Use of pyridinium ionic liquids as catalysts for the synthesis of 3,5-bis(dodecyloxycarbonyl)-1,4-dihydropyridine derivative

Evaluation of diethyl 4-(5-bromo-1H-indol-3-yl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate: synthesis, anti-corrosion potential, and biomedical applications

The pursuit of advanced multifunctional compounds has gained significant momentum in recent scientific endeavours. This study is dedicated to elucidating the synthesis, rigorous characterization, and multifaceted applications-encompassing anti-corrosion, antimicrobial, and antioxidant properties-of Diethyl 4-(5-bromo-1H-indol-3-yl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate. The 1,4-dihydropyridine derivative was meticulously synthesized through a strategic reaction of ethyl acetoacetate, ammonium acetate, and 5-bromoindole-3-carboxaldehydein the ethanol medium at 60  C. Subsequent spectral validations were conducted using sophisticated techniques, namely FTIR, NMR, and Mass spectrometry, resulting in data that perfectly resonated with the hypothesized chemical structure of the compound. Its anti-corrosive potential was assessed on mild steel subjected to an aggressive acidic environment, employing comprehensive methodologies like gravimetric analysis, Tafel polarization, and EIS. Concurrently, its antimicrobial prowess was ascertained against a spectrum of bacterial and fungal pathogens viz., Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas, Candida albicansandAspergillusniger, leveraging the disc diffusion method and using Gentamicin as a reference standard.The empirical results illustrated a substantial decrement in corrosion rates with ascending concentrations of the organic compound, achieving an apex of anti-corrosive efficacy at 81.89% for a concentration of 2 × 103 M. Furthermore, the compound outperformed Gentamicin in antimicrobial screenings, manifesting superior efficacy against all tested pathogens. The antioxidant potential, quantified using the DPPH free radical scavenging assay against ascorbic acid as a benchmark, was found to have an IC50 value of 113.964 ± 0.076 µg/ml.This comprehensive investigation accentuates the paramount potential of the synthesized dihydropyridine derivative in diverse domains-from industrial applications as a corrosion inhibitor to therapeutic avenues given its pronounced antimicrobial and antioxidant capabilities. The compelling results obtained pave the way for expansive research and development initiatives cantered around this multifaceted compound.

Toxicity of ionic liquids in marine and freshwater microorganisms and invertebrates: state of the art

The variety of applications and expected growth in ionic liquid production are raising concerns about the release of these compounds into aquatic systems. Up to date, 103 studies have provided ecotoxicological data regarding the exposure effects of Ionic Liquids towards aquatic microorganisms and invertebrate species: 61 were devoted to freshwater species (n = 28), while marine species (n = 12) were mentioned in 42. The aim of this review, by gathering published studies on ionic liquids and model aquatic organisms, was to present the toxic effects described in distinct species and to understand which are the main factors influencing the toxicity of some ionic liquids. In accordance with the most recognized pattern, freshwater species were featured in a higher number of publications than marine ones. After literature analysis, algal species were the most represented organisms in aquatic toxicity assessments. Among tested compounds, the imidazolium cations in combination with long alkyl-chain anions, showed to be the most toxic one. In analytical terms, it is not straightforward to find the undissociated compound in a natural compartment, as ionic liquids are composed of ionic components, easily subjected to dissociation. Given the aforementioned, the present review paper points out the need of increasing the number of organisms being assessed in ionic liquids toxicity assays, in order to start defining monitoring procedures. Moreover, such would allow a better understanding of ionic liquids contamination status and, also, the opportunity to remark the effectiveness of new in silico methods for the ecotoxicity assessment of this kind of substances.

1,1′-{[3,5-Bis((dodecyloxycarbonyl)-4-phenyl-1,4-dihydropyridine-2,6-diyl]bis(methylene)}bis[4-(anthracen-9-yl)pyridin-1-ium] Dibromide

A synthesis of a cationic moiety and fluorescent moieties containing amphiphilic 1,4-dihydropyridine (1,4-DHP) derivatives was performed starting with the Hantzsch-type cyclization of dodecyl acetoacetate, phenylaldehyde and ammonium acetate. Bromination of the 2,6-dimethyl groups of a parent 1,4-DHP compound, followed by nucleophilic substitution of bromine with 4-(anthracen-9-yl)pyridine, produced the desired 1,1′-{[3,5-bis((dodecyloxycarbonyl)-4-phenyl-1,4-dihydropyridine-2,6-diyl]bis(methylene)}bis[4-(anthracen-9-yl)pyridin-1-ium] dibromide. The obtained target compound was fully characterized by the IR, 1H NMR, 13C NMR and HRMS data. Studies of the self-assembling properties and characterization of the nanoparticles obtained by the ethanol injection method were performed using dynamic light scattering (DLS) measurements. DLS measurement data showed that 1,1′-{[3,5-bis((dodecyloxycarbonyl)-4-phenyl-1,4-dihydropyridine-2,6-diyl]bis(methylene)}bis[4-(anthracen-9-yl)pyridin-1-ium] dibromide produced liposomes that had average diameters of 200 nm when the samples were freshly prepared, and 140 nm after 7 days or 1 month storage. The PDI values of the samples were approximately 0.50 and their zeta-potential values were approximately 41 mV when the samples were freshly prepared, and 33 mV after storage. The obtained nanoparticles were stored at room temperature for one month and remained stable during that period. The mean molecular area of the cationic 1,4-DHP-anthracene hybrid 4 was 118 Å2, while the mean molecular area of the cationic 1,4-DHP 5 without anthracene substituents was only 83 Å2. The photoluminescence quantum yield (PLQY) value for the EtOH solution of the 1,4-DHP derivative 4 was 10.8%, but for the 1,4-DHP derivative 5 it was only 1.8%. These types of compounds could be used as synthetic lipids in the further development of prospective theranostic delivery systems.

Synthesis and Characterisation of 1,1′-{[3,5-Bis(dodecyloxy-carbonyl)-4-(thiophen-3-yl)-1,4-dihydropyridine-2,6-diyl]bis-(methylene)}bis(pyridin-1-ium) Dibromide

In the present work, construction of double-charged cationic amphiphilic 1,1′-{[3,5-bis(dodecyl¬oxy-carbonyl)-4-(thiophen-3-yl)-1,4-dihydropyridine-2,6-diyl]bis-(methylene)}bis(pyridin-1-ium) dibromide (7) was performed in four steps. Dodecyl 3-oxobutanoate (1) was condensed with thiophene-3-carbaldehyde (2) which was necessary for Hantzsch cyclisation dodecyl (E/Z)-3-oxo-2-(thiophen-3-ylmethylene)butanoate (3). Two-component Hantzsch type cyclisation of dodecyl (E/Z)-3-aminobut-2-enoate (4) and dodecyl (E/Z)-3-oxo-2-(thiophen-3-ylmethylene)butanoate (3) gave 3,5-bis(dodecyloxycarbonyl)-2,6-dimethyl-4-(thiophen-3-yl)-1,4-dihydropyridine (5). Bromination of compound 5 followed by nucleophilic substitution of bromine with pyridine gave the desired cationic amphiphilic 1,4-dihydropyridine 7. The obtained target compound 7 and new intermediates 3, 5 and 6 were fully characterised by IR, UV, 1H NMR, 13C NMR, HRMS or microanalysis. Characterisation of nanoparticles formed by the cationic 1,4-dihydropyridine 7 in an aqueous solution was performed by DLS measurements.

Evaluation of Physicochemical Properties of Amphiphilic 1,4-Dihydropyridines and Preparation of Magnetoliposomes

This study was focused on the estimation of the targeted modification of 1,4-DHP core with (1) different alkyl chain lengths at 3,5-ester moieties of 1,4-DHP (C₁₂, C₁₄ and C₁₆); (2) N-substituent at position 1 of 1,4-DHP (N-H or N-CH₃); (3) substituents of pyridinium moieties at positions 2 and 6 of 1,4-DHP (H, 4-CN and 3-Ph); (4) substituent at position 4 of 1,4-DHP (phenyl and napthyl) on physicochemical properties of the entire molecules and on the characteristics of the obtained magnetoliposomes formed by them. It was shown that thermal behavior of the tested 1,4-DHP amphiphiles was related to the alkyl chains length, the elongation of which decreased their transition temperatures. The properties of 1,4-DHP amphiphile monolayers and their polar head areas were determined. The packing parameters of amphiphiles were in the 0.43–0.55 range. It was demonstrated that the structure of 1,4-DHPs affected the physicochemical properties of compounds. “Empty” liposomes and magnetoliposomes were prepared from selected 1,4-DHP amphiphiles. It was shown that the variation of alkyl chains length or the change of substituents at positions 4 of 1,4-DHP did not show a significant influence on properties of liposomes.

Pleiotropic Properties of Amphiphilic Dihydropyridines, Dihydropyridones, and Aminovinylcarbonyl Compounds

Three groups of synthetic lipids are chosen for studies: (1) 1,4-dihydropyridines (1,4-DHPs) containing two cationic moieties and their analogues; (2) 3,4-dihydro-2(1H)-pyridones containing a cationic moiety; and (3) acyclic, open-chain analogues, i.e., 2-amino-3-alkoxycarbonylalkylammonium derivatives. 1,4-DHPs possessing dodecyl alkyl chains in the ester groups in positions 3 and 5 and cationic nitrogen-containing groups in positions 2 and 6 have high cytotoxicity in cancer cells HT-1080 (human lung fibrosarcoma) and MH-22A (mouse hepatoma), but low cytotoxicity in the noncancerous NIH3T3 cells (mouse embryonic fibroblast). On the contrary, similar compounds having short (methyl, ethyl, or propoxyethyl) chains in the ester groups in positions 3 and 5 lack cytotoxicity in the cancer cells HT-1080 and MH-22A even at high doses. Inclusion of fluorine atoms in the alkyl chains in positions 3 and 5 of the DHP cycle decreases the cytotoxicity of the mentioned compounds. Structurally related dihydropyridones with a polar head group are substantially more toxic to normal and cancerous cells than the DHP analogues. Open-chain analogues of DHP lipids comprise the same conjugated aminovinylcarbonyl moiety and possess anticancer activity, but they also have high basal cytotoxicity. Electrochemical oxidation data demonstrate that oxidation potentials of selected compounds are in the range of 1.6-1.7 V for cationic 1,4-DHP, 2.0-2.4 V for cationic 3,4-dihydropyridones, and 1.2-1.5 V for 2-amino-3-alkoxycarbonylalkylammonium derivatives. Furthermore, the tested cationic 1,4-DHP amphiphiles possess antiradical activity. Molecular topological polar surface area values for the tested compounds were defined in accordance with the main fragments of compound structures. The determined logP values were highest for dodecyl ester groups in positions 3 and 5 of the 1,4-DHP and lowest for short alkyl chain-containing amphiphiles.

Synthesis and Comparative Evaluation of Novel Cationic Amphiphile C12-Man-Q as an Efficient DNA Delivery Agent In Vitro

New amphiphilic 1,4-DHP derivative C12-Man-Q with remoted cationic moieties at positions 2 and 6 was synthesised to study DNA delivery activity. The results were compared with data obtained for cationic 1,4-DHP derivative D19, which is known to be the most efficient one among the previously tested 1,4-DHP amphiphiles. We analysed the effects of C12-Man-Q concentration, complexation media, and complex/cell contact time on the gene delivery effectiveness and cell viability. Transmission electron microscopy data confirms that lipoplexes formed by the compound C12-Man-Q were quite uniform, vesicular-like structures with sizes of about 50 nm, and lipoplexes produced by compound D19 were of irregular shapes, varied in size in the range of 25⁻80 nm. Additionally, confocal microscopy results revealed that both amphiphiles effectively delivered green fluorescent protein expression plasmid into BHK-21 cells and produced a fluorescent signal with satisfactory efficiency, although compound C12-Man-Q was more cytotoxic to the BHK-21 cells with an increase of concentration. It can be concluded that optimal conditions for C12-Man-Q lipoplexes delivery in BHK-21 cells were the serum free media without 0.15 M NaCl, at an N/P ratio of 0.9. Compound D19 showed higher transfection efficiency to transfect BHK-21 and Cos-7 cell lines, when transfecting active proliferating cells. Although D19 was not able to transfect all studied cell lines we propose that it could be cell type specific. The compound C12-Man-Q showed modest delivery activity in all used cell lines, and higher activity was obtained in the case of H2-35 and B16 cells. The transfection efficiency in cell lines MCF-7, HeLa, and Huh-7 appears to be comparable to the reference compound D19 and minimal in the HepG2 cell line.

Study of interactions of mononucleotides with 1,4-dihydropyridine vesicles using NMR and ITC techniques

The possible binding site of mononucleotides is the phosphate group with important hydrophobic interactions between the mononucleotides and the alkyl chains of DHP derivatives.

Direct Aminolysis of Ethoxycarbonylmethyl 1,4-Dihydropyridine-3-carboxylates

The ethoxycarbonylmethyl esters of 1,4-dihydropyridines were directly converted into carbamoylmethyl esters in the presence of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) in good to excellent yields under mild conditions. The use of TBD is crucial for the successful aminolysis of ethoxycarbonylmethyl ester of 1,4-dihydropyridines with secondary amines as without it the reaction does not proceed at all. The aminolysis reaction proceeded regioselectively, as the alkyl ester conjugated with the 1,4-dihydropyridine cycle was not involved in the reaction. Screening of other N-containing bases, such as triethylamine (TEA), pyridine, 4-(N,N-dimethylamino)pyridine (DMAP), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), imidazole, tetramethyl guanidine (TMG) and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD) as catalysts revealed no activity in the studied reaction.

Bilayer properties of giant magnetic liposomes formed by cationic pyridine amphiphile and probed by active deformation under magnetic forces

We synthesize giant magnetic liposomes by a reverse-phase evaporation method (REV) using a new self-assembling Cationic Pyridine Amphiphile (CPA) derived from 1,4-dihydropyridine as liposome-forming agent and a magnetic ferrofluid based on γ-Fe(2)O(3) nanoparticles. Having in view the potential interest of CPA in targeted transport by magnetic forces, the mechanical elastic properties of such bilayers are here directly investigated in vesicles loaded with magnetic nanoparticles. Bending elastic modulus K(b) ∼ 0.2 to 5k(B)T and pre-stress τ ∼ 3.2 to 12.10(-6) erg/cm(2) are deduced from the under-field deformations of the giant magnetic liposomes. The obtained K(b) values are discussed in terms of A. Wurgers's theory.