate-resistant acid phosphatase (TRAP)-positive multinuclear cells and the expression of osteoclast phenotypic markers (calcitonin receptor, vitronectin receptor, cathepsin K, matrix metalloproteinase-9, carbonic anhydrase 2). High Ca2+(e) alone significantly stimulated osteoclast formation in a dose-dependent manner. However, in the presence of highly osteoclastogenic factors, high Ca2+(e) significantly inhibited osteoclastogenesis. High Ca2+(e) alone continuously up-regulated RANKL expression while only transiently increased OPG expression. However, in the presence of 1,25-(OH)(2)vitD(3), high Ca2+(e) did not change the 1,25-(OH)2vitD3-induced RANKL expression while increased OPG expression. Taken together, these findings suggest that high Ca2+(e) alone increase osteoclastogenesis but inhibit in the presence of other osteoclastogenic factors. In addition, high CaCa2+(e)-induced osteoclastogenesis may be mediated by osteoblasts via up-regulation of RANKL expression. Meanwhile up-regulated OPG might participate in the inhibitory effect of high Ca2+(e) on 1,25-(OH)2vitD3-induced osteoclastogenesis.  相似文献   

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