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11.
Zareath Pamela Terán Baptista Analía de los Angeles Gómez Raphaël Grougnet Tsvetelina Mandova Pedro Adrían Aredes Fernandez 《Natural product research》2020,34(12):1782-1785
AbstractExtracts from aerial parts of medicinal plants from northwest Argentina were screened for antibacterial activity against the phytopathogenic strains namely CECT 124 (Pseudomonas corrugata), CECT 126 (P. syringae pv. tomato), CECT 225 (Erwinia carotovora var. carotovora), CECT 472 (Agrobacterium tumefaciens) and CECT 792 (Xanthomonas campestres pv. vesicatoria). Leaves and stems of Aspidosperma quebracho-blanco, Schinus fasciculatus, S. gracilipes, Amphilophium cynanchoides and Tecoma stans were separately extracted with solvents of increasing polarity to obtain the dichloromethane (fCH2Cl2), ethyl acetate (fEtAc) and methanol extracts (fMeOH), respectively. Among the thirty extracts tested, only fEtAc from leaves and stems of S. fasciculatus reached the IC50 against the five bacterial strains tested (IC50?=?0.9?mg/ml). The fEtAc from the leaves contained kaempferol, quercetin and agathisflavone which had moderate to strong antibacterial activity. This extract and its identified flavonoids showed synergic (CECT 124,126 and 792) or additive effects (CECT 472 and 225) in mixtures with Kocide 3000. 相似文献
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Maya Guncheva Krassimira Idakieva Svetla Todinova Denitsa Yancheva Tsvetelina Paunova-Krasteva Paula Ossowicz Ewa Janus 《Molecules (Basel, Switzerland)》2021,26(6)
Novel biocompatible compounds that stabilize proteins in solution are in demand for biomedical and/or biotechnological applications. Here, we evaluated the effect of six ionic liquids, containing mono- or dicholinium [Chol]1or2 cation and anions of charged amino acids such as lysine [Lys], arginine [Arg], aspartic acid [Asp], or glutamic acid [Glu], on the structure, thermal, and storage stability of the Rapana thomasiana hemocyanin (RtH). RtH is a protein with huge biomedicinal potential due to its therapeutic, drug carrier, and adjuvant properties. Overall, the ionic liquids (ILs) induce changes in the secondary structure of RtH. However, the structure near the Cu-active site seems unaltered and the oxygen-binding capacity of the protein is preserved. The ILs showed weak antibacterial activity when tested against three Gram-negative and three Gram-positive bacterial strains. On the contrary, [Chol][Arg] and [Chol][Lys] exhibited high anti-biofilm activity against E. coli 25213 and S. aureus 29213 strains. In addition, the two ILs were able to protect RtH from chemical and microbiological degradation. Maintained or enhanced thermal stability of RtH was observed in the presence of all ILs tested, except for RtH-[Chol]2[Glu]. 相似文献
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Sirine Jaber Ivan Iliev Tsvetelina Angelova Veronica Nemska Inna Sulikovska Emilia Naydenova Nelly Georgieva Ivan Givechev Ivo Grabchev Dancho Danalev 《Molecules (Basel, Switzerland)》2021,26(4)
(1) Background: (KLAKLAK)2 is a representative of the antimicrobial peptide group which also shows good anticancer properties. (2) Methods: Herein, we report synthesis using SPPS and characterization by HPLC/MS of a series of shortened analogues of (KLAKLAK)2. They contain single sequence KLAKLAK as C-terminal amides. In addition, substitution of some natural amino acids with unnatural β-Ala and nor-Leu is realized. In addition, these structures are conjugated with second pharmacophore with well proven anticancer properties 1,8-naphthalimide or caffeic acid. Cytotoxicity, antiproliferative effect and antimicrobial activity of newly synthesized structures were studied. (3) Results: The obtained experimental results reveal significant selective index for substances with common chemical structure KLβAKLβAK-NH2. The antibacterial properties of newly synthesized analogues at two different concentrations 10 μM and 20 μM, were tested against Gram-negative microorganisms Escherichia coli K12 407. Only two of the studied compounds KLAKLAK-NH2 and the one conjugated with second pharmacophore 1,8-naphthalimide and unnatural amino acid nor-Leu showed moderate activity against tested strains at concentration of 20 μM. (4) Conclusions: The obtained results reveal that the introducing of 1,8-naphthalimideGly- and Caf- increase the cytotoxicity and antiproliferative activity of the peptides but not their selectivity. Only two compounds KLAKLAK-NH2 and 1,8-naphthalimideGKnLAKnLAK-NH2 show moderate activity against Escherichia coli K12 at low concentration of 20 μM. 相似文献
14.
Sirine Jaber Veronica Nemska Ivan Iliev Elena Ivanova Tsvetelina Foteva Nelly Georgieva Ivan Givechev Emilia Naydenova Veronika Karadjova Dancho Danalev 《Molecules (Basel, Switzerland)》2021,26(23)
(1) Background: Peptides are good candidates for anticancer drugs due to their natural existence in the body and lack of secondary effects. (KLAKLAK)2 is an antimicrobial peptide that also shows good anticancer properties. (2) Methods: The Solid Phase Peptide Synthesis (Fmoc-strategy) was used for the synthesis of target molecules, analogs of (KLAKLAK)2-NH2. The purity of all compounds was monitored by HPLC, and their structures were proven using mass spectrometry. Cytotoxicity and antiproliferative effects were studied using 3T3 NRU and MTT tests, respectively. For determination of antimicrobial activity, the disc-diffusion method was used. Hydrolytic stability at three pH values, which mimic the physiological pH in the body, was investigated by means of the HPLC technique. (3) Results: A good selective index against MCF-7 tumor cell lines, combined with good cytotoxicity and antiproliferative properties, was revealed for conjugates NphtG-(KLAKLAK)2-NH2 and Caf-(KLAKLAK)2-NH2. The same compounds showed very good antifungal properties and complete hydrolytic stability for 72 h. The compound Caf-(KLβ-AKLβ-AK)2-NH2 containing β-Ala in its structures exhibited good antimicrobial activity against Escherichia coli K12 407 and Bacillus subtilis 3562, in combination with very good antiproliferative and cytotoxic properties, as well as hydrolytic stability. (4) Conclusions: The obtained results reveal that all synthesized conjugates could be useful for medical practice as anticancer or antimicrobial agents. 相似文献
15.
Tsvetelina Merdzhanova Jan Woerdenweber Wolfhard Beyer Uwe Zastrow Helmut Stiebig Aad Gordijn 《固体物理学:研究快报》2010,4(11):323-325
For microcrystalline silicon based p–i–n solar cells the effect of deposition conditions on the critical oxygen concentration was investigated. All solar cells were prepared by 13.56 MHz plasma‐enhanced chemical vapour deposition. The critical oxygen concentration defines the lowest oxygen concentration in the intrinsic absorber layer causing a deterioration of the solar cell performance. For intentional contamination of ~1.2–1.3 µm thick i‐layers, the oxygen was inserted by a controllable leak at the process gases supply line, i.e. by a gas pipe leak. For µc‐Si:H deposited at a discharge power of 0.53 W/cm2 we find a critical oxygen concentration of 1–2 × 1019 cm–3 in agreement with values commonly reported in literature. However, changing the deposition conditions, we find that the critical oxygen concentration in µc‐Si:H cells is not fixed. At reduced power of 0.20 W/cm2 a much higher value for the critical oxygen concentration of 1 × 1020 cm–3 is observed. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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17.
Albena K. Detcheva Paunka S. Vassileva Ralitsa H. Georgieva Dimitrinka K. Voykova Tsvetelina I. Gerganova Yordanka Y. Ivanova 《Central European Journal of Chemistry》2011,9(5):932-940
In the present work the adsorption of some transition metal ions from aqueous solutions on a silica-based nanostructured hybrid
material modified by aluminium was investigated. The novel organic-inorganic material was synthesized via a sol-gel method through hydrolysis and co-condensation reactions. Its structure was characterized by means of SEM, XRD and
FTIR. Based on the data obtained the most probable cross-linking mechanism for the derived xerogel was proposed. The characterization
of its texture parameters was carried out by low-temperature adsorption of nitrogen. The adsorption properties of this material
with respect to Cu(II), Cr(III) and Pb(II) ions from single-component aqueous solutions and multi-component aqueous solutions
containing also Cd(II) and Fe(III) were evaluated. The effect of contact time, acidity of initial solutions and metal ion
concentrations was investigated using the batch method. Pseudo-first order, pseudo-second order and intraparticle diffusion
models were used to analyze kinetic data. In all cases the adsorption was significantly affected by the pH value. Equilibrium
modelling data were fitted to linear Langmuir, Freundlich and Dubinin-Radushkevich models. Best fit was observed for Langmuir
model, which showed determination coefficients greater than 0.992 for all ions studied. The maximum adsorption capacities
for single- and multi-component adsorption were calculated.
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