Substitution Effects in Aryl Halides and Amides into the Reaction Mechanism of Ullmann-Type Coupling Reactions.

In this article, we present a comprehensive computational investigation into the reaction mechanism of N-arylation of substituted aryl halides through Ullmann-type coupling reactions. Our computational findings, obtained through DFT ωB97X-D/6-311G(d,p) and ωB97X-D/LanL2DZ calculations, reveal a direct relation between the previously reported experimental reaction yields and the activation energy of haloarene activation, which constitutes the rate-limiting step in the overall coupling process. A detailed analysis of the reaction mechanism employing the Activation Strain Model indicates that the strain in the substituted iodoanilines is the primary contributor to the energy barrier, representing an average of 80% of the total strain energy. Additional analysis based on conceptual Density Functional Theory (DFT) suggests that the nucleophilicity of the nitrogen in the lactam is directly linked to the activation energies. These results provide valuable insights into the factors influencing energetic barriers and, consequently, reaction yields. These insights enable the rational modification of reactants to optimize the N-arylation process.

Direct Oral FXa Inhibitors Binding to Human Serum Albumin: Spectroscopic, Calorimetric, and Computational Studies.

Direct FXa inhibitors are an important class of bioactive molecules (rivaroxaban, apixaban, edoxaban, and betrixaban) applied for thromboprophylaxis in diverse cardiovascular pathologies. The interaction of active compounds with human serum albumin (HSA), the most abundant protein in blood plasma, is a key research area and provides crucial information about drugs' pharmacokinetics and pharmacodynamic properties. This research focuses on the study of the interactions between HSA and four commercially available direct oral FXa inhibitors, applying methodologies including steady-state and time-resolved fluorescence, isothermal titration calorimetry (ITC), and molecular dynamics. The HSA complexation of FXa inhibitors was found to occur via static quenching, and the complex formation in the ground states affects the fluorescence of HSA, with a moderate binding constant of 104 M-1. However, the ITC studies reported significantly different binding constants (103 M-1) compared with the results obtained through spectrophotometric methods. The suspected binding mode is supported by molecular dynamics simulations, where the predominant interactions were hydrogen bonds and hydrophobic interactions (mainly π-π stacking interactions between the phenyl ring of FXa inhibitors and the indole moiety of Trp214). Finally, the possible implications of the obtained results regarding pathologies such as hypoalbuminemia are briefly discussed.

Toward the cholinesterase inhibition potential of TADDOL derivatives: Seminal biological and computational studies.

Alzheimer's disease (AD) is a degenerative neurological disease characterized by gradual loss of cognitive skills and memory. The exact pathogenesis involved still remains unrevealed, but several studies indicate the involvement of an array of different enzymes, underlining the multifactorial character of the disease. Inhibition of these enzymes is therefore a powerful approach in the development of AD treatments, with promising candidates, including acetylcholinesterase (AChE), butyrylcholinesterase (BuChE), and monoamine oxidase. Interestingly, AChE is the target of a major pesticide family (organophosphates), with several reports indicating an intersection between the pesticide's activity and AD. In this study, various TADDOL derivatives were synthesized and their in vitro activities as AChE/BuChE inhibitors as well as their antioxidant activities were studied. Molecular modeling studies revealed the capability of TADDOL derivatives to bind to AChE and induce inhibition, especially compounds 2b and 3c furnishing IC50 values of 36.78 ± 8.97 and 59.23 ± 5.31 µM, respectively. Experimental biological activities and molecular modeling studies clearly demonstrate that TADDOL derivatives with specific stereochemistry have an interesting potential for the design of potent AChE inhibitors. The encouraging results for compounds 2b and 3c indicate them as promising scaffolds for selective and potent AChE inhibitors.

Discovery of New Phenylacetone Monooxygenase Variants for the Development of Substituted Indigoids through Biocatalysis.

Indigoids are natural pigments obtained from plants by ancient cultures. Romans used them mainly as dyes, whereas Asian cultures applied these compounds as treatment agents for several diseases. In the modern era, the chemical industry has made it possible to identify and develop synthetic routes to obtain them from petroleum derivatives. However, these processes require high temperatures and pressures and large amounts of solvents, acids, and alkali agents. Thus, enzyme engineering and the development of bacteria as whole-cell biocatalysts emerges as a promising green alternative to avoid the use of these hazardous materials and consequently prevent toxic waste generation. In this research, we obtained two novel variants of phenylacetone monooxygenase (PAMO) by iterative saturation mutagenesis. Heterologous expression of these two enzymes, called PAMOHPCD and PAMOHPED, in E. coli was serendipitously found to produce indigoids. These interesting results encourage us to characterize the thermal stability and enzyme kinetics of these new variants and to evaluate indigo and indirubin production in a whole-cell system by HPLC. The highest yields were obtained with PAMOHPCD supplemented with L-tryptophan, producing ~3000 mg/L indigo and ~130.0 mg/L indirubin. Additionally, both enzymes could oxidize and produce several indigo derivatives from substituted indoles, with PAMOHPCD being able to produce the well-known Tyrian purple. Our results indicate that the PAMO variants described herein have potential application in the textile, pharmaceutics, and semiconductors industries, prompting the use of environmentally friendly strategies to obtain a diverse variety of indigoids.

Hybrid molecules based on 1,3,5-triazine as potential therapeutics: A focused review.

Majority of the representative drugs customarily interact with multiple targets manifesting unintended side effects. In addition, drug resistance and over expression of the cellular efflux-pumps render certain classes of drugs ineffective. With only a few innovative formulations in development, it is necessary to identify pharmacophores and novel strategies for creating new drugs. The conjugation of dissimilar pharmacophoric moieties to design hybrid molecules with an attractive therapeutic profile is an emerging paradigm in the contemporary drug development regime. The recent decade witnessed the remarkable biological potential of 1,3,5-triazine framework in the development of various chemotherapeutics. The appending of the 1,3,5-triazine nucleus to biologically relevant moieties has delivered exciting results. The present review focuses on 1,3,5-triazine based hybrid molecules in the development of pharmaceuticals.

Innovative Three-Step Microwave-Promoted Synthesis of N-Propargyltetrahydroquinoline and 1,2,3-Triazole Derivatives as a Potential Factor Xa (FXa) Inhibitors: Drug Design, Synthesis, and Biological Evaluation.

The coagulation cascade is the process of the conversion of soluble fibrinogen to insoluble fibrin that terminates in production of a clot. Factor Xa (FXa) is a serine protease involved in the blood coagulation cascade. Moreover, FXa plays a vital role in the enzymatic sequence which ends with the thrombus production. Thrombosis is a common causal pathology for three widespread cardiovascular syndromes: acute coronary syndrome (ACS), venous thromboembolism (VTE), and strokes. In this research a series of N-propargyltetrahydroquinoline and 1,2,3-triazole derivatives as a potential factor Xa (FXa) inhibitor were designed, synthesized, and evaluated for their FXa inhibitor activity, cytotoxicity activity and coagulation parameters. Rational design for the desired novel molecules was performed through protein-ligand complexes selection and ligand clustering. The microwave-assisted synthetic strategy of selected compounds was carried out by using Ullmann-Goldberg, N-propargylation, Mannich addition, Friedel-Crafts, and 1,3-dipolar cycloaddition type reactions under microwave irradiation. The microwave methodology proved to be an efficient way to obtain all novel compounds in high yields (73-93%). Furthermore, a thermochemical analysis, optimization and reactivity indexes such as electronic chemical potential (µ), chemical hardness (η), and electrophilicity (ω) were performed to understand the relationship between the structure and the energetic behavior of all the series. Then, in vitro analysis showed that compounds 27, 29-31, and 34 exhibited inhibitory activity against FXa and the corresponding half maximal inhibitory concentration (IC50) values were calculated. Next, a cell viability assay in HEK293 and HepG2 cell lines, and coagulation parameters (anti FXa, Prothrombin time (PT), activated Partial Thromboplastin Time (aPTT)) of the most active novel molecules were performed to determine the corresponding cytotoxicity and possible action on clotting pathways. The obtained results suggest that compounds 27 and 29 inhibited FXa targeting through coagulation factors in the intrinsic and extrinsic pathways. However, compound 34 may target coagulation FXa mainly by the extrinsic and common pathway. Interestingly, the most active compounds in relation to the inhibition activity against FXa and coagulation parameters did not show toxicity at the performed coagulation assay concentrations. Finally, docking studies confirmed the preferential binding mode of N-propargyltetrahydroquinoline and 1,2,3-triazole derivatives inside the active site of FXa.

Theoretical study of C-arylations with aryl halides to determine the reaction mechanism, the effect of substituents and heteroatoms.

Carbon arylations are very important in the pharmaceutical industry. New synthesis routes are often studied with the objective of trying to insert new bonds and substituents into an organic framework. Ullman reactions have been very useful in this context. In light of this, a wB97XD/6-311g set of Ullman-like reactions among substituted amide arylations with iodoaniline were theoretically studied in order to understand their intrinsic reactivity and their reaction mechanisms. The studied systems included unsubstituted (C), sulphur (S), synthesized by the authors in a previous experimental work. In this study, amino (NH) and butyloxycarbonyl (NBoc) amides were added. IRC calculations on catalyzed species showed that the catalyst lowers the reaction barrier, and changes the reactivity in order to lower the nitrogen charge. The reaction mechanism proceeds by binding the CuI catalyst and N,N-dimethylethylenediamine (DMEN) to the N lactam, in a barrierless reaction, thereby activating the nitrogen to bond with the aryl iodine through a nucleophilic substitution, and thus recovering the catalyst.

Exploiting the natural poly(3-hydroxyalkanoates) production capacity of Antarctic Pseudomonas strains: from unique phenotypes to novel biopolymers.

Extreme environments are a unique source of microorganisms encoding metabolic capacities that remain largely unexplored. In this work, we isolated two Antarctic bacterial strains able to produce poly(3-hydroxyalkanoates) (PHAs), which were classified after 16S rRNA analysis as Pseudomonas sp. MPC5 and MPC6. The MPC6 strain presented nearly the same specific growth rate whether subjected to a temperature of 4 °C 0.18 (1/h) or 30 °C 0.2 (1/h) on glycerol. Both Pseudomonas strains produced high levels of PHAs and exopolysaccharides from glycerol at 4 °C and 30 °C in batch cultures, an attribute that has not been previously described for bacteria of this genus. The MPC5 strain produced the distinctive medium-chain-length-PHA whereas Pseudomonas sp. MPC6 synthesized a novel polyoxoester composed of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate-co-3-hydroxyoctanoate-co-3-hydroxydecanoate-co-3-hydroxydodecanoate). Batch bioreactor production of PHAs in MPC6 resulted in a titer of 2.6 (g/L) and 1.3 (g/L), accumulating 47.3% and 34.5% of the cell dry mass as PHA, at 30 and 4 °C, respectively. This study paves the way for using Antarctic Pseudomonas strains for biosynthesizing novel PHAs from low-cost substrates such as glycerol and the possibility to carry out the bioconversion process for biopolymer synthesis without the need for temperature control.

Novel FXa Inhibitor Identification through Integration of Ligand- and Structure-Based Approaches.

Factor Xa (FXa), a vitamin K-dependent serine protease plays a pivotal role in the coagulation cascade, one of the most interesting targets for the development of new anticoagulants. In the present work, we performed a virtual screening campaign based on ligand-based shape and electrostatic similarity search and protein-ligand docking to discover novel FXa-targeted scaffolds for further development of inhibitors. From an initial set of 260,000 compounds from the NCI Open database, 30 potential FXa inhibitors were identified and selected for in vitro biological evaluation. Compound 5 (NSC635393, 4-(3-methyl-4H-1,4-benzothiazin-2-yl)-2,4-dioxo-N-phenylbutanamide) displayed an IC50 value of 2.02 nM against human FXa. The identified compound may serve as starting point for the development of novel FXa inhibitors.

Targeting Allosteric Site of PCSK9 Enzyme for the Identification of Small Molecule Inhibitors: An In Silico Drug Repurposing Study.

The primary cause of atherosclerotic cardiovascular disease (ASCVD) is elevated levels of low-density lipoprotein cholesterol (LDL-C). Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a crucial role in this process by binding to the LDL receptor (LDL-R) domain, leading to reduced influx of LDL-C and decreased LDL-R cell surface presentation on hepatocytes, resulting higher circulating levels of LDL-C. As a consequence, PCSK9 has been identified as a crucial target for drug development against dyslipidemia and hypercholesterolemia, aiming to lower plasma LDL-C levels. This research endeavors to identify promising inhibitory candidates that target the allosteric site of PCSK9 through an in silico approach. To start with, the FDA-approved Drug Library from Selleckchem was selected and virtually screened by docking studies using Glide extra-precision (XP) docking mode and Smina software (Version 1.1.2). Subsequently, rescoring of 100 drug compounds showing good average docking scores were performed using Gnina software (Version 1.0) to generate CNN Score and CNN binding affinity. Among the drug compounds, amikacin, bestatin, and natamycin were found to exhibit higher docking scores and CNN affinities against the PCSK9 enzyme. Molecular dynamics simulations further confirmed that these drug molecules established the stable protein-ligand complexes when compared to the apo structure of PCSK9 and the complex with the co-crystallized ligand structure. Moreover, the MM-GBSA calculations revealed binding free energy values ranging from -84.22 to -76.39 kcal/mol, which were found comparable to those obtained for the co-crystallized ligand structure. In conclusion, these identified drug molecules have the potential to serve as inhibitors PCSK9 enzyme and these finding could pave the way for the development of new PCSK9 inhibitory drugs in future in vitro research.

Zerumbone-incorporated liquid crystalline nanoparticles inhibit proliferation and migration of non-small-cell lung cancer in vitro.

Lung cancer is the second most prevalent type of cancer and is responsible for the highest number of cancer-related deaths worldwide. Non-small-cell lung cancer (NSCLC) makes up the majority of lung cancer cases. Zerumbone (ZER) is natural compound commonly found in the roots of Zingiber zerumbet which has recently demonstrated anti-cancer activity in both in vitro and in vivo studies. Despite their medical benefits, ZER has low aqueous solubility, poor GI absorption and oral bioavailability that hinders its effectiveness. Liquid crystalline nanoparticles (LCNs) are novel drug delivery carrier that have tuneable characteristics to enhance and ease the delivery of bioactive compounds. This study aimed to formulate ZER-loaded LCNs and investigate their effectiveness against NSCLC in vitro using A549 lung cancer cells. ZER-LCNs, prepared in the study, inhibited the proliferation and migration of A549 cells. These inhibitory effects were superior to the effects of ZER alone at a concentration 10 times lower than that of free ZER, demonstrating a potent anti-cancer activity of ZER-LCNs. The underlying mechanisms of the anti-cancer effects by ZER-LCNs were associated with the transcriptional regulation of tumor suppressor genes P53 and PTEN, and metastasis-associated gene KRT18. The protein array data showed downregulation of several proliferation associated proteins such as AXL, HER1, PGRN, and BIRC5 and metastasis-associated proteins such as DKK1, CAPG, CTSS, CTSB, CTSD, and PLAU. This study provides evidence of potential for increasing the potency and effectiveness of ZER with LCN formulation and developing ZER-LCNs as a treatment strategy for mitigation and treatment of NSCLC.

Zerumbone liquid crystalline nanoparticles protect against oxidative stress, inflammation and senescence induced by cigarette smoke extract in vitro.

The purpose of this study was to evaluate the potential of zerumbone-loaded liquid crystalline nanoparticles (ZER-LCNs) in the protection of broncho-epithelial cells and alveolar macrophages against oxidative stress, inflammation and senescence induced by cigarette smoke extract in vitro. The effect of the treatment of ZER-LCNs on in vitro cell models of cigarette smoke extract (CSE)-treated mouse RAW264.7 and human BCi-NS1.1 basal epithelial cell lines was evaluated for their anti-inflammatory, antioxidant and anti-senescence activities using colorimetric and fluorescence-based assays, fluorescence imaging, RT-qPCR and proteome profiler kit. The ZER-LCNs successfully reduced the expression of pro-inflammatory markers including Il-6, Il-1ß and Tnf-α, as well as the production of nitric oxide in RAW 264.7 cells. Additionally, ZER-LCNs successfully inhibited oxidative stress through reduction of reactive oxygen species (ROS) levels and regulation of genes, namely GPX2 and GCLC in BCi-NS1.1 cells. Anti-senescence activity of ZER-LCNs was also observed in BCi-NS1.1 cells, with significant reductions in the expression of SIRT1, CDKN1A and CDKN2A. This study demonstrates strong in vitro anti-inflammatory, antioxidative and anti-senescence activities of ZER-LCNs paving the path for this formulation to be translated into a promising therapeutic agent for chronic respiratory inflammatory conditions including COPD and asthma.

Opening avenues for treatment of neurodegenerative disease using post-biotics: Breakthroughs and bottlenecks in clinical translation.

Recent studies have indicated the significant involvement of the gut microbiome in both human physiology and pathology. Additionally, therapeutic interventions based on microbiome approaches have been employed to enhance overall health and address various diseases including aging and neurodegenerative disease (ND). Researchers have explored potential links between these areas, investigating the potential pathogenic or therapeutic effects of intestinal microbiota in diseases. This article provides a summary of established interactions between the gut microbiome and ND. Post-biotic is believed to mediate its neuroprotection by elevating the level of dopamine and reducing the level of α-synuclein in substantia nigra, protecting the loss of dopaminergic neurons, reducing the aggregation of NFT, reducing the deposition of amyloid ß peptide plagues and ameliorating motor deficits. Moreover, mediates its neuroprotective activity by inhibiting the inflammatory response (decreasing the expression of TNFα, iNOS expression, free radical formation, overexpression of HIF-1α), apoptosis (i.e. active caspase-3, TNF-α, maintains the level of Bax/Bcl-2 ratio) and promoting BDNF secretion. It is also reported to have good antioxidant activity. This review offers an overview of the latest findings from both preclinical and clinical trials concerning the use of post-biotics in ND.

Solid Lipid Nanoparticles (SLN) and Nanostructured Lipid Carriers (NLC) Prepared by Microwave and Ultrasound-Assisted Synthesis: Promising Green Strategies for the Nanoworld.

Many pharmaceutically active molecules are highly lipophilic, which renders their administration and adsorption in patients extremely challenging. Among the countless strategies to overcome this problem, synthetic nanocarriers have demonstrated superb efficiency as drug delivery systems, since encapsulation can effectively prevent a molecules' degradation, thus ensuring increased biodistribution. However, metallic and polymeric nanoparticles have been frequently associated with possible cytotoxic side effects. Solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC), which are prepared with physiologically inert lipids, therefore emerged as an ideal strategy to bypass toxicities issues and avoid the use of organic solvents in their formulations. Different approaches to preparation, using only moderate amounts of external energy to facilitate a homogeneous formation, have been proposed. Greener synthesis strategies have the potential to provide faster reactions, more efficient nucleation, better particle size distribution, lower polydispersities, and furnish products with higher solubility. Particularly microwave-assisted synthesis (MAS) and ultrasound-assisted synthesis (UAS) have been utilized in the manufacturing of nanocarrier systems. This narrative review addresses the chemical aspects of those synthesis strategies and their positive influence on the characteristics of SLNs and NLCs. Furthermore, we discuss the limitations and future challenges for the manufacturing processes of both types of nanoparticles.

Efficient indium-mediated dehalogenation of aromatics in ionic liquid media.

An efficient indium-mediated dehalogenation reaction of haloaromatics and haloheteroaromatics in ionic liquids has been studied. This method is simple and effective in the presence of [bmim]Br. Furthermore, this methodology is environmentally friendly compared with conventional ones.

Bio-click chemistry: a bridge between biocatalysis and click chemistry.

The fields of click chemistry and biocatalysis have rapidly grown over the last two decades. The development of robust and active biocatalysts and the widespread use of straightforward click reactions led to significant interactions between these two fields. Therefore the name bio-click chemistry seems to be an accurate definition of chemoenzymatic reactions cooperating with click transformations. Bio-click chemistry can be understood as the approach towards molecules of high-value using a green and sustainable approach by exploiting the potential of biocatalytic enzyme activity combined with the reliable nature of click reactions. This review summarizes the principal bio-click chemistry reactions reported over the last two decades, with a special emphasis on small molecules. Contributions to the field of bio-click chemistry are manifold, but the synthesis of chiral molecules with applications in medicinal chemistry and sustainable syntheses will be especially highlighted.

PCSK9 conjugated liposomes for targeted delivery of paclitaxel to the cancer cell: A proof-of-concept study.

Ligand-based targeting of the receptors that are overexpressed explicitly on cancer cells represents an effective drug delivery approach to enhance the chemotherapeutic efficacy. Proprotein convertase subtilisin/kexin type 9 (PCSK9) which is a serine protease enzyme primarily produced by the liver cells, can potentially be used as a targeting ligand. PCSK9 binds to the LDL-r on hepatocytes' surface, leading to endocytosis and endosomal degradation. High LDL-r expression, which is believed to meet the higher demand of the cholesterol and phospholipids to build proliferating cancer cell membrane, ensures selective uptake of the PCSK9 conjugated liposomes. In the present work, the PCSK9 conjugated liposomal system was developed to deliver paclitaxel (PTX) to cancer cells. The protein was conjugated by EDC and NHS in a two-step coupling reaction to the liposomes containing COOH-PEG2000-COOH lipid. Conjugation was confirmed by NMR, and liposomes were further characterized by SEM and zeta sizer. PCSK9-conjugated liposomes showed high encapsulation efficiency of 69.1% with a diameter of 90.0 ± 4.9 nm. Long-term stability (30 days) study (Zeta potential: -9.88) confirmed excellent constancy and significant drug retention (58.2%). Invitro cytotoxicity and targeting efficiency was explored using MTS assay in human embryonic kidney cells (HEK293), liver hepatocellular cells (HEPG2), and a human colon cancer cell line (HCT116) for 24 h. PCSK9 conjugated liposomes exhibited significantly higher growth inhibition than the unconjugated (control) liposomes in HCT116 cell line (p < 0.001). The novel PCSK9 conjugated liposomes presented potent and precise in vitro anticancer activity and, therefore, are suggested for the first time as a promising targeted delivery system for cancer treatment.

The Human Dermis as a Target of Nanoparticles for Treating Skin Conditions.

Skin has a preventive role against any damage raised by harmful microorganisms and physical and chemical assaults from the external environment that could affect the body's internal organs. Dermis represents the main section of the skin, and its contribution to skin physiology is critical due to its diverse cellularity, vasculature, and release of molecular mediators involved in the extracellular matrix maintenance and modulation of the immune response. Skin structure and complexity limit the transport of substances, promoting the study of different types of nanoparticles that penetrate the skin layers under different mechanisms intended for skin illness treatments and dermo-cosmetic applications. In this work, we present a detailed morphological description of the dermis in terms of its structures and resident cells. Furthermore, we analyze the role of the dermis in regulating skin homeostasis and its alterations in pathophysiological conditions, highlighting its potential as a therapeutic target. Additionally, we describe the use of nanoparticles for skin illness treatments focused on dermis release and promote the use of metal-organic frameworks (MOFs) as an integrative strategy for skin treatments.

A new era in oxygen therapeutics? From perfluorocarbon systems to haemoglobin-based oxygen carriers.

Blood transfusion is the key to life in case of traumatic emergencies, surgeries and in several pathological conditions. An important goal of whole blood or red blood cell transfusion is the fast delivery of oxygen to vital organs and restoration of circulation volume. Whole blood or red blood cell transfusion has several limitations. Free haemoglobin not only loses its tetrameric configuration and extracts via the kidney leading to nephrotoxicity but also scavenges nitric oxide (NO), leading to vasoconstriction and hypertension. PFC based formulations transport oxygen in vivo, the contribution in terms of clinical outcome is challenging. The oxygen-carrying capacity is not the only criterion for the successful development of haemoglobin-based oxygen carriers (HBOCs). This review is a bird's eye view on the present state of the PFCs and HBOCs in which we analyzed the current modifications made or which are underway in development, their promises, and hurdles in clinical implementation.