TY  - JOUR
AU  - Ušjak, Dušan
AU  - Novović, Katarina
AU  - Ivković, Branka
AU  - Tomić, Branko
AU  - Đorđević, Valentina
AU  - Milenković, Marina
PY  - 2023
UR  - https://doi.org/10.1080/08927014.2023.2215693
UR  - https://imagine.imgge.bg.ac.rs/handle/123456789/1896
AB  - Biofilm production facilitates microbial colonization of wounds and catheters. Acinetobacter baumannii produces high levels of biofilm and causes difficult-to-treat nosocomial infections. Candida albicans is another strong biofilm producer which may facilitate A. baumannii adhesion by providing hyphae-mediated OmpA-binding sites. Here we tested the potential of 2′-hydroxychalcones to inhibit dual-species biofilm production of A. baumannii and Candida spp., and further predicted the mechanism of structure-related difference in activity. The results suggest that 2′-hydroxychalcones exhibit potent activity against Candida spp./A. baumannii dual-species biofilm production. Particularly active was trifluoromethyl-substituted derivative (p-CF3), which decreased C. albicans/A. baumannii biomass produced on vein-indwelling parts of the central venous catheterization set by up to 99%. Further, higher OmpA-binding affinity was also calculated for p-CF3, which together with demonstrated significant ompA-downregulating activity, suggests that superior antibiofilm activity of this chalcone against the tested dual-species community of A. baumannii is mediated through the OmpA.
T2  - Biofouling
T2  - Biofouling
T1  - Targeting outer membrane protein A (OmpA) – inhibitory effect of 2′-hydroxychalcone derivatives on Acinetobacter baumannii and Candida albicans dual-species biofilm formation
EP  - 11
SP  - 1
DO  - 10.1080/08927014.2023.2215693
ER  - 

@article{
author = "Ušjak, Dušan and Novović, Katarina and Ivković, Branka and Tomić, Branko and Đorđević, Valentina and Milenković, Marina",
year = "2023",
abstract = "Biofilm production facilitates microbial colonization of wounds and catheters. Acinetobacter baumannii produces high levels of biofilm and causes difficult-to-treat nosocomial infections. Candida albicans is another strong biofilm producer which may facilitate A. baumannii adhesion by providing hyphae-mediated OmpA-binding sites. Here we tested the potential of 2′-hydroxychalcones to inhibit dual-species biofilm production of A. baumannii and Candida spp., and further predicted the mechanism of structure-related difference in activity. The results suggest that 2′-hydroxychalcones exhibit potent activity against Candida spp./A. baumannii dual-species biofilm production. Particularly active was trifluoromethyl-substituted derivative (p-CF3), which decreased C. albicans/A. baumannii biomass produced on vein-indwelling parts of the central venous catheterization set by up to 99%. Further, higher OmpA-binding affinity was also calculated for p-CF3, which together with demonstrated significant ompA-downregulating activity, suggests that superior antibiofilm activity of this chalcone against the tested dual-species community of A. baumannii is mediated through the OmpA.",
journal = "Biofouling, Biofouling",
title = "Targeting outer membrane protein A (OmpA) – inhibitory effect of 2′-hydroxychalcone derivatives on Acinetobacter baumannii and Candida albicans dual-species biofilm formation",
pages = "11-1",
doi = "10.1080/08927014.2023.2215693"
}

Ušjak, D., Novović, K., Ivković, B., Tomić, B., Đorđević, V.,& Milenković, M.. (2023). Targeting outer membrane protein A (OmpA) – inhibitory effect of 2′-hydroxychalcone derivatives on Acinetobacter baumannii and Candida albicans dual-species biofilm formation. in Biofouling, 1-11.
https://doi.org/10.1080/08927014.2023.2215693

Ušjak D, Novović K, Ivković B, Tomić B, Đorđević V, Milenković M. Targeting outer membrane protein A (OmpA) – inhibitory effect of 2′-hydroxychalcone derivatives on Acinetobacter baumannii and Candida albicans dual-species biofilm formation. in Biofouling. 2023;:1-11.
doi:10.1080/08927014.2023.2215693 .

Ušjak, Dušan, Novović, Katarina, Ivković, Branka, Tomić, Branko, Đorđević, Valentina, Milenković, Marina, "Targeting outer membrane protein A (OmpA) – inhibitory effect of 2′-hydroxychalcone derivatives on Acinetobacter baumannii and Candida albicans dual-species biofilm formation" in Biofouling (2023):1-11,
https://doi.org/10.1080/08927014.2023.2215693 . .

TY  - JOUR
AU  - Ušjak, Dušan
AU  - Dinić, Miroslav
AU  - Novović, Katarina
AU  - Ivković, Branka
AU  - Filipović, Nenad
AU  - Stevanović, Magdalena
AU  - Milenković, Marina T.
PY  - 2021
UR  - https://imagine.imgge.bg.ac.rs/handle/123456789/1509
AB  - An increasing lack of available therapeutic options against Acinetobacter baumannii urged researchers to seek alternative ways to fight this extremely resistant nosocomial pathogen. Targeting its virulence appears to be a promising strategy, as it offers considerably reduced selection of resistant mutants. In this study, we tested antibiofilm potential of four synthetic chalcone derivatives against A. baumannii. Compound that showed the greatest activity was selected for further evaluation of its antivirulence properties. Real-time PCR was used to evaluate mRNA expression of biofilm-associated virulence factor genes (ompA, bap, abaI) in treated A. baumannii strains. Also, we examined virulence properties related to the expression of these genes, such as fibronectin- and collagen-mediated adhesion, surface motility, and quorum-sensing activity. The results revealed that the expression of all tested genes is downregulated together with the reduction of adhesion and motility. The conclusion is that 2 '-hydroxy-2-methoxychalcone exhibits antivirulence activity against A. baumannii by inhibiting the expression of ompA and bap genes, which is reflected in reduced biofilm formation, adhesion, and surface motility.
PB  - Wiley-V C H Verlag Gmbh, Weinheim
T2  - Chemistry & Biodiversity
T1  - Methoxy-Substituted Hydroxychalcone Reduces Biofilm Production, Adhesion and Surface Motility of Acinetobacter baumannii by Inhibiting ompA Gene Expression
IS  - 1
VL  - 18
DO  - 10.1002/cbdv.202000786
ER  - 

@article{
author = "Ušjak, Dušan and Dinić, Miroslav and Novović, Katarina and Ivković, Branka and Filipović, Nenad and Stevanović, Magdalena and Milenković, Marina T.",
year = "2021",
abstract = "An increasing lack of available therapeutic options against Acinetobacter baumannii urged researchers to seek alternative ways to fight this extremely resistant nosocomial pathogen. Targeting its virulence appears to be a promising strategy, as it offers considerably reduced selection of resistant mutants. In this study, we tested antibiofilm potential of four synthetic chalcone derivatives against A. baumannii. Compound that showed the greatest activity was selected for further evaluation of its antivirulence properties. Real-time PCR was used to evaluate mRNA expression of biofilm-associated virulence factor genes (ompA, bap, abaI) in treated A. baumannii strains. Also, we examined virulence properties related to the expression of these genes, such as fibronectin- and collagen-mediated adhesion, surface motility, and quorum-sensing activity. The results revealed that the expression of all tested genes is downregulated together with the reduction of adhesion and motility. The conclusion is that 2 '-hydroxy-2-methoxychalcone exhibits antivirulence activity against A. baumannii by inhibiting the expression of ompA and bap genes, which is reflected in reduced biofilm formation, adhesion, and surface motility.",
publisher = "Wiley-V C H Verlag Gmbh, Weinheim",
journal = "Chemistry & Biodiversity",
title = "Methoxy-Substituted Hydroxychalcone Reduces Biofilm Production, Adhesion and Surface Motility of Acinetobacter baumannii by Inhibiting ompA Gene Expression",
number = "1",
volume = "18",
doi = "10.1002/cbdv.202000786"
}

Ušjak, D., Dinić, M., Novović, K., Ivković, B., Filipović, N., Stevanović, M.,& Milenković, M. T.. (2021). Methoxy-Substituted Hydroxychalcone Reduces Biofilm Production, Adhesion and Surface Motility of Acinetobacter baumannii by Inhibiting ompA Gene Expression. in Chemistry & Biodiversity
Wiley-V C H Verlag Gmbh, Weinheim., 18(1).
https://doi.org/10.1002/cbdv.202000786

Ušjak D, Dinić M, Novović K, Ivković B, Filipović N, Stevanović M, Milenković MT. Methoxy-Substituted Hydroxychalcone Reduces Biofilm Production, Adhesion and Surface Motility of Acinetobacter baumannii by Inhibiting ompA Gene Expression. in Chemistry & Biodiversity. 2021;18(1).
doi:10.1002/cbdv.202000786 .

Ušjak, Dušan, Dinić, Miroslav, Novović, Katarina, Ivković, Branka, Filipović, Nenad, Stevanović, Magdalena, Milenković, Marina T., "Methoxy-Substituted Hydroxychalcone Reduces Biofilm Production, Adhesion and Surface Motility of Acinetobacter baumannii by Inhibiting ompA Gene Expression" in Chemistry & Biodiversity, 18, no. 1 (2021),
https://doi.org/10.1002/cbdv.202000786 . .

TY  - JOUR
AU  - Ušjak, Dušan
AU  - Ivković, Branka
AU  - Božić, Dragana D.
AU  - Bošković, Lidija
AU  - Milenković, Marina
PY  - 2019
UR  - https://www.sciencedirect.com/science/article/pii/S0882401018319132
UR  - https://imagine.imgge.bg.ac.rs/handle/123456789/1770
AB  - Acinetobacter baumannii and Pseudomonas aeruginosa are frequent multiresistant nosocomial pathogens that cause wound and pulmonary infections in hospitalized patients. As being increasingly resistant to most clinically available antibiotics, there is a constant need for exploration of new substances that could kill them or inhibit their growth, or alternatively inhibit some of their essential virulence factors. Chalcones are chemical compounds with well-documented antimicrobial potential. The aim of this study was to examine effectiveness of four newly-synthesized chalcones against the multiresistant clinical strains of A. baumannii and P. aeruginosa. Antibacterial activity of chalcones was investigated with broth-microdilution test and time-dependent killing assay. Synergistic effects of tested compounds with antibiotics (meropenem, amikacin and ciprofloxacin) were determined by checkerboard assay. The effects of chalcones on expression of virulence factors in P. aeruginosa (pyocyanin production, swimming and swarming motility) and A. baumannii (twitching and surface-associated motility), along with their biofilm production, were also examined. The obtained results indicate substantial antimicrobial activity of the tested chalcones (MICs = 100–175 μg/mL) and several synergistic interactions with antibiotics, as well as notable reduction in expression of all investigated virulence factors. These promising results may constitute a good basis for further research.
T2  - Microbial Pathogenesis
T2  - Microbial PathogenesisMicrobial Pathogenesis
T1  - Antimicrobial activity of novel chalcones and modulation of virulence factors in hospital strains of Acinetobacter baumannii and Pseudomonas aeruginosa
EP  - 196
SP  - 186
VL  - 131
DO  - 10.1016/j.micpath.2019.04.015
ER  - 

@article{
author = "Ušjak, Dušan and Ivković, Branka and Božić, Dragana D. and Bošković, Lidija and Milenković, Marina",
year = "2019",
abstract = "Acinetobacter baumannii and Pseudomonas aeruginosa are frequent multiresistant nosocomial pathogens that cause wound and pulmonary infections in hospitalized patients. As being increasingly resistant to most clinically available antibiotics, there is a constant need for exploration of new substances that could kill them or inhibit their growth, or alternatively inhibit some of their essential virulence factors. Chalcones are chemical compounds with well-documented antimicrobial potential. The aim of this study was to examine effectiveness of four newly-synthesized chalcones against the multiresistant clinical strains of A. baumannii and P. aeruginosa. Antibacterial activity of chalcones was investigated with broth-microdilution test and time-dependent killing assay. Synergistic effects of tested compounds with antibiotics (meropenem, amikacin and ciprofloxacin) were determined by checkerboard assay. The effects of chalcones on expression of virulence factors in P. aeruginosa (pyocyanin production, swimming and swarming motility) and A. baumannii (twitching and surface-associated motility), along with their biofilm production, were also examined. The obtained results indicate substantial antimicrobial activity of the tested chalcones (MICs = 100–175 μg/mL) and several synergistic interactions with antibiotics, as well as notable reduction in expression of all investigated virulence factors. These promising results may constitute a good basis for further research.",
journal = "Microbial Pathogenesis, Microbial PathogenesisMicrobial Pathogenesis",
title = "Antimicrobial activity of novel chalcones and modulation of virulence factors in hospital strains of Acinetobacter baumannii and Pseudomonas aeruginosa",
pages = "196-186",
volume = "131",
doi = "10.1016/j.micpath.2019.04.015"
}

Ušjak, D., Ivković, B., Božić, D. D., Bošković, L.,& Milenković, M.. (2019). Antimicrobial activity of novel chalcones and modulation of virulence factors in hospital strains of Acinetobacter baumannii and Pseudomonas aeruginosa. in Microbial Pathogenesis, 131, 186-196.
https://doi.org/10.1016/j.micpath.2019.04.015

Ušjak D, Ivković B, Božić DD, Bošković L, Milenković M. Antimicrobial activity of novel chalcones and modulation of virulence factors in hospital strains of Acinetobacter baumannii and Pseudomonas aeruginosa. in Microbial Pathogenesis. 2019;131:186-196.
doi:10.1016/j.micpath.2019.04.015 .

Ušjak, Dušan, Ivković, Branka, Božić, Dragana D., Bošković, Lidija, Milenković, Marina, "Antimicrobial activity of novel chalcones and modulation of virulence factors in hospital strains of Acinetobacter baumannii and Pseudomonas aeruginosa" in Microbial Pathogenesis, 131 (2019):186-196,
https://doi.org/10.1016/j.micpath.2019.04.015 . .

TY  - JOUR
AU  - Jovanović, Predrag
AU  - Jeremić, Sanja
AU  - Đokić, Lidija
AU  - Savić, Vladimir
AU  - Milovanović, Jelena
AU  - Maslak, Veselin
AU  - Ivković, Branka
AU  - Vasiljević, Branka
AU  - Nikodinović-Runić, Jasmina
PY  - 2014
UR  - https://imagine.imgge.bg.ac.rs/handle/123456789/716
AB  - Chemoselective reduction of activated carbon-carbon double bond in conjugated nitroalkenes was achieved using Escherichia coli BL21(DE3) whole cells. Nine different substrates have been used furnishing the reduced products in moderate to good yields. 1-Nitro-4-phenyl-1,3-butadiene and (2-nitro-1-propenyl)benzene were successfully biotransformed with corresponding product yields of 54% and 45% respectively. Using this simple and environmentally friendly system 2-(2-nitropropyl)pyridine and 2-(2-nitropropyl)naphthalene were synthesized and characterized for the first time. High substrate conversion efficiency was coupled with low enantioselectivity, however 29% enantiomeric excess was detected in the case of 2-(2-nitropropyl)pyridine. It was shown that electronic properties of the aromatic ring, which affected polarity of the double bond, were not highly influential factors in the reduction process, but the presence of the nitro functionality was essential for the reaction to proceed. 1-Phenyl-4-nitro-1,3-butadiene could not be biotransformed by whole cells of Pseudomonas putida KT2440 or Bacillus subtilis 168 while it was successfully reduced by E. coli DH5 alpha but with lower efficiency in comparison to E. coli BL21(DE3). Knockout mutant affected in nemA gene coding for N-ethylmaleimide reductase (BL21 Delta nemA) could still catalyze bioreductions suggesting multiple active reductases within E. coli BL21(DE3) biocatalyst. The described biocatalytic reduction of substituted nitroalkenes provides an efficient route for the preparation of the corresponding nitroalkanes and introduces the new application of the strain traditionally utilized for recombinant protein expression.
PB  - Elsevier Science Inc, New York
T2  - Enzyme and Microbial Technology
T1  - Chemoselective biocatalytic reduction of conjugated nitroalkenes: New application for an Escherichia coli BL21(DE3) expression strain
EP  - 23
SP  - 16
VL  - 60
DO  - 10.1016/j.enzmictec.2014.03.010
ER  - 

@article{
author = "Jovanović, Predrag and Jeremić, Sanja and Đokić, Lidija and Savić, Vladimir and Milovanović, Jelena and Maslak, Veselin and Ivković, Branka and Vasiljević, Branka and Nikodinović-Runić, Jasmina",
year = "2014",
abstract = "Chemoselective reduction of activated carbon-carbon double bond in conjugated nitroalkenes was achieved using Escherichia coli BL21(DE3) whole cells. Nine different substrates have been used furnishing the reduced products in moderate to good yields. 1-Nitro-4-phenyl-1,3-butadiene and (2-nitro-1-propenyl)benzene were successfully biotransformed with corresponding product yields of 54% and 45% respectively. Using this simple and environmentally friendly system 2-(2-nitropropyl)pyridine and 2-(2-nitropropyl)naphthalene were synthesized and characterized for the first time. High substrate conversion efficiency was coupled with low enantioselectivity, however 29% enantiomeric excess was detected in the case of 2-(2-nitropropyl)pyridine. It was shown that electronic properties of the aromatic ring, which affected polarity of the double bond, were not highly influential factors in the reduction process, but the presence of the nitro functionality was essential for the reaction to proceed. 1-Phenyl-4-nitro-1,3-butadiene could not be biotransformed by whole cells of Pseudomonas putida KT2440 or Bacillus subtilis 168 while it was successfully reduced by E. coli DH5 alpha but with lower efficiency in comparison to E. coli BL21(DE3). Knockout mutant affected in nemA gene coding for N-ethylmaleimide reductase (BL21 Delta nemA) could still catalyze bioreductions suggesting multiple active reductases within E. coli BL21(DE3) biocatalyst. The described biocatalytic reduction of substituted nitroalkenes provides an efficient route for the preparation of the corresponding nitroalkanes and introduces the new application of the strain traditionally utilized for recombinant protein expression.",
publisher = "Elsevier Science Inc, New York",
journal = "Enzyme and Microbial Technology",
title = "Chemoselective biocatalytic reduction of conjugated nitroalkenes: New application for an Escherichia coli BL21(DE3) expression strain",
pages = "23-16",
volume = "60",
doi = "10.1016/j.enzmictec.2014.03.010"
}

Jovanović, P., Jeremić, S., Đokić, L., Savić, V., Milovanović, J., Maslak, V., Ivković, B., Vasiljević, B.,& Nikodinović-Runić, J.. (2014). Chemoselective biocatalytic reduction of conjugated nitroalkenes: New application for an Escherichia coli BL21(DE3) expression strain. in Enzyme and Microbial Technology
Elsevier Science Inc, New York., 60, 16-23.
https://doi.org/10.1016/j.enzmictec.2014.03.010

Jovanović P, Jeremić S, Đokić L, Savić V, Milovanović J, Maslak V, Ivković B, Vasiljević B, Nikodinović-Runić J. Chemoselective biocatalytic reduction of conjugated nitroalkenes: New application for an Escherichia coli BL21(DE3) expression strain. in Enzyme and Microbial Technology. 2014;60:16-23.
doi:10.1016/j.enzmictec.2014.03.010 .

Jovanović, Predrag, Jeremić, Sanja, Đokić, Lidija, Savić, Vladimir, Milovanović, Jelena, Maslak, Veselin, Ivković, Branka, Vasiljević, Branka, Nikodinović-Runić, Jasmina, "Chemoselective biocatalytic reduction of conjugated nitroalkenes: New application for an Escherichia coli BL21(DE3) expression strain" in Enzyme and Microbial Technology, 60 (2014):16-23,
https://doi.org/10.1016/j.enzmictec.2014.03.010 . .