1,1′-{[3,5-Bis(dodecyloxycarbonyl)-4-(naphthalen-2-yl)-1,4-dihydropyridine-2,6-diyl]bis(methylene)}bis{4-[(E)-2-(naphthalen-2-yl)vinyl]pyridin-1-ium}dibromide

Funding Information: Funding: This research was funded by the EuroNanoMed3 project TENTACLES No ES RTD/2020/18. Publisher Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland.Synthesis of a double-charged cationic amphiphilic 1,4-dihydropyridine derivative with dodecyl ester groups at positions 3 and 5 of the 1,4-DHP ring was performed starting from Hantzsch type cyclization of dodecyl acetoacetate, 2-naphthaldehyde and ammonium acetate. Bromination of this compound followed by nucleophilic substitution of bromine with (E)-4-(2-(naphthalen-2-yl)vinyl)pyridine gave the desired cationic amphiphilic 1,1′-{[3,5-bis(dodecyloxycarbonyl)-4-(naph-thalen-2-yl)-1,4-dihydropyridine-2,6-diyl]bis(methylene)}bis{4-[(E)-2-(naphthalen-2-yl)vinyl]pyridin-1-ium}dibromide. The obtained target compound was fully characterized by IR, UV,1 H-NMR,13 C-NMR, HRMS and microanalysis. The characterization of the cationic 1,4-DHP nanoparticles in an aqueous solution was performed by DLS measurements. The obtained results showed that the compound formed nanoparticles with an average diameter of around 300 nm, a PDI value of around 490 and a zeta-potential of around 20 mV for freshly prepared samples. However, after one week of storage at room temperature, an aggregation of nanoparticles was detected.publishersversionPeer reviewe

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

Funding Information: Funding: This research was funded by The Joint Ukraine-Latvia R&D Project “Design and study of physicochemical properties and bioactivity of self-assembling calixarene and dihydropyridine hybrids for DNA delivery”, grant number LV-UA/2020/3. Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.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,1 H NMR,13 C NMR, HRMS or microanalysis. Characterisation of nanoparticles formed by the cationic 1,4-dihydropyridine 7 in an aqueous solution was performed by DLS measurements.publishersversionPeer reviewe

Synthesis and Evaluation of Self-Assembling Properties of 3-(3,5-Difluoro-3,5-bis((alkoxy)carbonyl)-2,6-dioxoheptan-4-yl)-1-methylpyridin-1-ium Iodides

Funding Information: Funding: This research was funded by EuroNanoMed3 project NANO4GLIO No ES RTD/2020/9 and PostDocLatvia Project No 1.1.1.2/VIAA/3/19/587 (K.Pajuste). Publisher Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland.A synthesis of 3-(3,5-difluoro-3,5-bis((alkoxy)carbonyl)-2,6-dioxoheptan-4-yl)-1-methylpyridin-1-ium iodides with ethyl or nonyl ester groups at positions 3 and 5 was performed. Treatment of the corresponding 2’,6’-dimethyl-1’,4’-dihydro-[3,4’-bipyridine]-3’,5’-dicarboxylates with Selectfluor® followed by quaternization of pyridine moiety in the obtained dialkyl 2,4-diacetyl-2,4-difluoro-3-(pyridin-3-yl)pentanedioates with methyl iodide gave the desired 3-(3,5-difluoro-3,5-bis((alkoxy)carbonyl)-2,6-dioxoheptan-4-yl)-1-methylpyridin-1-ium iodides. This type of compound would be useful as synthetic lipids for further development of the delivery systems. The obtained target compounds were fully characterized by1H NMR,19F NMR,13C NMR, HRMS, IR and UV data. The estimation of self-assembling properties and characterization of the nanoparticles obtained by ethanol solution injection in an aqueous media were performed by dynamic light scattering (DLS) measurements. DLS measurement data showed that 3-(3,5-difluoro-3,5-bis((nonyloxy)carbonyl)-2,6-dioxoheptan-4-yl)-1-methylpyridin-1-ium iodide created liposomes with the average diameter of 300–400 nm and polydispersity index (PDI) value around 0.30–0.40, while 3-(3,5-difluoro-3,5-bis((ethyloxy)carbonyl)-2,6-dioxoheptan-4-yl)-1-methylpyridin-1-ium iodide formed a heterogeneous sample with PDI value 1, which was not prospective for delivery system development.publishersversionPeer reviewe

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

Funding Information: This research was funded by the EuroNanoMed3 Project NANO4GLIO No ES RTD/2020/9, the PostDocLatvia Project No 1.1.1.2/VIAA/2/18/373 (N.P.) and the PostDocLatvia Project No 1.1.1.2/VIAA/3/19/587 (K.P.). Publisher Copyright: © 2022 by the authors.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.publishersversionPeer reviewe

Data for characterisation of nanoformulations formed by cationic 1,4-dihydopyridine and calix[4]arene compositions

Funding Information: This research was funded by The Joint Ukraine-Latvia R&D Project ??Design and study of physicochemical properties and bioactivity of self-assembling calixarene and dihydropyridine hybrids for DNA delivery??, grant number LV-UA/2020/3. The authors would like to acknowledge to Institute of Chemical Physics, University of Latvia, Riga, Latvia for support with SEM imaging. Authors are thankful to Mr. Aldis Janis Pivars for technical assistance. Publisher Copyright: © 2022In this data file the characterisation of nanoformulations obtained from calix[4]arene/1,4-dihydropyridine (1,4-DHP) compositions in the various component ratio in an aqueous medium was performed by dynamic light scattering (DLS) technique. The hydrodynamic diameters of nanoparticle main population, polydispersity index and stability of nanoformulation were determined. In this article provided data are directly related to the previously published research articles – “Gene delivery agents possessing antiradical activity: Self-assembling cationic amphiphilic 1,4-dihydropyridine derivatives” [1], and “Studies of the physicochemical and structural properties of self-assembling cationic pyridine derivatives as gene delivery agents” [2] where was described synthesis, transfection activity of 1,1′-((3,5-bis((dodecyloxy)carbonyl)-4-phenyl-1,4-dihydropyridine-2,6-diyl)bis(methylene))bis(pyridin-1-ium) dibromide presented in this data file; and with articles “Cationic amphiphilic calixarenes to compact DNA into small nanoparticles for gene delivery” [3] and “Self-aggregation in aqueous solution of amphiphilic cationic calix[4]arenes. Potential use as vectors and nanocarriers” [4] where was described synthesis and ability to condense DNA for also mentioned calix[4]arenes – 5,11,17,23-tetra-(3-methylimidazolium)-methylene-25,26,27,28-etradodecyloxycalix[4]arene tetrachloride, 5,11,17,23-tetra(N,N-dimethyl-N-hydroxyethylammonium)-methylene-25,26,27,28-tetradodecyloxycalix[4]arene tetrachloride and 5,11,17,23-tetra(N,N-dimethyl-N-hydroxyethylammonium)-methylene-25,26,27,28-tetrahexadecyloxycalix[4]arene tetrachloride. Information provided in this data file can be used in medicinal chemistry for development of novel synthetic lipid nanoformulations.publishersversionPeer reviewe

Evaluation of physicochemical properties of amphiphilic 1,4-dihydropyridines and preparation of magnetoliposomes

Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.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.publishersversionPeer reviewe

Synthesis and comparative evaluation of novel cationic amphiphile C12-Man-Q as an efficient DNA delivery agent in vitro

Funding Information: This research was funded by the National Research programme “Biomedicine for Public Health” (BIOMEDICINE) (2014–2017): Project: No 3 “Development of novel anticancer drugs and immunotherapeutic approaches”. We are indebted to Dr.habil. V.Ose for transmission electron microscopy analysis. Funding Information: Funding: This research was funded by the National Research programme “Biomedicine for Public Health” (BIOMEDICINE) (2014–2017): Project: No 3 “Development of novel anticancer drugs and immunotherapeutic approaches”. Publisher Copyright: © 2018 by the authors.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.publishersversionPeer reviewe

Contribution of molecular structure to self-assembling and biological properties of bifunctional lipid-like 4-(N-alkylpyridinium)-1,4-Dihydropyridines

Funding Information: Funding: This research was funded by the EuroNanoMed2 project INNOCENT, PostDoc project Synthesis of new magneto-active functional nanomaterials (1.1.1.2/VIAA/1/16/018) (for O.P.), PostDoc project Molecular mechanisms of purine and pyrimidine auxotrophic starvation in budding yeast (YEAUX) (1.1.2/1/16/067) (for J.L.) and scientific grant from the Student Council of University of Latvia (for S.K.). Publisher Copyright: © 2019 by the authors. Licensee MDPI, Basel, Switzerland.The design of nanoparticle delivery materials possessing biological activities is an attractive strategy for the development of various therapies. In this study, 11 cationic amphiphilic 4-(N-alkylpyridinium)-1,4-dihydropyridine (1,4-DHP) derivatives differing in alkyl chain length and propargyl moiety/ties number and position were selected for the study of their self-assembling properties, evaluation of their cytotoxicity in vitro and toxicity on microorganisms, and the characterisation of their interaction with phospholipids. These lipid-like 1,4-DHPs have been earlier proposed as promising nanocarriers for DNA delivery. We have revealed that the mean diameter of freshly prepared nanoparticles varied from 58 to 513 nm, depending upon the 4-(N-alkylpyridinium)-1,4-DHP structure. Additionally, we have confirmed that only nanoparticles formed by 4-(N-dodecylpyridinium)-1,4-DHP derivatives 3 and 6, and by 4-(N-hexadecylpyridinium)-1,4-DHP derivatives 10 and 11 were stable after two weeks of storage. The nanoparticles of these compounds were found to be homogenous in size distribution, ranging from 124 to 221 nm. The polydispersity index (PDI) values of 1,4-DHPs samples 3, 6, 10, and 11 were in the range of 0.10 to 0.37. We also demonstrated that the nanoparticles formed by 4-(N-dodecylpyridinium)-1,4-DHP derivatives 3, 6, and 9, and 4-(N-hexadecylpyridinium)-1,4-DHP derivatives 10 and 11 had zeta-potentials from +26.07 mV (compound 6) to +62.80 mV (compound 11), indicating a strongly positive surface charge and confirming the relative electrostatic stability of these nanoparticle solutions. Transmission electron microscopy (TEM) images of nanoaggregates formed by 1,4-DHPs 3 and 11 confirmed liposome-like structures with diameters around 70 to 170 nm. The critical aggregation concentration (CAC) value interval for 4-(N-alkylpyridinium)-1,4-DHP was from 7.6 µM (compound 11) to 43.3 µM (compound 6). The tested 4-(N-alkylpyridinium)-1,4-DHP derivatives were able to quench the fluorescence of the binary 1,6-diphenyl-1,3,5-hexatriene (DPH)—1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) system, demonstrating hydrophobic interactions of 1,4-DHPs with phospholipids. Thus, 4-(N-dodecylpyridinium)-1,4-DHP derivative 3 quenched the fluorescence of the DPH–DPPC system more efficiently than the other 4-(N-alkylpyridinium)-1,4-DHP derivatives. Likewise the compound 3, also 4-(N-dodecylpyridinium)-1,4-DHP derivative 9 interacted with the phospholipids. Moreover, we have established that increasing the length of the alkyl chain at the quaternised nitrogen of the 4-(N-alkylpyridinium)-1,4-DHP molecule or the introduction of propargyl moieties in the 1,4-DHP molecule significantly influences the cytotoxicity on HT-1080 (human fibrosarcoma) and MH-22A (mouse hepatocarcinoma) cell lines, as well as the estimated basal cytotoxicity. Additionally, it was demonstrated that the toxicity of the 4-(N-alkylpyridinium)-1,4-DHP derivatives on the Gram-positive and Gram-negative bacteria species and eukaryotic microorganism depended on the presence of the alkyl chain length at the N-alkyl pyridinium moiety, as well as the number of propargyl groups. These lipid-like compounds may be proposed for the further development of drug formulations to be used in cancer treatment.publishersversionPeer reviewe

Selected strategies to fight pathogenic bacteria

Natural products and analogues are a source of antibacterial drug discovery. Considering drug resistance levels emerging for antibiotics, identification of bacterial metalloenzymes and the synthesis of selective inhibitors are interesting for antibacterial agent development. Peptide nucleic acids are attractive antisense and antigene agents representing a novel strategy to target pathogens due to their unique mechanism of action. Antisense inhibition and development of antisense peptide nucleic acids is a new approach to antibacterial agents. Due to the increased resistance of biofilms to antibiotics, alternative therapeutic options are necessary. To develop antimicrobial strategies, optimised in vitro and in vivo models are needed. In vivo models to study biofilm-related respiratory infections, device-related infections: ventilator-associated pneumonia, tissue-related infections: chronic infection models based on alginate or agar beads, methods to battle biofilm-related infections are discussed. Drug delivery in case of antibacterials often is a serious issue therefore this review includes overview of drug delivery nanosystems.Peer reviewe

Recent Approaches to Chiral 1,4-Dihydropyridines and their Fused Analogues

The purpose of this review is to highlight recent developments in the synthesis of chiral 1,4-dihydropyridines and their fused analogues. 1,4-Dihydropyridines are among the most active calcium antagonists that are used for the treatment of hypertension. Enantiomers of unsymmetrical 1,4-dihydropyridines often show different biological activities and may have even an opposite action profile. Hantzsch synthesis usually produces racemic mixtures of unsymmetrical 1,4-dihydropyridines. Therefore, the development of stereoselective synthesis of 1,4-dihydropyridines is one of the priorities of medicinal chemistry. Over the years, numerous methodologies have been developed for the production of enantiopure 1,4-dihydropyridines, such as stereoselective synthesis using chiral auxiliaries and chiral cyclocondensation partners, chromatographical methods, resolution of diastereomeric 1,4-dihydropyridine salts, enzyme catalysed kinetic resolution, or asymmetrisation of ester groups of 1,4-dihydropyridines. These approaches have been studied in detail and are relatively well established. The catalytic asymmetric approach holds the greatest promise in delivering the most practical and widely applicable methods. Substantial progress has been made toward the development of enantioselective organocatalytic methods for the construction of the chiral dihydropyridines. However, most of them do not provide a convenient way to pharmacologically important 1,4-dihydropyridine-3,5-dicarboxylates. Organocatalytic enantioselective desymmetrisation of prochiral 1,4-dihydropyridine-3,5-dicarbaldehydes also has great promise in the synthesis of pharmacologically important 1,4-dihydropyridine-3,5-dicarboxylates