Poster Proceedings
PHYTOCHEMICAL INVESTIGATION OF CAREX PRAECOX
Zsuzsanna Csilla Dávid1, Norbert Kúsz1, László Bakacsy2, Judit Hohmann1,3, Andrea Vasas1
1Department of Pharmacognosy, University of Szeged, H-6720 Szeged, Zrínyi utca 9, Hungary
Department of Plant Biology, University of Szeged, H-6726 Szeged, Közép fasor 52, Hungary
3Interdisciplinary Centre of Natural Products, University of Szeged, H-6720 Szeged, Eötvös utca 6, Hungary
e-mail: david.zsuzsanna@pharmacognosy.hu Introduction
Carex praecox belongs to the family Cyperaceae, the third largest family of monocotyledonous plants, containing approximately 100 genera and 5000 species.[1] Several species of the family have been traditionally used as nutritional food or for medicinal purposes, however, the phytochemical and pharmacological investigation of biologically active compounds have been carried out only in the case of a limited number of species. According to the literature data, Cyperaceae species accumulate a variety of secondary metabolites, among them flavonoids, terpenoids, phenolic compounds, steroids, alkaloids and stilbenes.
The aim of our work is to isolate the secondary metabolites of Carex praecox followed by the investigation of the pharmacological effects of the pure compounds.
Results and discussion
Dried aerial parts of C. praecox were ground and extracted with methanol. After evaporation, the extract was dissolved in 50% methanol and then subjected to solvent–solvent partition with n-hexane, chloroform and ethyl acetate. The chloroformic extract was purified by column- and preparative thin layer chromatography, and HPLC methods. The structures of the isolated compounds were determined by a combination of 1D and 2D NMR, and MS measurements. As a result of the preparative work, two novel flavonoids, two novel lignans, an aldehyde and a chromene derivative were identified from the plant.
Conclusion
With the use of diverse chromatographic methods, altogether six compounds have been identified from C. praecox, among them four novel metabolites (two flavonoids, two lignans).
All compounds have been isolated for the first time from the plant.
Isolation and structure elucidation of further compounds from C. praecox are going to be continued. Furthermore, pharmacological studies, especially antibacterial tests will be performed with the pure compounds.
Acknowledgements
This work was supported by the Economic Development and Innovation Operative Program GINOP-2.3.2-15-2016-00012.
References
[1] D.A. Simpson, C.A. Inglis. Kew. Bull. 56 (2001) 257–360.
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CHARACTERIZATION OF WASTE-WOOD DERIVED BIO- AND HYDRO-CHAR Mirjana Petronijević1, Nataša Đurišić-Mladenović1, Sanja Panić1, Igor Antić1,
Predrag Kojić1, Dragan Govedarica1, Milan Tomić2
1 University of Novi Sad, Faculty of Technology Novi Sad, 21000 Novi Sad, Bulevar cara Lazara 1, Serbia
2 University of Novi Sad, Faculty of Agriculture, 21000 Novi Sad, Trg Dositeja Obradovića 8, Serbia
e-mail: natasadjm@tf.uns.ac.rs Abstract
Carbon materials, such as biochar (BC) and hydrochar (HC) have attracted special attention recently due to the cheap feedstock, wide range of the application possibilities, as well as non-toxicity to the environment. BC and HC could be produced from various biomasses under relatively low reaction temperatures and anoxic conditions [1]. These carbon materials are characterized by a large surface area and porous structure, which makes them a good candidate as a soil conditioner in agriculture [2] and adsorbent important for removal of environmental pollutants [3]. The aim of this work was to compare morphological and chemical characteristics of BC and HC obtained from woody biomass. The BC was synthesized from sawdust of beech and oak wood mixture by pyrolysis at 700°C under atmospheric pressure (Basna doo, Čačak, Serbia). The HC was synthesized by hydrothermal carbonization of wood sawdust at 200°C under auto generated pressure of about 1.5 MPa. The results of gravimetric analysis showed that both BC and HC have very high presence of dry matter (85% BC and 95% HC), of which the largest part is volatile organic matter (78% and 94%, respectively), while the ash content is less than 5%. Both samples are characterized by a heterogeneous surface and a very porous structure determined by scanning electron microscopy (SEM). The pore sizes of BC (5-14 µm) are much higher than the pore size of HC (1-2 µm). Elemental analysis performed by X-ray energy dispersion (EDS) showed that carbon and oxygen are two dominant elements in BC (90% C and 9% O) and HC (76% C and 24% O); potassium and calcium are present in traces in BC , while copper is detected in traces in HC. The gas chromatographic analysis with mass spectrometric detection (GC-MS) of the contents of 12 selected polycyclic aromatic hydrocarbons (PAHs) from a group of 16 EPA PAHs revealed rather similar content of 3-ring and 4-ring compounds in the toluene extracts of both types of char, being the most dominant and representing about 46% and 36% of the total sum, respectively. The most carcinogenic PAHs benzo(a)pyrene and dibenz(ah)anthracene were not detected.
Acknowledgements
This work was supported by the Ministry of Education, Science and Technological Development of Republic of Serbia (Project 451-03-68/2020-14/200134).
References
[1] G. Gascó, J. Paz-Ferreiro, M.L. Álvarez, A. Saa, A. Méndez, Waste Manag. 79 (2018) 395.
[2] Z. Zhang, Z. Zhu, B. Shen, L. Liu, Energy 171 (2019) 581.
[3] X. Tan, Y. Liu, G. Zeng, X. Wang, X. Hu, Y. Gu, et al., Chemosphere 125 (2015) 70.
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INVESTIGATION OF ANTIMICROBIAL AGENTS PRODUCED BY GRAM-NEGATIVE BACTERIA
Gábor Endre1,2, Csenge Kasuba1, Babett Edit Nagy1, Dániel Hercegfalvi1, Mónika Vörös1 Mónika Varga1, Csaba Vágvölgyi1, András Szekeres1
1University of Szeged, Faculty of Science and Informatics, Departement of Microbiology, Közép fasor 52. Szeged H-6726
2Doctoral School in Biology, Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
e-mail: egabcy@gmail.com, andras.j.szekeres@gmail.com Abstract
Bacterial secondary metabolites are low molecular mass compounds, which are not essential for bacterial growth. These secondary metabolites are produced in the stationary phase of bacterial growth and the produced compounds could have a variety of biological functions. One of these functions are the antibiotic or antimicrobial function that is gaining interest in the microbial community recently.
In this work Gram-negative bacterial strains were cultivated, and their produced secondary metabolites were extracted and tested in antimicrobial plate assays against Gram-positive and Gram-negative bacterial strains as well. The well-known antibiotic, pyrrolnitrin content of the extracts were also determined by HPLC-Quadrupole-Orbitrap MS.
Introduction
Bacterial secondary metabolites are low molecular mass compounds, which are not essential for bacterial growth. They provide many different biological functions for bacteria in nature [1]. There are many compounds that can be considered as secondary metabolites from bacterial sources such as antibiotics [2], enzymes inhibitors [3] and growth promoters [4]. These types of metabolites are produced during the stationary phase of bacterial growth.
Natural antibiotics are compounds that are produced by certain types of bacteria as secondary metabolites [5]. They began to take a wide range of interest especially in the medical and microbiological fields [6,7].
Experimental
Five bacterial strains (Serratia marcescens, SZMC 0567; Serratia plymuthica, SZMC 24063;
Pseudomonas chlororaphis, SZMC 24067; S. plymuthica, SZMC 24069; S. plymuthica, SZMC 24070) were collected from the Szeged Microbial Collection (SZMC).
Strains were cultivated on three different media to get the antimicrobial effects of their secondary metabolites tested. The three media were Czapek-Dox broth (CzDb), glutamate-nitrate medium (GNM) and glutamate-glutamate-nitrate medium completed with D-tryptophan (GNM+Trp).
Grown cultures were centrifuged and the supernatant was extracted with ethyl-acetate. Organic phases were dried over MgSO4 and were filtered as well as evaporated.
Gained crude extracts were redissolved in 10% methanol (in water (v/v%)) and were centrifuged to get rid of the precipitate. With the solutions antimicrobial microplate assays were performed against three Gram-positive and three Gram-negative bacteria, to get their antimicrobial properties determined. After 24h of incubation, inhibitory rates were calculated.
The pyrrolnitrin content of the crude extracts was determined by HPLC-Quadrupole-Orbitrap MS. 1 mg of each crude extract was redissolved in 1 ml MS grade methanol and was injected
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to the HPLC-QOMS. The pyrrolnitrin content was determined by ESTD calibration in the range of 25-500 ng/ml concentration.
Results and discussion
After successful cultivation of the five bacterial strains in three different media the fermentation material was extracted by ethyl-acetate. The antimicrobial activity of the crude extracts was tested against Gram-positive (Bacillus subtilis, Micrococcus luteus and Saphylococcus aureus) and Gram-negative (Eserichia coli, S. marcescens and Pseudomonas aeruginosa) bacteria as well. The experiments resulted that the extracts were active against Gram-positive bacteria and were no growth inhibition against Gram-negative ones. The samples were most active against B. subtilis and less active in the cases of M. luteus and S. aureus. There were two of the cultivated bacteria that might produce high concentrations of antimicrobial agents, because when the extract was in contact with B. subtilis inhibitory rates reached above 80%. These bacteria were S. plymuthica (SZMC 24063) grown on CzDb and GNM media and S.
plymuthica, (SZMC 24069) grown on CzDb.
For further investigation a well-known antibiotic compound, the concentration pyrrolnitrin was determined in the crude samples by HPLC-Quadrupole-Orbitrap MS. External standard calibration was carried out in the range of 25-500 ng/ml concentration. It was found that S.
plymuthica (SZMC 24069) grown on CzDb produced high concentrations of pyrrolnitrin (1687 ng/ml) and S. plymuthica, (SZMC 24070) grown on GNM+Trp (868 ng/ml). The pyrrolnitrin production of SZMC 24069 can be correlated to the antimicrobial plate assay, this high concentration of an antibiotic in a solution might cause the growth inhibition of Gram-positive bacteria.
Conclusion
Cultivation of five bacterial strains on three culture media was carried out. The secondary metabolites were successfully extracted from the liquid media. The antimicrobial activity of the crude extracts was tested against Gram-positive and Gram-negative bacteria.
It can be concluded that two bacteria had produced secondary metabolites on certain culture media that are effective against Gram-positive bacteria. The pyrrolnitrin concentrations were also determined by HPLC-Quadrupole-Orbitrap MS , and in one case, the antimicrobial activity can be correlated to the measured high concentration of pyrrolnitrin.
Acknowledgements
SUPPORTED BY THE ÚNKP-20-4-582NEW NATIONAL EXCELLENCE PROGRAM OF THE MINISTRY FOR INNOVATION AND TECHNOLOGY FROM THE SOURCE OF THE NATIONAL RESEARCH, DEVELOPMENT AND INNOVATION FUND.
References
[1.] B. Ruiz., Crit. Rev. Microbiol., 2 (2010) 146–167.
[2.] M. O’Neill, Microb. Biotechnol., 46 (1999) 621–657.
[3.] R. K. Pettit, Microb. Biotechnol. 4 (2011) 471–478.
[4.] R. Singh., Biotech. 1 (2017) 1–14.
[5.] M. H. Medema., Res. Suppl. 2 (2011) 339–346.
[6.] S. Nayak, Int. J. Med. Sci. 12 (2016) 2512.
[7.] C. J. Schofield., Nat. Microbiol. 7 (2018) 752–753.
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IMPROVED PIEZOELECTRIC PROPERTIES IN (K, Na)NbO3 LEAD FREE CERAMICS
Bucur Raul Alin, Farkas Iuliana, Bucur Alexandra Ioana
National Institute for Research and Development in Electrochemistry and Condensed Matter, Condensed Matter Department, No. 1 Plautius Andronescu, 300224 Timisoara, Romania.
e-mail: raul_alin_bucur@yahoo.com Abstract
Piezoelectric ceramics are nowadays used in many applications like medical, communication or aerospace. However, lead oxide based materials are the most widely used ferroelectrics. Because of the toxicity of lead oxide, researchers are now focusing on to substituting this compound with newer, environmental friendly materials [1]. Of considerable interest is the (K,Na)NbO3 based group of materials (doped potassium sodium niobate), which possesses a relatively high Curie temperature and good piezoelectric properties [2]. Also, the temperature independence of the morphologic phase boundary implies good temperature stability of the piezoelectric and ferroelectric properties [3, 4].
New results related to GdXO3 (where X= Al, Co, Cr, Fe) doped (K0.5Na0.5)NbO3
ferroelectrics are presented in this paper. Pure (K0.5Na0.5)NbO3 and (K0.5Na0.5)NbO3 doped with 0.25, 0.5, 0.75, 1, 2.5, 5 mol% GdXO3 were produced by the conventional solid state synthesis.
The ceramics obtained were structurally characterized using x-ray diffraction with a PANalytical X’Pert Pro MPD diffractometer. A morphological phase transition was observed, from orthorhombic to tetragonal crystalline symmetry. The frequency dependence (100 Hz – 5MHz) of the real part of the dielectric constant was studied using a LCR meter TEGAM model 3550. The dielectric constant decreases with the increase off frequency. Such behavior is to be explained based on the dispersion of polarization with frequency. The microstructure of the samples was analyzed using a scanning electron microscope Inspect S - FEI Company. Before piezoelectric measurements, the samples were poled at 60 KV/ cm, at 100 ˚C. A complete set of the piezoelectric constants was obtained using the resonance method with a network analyzer Agilent E5100A. The improvement of the piezoelectric properties is to be related to the decrease of the grain size and the presence of the orthorhombic – tetragonal phase transition.
The results show that such materials can be successfully used for new environmental friendly piezoelectric applications.
References
1. J. Rodel, W. Jo, K.T.P. Seifert, E.M. Anton, T. Granzow, D. Damjanovic, J. Am. Ceram.
Soc. 92, 1153 (2009).
2. Saito, H. Takao, I. Tani, T. Nonoyama, K. Takatori, T. Homma et al., High performance lead-free piezoelectric materials, Nature 432, 84 (2004) ;
3. L.J. Rigoberto, G.V. Virginia, M.P. Cruz, M.E. Villafuerte-Castrejon, J. Electron. Mater. 44, 2862 (2015).
4. M.D. Maeder, D. Damjanovic, N. Setter, J. Electroceram. 13 (2004) 385.
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VOLTAMMETRIC MONITORING OF LACCASE-CATALYSED REACTIONS OF