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    Highly Efficient Aggregation-Induced Room-Temperature Phosphorescence with Extremely Large Stokes Shift Emitted from Trinuclear Gold(I)Complex Crystals

    Osamu TsutsumiMasakazu TamaruHitoya Nakasato
    12页
    查看更多>>摘要：Highly efficient(~75% quantum yield),aggregation-induced phosphorescence is reported.The phosphorescence is emitted at room temperature and in the presence of air from crystals of trinuclear Au(I)complexes,accompanied by an extremely large Stokes shift of 2.2 × 10~4 cm~(-1)(450 nm).The mechanism of the aggregation-induced room-temperature phosphorescence from the Au complex crystals was investigated in terms of the crystal packing structure and the primary structure of the molecules.It was found that two kinds of intermolecular interactions occurred in the crystals,and that these multiple dual-mode intermolecular interactions in the crystals play a crucial role in the in-air room-temperature phosphorescence of the trinuclear Au(I)complexes.
      原文链接:
    • NSTL
    • Mdpi

    Preparative Separation of Alkaloids from Stem of Euchresta tubulosa Dunn.by High-Speed Counter-Current Chromatography Using Stepwise Elution

    Weixin LiAiwen DongHuan Wang
    2页
    查看更多>>摘要：Euchresta tubulosa Dunn.is a Chinese herbal medicine with biological activity,but there are few studies on its components at present.Alkaloids in the stem of Euchresta tubulosa Dunn.were isolated and purified by high-speed counter-current chromatography(HSCCC)using stepwise elution.First of all,liquid-liquid extraction(methylene chloride-methanol-water,5:1:4,v/v)was used for the preliminary enrichment.According to the partition coefficient(K)of a target compound in a series of different two-phase solvents,the final result was that carbon tetrachloride-methylene chloride-methanol-water(2:3:3:2,v/v)(1)and methylene chloride-methanol-water(5:3:2,v/v)(2)were suitable for the HSCCC using stepwise elution.As a result,the purity was all higher than 93% and matrine(1),oxymatrine(2),N-formyl cytisine(3),and N-acetyl cytisine(4)can be eluted at one time by this mode.Cytisine-type alkaloids were isolated for the first time in this plant.Finally,the applicability of the mode was verified.
      原文链接:
    • NSTL
    • Mdpi

    Study of the Variation of Phenolic Acid and Flavonoid Content from Fresh Artemisiae argyi Folium to Moxa Wool

    Min LiXin ChaiLuyao Wang
    13页
    查看更多>>摘要：Artemisiae argyi Folium(AAF)is a popular herbal medicine that is always employed in moxa sticks and by oral dosage in clinical use.Less attention has been paid to nonvolatile compounds as active compounds,such as phenolic acids and flavonoids.In this study,we focused on the variation rule of phenolic acids and flavonoids in the various transformations of Artemisiae argyi Folium.Using the established ultra-performance liquid chromatography(UPLC)method with an excellent methodology under"spider-web"mode,six phenolic acids and three flavonoids were simultaneously quantified in fresh and drying Artemisiae argyi Folium as well as in moxa wool and residue.Some interesting phenomena about the variation rule of phenolic acids and flavonoids were uncovered.First,a sharp increase was observed in the detected compounds'content as the moisture gradually decreased,when fresh Artemisiae argyi Folium was exposed to sunlight and ambient or high temperature.Nevertheless,the increased phenolic acids were subjected to high temperature,leading to obvious degradation under oven-drying(60 ℃ and 80 ℃).Second,a wide content distribution was revealed for the detected compounds in Artemisiae argyi Folium from different habitats,especially rutin,caffeic acid,chlorogenic acid,jaceosidin,eupatilin,and cryptochlorogenic acid.Third,accompanied by the elevated ratio of Artemisiae argyi Folium/moxa wool,the detected compounds conspicuously decreased in moxa wool and the correspondingly removed powder as residue.Importantly,a greater variation was found in moxa wool.Our findings contribute to the optimization of the drying process,the quality evaluation of the various transformations of Artemisiae argyi Folium,and the distinctive characterization of moxa wool produced at different ratios of Artemisiae argyi Folium/moxa wool.
      原文链接:
    • NSTL

    Glycan Mimetics from Natural Products:New Therapeutic Opportunities for Neurodegenerative Disease

    Wenyue WangSandeep GopalRoger Pocock
    23页
    查看更多>>摘要：Neurodegenerative diseases(NDs)affect millions of people worldwide.Characterized by the functional loss and death of neurons,NDs lead to symptoms(dementia and seizures)that affect the daily lives of patients.In spite of extensive research into NDs,the number of approved drugs for their treatment remains limited.There is therefore an urgent need to develop new approaches for the prevention and treatment of NDs.Glycans(carbohydrate chains)are ubiquitous,abundant,and structural complex natural biopolymers.Glycans often covalently attach to proteins and lipids to regulate cellular recognition,adhesion,and signaling.The importance of glycans in both the developing and mature nervous system is well characterized.Moreover,glycan dysregulation has been observed in NDs such as Alzheimer's disease(AD),Huntington's disease(HD),Parkinson's disease(PD),multiple sclerosis(MS),and amyotrophic lateral sclerosis(ALS).Therefore,glycans are promising but underexploited therapeutic targets.In this review,we summarize the current understanding of glycans in NDs.We also discuss a number of natural products that functionally mimic glycans to protect neurons,which therefore represent promising new therapeutic approaches for patients with NDs.
      原文链接:
    • NSTL
    • Mdpi

    Extraction of Metal Ions with Metal-Organic Frameworks

    Natalia ManousiDimitrios A.GiannakoudakisErwin Rosenberg
    21页
    查看更多>>摘要：Metal-organic frameworks(MOFs)are crystalline porous materials composed of metal ions or clusters coordinated with organic linkers.Due to their extraordinary properties such as high porosity with homogeneous and tunable in size pores/cages,as well as high thermal and chemical stability,MOFs have gained attention in diverse analytical applications.MOFs have been coupled with a wide variety of extraction techniques including solid-phase extraction(SPE),dispersive solid-phase extraction(d-SPE),and magnetic solid-phase extraction(MSPE)for the extraction and preconcentration of metal ions from complex matrices.The low concentration levels of metal ions in real samples including food samples,environmental samples,and biological samples,as well as the increased number of potentially interfering ions,make the determination of trace levels of metal ions still challenging.A wide variety of MOF materials have been employed for the extraction of metals from sample matrices prior to their determination with spectrometric techniques.
      原文链接:
    • NSTL
    • Mdpi

    Novel Synthetic Approaches for Bisnaphthalimidopropyl(BNIP)Derivatives as Potential Anti-Parasitic Agents for the Treatment of Leishmaniasis

    Elif KeskinMehmet Hikmet UcisikBilgesu Onur Sucu
    11页
    查看更多>>摘要：Leishmaniasis is a neglected parasitic disease that is widely seen in more than 60 countries worldwide,including Turkey and its subcontinental region.There are several chemotherapy agents for the treatment of leishmaniasis,including pentavalent antimonials-i.e.,sodium stibogluconate(Pentostan)and meglumine antimoniate(Glucantim),pentamidine,conventional amphotericin B deoxycholate,miltefosine,paramomycin(aminosidine),and liposomal amphotericin B.However,these therapies are usually unsatisfactory due to dose-limiting toxicity issues and limited efficacy.Furthermore,resistance gained by parasites endangers future success of these therapies.Addressing these issues,the development of novel drugs with high efficacy has a vital importance.Latest studies have shown that bisnaphthalimidopropyl(BNIP)derivatives display high activity against Leishmaniasis parasites by selectively targeting parasitic sirtuin proteins and interacting with DNA.Despite the promising anti-parasitic activity,the low solubility and toxicity on human macrophages are the limitations to overcome.This study describes the new synthesis strategies for existing-i.e.,BNIPDaoct and BNIPDanon-and novel BNIP derivatives differing in respect of their alkyl linker chain lengths.The new synthesis approach provides certain advantages compared to its existing alternatives reported in the literature.The proposed methodology does not only decrease the number of synthesis steps and production time of BNIPDaoct and BNIPDanon,but also provides higher yields,thereby making the synthesis highly cost-effective.
      原文链接:
    • NSTL
    • Mdpi

    Extraction and Determination of Polar Bioactive Compounds from Alfalfa(Medicago sativa L.)Using Supercritical Techniques

    Olga WronaKatarzyna RafinskaJustyna Walczak-Skierska
    17页
    查看更多>>摘要：The aim of this research was to select parameters for supercritical extraction with CO2-Medicago sativa L.,considered as functional food,in quarter-technical plant,providing the highest concentration of bioactive polar constituents and simultaneously maintaining the highest efficiency of the process.For the purpose of optimization,mathematical statistics was used.Qualitative analysis of products was performed with supercritical fluid chromatography(SFC).The SFC analysis revealed a proper separation of flavonoids and phenolics acids for dedicated TFC and TPC optimal parameters.The obtained results have proved that it is a possibility to extract polar compounds with non-polar solvent under higher values of pressure and temperature and to enrich product with desired group of bioactive compounds with proper optimization.The proposed extraction technique allows to obtain on an industrial scale,using an environmentally friendly solvent,a preparation rich in biologically active nutrients that can be implemented in the cosmetics,pharmaceutical and food industries.
      原文链接:
    • NSTL
    • Mdpi

    Quantitative Analysis of Cold Stress Inducing Lipidomic Changes in Shewanella putrefaciens Using UHPLC-ESI-MS/MS

    Xin GaoWenru LiuJun Mei
    13页
    查看更多>>摘要：Shewanella putrefaciens is a well-known specific spoilage organism(SSO)and cold-tolerant microorganism in refrigerated fresh marine fish.Cold-adapted mechanism includes increased fluidity of lipid membranes by the ability to finely adjust lipids composition.In the present study,the lipid profile of S.putrefaciens cultivated at 30,20,10,4,and 0 ℃ was explored using ultra-high-pressure liquid chromatography/electrospray ionization tandem mass spectrometry(UHPLC-ESI-MS/MS)to discuss the effect of lipid composition on cold-adapted tolerance.Lipidomic analysis detected a total of 27 lipid classes and 606 lipid molecular species in S.putrefaciens cultivated at 30,20,10,4,and 0 ℃.S.putrefaciens cultivated at 30 ℃(SP-30)had significantly higher content of glycerolipids,sphingolipids,saccharolipids,and fatty acids compared with that at 0 ℃(SP-0);however,the lower content of phospholipids(13.97%)was also found in SP-30.PE(30:0),PE(15:0/15:0),PE(31:0),PA(33:1),PE(32:1),PE(33:1),PE(25:0),PC(22:0),PE(29:0),PE(34:1),dMePE(15:0/16:1),PE(31:1),dMePE(15:1/15:0),PG(34:2),and PC(11:0/11:0)were identified as the most abundant lipid molecular species in S.putrefaciens cultivated at 30,20,10,4,and 0 ℃.The increase of PG content contributes to the construction of membrane lipid bilayer and successfully maintains membrane integrity under cold stress.S.putrefaciens cultivated at low temperature significantly increased the total unsaturated liquid contents but decreased the content of saturated liquid contents.
      原文链接:
    • NSTL
    • Mdpi

    Lignin-Only Polymeric Materials Based on Unmethylated Unfractionated Kraft and Ball-Milled Lignins Surpass Polyethylene and Polystyrene in Tensile Strength

    Yi-ru ChenSimo SarkanenYun-Yan Wang
    15页
    查看更多>>摘要：Functional polymeric materials composed solely of lignin preparations appeared only very recently.A gradual paradigm shift spanning 56 years has revealed how lignin-lignin blends can upgrade the performance of 100 wt% lignin-based plastics.The view,first espoused in 1960,that lignin macromolecules are crosslinked reduces the plausibility of creating functional polymeric materials that are composed only of lignin preparations.Lignin-based materials would be much weaker mechanically if interstices remain in significant numbers between adjoining macromolecular structures that consist of rigid crosslinked chains.In 1982,random-coil features in the hydrodynamic character of kraft lignin(KL)components were evident from ultracentrifugal sedimentation equilibrium studies of their SEC behavior.In 1997,it was recognized that the macromolecular species in plastics with 85 wt% levels of KL are associated complexes rather than individual components.Finally,in 2016,the first polymeric material composed entirely of ball-milled softwood lignin(BML)was found to support a tensile strength above polyethylene.Except in its molecular weight,the BML was similar in structure to the native biopolymer.It was composed of associated lignin complexes,each with aromatic rings arranged in two domains.The inner domain maintains structural integrity largely through noncovalent interactions between cofacially-offset aromatic rings;the peripheral domain contains a higher proportion of edge-on aromatic-ring arrangements.Interdigitation between peripheral domains in adjoining complexes creates material continuity during casting.By interacting at low concentrations with the peripheral domains,non-lignin blend components can improve the tensile strengths of BML-based plastics to values well beyond those seen in polystyrene.The KL-based plastics are weaker because the peripheral domains of adjoining complexes are less capable of interdigitation than those of BML.Blending with 5 wt% 1,8-dinitroanthraquinone results in a tensile strength above that of polyethylene.Analogous effects can be achieved with 10 wt% maple γ-valerolactone(GVL)lignin which,with a structure close to the native biopolymer,imparts some native character to the peripheral domains of the KL complexes.Comparable enhancements in the behavior of BML complexes upon blending with 10 wt% ball-milled corn-stover lignin(BMCSL)result in lignin-only polymeric materials with tensile strengths well beyond polystyrene.
      原文链接:
    • NSTL
    • Mdpi

    Synthesis and Structural Determination of New Brassinosteroid 24-Nor-5a-Cholane Type Analogs

    Jocelyn OyarceVanessa AitkenCesar Gonzalez
    14页
    查看更多>>摘要：Natural brassinosteroids possess a 22R,23R configuration that appears essential for biological activity.It is,therefore,interesting to elucidate if the activity of brassinosteroids with a short side chain depends on the C22 configuration.Herein,we describe the synthesis of new brassinosteroids analogs with 24-norcholane type of side chain and R configuration at C22.The initial reaction is the dihydroxylation of a terminal olefin that leads to S/R epimers.Three different methods were tested in order to evaluate the obtained S/R ratio and the reaction yields.The results indicate that Upjohn dihydroxylation is the most selective reaction giving a 1.0:0.24 S/R ratio,whereas a Sharpless reaction leads to a mixture of 1.0:0.90 S/R with 95% yield.Using the latter mixture and following a previous reported method,benzoylated derivatives and both S and R brassinosteroids analogs were synthesized.All synthesized compounds were completely characterized by NMR spectroscopy,and HRMS of new compounds are also given.In conclusion,a synthetic route for preparation of new analogs of brassinosteroids of 24-norcholane type and R configuration at C22 were described.It is expected that this will help to elucidate if a configuration at C22 is a structural requirement for hormonal growth activity in plants.
      原文链接:
    • NSTL
    • Mdpi