Florin Dan Irimie | Babes-Bolyai University (original) (raw)

Papers by Florin Dan Irimie

Biochimica et Biophysica Acta (BBA) - Bioenergetics, 2010

Horseradish peroxidase was verified to catalyze, without any phenol, the hydrogen peroxide oxidat... more Horseradish peroxidase was verified to catalyze, without any phenol, the hydrogen peroxide oxidation of chlorophyll a (Chl a), solubilized with Triton X-100. The 13 2 (S) and 13 2 (R) diastereomers of 13 2-hydroxyChl a were characterized as major oxidation products (ca. 60%) by TLC on sucrose, UV-vis, 1 H, and 13 C NMR spectra, as well as fast-atom bombardment MS. A minor amount of the 15 2-methyl, 17 3-phytyl ester of Mg-unstable chlorin was identified on the basis of its UV-vis spectrum and reactivity with diazomethane, which converted it to the 13 1 ,15 2-dimethyl, 17 3-phytyl ester of Mg-purpurin 7. The side products (ca. 10%) were suggested to include the 17 3-phytyl ester of Mg-purpurin 18, which is known to form easily from the Mg-unstable chlorin. The side products also included two red components with UV-vis spectral features resembling those of pure Chl a enolate anion. Hence, the two red components were assigned to the enolate anions of Chl a and pheophytin a or, alternatively, two different complexes of the Chl a enolate ion with Triton X-100. All the above products characterized by us are included in our published free-radical allomerization mechanism of Chl a, i.e. oxidation by ground-state dioxygen. The HRP clearly accelerated the allomerization process, but it did not produce bilins, that is, open-chain tetrapyrroles, the formation of which would require oxygenolysis of the chlorin macrocycle. In this regard, our results are in discrepancy with the claim by several researchers that 'bilirubin-like compounds' are formed in the HRP-catalyzed oxidation of Chl a. Inspection of the likely reactions that occurred on the distal side of the heme in the active centre of HRP provided a reasonable explanation for the observed catalytic effect of the HRP on the allomerization of Chl. In the active centre of HRP, the imidazole nitrogen of His-42 was considered to play a crucial role in the C-13 2 deprotonation of Chl a, which resulted in the Chl a enolate ion resonance hybrid. The Chl enolate was then oxidized to the Chl 13 2-radical while the HRP Compound I was reduced to Compound II. The same reactive Chl derivatives, i.e. the Chl enolate anion and the Chl 13 2-radical, which are produced twice in the HRP reaction cycle, happen to be the crucial intermediates in the initial stages of the Chl allomerization mechanism.

Lipase-catalyzed kinetic resolution of racemic 1-heteroarylethanols—experimental and QM/MM study

Tetrahedron-asymmetry, Aug 1, 2008

The kinetic resolution of racemic 1-(benzothiazol-2-yl)ethanol rac-2a, 1-(benzo[b]thiophen-2-yl)e... more The kinetic resolution of racemic 1-(benzothiazol-2-yl)ethanol rac-2a, 1-(benzo[b]thiophen-2-yl)ethanol rac-2b, 1-(benzo[b]furan-3-yl)ethanol rac-2c and 1-(benzo[b]thiophen-3-yl)ethanol rac-2d was studied by enantiomer selective acylation catalyzed by a selection of commercially available and in house produced lipases. Alcoholysis of the corresponding racemic acetates rac-3a–d catalyzed by Candida antarctica lipase B (CaLB) was also investigated. Two racemic 1-heteroarylethanols rac-2a,b were prepared by addition of the corresponding

Stereoselectivity of Pal under non-optimal conditions: Pb-089

Protein Science, Oct 1, 2015

Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca: Horticulture, 2008

ChemInform, May 24, 2010

Synthesis and Stereochemistry of Some New Trispiro-1,3-dioxanes with Axial and Helical Chirality.... more Synthesis and Stereochemistry of Some New Trispiro-1,3-dioxanes with Axial and Helical Chirality.-New trispiro-1,3-dioxane [cf. (III) and (V)] are synthesized by acetalization of the corresponding substituted cyclohexanones with pentaerythritol and their stereoisomerism and conformational behavior is discussed.

Studia Universitatis Babes-bolyai Chemia, Sep 30, 2017

This study describes the cloning of the gene encoding a novel phenylalanine ammonia-lyase from Ka... more This study describes the cloning of the gene encoding a novel phenylalanine ammonia-lyase from Kangiella koreensis (KkPAL) into pET19b expression vector. Optimization of protein expression and purification conditions yielded 15 mg pure soluble protein from one liter of E. coli culture. Enzymatic activity measurements of the ammonia elimination reaction from different natural aromatic amino acids proved the protein to be a phenylalanine ammonia-lyase. The isolated protein showed remarkably high, 81.7 °C melting temperature, making it especially suitable for biocatalytic applications.

RSC Advances, 2016

In this study enantiomer selective isomerization of various racemic aand b-arylalanines catalysed... more In this study enantiomer selective isomerization of various racemic aand b-arylalanines catalysed by phenylalanine 2,3-aminomutase from Pantoea agglomerans (PaPAM) was investigated. Both aand barylalanines were accepted as substrates when the aryl moiety was relatively small, like phenyl, 2-, 3-, 4fluorophenyl or thiophen-2-yl. While 2-substituted a-phenylalanines bearing bulky electron withdrawing substituents did not react, the corresponding substituted b-aryl analogues were converted rapidly. Conversion of 3-and 4-substituted a-arylalanines happened smoothly, while conversion of the corresponding b-arylalanines was poor or non-existent. In the range of pH 7-9 there was no significant influence on the conversion of racemic aor b-(thiophen-2-yl)alanines, whereas increasing the concentration of ammonia (ammonium carbonate from 50 to 1000 mM) inhibited the isomerization progressively and decreased the amount of the by-product (i.e. (E)-3-(thiophen-2-yl)acrylic acid was detected). In all cases, the high ee values of the products indicated excellent enantiomer selectivity and stereospecificity of the isomerization except for (S)-2-nitro-a-phenylalanine (ee 92%) from the b-isomer. Substituent effects were rationalized by computational modelling revealing that one of the main factors controlling biocatalytic activity was the energy difference between the covalent regioisomeric enzymesubstrate complexes.

Corrigendum: Composite Aromatic Boxes for Enzymatic Transformations of Quaternary Ammonium Substrates

Angewandte Chemie, Jul 21, 2015

Biodiesel (fatty acid methyl esters), which is derived from triglycerides by transesterification ... more Biodiesel (fatty acid methyl esters), which is derived from triglycerides by transesterification with methanol, has attracted considerable attention during the past decade as a renewable, biodegradable, nontoxic fuel, being an important mean of progress to reduce greenhouse gases and local pollution. Biodiesel can be used either in the pure form or as blends on conventional petrodiesel in automobiles without any major modifications. This review paper presents the general aspects of biodiesel production, its properties, composition and its future potential.

Vibrational Spectroscopy, Jul 1, 2002

FT-Raman of solid state sample and surface enhanced Raman (SER) spectra of 5-(4-fluor-phenyl)-fur... more FT-Raman of solid state sample and surface enhanced Raman (SER) spectra of 5-(4-fluor-phenyl)-furan-2 carbaldehyde (5-(4FP)-F-2C) at pH 1 were recorded and analyzed. The absence of carbonyl band in SER spectra was explained by the hydration of carbonyl bond. The shift by 5-10 cm À1 of the surface enhanced Raman spectroscopy (SERS) bands and change in their relative intensity by comparing with the ordinary Raman spectrum (ORS) indicate the chemisorption of the sample molecules on the silver surface via the nonbonding electrons of the ring oxygen.

Ethanol derived from woody biomass has the potential to be a renewable transportation fuel than c... more Ethanol derived from woody biomass has the potential to be a renewable transportation fuel than can replace gasoline. The paper presents the bioconversion of woody biomass to ethanol, pretreatment of the material prior to acid hydrolysis is important to obtain high overall yield of sugar and ethanol. In this study, steam explosion pretreatment, two step hydrolysis process and fermentation has been investigated.

A graphite furnace atomic absorption spectrometry (GFAAS) was used for trace elements (Cu, Fe, Mn... more A graphite furnace atomic absorption spectrometry (GFAAS) was used for trace elements (Cu, Fe, Mn, Zn, Cd, Cr, Ni, Pb) determination in “Rakija” samples, a grape brandy traditionally produced in Republic of Macedonia by distillation of grape pomace or wine for characterization. Principal component analysis was used to establish pattern recognition of the Macedonian brandies and classification depending of aging mode (oak barrels/oak chips) and distillation system (home-made/industrial). Two home-made brandies showed Cu, Fe and Zn concentrations higher than in the industrial distillates. These brandies were found to be not safe for consumption because of Cu and Zn over the maximum allowed values. For industrially produced brandies, Mn was identified to be a suitable marker related to aging with oak chips regardless variety, while Cu a marker for the influence of oak chips type.

ChemCatChem, 2018

Tailored mutants of phenylalanine ammonia‐lyase from Petroselinum crispum (PcPAL) were created an... more Tailored mutants of phenylalanine ammonia‐lyase from Petroselinum crispum (PcPAL) were created and tested in ammonia elimination from various sterically demanding, non‐natural analogues of phenylalanine and in ammonia addition reactions into the corresponding (E)‐arylacrylates. The wild‐type PcPAL was inert or exhibited quite poor conversions in both reactions with all members of the substrate panel. Appropriate single mutations of residue F137 and the highly conserved residue I460 resulted in PcPAL variants that were active in ammonia elimination but still had a poor activity in ammonia addition onto bulky substrates. However, combined mutations that involve I460 besides the well‐studied F137 led to mutants that exhibited activity in ammonia addition as well. The synergistic multiple mutations resulted in substantial substrate scope extension of PcPAL and opened up new biocatalytic routes for the synthesis of both enantiomers of valuable phenylalanine analogues, such as (4‐methoxyp...

ACS Catalysis, 2019

Modification of the hydrophobic binding pocket of phenylalanine ammonia-lyase from Petroselinum c... more Modification of the hydrophobic binding pocket of phenylalanine ammonia-lyase from Petroselinum crispum (PcPAL) enables increased activity and selectivity towards phenylalanines and cinnamic acids mono-substituted with both electron donating (-CH 3 ,-OCH 3) and electron withdrawing (-CF 3 ,-Br) groups at all positions (o-, m-, p-) of their aromatic ring. The results reveal specific residues involved in accommodating substituents at o-, m-, p-positions of the substrate's phenyl ring. The predicted interactions were validated by crystallographic analysis of the binding mode of paramethoxy cinnamic acid complexed at the active site of PcPAL. The biocatalytic utility of the tailored PcPAL mutants was demonstrated by the efficient preparative scale synthesis of (S)-m-bromo-phenylalanine (ee: > 99%, yield: 60%

Food Analytical Methods, 2016

A graphite furnace atomic absorption spectrometry (GFAAS) was used for determination of trace ele... more A graphite furnace atomic absorption spectrometry (GFAAS) was used for determination of trace elements (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in Brakija^samples, a grape brandy traditionally produced in Republic of Macedonia by distillation of grape pomace or wine, for characterization and safety evaluation. Cd, Pb, Cr, and Ni were determined directly, while Cu, Fe, Mn, and Zn were quantified after appropriate dilution. The calibration curves of all elements were linear with correlation coefficients (R 2) ranging from 0.9995 to 0.9998. The accuracy of the method was checked with a standard addition method showing good repeatability and reproducibility (relative standard deviation (RSD) <10 %). Relationship between several metal concentrations (Cu, Fe, Mn, Zn) in brandies and distillation system (homemade/industrial) on one side and aging mode (oak barrels/oak chips) on the other side were demonstrated. Two homemade brandies showed Cu, Fe, and Zn concentrations higher than industrial distillates and thus were found to be not safe for consumption because of Cu and Zn over the maximum allowed values. For the industrially produced brandies, Mn was identified to be a suitable marker related to aging with oak chips regardless variety, while Cu a marker for the influence of oak chip type. Principal component analysis applied on the content of elements clearly showed a good separation in terms of distillation and aging method.

Evaluation of tumor angiogenesis through VEGF modulation in ovarian cancer in vivo using RNA interference

The aim of the study was to identify specific correlation between VEGF inhibition by RNA interfer... more The aim of the study was to identify specific correlation between VEGF inhibition by RNA interference and several functional genes involved in in vivo ovarian cancer evolution in vivo. We used RT-PCR evaluation for VEGFA multiple isoforms and PCR Array for 84 angiogenesis genes, of which we have found 11 overexpressed and 13 downregulated genes. siVEGF has demonstrated a good response in ovarian cancer cell lines HeLa at 24 h and a 70% performant inhibition of its expression. RNA interference tool could be used in cancer therapy, if it is targeted on several genes covering multiple activation pathways for angiogenic mechanisms.

Corrigendum: Composite Aromatic Boxes for Enzymatic Transformations of Quaternary Ammonium Substrates

Angewandte Chemie (International ed. in English), Jan 27, 2015

Vibrational Spectroscopy, 2002

FT-Raman of solid state sample and surface enhanced Raman (SER) spectra of 5-(4-fluor-phenyl)-fur... more FT-Raman of solid state sample and surface enhanced Raman (SER) spectra of 5-(4-fluor-phenyl)-furan-2 carbaldehyde (5-(4FP)-F-2C) at pH 1 were recorded and analyzed. The absence of carbonyl band in SER spectra was explained by the hydration of carbonyl bond. The shift by 5-10 cm À1 of the surface enhanced Raman spectroscopy (SERS) bands and change in their relative intensity by comparing with the ordinary Raman spectrum (ORS) indicate the chemisorption of the sample molecules on the silver surface via the nonbonding electrons of the ring oxygen.

Quantification of Ibuprofen and Pseudoephedrine in Human Plasma by LC/MS/MS for Pharmacokinetic Studies

UNIVERSITATIS …

ACS Sustainable Chemistry & Engineering, 2020

Fatty acid diesters of 2,5-bis-(hydroxymethyl)furan (BHMF), promising candidates as sustainable b... more Fatty acid diesters of 2,5-bis-(hydroxymethyl)furan (BHMF), promising candidates as sustainable bioadditives, increasing the cetane number of biodiesel fuels, were prepared through a solventfree Novozym 435 mediated diesterification of BHMF with the fatty acid mixture (FAM) resulted from the hydrolysis of commercial sunflower oil. Under solvent-free conditions and a 15 mbar vacuum, high conversions into diesters were obtained in the heterogeneous reaction, after the gradual solubilization of BHMF. After optimization studies (temperature, reaction time, BHMF-FAM ratio and biocatalyst loading), more than 97% conversions into diesters were achieved. The calculated sustainability metrics supports that the currently described solvent-free method represents an improved synthetic procedure for BHMF fatty acid diesters preparation.

Biochimica et Biophysica Acta (BBA) - Bioenergetics, 2010

Horseradish peroxidase was verified to catalyze, without any phenol, the hydrogen peroxide oxidat... more Horseradish peroxidase was verified to catalyze, without any phenol, the hydrogen peroxide oxidation of chlorophyll a (Chl a), solubilized with Triton X-100. The 13 2 (S) and 13 2 (R) diastereomers of 13 2-hydroxyChl a were characterized as major oxidation products (ca. 60%) by TLC on sucrose, UV-vis, 1 H, and 13 C NMR spectra, as well as fast-atom bombardment MS. A minor amount of the 15 2-methyl, 17 3-phytyl ester of Mg-unstable chlorin was identified on the basis of its UV-vis spectrum and reactivity with diazomethane, which converted it to the 13 1 ,15 2-dimethyl, 17 3-phytyl ester of Mg-purpurin 7. The side products (ca. 10%) were suggested to include the 17 3-phytyl ester of Mg-purpurin 18, which is known to form easily from the Mg-unstable chlorin. The side products also included two red components with UV-vis spectral features resembling those of pure Chl a enolate anion. Hence, the two red components were assigned to the enolate anions of Chl a and pheophytin a or, alternatively, two different complexes of the Chl a enolate ion with Triton X-100. All the above products characterized by us are included in our published free-radical allomerization mechanism of Chl a, i.e. oxidation by ground-state dioxygen. The HRP clearly accelerated the allomerization process, but it did not produce bilins, that is, open-chain tetrapyrroles, the formation of which would require oxygenolysis of the chlorin macrocycle. In this regard, our results are in discrepancy with the claim by several researchers that 'bilirubin-like compounds' are formed in the HRP-catalyzed oxidation of Chl a. Inspection of the likely reactions that occurred on the distal side of the heme in the active centre of HRP provided a reasonable explanation for the observed catalytic effect of the HRP on the allomerization of Chl. In the active centre of HRP, the imidazole nitrogen of His-42 was considered to play a crucial role in the C-13 2 deprotonation of Chl a, which resulted in the Chl a enolate ion resonance hybrid. The Chl enolate was then oxidized to the Chl 13 2-radical while the HRP Compound I was reduced to Compound II. The same reactive Chl derivatives, i.e. the Chl enolate anion and the Chl 13 2-radical, which are produced twice in the HRP reaction cycle, happen to be the crucial intermediates in the initial stages of the Chl allomerization mechanism.

Lipase-catalyzed kinetic resolution of racemic 1-heteroarylethanols—experimental and QM/MM study

Tetrahedron-asymmetry, Aug 1, 2008

The kinetic resolution of racemic 1-(benzothiazol-2-yl)ethanol rac-2a, 1-(benzo[b]thiophen-2-yl)e... more The kinetic resolution of racemic 1-(benzothiazol-2-yl)ethanol rac-2a, 1-(benzo[b]thiophen-2-yl)ethanol rac-2b, 1-(benzo[b]furan-3-yl)ethanol rac-2c and 1-(benzo[b]thiophen-3-yl)ethanol rac-2d was studied by enantiomer selective acylation catalyzed by a selection of commercially available and in house produced lipases. Alcoholysis of the corresponding racemic acetates rac-3a–d catalyzed by Candida antarctica lipase B (CaLB) was also investigated. Two racemic 1-heteroarylethanols rac-2a,b were prepared by addition of the corresponding

Stereoselectivity of Pal under non-optimal conditions: Pb-089

Protein Science, Oct 1, 2015

Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca: Horticulture, 2008

ChemInform, May 24, 2010

Synthesis and Stereochemistry of Some New Trispiro-1,3-dioxanes with Axial and Helical Chirality.... more Synthesis and Stereochemistry of Some New Trispiro-1,3-dioxanes with Axial and Helical Chirality.-New trispiro-1,3-dioxane [cf. (III) and (V)] are synthesized by acetalization of the corresponding substituted cyclohexanones with pentaerythritol and their stereoisomerism and conformational behavior is discussed.

Studia Universitatis Babes-bolyai Chemia, Sep 30, 2017

This study describes the cloning of the gene encoding a novel phenylalanine ammonia-lyase from Ka... more This study describes the cloning of the gene encoding a novel phenylalanine ammonia-lyase from Kangiella koreensis (KkPAL) into pET19b expression vector. Optimization of protein expression and purification conditions yielded 15 mg pure soluble protein from one liter of E. coli culture. Enzymatic activity measurements of the ammonia elimination reaction from different natural aromatic amino acids proved the protein to be a phenylalanine ammonia-lyase. The isolated protein showed remarkably high, 81.7 °C melting temperature, making it especially suitable for biocatalytic applications.

RSC Advances, 2016

In this study enantiomer selective isomerization of various racemic aand b-arylalanines catalysed... more In this study enantiomer selective isomerization of various racemic aand b-arylalanines catalysed by phenylalanine 2,3-aminomutase from Pantoea agglomerans (PaPAM) was investigated. Both aand barylalanines were accepted as substrates when the aryl moiety was relatively small, like phenyl, 2-, 3-, 4fluorophenyl or thiophen-2-yl. While 2-substituted a-phenylalanines bearing bulky electron withdrawing substituents did not react, the corresponding substituted b-aryl analogues were converted rapidly. Conversion of 3-and 4-substituted a-arylalanines happened smoothly, while conversion of the corresponding b-arylalanines was poor or non-existent. In the range of pH 7-9 there was no significant influence on the conversion of racemic aor b-(thiophen-2-yl)alanines, whereas increasing the concentration of ammonia (ammonium carbonate from 50 to 1000 mM) inhibited the isomerization progressively and decreased the amount of the by-product (i.e. (E)-3-(thiophen-2-yl)acrylic acid was detected). In all cases, the high ee values of the products indicated excellent enantiomer selectivity and stereospecificity of the isomerization except for (S)-2-nitro-a-phenylalanine (ee 92%) from the b-isomer. Substituent effects were rationalized by computational modelling revealing that one of the main factors controlling biocatalytic activity was the energy difference between the covalent regioisomeric enzymesubstrate complexes.

Corrigendum: Composite Aromatic Boxes for Enzymatic Transformations of Quaternary Ammonium Substrates

Angewandte Chemie, Jul 21, 2015

Biodiesel (fatty acid methyl esters), which is derived from triglycerides by transesterification ... more Biodiesel (fatty acid methyl esters), which is derived from triglycerides by transesterification with methanol, has attracted considerable attention during the past decade as a renewable, biodegradable, nontoxic fuel, being an important mean of progress to reduce greenhouse gases and local pollution. Biodiesel can be used either in the pure form or as blends on conventional petrodiesel in automobiles without any major modifications. This review paper presents the general aspects of biodiesel production, its properties, composition and its future potential.

Vibrational Spectroscopy, Jul 1, 2002

FT-Raman of solid state sample and surface enhanced Raman (SER) spectra of 5-(4-fluor-phenyl)-fur... more FT-Raman of solid state sample and surface enhanced Raman (SER) spectra of 5-(4-fluor-phenyl)-furan-2 carbaldehyde (5-(4FP)-F-2C) at pH 1 were recorded and analyzed. The absence of carbonyl band in SER spectra was explained by the hydration of carbonyl bond. The shift by 5-10 cm À1 of the surface enhanced Raman spectroscopy (SERS) bands and change in their relative intensity by comparing with the ordinary Raman spectrum (ORS) indicate the chemisorption of the sample molecules on the silver surface via the nonbonding electrons of the ring oxygen.

Ethanol derived from woody biomass has the potential to be a renewable transportation fuel than c... more Ethanol derived from woody biomass has the potential to be a renewable transportation fuel than can replace gasoline. The paper presents the bioconversion of woody biomass to ethanol, pretreatment of the material prior to acid hydrolysis is important to obtain high overall yield of sugar and ethanol. In this study, steam explosion pretreatment, two step hydrolysis process and fermentation has been investigated.

A graphite furnace atomic absorption spectrometry (GFAAS) was used for trace elements (Cu, Fe, Mn... more A graphite furnace atomic absorption spectrometry (GFAAS) was used for trace elements (Cu, Fe, Mn, Zn, Cd, Cr, Ni, Pb) determination in “Rakija” samples, a grape brandy traditionally produced in Republic of Macedonia by distillation of grape pomace or wine for characterization. Principal component analysis was used to establish pattern recognition of the Macedonian brandies and classification depending of aging mode (oak barrels/oak chips) and distillation system (home-made/industrial). Two home-made brandies showed Cu, Fe and Zn concentrations higher than in the industrial distillates. These brandies were found to be not safe for consumption because of Cu and Zn over the maximum allowed values. For industrially produced brandies, Mn was identified to be a suitable marker related to aging with oak chips regardless variety, while Cu a marker for the influence of oak chips type.

ChemCatChem, 2018

Tailored mutants of phenylalanine ammonia‐lyase from Petroselinum crispum (PcPAL) were created an... more Tailored mutants of phenylalanine ammonia‐lyase from Petroselinum crispum (PcPAL) were created and tested in ammonia elimination from various sterically demanding, non‐natural analogues of phenylalanine and in ammonia addition reactions into the corresponding (E)‐arylacrylates. The wild‐type PcPAL was inert or exhibited quite poor conversions in both reactions with all members of the substrate panel. Appropriate single mutations of residue F137 and the highly conserved residue I460 resulted in PcPAL variants that were active in ammonia elimination but still had a poor activity in ammonia addition onto bulky substrates. However, combined mutations that involve I460 besides the well‐studied F137 led to mutants that exhibited activity in ammonia addition as well. The synergistic multiple mutations resulted in substantial substrate scope extension of PcPAL and opened up new biocatalytic routes for the synthesis of both enantiomers of valuable phenylalanine analogues, such as (4‐methoxyp...

ACS Catalysis, 2019

Modification of the hydrophobic binding pocket of phenylalanine ammonia-lyase from Petroselinum c... more Modification of the hydrophobic binding pocket of phenylalanine ammonia-lyase from Petroselinum crispum (PcPAL) enables increased activity and selectivity towards phenylalanines and cinnamic acids mono-substituted with both electron donating (-CH 3 ,-OCH 3) and electron withdrawing (-CF 3 ,-Br) groups at all positions (o-, m-, p-) of their aromatic ring. The results reveal specific residues involved in accommodating substituents at o-, m-, p-positions of the substrate's phenyl ring. The predicted interactions were validated by crystallographic analysis of the binding mode of paramethoxy cinnamic acid complexed at the active site of PcPAL. The biocatalytic utility of the tailored PcPAL mutants was demonstrated by the efficient preparative scale synthesis of (S)-m-bromo-phenylalanine (ee: > 99%, yield: 60%

Food Analytical Methods, 2016

A graphite furnace atomic absorption spectrometry (GFAAS) was used for determination of trace ele... more A graphite furnace atomic absorption spectrometry (GFAAS) was used for determination of trace elements (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in Brakija^samples, a grape brandy traditionally produced in Republic of Macedonia by distillation of grape pomace or wine, for characterization and safety evaluation. Cd, Pb, Cr, and Ni were determined directly, while Cu, Fe, Mn, and Zn were quantified after appropriate dilution. The calibration curves of all elements were linear with correlation coefficients (R 2) ranging from 0.9995 to 0.9998. The accuracy of the method was checked with a standard addition method showing good repeatability and reproducibility (relative standard deviation (RSD) <10 %). Relationship between several metal concentrations (Cu, Fe, Mn, Zn) in brandies and distillation system (homemade/industrial) on one side and aging mode (oak barrels/oak chips) on the other side were demonstrated. Two homemade brandies showed Cu, Fe, and Zn concentrations higher than industrial distillates and thus were found to be not safe for consumption because of Cu and Zn over the maximum allowed values. For the industrially produced brandies, Mn was identified to be a suitable marker related to aging with oak chips regardless variety, while Cu a marker for the influence of oak chip type. Principal component analysis applied on the content of elements clearly showed a good separation in terms of distillation and aging method.

Evaluation of tumor angiogenesis through VEGF modulation in ovarian cancer in vivo using RNA interference

The aim of the study was to identify specific correlation between VEGF inhibition by RNA interfer... more The aim of the study was to identify specific correlation between VEGF inhibition by RNA interference and several functional genes involved in in vivo ovarian cancer evolution in vivo. We used RT-PCR evaluation for VEGFA multiple isoforms and PCR Array for 84 angiogenesis genes, of which we have found 11 overexpressed and 13 downregulated genes. siVEGF has demonstrated a good response in ovarian cancer cell lines HeLa at 24 h and a 70% performant inhibition of its expression. RNA interference tool could be used in cancer therapy, if it is targeted on several genes covering multiple activation pathways for angiogenic mechanisms.

Corrigendum: Composite Aromatic Boxes for Enzymatic Transformations of Quaternary Ammonium Substrates

Angewandte Chemie (International ed. in English), Jan 27, 2015

Vibrational Spectroscopy, 2002

FT-Raman of solid state sample and surface enhanced Raman (SER) spectra of 5-(4-fluor-phenyl)-fur... more FT-Raman of solid state sample and surface enhanced Raman (SER) spectra of 5-(4-fluor-phenyl)-furan-2 carbaldehyde (5-(4FP)-F-2C) at pH 1 were recorded and analyzed. The absence of carbonyl band in SER spectra was explained by the hydration of carbonyl bond. The shift by 5-10 cm À1 of the surface enhanced Raman spectroscopy (SERS) bands and change in their relative intensity by comparing with the ordinary Raman spectrum (ORS) indicate the chemisorption of the sample molecules on the silver surface via the nonbonding electrons of the ring oxygen.

Quantification of Ibuprofen and Pseudoephedrine in Human Plasma by LC/MS/MS for Pharmacokinetic Studies

UNIVERSITATIS …

ACS Sustainable Chemistry & Engineering, 2020

Fatty acid diesters of 2,5-bis-(hydroxymethyl)furan (BHMF), promising candidates as sustainable b... more Fatty acid diesters of 2,5-bis-(hydroxymethyl)furan (BHMF), promising candidates as sustainable bioadditives, increasing the cetane number of biodiesel fuels, were prepared through a solventfree Novozym 435 mediated diesterification of BHMF with the fatty acid mixture (FAM) resulted from the hydrolysis of commercial sunflower oil. Under solvent-free conditions and a 15 mbar vacuum, high conversions into diesters were obtained in the heterogeneous reaction, after the gradual solubilization of BHMF. After optimization studies (temperature, reaction time, BHMF-FAM ratio and biocatalyst loading), more than 97% conversions into diesters were achieved. The calculated sustainability metrics supports that the currently described solvent-free method represents an improved synthetic procedure for BHMF fatty acid diesters preparation.