Chemija最新文献

{"title":"Comparative evaluation of antioxidant activity of Cannabis sativa L. using FRAP and CUPRAP assays","authors":"A. Kubiliene, M. Marksa, J. Baranauskaite, O. Ragažinskienė, L. Ivanauskas","doi":"10.6001/chemija.v31i3.4289","DOIUrl":"https://doi.org/10.6001/chemija.v31i3.4289","url":null,"abstract":"3 Kaunas Botanical Garden of Vytautas Magnus University, 4 Ž. A. Žiliberas Street, 46324 Kaunas, Lithuania Cannabis is one of the oldest plants on earth, which is known and used for medical purposes. There are many articles on hempseed oil research in the scientific databases, while the antioxidant activity of Cannabis sativa L. herb extracts has not been extensively studied yet, to our knowledge. In the present study, antioxidant properties of different Cannabis sativa L. varieties from different regions of Lithuania were examined. Spectrophotometric FRAP (ferric reducing antioxidant power) and CUPRAC (cupric reducing antioxidant capacity) methods were used for determination. It was found that Cannabis sativa L. herb extracts possess antioxidant activity. The strongest antioxidant activity was evaluated in the Futura variety and the lowest in Manoica. The obtained results showed that a statistically significant (p ˂ 0.05) higher reductive power was determined by analysing the raw material by the spectrophotometric FRAP method. According to the hemp growth location in Lithuania, the highest TEAC values were estimated in the samples from the North region.","PeriodicalId":9720,"journal":{"name":"Chemija","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2020-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47689046","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Towards adaptive method for peak migration time correction: discretization period in electropherograms","authors":"Tomas Drevinskas, A. Maruška, Gintarė Naujokaitytė, L. Telksnys, M. Kaljurand, V. Stanys, J. Cowles, Jelena Gorbatšova","doi":"10.6001/chemija.v31i3.4288","DOIUrl":"https://doi.org/10.6001/chemija.v31i3.4288","url":null,"abstract":"6 Département Biologique, Institut Universitaire de Technologie, University of Angers, 4 bd Lavoisier, 49016 Angers, France Capillary electrophoresis often causes unrepeatable peak migration times in the electropherogram due to changes of electroosmosis, yet in some cases this separation technique does not have a replacement alternative. Some attempts to overcome this issue have been performed introducing internal standards into the sample and compensating peak shifting in time. However, existing vector calculation-based methods are computationally intensive for portable instrumentation and usually limited to post-processing applications with 1 or 2 markers. In this work, an original approach of compensating peak migration time shift via signal discretization period correction is proposed. Using the proposed method, the number of reference points or markers that are used for compensation is extended. This method is effective in compensating migration time of peaks in real samples, where high sample injection volumes are used. Using 4 reference peaks in compensation, the method was capable of reducing the relative standard deviation of migration time of the peaks in the electropherograms more than 15 times. Corrected signal discretization periods indicated very high correlations with recorded separation currents, what can be perspective developing an adaptive peak migration time compensation method in capillary electrophoresis.","PeriodicalId":9720,"journal":{"name":"Chemija","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2020-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47061876","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Biosynthesis, purification, characterization and immobilization of laccase from Lithothelium sp.","authors":"Ingrida Radveikienė, Ingrida Pilotaitė, Rimgailė Dainytė, R. Vidziūnaitė","doi":"10.6001/chemija.v31i3.4292","DOIUrl":"https://doi.org/10.6001/chemija.v31i3.4292","url":null,"abstract":"2 Vilnius Gediminas Technical University, 11 Saulėtekio Avenue, 10223 Vilnius, Lithuania Novel fungal laccase isoenzymes (namely L95-1 and L95-2) produced by the Ascomycete Lithothelium sp. isolated from the forest soil were purified. However, only one of them was characterized, because the other isoenzyme lost its activity during purification. Extracellular L95-1 laccase was purified 30-fold using ion-exchange and hydrophobic interaction chromatography, with an overall yield of 88%. The molecular mass of purified L95-1 was estimated to be 85 kDa by SDS-PAGE analysis. L95-1 laccase was stable at temperature 4–22°C and pH 6.0–6.5. The substrate specificity of L95-1 laccase was examined with various compounds. Determined affinity constants (KM) varied in a wide range of 3.7–2020.0 μM, whereas catalytic efficiency constants (kcat/KM) covered a range of 0.008–1.9 μM–1 s–1. The optimum pH for most substrates varied in a range from pH 5.0 to 6.0. Sodium azide and fluoride strongly inhibited L95-1 activity, whereas sulphate salts inhibited weakly. The laccase was immobilized on the Fe3O4 nanoparticles and characterized. Residual activity remained at 20% after ten cycles of ABTS oxidation reaction. The immobilized laccase showed higher tolerance to various metal salts. The properties of L95-1 laccase make it potentially useful in the biotechnological applications.","PeriodicalId":9720,"journal":{"name":"Chemija","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2020-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43068781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"5-Vinylquinoline-substituted nitrofurans as inhibitors of trypanothione reductase and antitrypanosomal agents","authors":"D. Benítez, M. Comini, Ž. Anusevičius, J. Šarlauskas, V. Miliukiené, Eglė Miliuvienė, N. Čėnas","doi":"10.6001/chemija.v31i2.4223","DOIUrl":"https://doi.org/10.6001/chemija.v31i2.4223","url":null,"abstract":"3 Vilnius University Hospital Santaros Klinikos, 2 Santariškių Street, 08406 Villnius, Lithuania Trypanothione reductase (TR) and trypanothione synthase (TS) are critical for the maintenance of thiol-redox homeostasis and antioxidant protection in trypanosomal parasites, which cause African sleeping sickness and Chagas disease. Both enzymes are absent in mammals. Thus, the design of efficient and specific TR and TS inhibitors represents one of the pathways for a development of new antitrypanosomal drugs. 5-Vinylquinoline-substituted nitrofurans (n = 7), studied in this work, acted as unor noncompetitive to trypanothione inhibitors of Trypanosoma congolense TR. Their inhibition constants (Ki) varied from 2.3 μM to 150 μM. We for the first time observed a parallelism between their antitrypanosomal in vitro activity and their efficacy as TR inhibitors. The inhibition of TS appears not to be a significant factor of trypanocidal activity of examined compounds.","PeriodicalId":9720,"journal":{"name":"Chemija","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2020-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41778945","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electrocatalytic activity of AuCeO2/C towards ethylene glycol oxidation and oxygen reduction reactions","authors":"V. Kepenienė, R. Stagniūnaitė, Daina Upskuvienė, L. Tamašauskaitė-Tamašiūnaitė, V. Pakštas, Audrius Drabavičius, M. Andrulevičius, E. Norkus","doi":"10.6001/chemija.v31i2.4217","DOIUrl":"https://doi.org/10.6001/chemija.v31i2.4217","url":null,"abstract":"2 Institute of Materials Science of Kaunas University of Technology, 59 Baršausko Street, 50131 Kaunas, Lithuania AuCeO2/C and Au/C catalysts were obtained by adsorption of AuNPs on the CeO2/C and pure carbon (C) substrates from an Au colloidal solution. It has been found that AuNPs of ca. 50 nm in size were adsorbed on the surfaces of CeO2/C and C; however, electrocatalytic activity of the investigated AuCeO2/C and Au/C catalysts was different. Ethylene glycol oxidation current density values are ca. 3 times higher on the AuCeO2/C catalyst as compared to those of the bare Au/C catalyst. Moreover, the AuCeO2/C catalyst showed more positive onset potentials, as well as higher current in the mixed-kinetic-diffusion region towards the oxygen reduction reaction in an alkaline medium compared to that of the Au/C catalyst.","PeriodicalId":9720,"journal":{"name":"Chemija","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2020-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47328742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electrochemical investigations of the anticorrosive behaviour of the phosphated electrogalvanized steel additionally coated with conversion layer of cerium oxide","authors":"O. Girčienė, L. Gudavičiūtė, A. Selskienė, A. Kirdeikiene, R. Ramanauskas","doi":"10.6001/chemija.v31i2.4219","DOIUrl":"https://doi.org/10.6001/chemija.v31i2.4219","url":null,"abstract":"Center for Physical Sciences and Technology, 3 Saulėtekio Avenue, 10257, Vilnius, Lithuania The anticorrosive behaviour of the electrogalvanized carbon steel with PZn, PZnCa and PZnNi phosphate layers additionally coated with the conversion layers of cerium oxide in chloride-contaminated media has been studied. The composition and structure of investigated samples were characterized by scanning electron microscope SEM, while the corrosion behaviour was investigated applying voltammetric and electrochemical impedance spectroscopy EIS measurements. The data obtained have shown that all investigated samples additionally coated with cerium oxide conversion coatings exhibited better protective abilities. To summarize the results of electrochemical and SEM measurements it was stated that the most porous (F = ~1–2%) PZnNi/Ce coating exhibited the best protective abilities in a chloride-contaminated solution. Therefore, cerium ions are able to penetrate into the substrate, which is zinc coated steel, through the open pores of the PZnNi layer.","PeriodicalId":9720,"journal":{"name":"Chemija","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2020-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45832559","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Seasonal variation of the qualitative and quantitative composition of triterpenic compounds and antioxidant activity in vitro in the apple extracts of cultivars grown in Lithuania","authors":"Aurita Butkevičiūtė, R. Urbštaitė, M. Liaudanskas, D. Kviklys, J. Viškelis, V. Janulis","doi":"10.6001/chemija.v31i2.4222","DOIUrl":"https://doi.org/10.6001/chemija.v31i2.4222","url":null,"abstract":"2 Institute of Horticulture, Lithuanian Research Centre for Agriculture and Forestry, 30 Kauno Street, 54333 Babtai, Kaunas District, Lithuania Apple (Malus domestica Borkh.) fruits are rich in phenolic glycosides, triterpenic acids and other biologically active compounds. The apples are widely used as food products due to their biologically active compounds that have specific biological effects. It is important to use high quality apples or their recycling products, so it is necessary to investigate the qualitative and quantitative composition of the bioactive compounds. The amount of triterpenic acids varies during different phenological stages of apple development and maturation. In order to determine in which phenological stage of apple growth the quantity of triterpenic acids was highest, high-performance liquid chromatography was applied. The highest total amounts of triterpenic compounds were detected at the beginning of the phenological stage of fruit development. The study showed that the highest amounts of triterpenic acids were detected at the beginning of the phenological stage of apple development, while as the apple matured, the amount of triterpenic acids decreased from 2.63 ± 0.26 mg/g to 1.6 ± 0.28 mg/g. In this study, we identified and quantified four triterpenic compounds, which by the quantitative composition of triterpenic acids could be arranged in the following ascending order: betulinic acid < corosolic acid < oleanolic acid < ursolic acid. In order to use herbal extracts for medical practice it is important to perform biological effects study in vitro and in vivo. Antioxidants with different mechanisms of action neutralize harmful reactive oxygen and nitrogen forms and enhance antioxidants protection systems. The antioxidant activity of apple extracts in vitro varied during different phenological stages of the fruit. The strongest antiradical and reductive activities were observed at the beginning of apple development. In order to determine the relationship between the antioxidant activity of the acetone extracts of apples assessed by DPPH, ABTS, CUPRAC and FRAP assays and the total amount of triterpenic acids in these extracts, a correlation analysis was carried out. The strongest positive correlation was observed between the amount of oleanolic acid and the antioxidant activity assessed by DPPH, ABTS and CUPRAC methods (respectively, r = 0.778, r = 0.784 and r = 0.720).","PeriodicalId":9720,"journal":{"name":"Chemija","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2020-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47072947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Carbon supported manganese(IV)–cobalt(II/III) oxides nanoparticles for high-performance electrochemical supercapacitors","authors":"J. Jablonskienė, D. Šimkūnaitė, J. Vaičiūnienė, G. Stalnionis, A. Drabavičius, L. Tamašauskaitė-Tamašiūnaitė, E. Norkus","doi":"10.6001/chemija.v31i2.4220","DOIUrl":"https://doi.org/10.6001/chemija.v31i2.4220","url":null,"abstract":"Center for Physical Sciences and Technology, 3 Saulėtekio Avenue, 10257 Vilnius, Lithuania The carbon supported manganese(IV)–cobalt (II/III) oxides nanoparticles labelled as MnO2–Co3O4/C nanocomposites have been prepared by a simple one-step microwave-assisted heating method using different precursor materials. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and inductively coupled plasma optical emission spectroscopy (ICP-OES) have been used for the characterization of morphology, structure and composition of the synthesized nanocomposites, whereas the electrochemical performance of the prepared nanocomposites has been evaluated by using cyclic voltammetry (CV). It was determined that the use of different precursor materials for the synthesis of the carbon supported MnO2 and Co3O4 nanocomposites results in a different morphology of the prepared substances. A high specific capacitance (Cs) of 658.8 F g −1 at a scan rate of 10 mV s−1 in a 1 M Na2SO4 solution has been obtained for the MnO2– Co3O4/C-2 nanocomposite that has a spherical shape of nanoparticles. Moreover, it significantly outperforms the MnO2–Co3O4/C-1 nanocomposite that has a lamellar shape of nanoparticles.","PeriodicalId":9720,"journal":{"name":"Chemija","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2020-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41807647","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Static headspace gas chromatographic determination of hexanal as a marker of lipid oxidation in fat-rich food","authors":"V. Vickackaite, Gintarė Pipiraitė, Vilius Poškus, Ingrida Jurkutė, B. Bugelytė","doi":"10.6001/chemija.v31i2.4221","DOIUrl":"https://doi.org/10.6001/chemija.v31i2.4221","url":null,"abstract":"Department of Analytical and Environmental Chemistry, Vilnius University, 24 Naugarduko Street, 03225 Vilnius, Lithuania Static headspace gas chromatographic method for determination of hexanal as a marker of lipid oxidation was developed. Tetradecane was suggested as a matrix for hexanal release from the sample. Sample equilibration temperature and time, tetradecane volume, injection time were optimized. Benzaldehyde was selected as an internal standard. Under the optimized conditions quality parameters were determined. The calibration curve was linear in the concentration range from 25 μg l–1 to 2 g l–1, the detection limit was 15 μg l–1, RSD was determined by five replication analysis with hexanal concentration 0.1 g l–1 and was 1.2%. The technique was applied for hexanal determination in potato chips and fried potatoes.","PeriodicalId":9720,"journal":{"name":"Chemija","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2020-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44752793","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sol–gel synthesis of calcium phosphate-based coatings – A review","authors":"K. Ishikawa, A. Kareiva","doi":"10.6001/chemija.v31i1.4169","DOIUrl":"https://doi.org/10.6001/chemija.v31i1.4169","url":null,"abstract":"2 Institute of Chemistry, Vilnius University, 24 Naugarduko Street, 03225 Vilnius, Lithuania Calcium phosphate (CP)-based biomaterials, especially nanostructured ones, show a high biocompatibility and increased biological properties. The coatings composed of stoichiometric hydroxyapatite have been extensively used to improve integration of metallic implants in the host bone. However, these coatings exhibited several drawbacks that limited their successful application. It was concluded in numerous articles that the sol–gel derived coatings can undergo cracking and delamination and are scarcely uniform. In this review article the recent advances on the sol–gel synthesis of different phosphate coatings and thin films are summarized. The attention is paid to coatings and thin films of calcium hydroxyapatite (CHAp), other phosphates, bioglasses and different composite materials. The state of the art, limitations, potentialities, open challenges, and the future scenarios for the application of CP bioceramics are highlighted in this study.","PeriodicalId":9720,"journal":{"name":"Chemija","volume":" ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2020-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49131959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}