Most organic solvents used in quaternization reactions are volatile, hazardous, toxic and form by-products, thus inducing health issues and pollution. Deep eutectic solvents are greener alternatives, ...but they have not been tested yet in the quaternization reaction. Here we propose eutectic solvents in the quaternization reaction of nicotinamide with substituted 2-bromoacetophenones. The reaction was performed at 80 °C by three synthetic approaches: conventional during 2–6 h, microwave during 20 min and ultrasonic during 3 h. The highest yields of about 98% were obtained by microwave. The most suitable eutectic solvents were choline chloride with either urea, oxalic or levulinic acid. The use of deep eutectic solvents has several advantages: environmental benignity, biodegradability, easy purification and simple preparation. All tested compounds showed antifungal activities against
Botrytis cinerea
,
Colletotrichum acutatum
,
Alternaria radicina
and
Fusarium graminearum
at 10 and 100 µg/mL.
The effect of different hydrodistillation pretreatments, namely, reflux extraction, reflux extraction with the addition of cell wall-degrading enzymes, and ultrasound, on the yield and chemical ...composition of essential oils of sage, bay laurel, and rosemary was examined. All pretreatments improved essential oil yield compared to no-pretreatment control (40–64% yield increase), while the oil quality remained mostly unchanged (as shown by statistical analysis of GC-MS results). However, enzyme-assisted reflux extraction pretreatment did not significantly outperform reflux extraction (no-enzyme control), suggesting that the observed yield increase was mostly a consequence of reflux extraction and enzymatic activity had only a minute effect. Thus, we show that ultrasound and reflux extraction pretreatments are beneficial in the production of essential oils of selected Mediterranean plants, but the application of enzymes has to be carefully re-evaluated.
•Pectin extraction from tomato waste was studied.•Ultrasound-assisted extracted pectin was compared to conventional extracted pectin.•Ultrasound treatment significantly shortened extraction time.•1H ...and 13C NMR spectra confirmed the existence of pectin biopolymer structure.•FTIR spectra showed the presence of predominantly esterified pectin form.
Pectin was extracted from tomato waste using two different extraction methods to assess its potential utilization as an alternative source of commercial pectin production. Tomato waste was treated with ammonium oxalate/oxalic acid by conventional extraction (CE), under reflux and ultrasound assisted extraction (UAE) at 37kHz and temperatures of 60°C and 80°C. The pectin obtained from these methods was analysed and compared in terms of yield, chemical properties and structure. Among examined methods, CE at 60°C resulted with the highest yield, but UAE during 15min of sonication produced the pectin of better quality (anhydrouronic acid, methoxy and calcium pectate contents and degree of esterification). NMR and FTIR spectroscopy of isolated pectins revealed predominantly esterified structure, irrespective of extraction conditions. The comparison of the pectin yields obtained after extraction at 80°C, indicate that similar values were found at times of 24h and 15min for CE and UAE, respectively. According to obtained results it can be concluded that main advantage of UAE is considerable shortening of extraction procedure with strong emphasis on environmental friendly processing approach. Therefore, these results suggested that UAE could be used as an efficient technique for the extraction of pectin from tomato waste and by-products.
In the present investigation, a series of couniarin-based compounds containing a chalcone moiety were studied for their in vitro and in silico properties. DFT global chemical reactivity descriptors ...(chemical hardness, total energy, electronic chemical potential and electrophilicity) are calculated for four synthesized compounds and used to predict their relative stability and reactivity. The antibacterial activities of all compounds have been screened against Bacillus subtilis (ATCC No. 6633) and Bacillus cereus (ATCC No. 11778). Quantum-chemical calculations indicate that antibacterial activity correlates well with chemical reactivity descriptors of molecules.
•The chiral-at-metal, piano-stool Ru(II) racemic organometallic was prepared.•The compound was fully characterised by spectroscopy in solid state and solution, as well as by single crystal X-ray ...diffraction study.•Coordination of pyridine to Ru(II) was monitored ex-situ by infrared spectroscopy.•Interaction of complex and chalcone ligand with BSA and DNA was investigated.•The complex binds more vigorously to BSA, as compared to DNA.
The chiral-at-metal, piano-stool ruthenium(II) racemic organometallic Ru(cymene)(chalconato)(pyridine)PF6 was prepared by a multistep solution synthesis and its molecular and crystal structure was determined by single crystal X-ray diffraction. The compound crystallizes in a centrosymmetric triclinic P-1 space group with two molecules of opposite chirality within the asymmetric unit. Ruthenium is embedded in an octahedral half-sandwich coordination environment with four different donors, which generates the chirality of the metal centre. The formation of the organometallic was monitored ex-situ by infrared spectroscopy. The pyridine coordination to Ru(II) was particularly analysed to find its characteristic marker bands. The complex was also characterized by elemental analysis and NMR spectroscopy in solution. Its interaction with CT DNA and bovine serum albumin (BSA) was investigated by electron spectroscopy and spectrofluorimetry. The organometallic binds to DNA predominantly by electrostatic forces with low Kb value. On the contrary, its high affinity for BSA was confirmed by strong fluorescence quenching. The synchronous emission spectra revealed that the microenvironment of tryptophan is more affected compared to the environment of tyrosine.
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•Four Ru(II) organometallics of chloro substituted 2’-hydroxychalcones were prepared.•Solid state and solution structures were determined.•At low μM concentrations compounds have solvent-dependent ...catecholase activity.•The kinetic portrait of catechol oxidation in methanol and ethanol is not the same.•The highest catalytic activity was found in ethanol for complex with chloro substituent in para position at chalcone ligand.
Four new organoruthenium(II) compounds of 2’-hydroxychalcones, differing in the position of the chloro substituent at chalcone moiety, were prepared by solution synthesis and characterized by chemical analysis, infrared and electron spectroscopy, mass spectrometry and 1D and 2D NMR spectroscopy, as biomimetic functional models of catechol oxidase. The molecular and crystal structures of three compounds were determined by single crystal X-ray diffraction. The organometallics are neutral species having piano-stool pseudo octahedral geometry with ruthenium(II) coordinated by η6-cymene, bidentate monobasic 2’-hydroxychalcone ligand, and chloride ion. The catecholase activity of new organometallics was investigated by electron spectroscopy in three solvents at three temperatures. The kinetic measurements were done under pseudo first order conditions and vmax, kcat, KM, TON, TOF, and Ea values are determined. Compounds (1) – (4) have solvent-dependent catecholase activity with activity decreasing in order ethanol > methanol ≫ acetonitrile. The highest kcat value and the lowest activation energy were found for the reaction catalyzed by organometallic (4), having a chloro substituent at the B ring of the chalcone ligand in the para position. The kcat values of 104 h−1 and 105 h−1 order at 297 K and 307 K, respectively classify these organometallics among the best artificial functional models of catechol oxidase. The results indicate that the catechol oxidation mediated by organometallics (1) – (4) proceeds via semiquinone radical formation.
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Solution synthesis afforded five novel neutral heteroleptic octahedral paramagnetic mononuclear oxidovanadium(IV) complexes of general composition VO(bpy)L, where L is a dianionic tridentate ...ONO-donor hydrazone ligand derived from 2-furoic acid hydrazide and salicylaldehyde and its 5-substituted derivatives. Characterization was carried out by elemental analysis, mass spectrometry, infrared, electron, NMR, and EPR spectroscopy, cyclic voltammetry and conductometry. The molecular and crystal structure of the complex with 5-chloro-salicylaldehyde 2-furoic acid hydrazone (2) was determined. The quantum chemical properties of the vanadium complexes were studied at B3LYP and M062X levels with the lanl2dz basis set using Gaussian. Additionally, Swiss-ADME analysis was performed and complex (4), featuring a 5-nitro substituent on the hydrazone ligand, was selected for further investigation. The effects of the in vivo application of the complex on selected biochemical parameters in healthy and diabetic Wistar rats were investigated. Strong antidiabetic effect associated with moderate hypoalbuminemia was observed. Furthermore, the interaction of complexes with BSA was studied by spectrofluorimetry. A significant conformational change of BSA in the presence of vanadium complexes was found. Synchronous fluorescence spectra revealed significant changes in the tyrosine microenvironment of BSA. The FRET analysis was also used and the non-radiative process of energy transfer is elucidated. Thermodynamic data suggest van der Waals forces and hydrogen bonding as predominant binding modes of complexes to BSA.
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•Five novel heteroleptic oxidovanadium(IV) hydrazone complexes are reported•Complex with nitro substituent showed promising antidiabetic properties in Wistar rats•Mild hypoalbuminemia was observed in vivo•Moderate affinity of complexes for albumin was found in vitro
•Substituent effects in salicylaldehyde 2-furoic acid hydrazones.•Moderate DNA groove binders.•Moderate BSA binding via van der Waals forces and hydrogen bonding.•Potent antioxidants: nitro & hydroxy ...derivatives comparable to ascorbic acid.•Broad-spectrum antimicrobials; nitro derivative the most potent.
The biological properties of five aroylhydrazones derived from salicylaldehyde and its 5-substituted derivatives with 2-furoic acid hydrazide were thoroughly investigated. NMR analysis confirmed the predominant existence of the aroylhydrazones in the keto-amine form in aqueous solution. Geometries of these compounds were optimized using density functional theory (DFT) calculations with the B3LYP hybrid functional, while ADMET analysis predicted their pharmacokinetic and toxicological properties. Substituent effects on the interactions between the salicyl aroylhydrazones and BSA and DNA were elucidated through experimental and molecular docking studies, revealing the bromo-substituted hydrazone as the most potent binder to both biomolecular targets. Experimental results aligned well with theoretical predictions, indicating that salicyl hydrazones predominantly act as DNA groove binders. Thermodynamic analysis suggested that the hydrazones predominantly interact with BSA through hydrogen bonding and van der Waals forces. Moreover, antioxidant potential assessment using DPPH, ABTS, FRAP, and metal chelating assays demonstrated the potent antioxidant power of nitro and hydroxy-substituted derivatives. Additionally, the antimicrobial properties of hydrazone against Gram-positive and Gram-negative bacteria, as well as fungi, were thoroughly explored, highlighting the nitro derivative as the most prominent candidate with broad-spectrum antimicrobial potential.
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The concept of peptidomimetics is based on structural modifications of natural peptides that aim not only to mimic their 3D shape and biological function, but also to reduce their limitations. The ...peptidomimetic approach is used in medicinal chemistry to develop drug-like compounds that are more active and selective than natural peptides and have fewer side effects. One of the synthetic strategies for obtaining peptidomimetics involves mimicking peptide α-helices, β-sheets or turns. Turns are usually located on the protein surface where they interact with various receptors and are therefore involved in numerous biological events. Among the various synthetic tools for turn mimetic design reported so far, our group uses an approach based on the insertion of different ferrocene templates into the peptide backbone that both induce turn formation and reduce conformational flexibility. Here, we conjugated methyl 1'-aminoferrocene-carboxylate with homo- and heterochiral Pro-Ala dipeptides to investigate the turn formation potential and antiproliferative properties of the resulting peptidomimetics
-
. Detailed spectroscopic (IR, NMR, CD), X-ray and DFT studies showed that the heterochiral conjugates
and
were more suitable for the formation of β-turns. Cell viability study, clonogenic assay and cell death analysis showed the highest biological potential of homochiral peptide
.
Seven pyridoxal dioxime quaternary salts (1–7) were synthesized with the aim of studying their interactions with human acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). The synthesis was ...achieved by the quaternization of pyridoxal monooxime with substituted 2-bromoacetophenone oximes (phenacyl bromide oximes). All compounds, prepared in good yields (43–76%) and characterized by 1D and 2D NMR spectroscopy, were evaluated as reversible inhibitors of cholinesterase and/or reactivators of enzymes inhibited by toxic organophosphorus compounds. Their potency was compared with that of their monooxime analogues and medically approved oxime HI-6. The obtained pyridoxal dioximes were relatively weak inhibitors for both enzymes (Ki = 100–400 µM). The second oxime group in the structure did not improve the binding compared to the monooxime analogues. The same was observed for reactivation of VX-, tabun-, and paraoxon-inhibited AChE and BChE, where no significant efficiency burst was noted. In silico analysis and molecular docking studies connected the kinetic data to the structural features of the tested compound, showing that the low binding affinity and reactivation efficacy may be a consequence of a bulk structure hindering important reactive groups. The tested dioximes were non-toxic to human neuroblastoma cells (SH-SY5Y) and human embryonal kidney cells (HEK293).
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