1,4-Dihydropyridine Antihypertensive Drugs: Recent Advances in Photostabilization Strategies

Recent advances in metal-free catalysts for the synthesis of N-heterocyclic frameworks focusing on 5- and 6-membered rings: a review

The tremendous potential of transition metal-free multi-component reactions (MCR) in the synthesis of N-heterocyclic frameworks is examined in this review, offering a complete overview of this subject matter. The discussion on the mechanistic rationale of the reaction routes and intermediates provides profound insights into the underlying changes, encouraging deeper investigation into various molecular frameworks. This review serves as a doorway to study the practicality of exploiting these reactions for the efficient and uncomplicated synthesis of specific nitrogen heterocycles. Specifically, we reveal the potential of transition metal-free catalysts in this field. Because of their extensive scope and diversity, these reactions enable the synthesis of various heterocycles that contain nitrogen, which include 5-membered (carbazole, pyrimidines, and pyrroles) and 6-membered rings (piperidine, pyridine, quinoline, diazinane, pyrazine, quinoxaline, and 1,2,3-triazine). In addition, the compatibility of transition metal-free catalysts with various functional groups and substrates not only increases the synthetic value of these compounds but also broadens their relevance in the domains of medical chemistry, materials science, and other relevant areas of study. To motivate future study and development in this field, the successful examples described in this review highlight the potential of transition metal-free catalysts as powerful instruments for the quick and efficient synthesis of nitrogen heterocycles. In general, this review provides a thorough and insightful examination of transition metal-free catalysts, highlighting the relevance of these compounds in contemporary organic synthesis and their potential to revolutionize the field of nitrogen heterocycle synthesis.

Biginelli dihydropyrimidines and their acetylated derivatives as L-/T-type calcium channel blockers: Synthesis, enantioseparation, and molecular modeling studies

Biginelli dihydropyrimidines (DHPMs) are considered superior over 1,4-dihydropyridines (DHPs) in terms of both light and metabolic stabilities. Nevertheless, DHPs dominate the market as the most prescribed calcium channel blockers with strong therapeutic potential in managing cardiovascular ailments. To overcome the restrictions that complicate the formulation and postadministration of DHPs, employing bioisosteric replacement by exchanging the DHP ring with DHPM appears as a logical approach for the improved formulations of new calcium channel blockers. In this study, we obtained DHPM derivatives via Biginelli synthesis and acetylated their N-3 position by heating them in acetic anhydride (GD1-GD12). We also incorporated the DHPM scaffold into a condensed ring system (GD13 and GD14). These DHPMs were evaluated for their ability to block both L- (Cav1.2) and T- (Cav3.2) type calcium channels. Compounds carrying acetyl moiety on the N-3 position of the DHPM scaffold appeared to be more effective inhibitors of both channels. Retesting GD4 enantiomers, separated using high-performance liquid chromatography (HPLC) on a chiral stationary phase, revealed that the (R)-isomer predominantly contributes to the outstanding inhibitory activity of GD4 on calcium channels. Molecular modeling studies, including docking, molecular dynamics simulations, and dynophore analysis, provided insights into the binding mechanism of DHPMs to Cav1.2 and Cav3.2, for the first time.

Enantioselective Synthesis of Spiro[Indoline-3,4-Pyrrolo[3,4-b]Pyridines] Via an Organocatalysed Three-Component Cascade Reaction

Asymmetric synthesis of derivatives of spiro[indoline-3,4-pyrrolo[3,4-b]pyridines] were first developed through the organocatalytic cascade of Knoevenagel/Michael/cyclization reactions using a quinidine-derived squaramide. Under the optimized conditions, the three-component reactions of isatins, cyanoacetates, and 3-aminomaleimides yield the desired heterocycle-fused spirooxindoles in good yields (78-91 %) with 53 %-99 % enantiomeric excess (ee). Notably, this reaction enables a broad substrate scope under mild conditions and provides a convenient method for the enantioselective construction of diverse spirooxindoles combined with dihydropyridine and maleimide skeletons, which has great potential for the construction of new bioactive chemical entities.

Cyclodextrins and their applications in pharmaceutical and related fields

This chapter presents an overall account of cyclodextrins (CDs) with a brief description of the history, classification, and properties of these macromolecules. CDs act as complexing agents for drugs to form CD-drug inclusion complexes by various techniques. These complexes lead to the modification of the physicochemical properties of drugs to make them more soluble, chemically, and photochemically stable, and less toxic. It focuses in detail on various pharmaceutical uses of CDs and their derived forms in drug solubility, bioavailability, drug stability, drug delivery, and drug safety which have been specifically highlighted. The role of CDs and derivatives as excipients in the drug formulation of solid dosage forms, parenteral dosage forms, and anticancer drugs has been emphasized. Some other applications of CDs in cosmetics, environmental protection, food technology, and analytical methods have been described.

Grignard Reagent Addition to Pyridinium Salts: A Catalytic Approach to Chiral 1,4-Dihydropyridines

Catalytic dearomatization of pyridinium salts is a powerful technique for constructing chiral N-heterocycles, which are crucial in alkaloid natural products and drugs. Despite its potential, progress in metal-catalyzed asymmetric dearomatization of pyridinium derivatives has been limited. Here, we present the enantioselective 1,4-dearomatization of pyridinium salts using Grignard reagents and chiral copper catalysis. This approach yields enantioenriched functionalized 1,4-dihydropyridines. Experimental kinetic isotope effects and density functional theory calculations provide insights into the reaction mechanism, regio- and enantioselectivity, and the rate-limiting step.

Anticancer potential of novel symmetrical and asymmetrical dihydropyridines against breast cancer via EGFR inhibition: molecular design, synthesis, analysis and screening

A series of novel symmetrical and asymmetrical dihydropyridines (HD 1-15) were designed, subjected to in silico ADMET prediction, synthesized, analyzed by IR, NMR, Mass analytical techniques and evaluated against epidermal growth factor receptor (EGFR) as inhibitors against Breast cancer. The results of predicted ADMET studies demonstrated the drug-likeness properties of the reported compounds. The in vitro cytotoxicity assessment of the synthesized compounds revealed that all of them showed good activity (IC50 ranging from 16.75 to 66.54 μM) towards MCF-7 breast cancer cells compared to the standard drug, Lapatinib (IC50 = 2.02 μM). Among these, compounds HD-6, HD-7, and HD-8 displayed the most potent activity with IC50 value of 21.26, 16.75, and 18.33 μM, respectively. Cytotoxicity of all compounds was tested on normal vero cells for comparison at different concentrations using the MTT assay. In addition to the MTT assay, the potent dihydropyridines derivatives were screened for EGFRwt kinase inhibition assay at concentrations ranging from 1 nM to 360 nM. Among the three compounds tested, HD-8 showed reasonably good inhibition with an IC50 value of 15.90 ± 1.20 nM compared to a standard Lapatinib IC50 value of 10.28 ± 1.01 nM. Based on the molecular docking study against EGFR, the most active derivatives HD-7 and HD-8 were docked against the active site of the protein and showed better binding affinity than the standard lapatinib. Additionally, molecular dynamics (MD) simulations were performed to explore the stability of the protein-ligand complex, its dynamic behavior, and the binding affinity.

Facile One-Pot Synthesis and Anti-Microbial Activity of Novel 1,4-Dihydropyridine Derivatives in Aqueous Micellar Solution under Microwave Irradiation

The current study describes a novel and eco-conscious method to synthesize 1,4-dihydropyridine derivatives utilizing an aqueous micellar solution containing aluminum dodecyl sulfate, Al(DS)3, using readily available starting material. The final products were synthesized with excellent yields within remarkably quick reaction durations, promoting remarkable atom economy and minimizing environmental impacts. The present protocol has several advantages over other methodologies in terms of high yield (up to 97%) with excellent purity. Further, the synthesized 1,4-DHPs exhibit favorable to excellent resistance against examined bacterial and fungal species. Intriguingly, polar groups on the phenyl ring (5b, 5c, 5i and 5j) make the 1,4-DHPs equally potent against the microbes as compared to the standard drugs.

Design, synthesis, pharmacological evaluation, and in silico studies of the activity of novel spiro pyrrolo[3,4-d]pyrimidine derivatives

In the present study, spiro compounds are shown to have distinctive characteristics because of their interesting conformations and their structural impacts on biological systems. A new family of functionalized spiro pyrrolo[3,4-d]pyrimidines is prepared via the one-pot condensation reaction of amino cyclohexane derivatives with benzaldehyde to prepare fused azaspiroundecanedione and azaspirodecenone/thione derivatives. A series of synthesized spiro compounds were scanned against DPPH and evaluated for their ability to inhibit COX-1 and COX-2. All compounds exhibit significant antiinflammatory activity, and they inhibited both COX-1 and COX-2 enzymes with a selectivity index higher than celecoxib as a reference drug. The most powerful and selective COX-2 inhibitor compounds were 11 and 6, with selectivity indices of 175 and 129.21 in comparison to 31.52 of the standard celecoxib. However, candidate 14 showed a very promising antiinflammatory activity with an IC50 of 6.00, while celecoxib had an IC50 of 14.50. Our findings are promising in the area of medicinal chemistry for further optimization of the newly designed and synthesized compounds regarding the discussed structure-activity relationship study (SAR), in order to obtain a superior antioxidant lead compound in the near future. All chemical structures of the novel synthesized candidates were unequivocally elucidated and confirmed utilizing spectroscopic and elemental investigations.

Synthesis and Evaluation of Novel Substituted N-Aryl 1,4-Dihydropyridines as Antituberculostatic Agents

BACKGROUND

Tuberculosis has been the main cause of mortality of infectious diseases worldwide, with strongly limited therapeutic options. With increasing resistance and missing suitable drugs in those cases, there is a strong need for novel antituberculostatic drugs. We developed novel N-aryl 1,4-dihydropyridines with various substitution patterns to evaluate them as antituberculostatic agents.

METHODS

1,4-Dihydropyridine derivatives were synthesized and purified by column chromatography or recrystallization. The mycobacterial growth inhibition was determined in a fluorescent mycobacterial growth assay.

RESULTS

The compounds were prepared in a simple one-pot reaction under acidic conditions with structurally varied components. The substituent effects on the determined mycobacterial growth inhibitory properties are discussed.

CONCLUSION

Lipophilic diester substituted derivatives show promising activities that were additionally affected by the aromatic substituent functions. Thus, we identified compounds with activities almost reaching that of the used antimycobacterial drug as control.

Biological evaluation, docking studies, and in silico ADME prediction of some pyrimidine and pyridine derivatives as potential EGFRWT and EGFRT790M inhibitors

Herein, a set of pyridine and pyrimidine derivatives were assessed for their impact on the cell cycle and apoptosis. Human breast cancer (MCF7), hepatocellular carcinoma (HEPG2), larynx cancer (HEP2), lung cancer (H460), colon cancers (HCT116 and Caco2), and hypopharyngeal cancer (FADU), and normal Vero cell lines were used. Compounds 8 and 14 displayed outstanding effects on the investigated cell lines and were further tested for their antioxidant activity in MCF7, H460, FADU, HEP2, HEPG2, HCT116, Caco2, and Vero cells by measuring superoxide dismutase (SOD), malondialdehyde content (MDA), reduced glutathione (GSH), and nitric oxide (NO) content. Besides, Annexin V-FITC apoptosis detection and cell cycle DNA index using the HEPG-2 cell line were established on both compounds as well. Furthermore, compounds 8 and 14 were assessed for their EGFR kinase (Wild and T790M) inhibitory activities, revealing eligible potential. Additionally, molecular docking, ADME, and SAR studies were carried out for the investigated candidates.

Construction of 1,4-Dihydropyridines: The Evolution of C4 Source

The field of cascade cyclization for the construction of 1,4-dihydropyridines (1,4-DHPs) has been continuously expanding during the last decades because of their broad-spectrum biological and synthetic importance. To date, many methods have been developed, mainly including the Hantzsch reaction, Hantzsch-like reaction and newly developed cascade cyclization, in which various synthons have been successively developed as C4 sources of 1,4-DHPs. This review presents the cascade cyclization synthesis strategy for the construction of 1,4-DHPs according to various C4 sources from carbonyl compounds, alkenyl fragments, alcohols, aliphatic amines, glycines and other C4 sources.

Synthesis of 4-Alkylated 1,4-Dihydropyridines: Fe(II)-Mediated Oxidative Cascade Cyclization Reaction of Cyclic Ethers with Enaminones

Syntheses of highly functionalized 4-alkylated 1,4-dihydropyridines (1,4-DHPs) from cyclic ethers and enaminones via iron(II)-mediated oxidative free radical cascade C(sp3)-H bond functionalization/C(sp3)-O bond cleavage/cyclization reaction have been first developed. This novel synthetic strategy offers an alternative method for the construction of 1,4-DHPs by using esters as the C4 sources, as well as expands the application of ethers in heterocycle synthesis.

Visible-light-induced organophotocatalytic and singlet oxygen-initiated domino construction of 1,4-dihydropyridines, C-3 functionalized spiro[indoline-3,4'-pyridines] and C-11 functionalized spiro[indeno-[1,2-b]quinoxaline-11,4'-pyridines]

A highly efficient pot, atom, and step economical method for the construction of pharmacologically potent structurally functionalized 1,4-dihydropyridines, quaternary centered C-3 functionalized spiro[indoline-3,4'-pyridines], and C-11 functionalized spiro[indeno[1,2-b]quinoxaline-11,4'-pyridines] via rose bengal photoredox catalysis under blue LED irradiation in an aqueous medium at room temperature has been developed. The products were isolated in excellent yields within a short reaction time for a variety of functional groups under transition metal- and ligand-free energy-efficient conditions in a green solvent system with high reaction mass efficiency and process mass intensity, which are the key advantages of the current work.

Synthesis, characterization, crystal structure and Hirshfeld surface analysis of a hexa-hydro-quinoline derivative: tert-butyl 4-([1,1'-biphen-yl]-4-yl)-2,6,6-trimethyl-5-oxo-1,4,5,6,7,8-hexa-hydro-quinoline-3-carboxyl-ate

The title compound, C29H33NO3, crystallizes with three mol-ecules (A, B and C) in the asymmetric unit. They differ in the twist of the phenyl and benzene rings of the 1,1'-biphenyl ring with respect to the plane of the 1,4-di-hydro-pyridine ring. In all three mol-ecules, the 1,4-di-hydro-pyridine ring adopts a distorted boat conformation. The cyclo-hexene ring has an envelope conformation in mol-ecules A and B, while it exhibits a distorted half-chair conformation for both the major and minor components in the disordered mol-ecule C. In the crystal, mol-ecules are linked by C-H⋯O and N-H⋯O hydrogen bonds, forming layers parallel to (100) defining R 1 4(6) and C(7) graph-set motifs. Additional C-H⋯π inter-actions consolidate the layered structure. Between the layers, van der Waals inter-actions stabilize the packing, as revealed by Hirshfeld surface analysis. The greatest contributions to the crystal packing are from H⋯H (69.6% in A, 69.9% in B, 70.1% in C), C⋯H/H⋯C (20.3% in A, 20.6% in B, 20.3% in C) and O⋯H/H⋯O (8.6% in A, 8.6% in B, 8.4% in C) inter-actions.

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

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-(naphthalen-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, 1H-NMR, 13C-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.

Photokinetics of Dacarbazine and Nifedipine under polychromatic light irradiation and their application as new reliable actinometers for the ultraviolet range

The photokinetic behaviour of drugs driven by polychromatic light is an area of pharmaceutics that has not received a lot of attention. Most often, such photokinetic data is treated by thermal kinetic models (i.e., the classical 0th-, 1st- or 2nd-order equations). Such models were not analytically derived from the rate-laws of the photodegradation reactions. Polychromatic light kinetic modelling is hence of importance, as a means to providing adequate toolkits and metrics. This paper aims at proposing two reliable drug-actinometers useful for polychromatic UVA range. The general actinometric methodology offered here is also useful for any drugs/materials obeying a primary photoprocess where both reactant and photoproduct absorb the incident light, of the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$AB{(1\Phi )}_{{\varepsilon }_{B}\ne 0}$$\end{document}AB(1Φ)εB≠0 type. The present method has been consolidated by the η-order kinetics. This framework further demonstrated the lamp-specificity of actinometers. Overall, Dacarbazine and Nifedipine photodegradations obeyed η-order kinetics, and stand as effective actinometers that can be recommended for the ICH Q1b photostability testing.

Application of novel metal-organic framework [Zr-UiO-66-PDC-SO3H]FeCl4 in the synthesis of dihydrobenzo[g]pyrimido[4,5-b]quinoline derivatives

In the current paper, we produce a new metal-organic framework (MOF) based on Zr metal, [Zr-UiO-66-PDC-SO3H]FeCl4, via an anion exchange method, which is fully characterized by FT-IR, SEM with elemental mapping and EDX, FE-SEM and TEM. Furthermore, the use of [Zr-UiO-66-PDC-SO3H]FeCl4 as a porous catalyst was examined for the one-pot synthesis of novel dihydrobenzo[g]pyrimido[4,5-b]quinoline derivatives by reaction of 6-amino-1,3-dimethylpyrimidine-2,4(1H,3H)-dione, 2-hydroxynaphthalene-1,4-dione and various aldehydes at 100 °C with good to excellent yields.

Preparation and Characterization of Indomethacin Supramolecular Systems with β-Cyclodextrin in Order to Estimate Photostability Improvement

Cyclodextrins have found wide application in contemporary chemistry, pharmacy and medicine. Because of their unique properties, cyclodextrins are constantly used in research on solubility or stability improvement, as well as other physicochemical properties of medicinal substances. Indomethacin (IND) is a photolabile molecule that also attracts the interest of researchers due to its therapeutic potential and the need to overcome its problematic photosensitivity. Supramolecular complexes of indomethacin with β-cyclodextrin (CD) are already known, and they show greater stability compared to complexes with other types of cyclodextrins. So far, however, the sensitivity to light of physical mixtures and inclusion complexes in the solid phase has not been studied, and their various stoichiometries have not yet been investigated. Due to this fact, the aim of the present study is to obtain supramolecular systems (inclusion complexes and physical mixtures) of indomethacin with three different amounts of β-cyclodextrin. Assessment of the photochemical stability of indomethacin-β-cyclodextrin systems in the solid state is performed in order to find the best correlation between IND stability and the amount of CD. Comparative analysis of physicochemical degradation for stoichiometry systems [CD:IND] = [1:1], [0.5:1] and [0.1:1] is performed by using ultraviolet spectroscopy, transmission—FTIR, reflection—ATR-FTIR infrared spectroscopy and DSC calorimetry.

Synthesis and Toxicity Evaluation of New Pyrroles Obtained by the Reaction of Activated Alkynes with 1-Methyl-3-(cyanomethyl)benzimidazolium Bromide

A series of new pyrrole derivatives were designed as chemical analogs of the 1,4-dihydropyridines drugs in order to develop future new calcium channel blockers. The new tri- and tetra-substituted N-arylpyrroles were synthesized by the one-pot reaction of 1-methyl-3-cyanomethyl benzimidazolium bromide with substituted alkynes having at least one electron-withdrawing substituent, in 1,2-epoxybutane, acting both as the solvent and reagent to generate the corresponding benzimidazolium N3-ylide. The structural characterization of the new substituted pyrroles was based on IR, NMR spectroscopy as well as on single crystal X-ray analysis. The toxicity of the new compounds was assessed on the plant cell using Triticum aestivum L. species and on the animal cell using Artemia franciscana Kellogg and Daphnia magna Straus crustaceans. The compounds showed minimal phytotoxicity on Triticum rootlets and virtually no acute toxicity on Artemia nauplii, while on Daphnia magna, it induced moderate to high toxicity, similar to nifedipine. Our research indicates that the newly synthetized pyrrole derivatives are promising molecules with biological activity and low acute toxicity.

Enabling modular dosage form concepts for individualized multidrug therapy: Expanding the design window for poorly water-soluble drugs

Multidrug dosage forms (aka combination dosage forms, polypills, etc.) create value for patients through reduced pill burdens and simplified administration to improve adherence to therapy. Enhanced flexibility of multidrug dosage forms would provide further opportunities to better match emerging needs for individualized therapy. Through modular dosage form concepts, one approach to satisfy these needs is to adapt multidrug dosage forms to a wider variety of drugs, each with a variety of doses and release profiles. This study investigates and technically explores design requirements for extending the capability of modular multidrug dosage form concepts towards individualization. This builds on our recent demonstration of independent tailoring of dose and drug release, which is here extended towards poorly water-soluble drugs. The challenging design requirement of carrying higher drug loads in smaller volumes to accommodate multiple drugs at their clinical dose is here met regarding dose and release performance. With a modular concept, we demonstrate high precision (<5% RSD) in dose and release performance of individual modules containing felodipine or naproxen in Kollidon VA64 at both a wide drug loading range (5% w/w and 50% w/w drug) and a small module size (3.6 mg). In a forward-looking design-based discussion, further requirements are addressed, emphasizing that reproducible individual module performance is predictive of dosage form performance, provided the modules are designed to act independently. Therefore, efforts to incorporate progressively higher drug loads within progressively smaller module volumes will be crucial to extend the design window further towards full flexibility of future dosage forms for individualized multidrug therapy.

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.

Recent developments in the nanomaterial-catalyzed green synthesis of structurally diverse 1,4-dihydropyridines

1,4-Dihydropyridine (1,4-DHP), a privileged heterocyclic scaffold, has been extensively utilized in various biological and therapeutic applications. In this review article, we discussed the role of different nano-catalysts, nanoflakes, nanocomposites, and other green-supported nanomaterials in the synthesis of a biologically active and vital pharmaceutical precursor 1,4-DHP and its derivatives such as polyhydroquinoline, benzopyranopyridines, and dihydropyridine since 2015. It is evident that although the use of various tailored nanostructures under different conditions to optimize the synthesis of 1,4-DHP and its compounds has provided sustainable and efficient proposals, yet the development of greener practices in the synthesis of 1,4-DHPs, which can be applied to design new synthetic routes and sequences in process development, is a far-reaching task to be accomplished.

Single pot multicomponent approaches using different nanomaterials as green catalysts for synthesis of 1,4-dihydropyridine (1,4-DHP), a privileged heterocyclic scaffold with vital biological and therapeutic applications are reviewed.

Dissolution of amorphous nifedipine from micelle-forming carboxymethylcellulose derivatives

We show that a novel amphiphilic graft copolymer combining the biodegradability and biocompatibility of oxidized carboxymethylcellulose (CMC) with that of hydrophilic poly(ethylene glycol) (PEG), and hydrophobic dodecylamine (DDA), improves the solubility and dissolution performance of nifedipine (NIF), considered as a model hydrophobic drug. The hydrophobic components of the graft copolymer have the multiple effect of favouring micelle formation and loading. At the same time, the interaction between the hydrophobic core and NIF has the secondary effect to suppress drug crystallization, favouring its dissolution, and to increase photostability. Oxidized CMC-g-PEG-DDA micelles reached values of drug concentration, loading capacity and encapsulation efficiency as high as 340 μg mL^-1, 6.4 % and 34.1 %, respectively. Loaded micelles showed a good stability with a limited release profile at pH 1.2, whereas at pH 7.4 the swollen cores enable much higher and progressive release, that reaches 3.4 and 6.6 % after 3 and 5 h, respectively, corresponding to very competitive concentration of 34 and 66 μg mL^-1.