Potential Ligands Research Articles

Insights into biomimetic system-ligand interaction of substituted isophthalic acid: A functionality induced photophysical study.

The present article attempts to interpret the modulation of photophysical properties of isophthalic acid (IPA) through its amino [5-amino isophthalic acid (5-amino IPA)] and azido [5-azido isophthalic acid (5-azido IPA)] substituted derivatives which are chemically potent organic ligands. The ground state structure-reactivity correlation of 5-amino IPA and 5-azido IPA has been deciphered through computational studies. The computed energetics show significant interaction feasibility of the substituted ligand systems with the biomimetic systems which is further validated experimentally. The binding interaction of the probes with oppositely polarized functionalization is studied to be significant with cetyltrimethylammonium bromide (CTAB) and bovine serum albumin (BSA) with the amino functionalized derivative having a comparatively stronger binding constant value. The steady-state absorption and fluorescence study establish significant modification of polarity of the heteronuclear probes. The micro polarity study in water-dioxane mixtures enables determination of polarity of 5-amino IPA in CTAB and BSA unlike 5-azido IPA. Presence of an overlapping region between the emission spectrum of BSA and the absorption spectrum of the probes as probable donor-acceptor pair are also scrutinized via the steady-state fluorescence studies. The photophysical behavior of 5-amino IPA is observed to be somewhat dissimilar to that of 5-azido IPA.

Targeting G4 motifs of various stem cell makers with designed peptide for therapeutic applications

Noncanonical secondary structures formed by Guanine-rich DNA sequences fold into four-stranded structures called the G-quadruplexes (G4s). Targeting G-quadruplexes is considered an attractive approach toward drug intervention. Here, we have studied the targeting of G4s of stem cell markers with designed short peptide (named as QW10) using biophysical and biochemical techniques. Our CD studies showed that G4 sequences of stem cell markers formed mixed G-quadruplexes in 100 mM Na+, 100 mM K+ and 100 mM K+ +40 wt% PEG 200. On titrating these structures with an increasing concentration of QW10 peptide, we observed a significant decrease in CD intensity followed by the complete disappearance of G4 CD signatures confirming their destabilization not only in dilute conditions but also under cell-mimicking molecular crowding conditions. Our electrophoretic mobility shift assay and significant decrease in the Tm values confirmed the significant destabilization of G4 structures Fluorescence results showed the formation of high-affinity G4 complex-peptide complex with binding affinities in the micromolar (µM) range of 2–8 µM in different ionic conditions. First time, this study may give insight into the use of peptides as leads for the development of more potent and selective ligands to regulate the potential therapeutic applications of cancer stem cell markers.

A highly potent, orally bioavailable pyrazole-derived cannabinoid CB2 receptor-selective full agonist for in vivo studies.

The cannabinoid CB2 receptor (CB2R) is a potential therapeutic target for distinct forms of tissue injury and inflammatory diseases. To thoroughly investigate the role of CB2R in pathophysiological conditions and for target validation in vivo, optimal pharmacological tool compounds are essential. Despite the sizable progress in the generation of potent and selective CB2R ligands, pharmacokinetic parameters are often neglected for in vivo studies. Here, we report the generation and characterization of a tetra-substituted pyrazole CB2R full agonist named RNB-61 with high potency (K i 0.13-1.81 nM, depending on species) and a peripherally restricted action due to P-glycoprotein mediated efflux from the brain. 3H and 14C labelled RNB-61 showed apparent K d values < 4 nM towards human CB2R in both cell and tissue experiments. The >6000-fold selectivity over CB1 receptors and negligible off-targets in vitro, combined with high oral bioavailability and suitable systemic pharmacokinetic (PK) properties, prompted the assessment of RNB-61 in a mouse ischemia-reperfusion model of acute kidney injury (AKI) and in a rat model of chronic kidney injury/inflammation and fibrosis (CKI) induced by unilateral ureteral obstruction. RNB-61 exerted dose-dependent nephroprotective and/or antifibrotic effects in the AKI/CKI models. Thus, RNB-61 is an optimal CB2R tool compound for preclinical in vivo studies with superior biophysical and PK properties over generally used CB2R ligands.

Repurposing AS1411 for constructing ANM-PROTACs

Proteolysis-targeting chimeras (PROTACs) are heterobifunctional molecules consisting of two ligands joined by a linker, enabling them to simultaneously bind with an E3 ligase and a protein of interest (POI) and trigger proteasomal degradation of the POI. Limitations of PROTAC include lack of potent E3 ligands, poor cell selectivity, and low permeability. AS1411 is an antitumor aptamer specifically recognizing a membrane-nucleus shuttling nucleolin (NCL). Here, we repurpose AS1411 as a ligand for an E3 ligase mouse double minute 2 homolog (MDM2) via anchoring the NCL-MDM2 complex. Then, we construct an AS1411-NCL-MDM2-based PROTAC (ANM-PROTAC) by conjugating AS1411 with large-molecular-weight ligands for "undruggable" oncogenic STAT3, c-Myc, p53-R175H, and AR-V7. We show that the ANM-PROTAC efficiently penetrates tumor cells, recruits MDM2 and degrades the POIs. The ANM-PROTAC achieves tumor-selective distribution and exhibits excellent antitumor activity with no systemic toxicity. This is a PROTAC with built-in tumor-targeting and cell-penetrating capacities.

Unveiling new myrsinoic acids and AChE ligands from Myrsine guianensis (Aubl.) Kuntze

Molecular dereplication and drug-like discovery are important tools for exploring the chemical profile of metabolites in a complex mixture. In order to establish a workflow for discovering novel acetylcholinesterase (AChE) ligands, we performed the chemical study of Myrsine guianensis (Aubl.) Kuntze (Primulaceae). To carry out the bioprospection, nine extracts were obtained from different parts of the plant. Through the dereplication approaches, seventeen metabolites were annotated. In order to confirm the putative inferences, a HPLC preparative method was developed to isolate three known myrsinoic acids, A(1), B(2) and C(3). Along with, we are reporting the obtention of two new congeners, G(5) and H(6), which their structures were elucidated by NMR and HRMS data. Besides that, two extracts were submitted to affinity assays to accelerate the discovery of AChE ligands. Desorbates were analyzed through LC-HRMS for calculating the affinity ratio (AR). Thus, (1) presented AR = 4.59, therefore was considered a potential ligand.

Prospective de novo drug design with deep interactome learning

De novo drug design aims to generate molecules from scratch that possess specific chemical and pharmacological properties. We present a computational approach utilizing interactome-based deep learning for ligand- and structure-based generation of drug-like molecules. This method capitalizes on the unique strengths of both graph neural networks and chemical language models, offering an alternative to the need for application-specific reinforcement, transfer, or few-shot learning. It enables the “zero-shot" construction of compound libraries tailored to possess specific bioactivity, synthesizability, and structural novelty. In order to proactively evaluate the deep interactome learning framework for protein structure-based drug design, potential new ligands targeting the binding site of the human peroxisome proliferator-activated receptor (PPAR) subtype gamma are generated. The top-ranking designs are chemically synthesized and computationally, biophysically, and biochemically characterized. Potent PPAR partial agonists are identified, demonstrating favorable activity and the desired selectivity profiles for both nuclear receptors and off-target interactions. Crystal structure determination of the ligand-receptor complex confirms the anticipated binding mode. This successful outcome positively advocates interactome-based de novo design for application in bioorganic and medicinal chemistry, enabling the creation of innovative bioactive molecules.

Enantioselective Construction of Chiral THIQUINOL and Its Derivatives via Chiral Phosphoric Acid Catalysis.

The first catalytic enantioselective construction of chiral THIQUINOL and its derivatives has been accomplished through a chiral phosphoric-acid-catalyzed direct aza-Friedel-Crafts reaction of 3,4-dihydroisoquinolines with 2-naphthols/anthracen-2-ols/phenanthren-9-ol. This method offers a powerful and straightforward synthetic route toward chiral THIQUINOL derivatives with good to excellent yields and enantioselectivities. These structural motifs are crucial chiral components for further transformations into established or potential chiral ligands and catalysis.

Targeted screening of multiple anti-inflammatory components from Chrysanthemi indici Flos by ligand fishing with affinity UF-LC/MS.

Chrysanthemi indic Flos (CIF) has been commonly consumed for the treatment of inflammation and related skin diseases. However, the potential bioactive components responsible for its anti-inflammatory and sensitive skin (SS) improvement activities, and the correlated mechanisms of action still remain unknown. In this work, it was firstly found that the CIF extract (CIFE) displayed arrestive free radical scavenging activity on DPPH and ABTS radicals, with no significant difference with positive control Trolox (p > 0.05). Then, compared to the negative group, CIFE markedly decreased the productions of the pro-inflammatory cytokines (IL-1β, IL-6, PEG2, TNF-α, IFN-γ, NO) in LPS induced RAW264.7 cells in a dose-dependent manner (p < 0.01). Besides, CIFE strongly inhibited the COX-2 and hyaluronidase (HAase) with the IC50 values of 1.06 ± 0.01μg/mL and 12.22 ± 0.39μg/mL, indicating higher inhibitory effect than positive control of aspirin of 6.33 ± 0.05μg/mL (p < 0.01), and comparable inhibitory effect with indometacin of 0.60 ± 0.03μg/mL, and ascorbic acid of 11.03 ± 0.41μg/mL (p > 0.05), respectively. Furthermore, kinetic assays with Lineweaver-Burk plot (Michaelis Menten equation) suggested that CIFE reversibly inhibited the COX-2 and HAase, with a mixed characteristics of competitive and non-competitive inhibition. Thereafter, multi-target affinity ultrafiltration liquid chromatography-mass spectrometry (UF-LC/MS) method was employed to fast fish out the potential COX-2 and HAase in CIFE. Herein, 13 components showed various affinity binding degrees to the COX-2 and HAase, while those components with relative binding affinity (RBA) value higher than 3.0, such as linarin and chlorogenic acid isomers, were deemed to be the most bioactive components for the anti-inflammatory and SS improvement activities of CIFE. Finally, the interaction mechanism, including binding energy, inhibition constant, docking sites, and the key amino acids involved in hydrogen bonds between the potential ligands and COX-2/HAase were simulated and confirmed with the molecule docking analysis. In summary, this study showcased the prominent anti-inflammatory and SS improvement activities of CIF, which would provide further insights on this functional medicinal plant to be a natural anti-SS remedy.

Vitamin D in Melanoma: Potential Role of Cytochrome P450 Enzymes.

Vitamin D is a promising anticancer agent for the prevention and treatment of several cancers, including melanoma. Low 25-hydroxyvitamin D levels, a routinely used marker for vitamin D, have been suggested as one of the factors in the development and progression of melanoma. The parent vitamin D needs activation by cytochrome P450 (CYP) enzymes to exert its actions via the vitamin D receptor (VDR). This review discusses the role of vitamin D in melanoma and how CYP-mediated metabolism can potentially affect the actions of vitamin D. Through interacting with the retinoid X receptor, VDR signaling leads to anti-inflammatory, antioxidative, and anticancer actions. Calcitriol, the dihydroxylated form of vitamin D3, is the most active and potent ligand of VDR. CYP27A1, CYP27B1, and CYP2R1 are involved in the activation of vitamin D, whereas CYP24A1 and CYP3A4 are responsible for the degradation of the active vitamin D. CYP24A1, the primary catabolic enzyme of calcitriol, is overexpressed in melanoma tissues and cells. Several drug classes and natural health products can modulate vitamin D-related CYP enzymes and eventually cause lower levels of vitamin D and its active metabolites in tissues. Although the role of vitamin D in the development of melanoma is yet to be fully elucidated, it has been proposed that melanoma prevention may be significantly aided by increased vitamin D signaling. Furthermore, selective targeting of the catabolic enzymes responsible for vitamin D degradation could be a plausible strategy in melanoma therapy. Vitamin D signaling can be improved by utilizing dietary supplements or by modulating CYP metabolism. A positive association exists between the intake of vitamin D supplements and improved prognosis for melanoma patients. Further investigation is required to determine the function of vitamin D supplementation and specific enzyme targeting in the prevention of melanoma.

Study anti-viral drugs for their efficiency against multiple SARS CoV-2 drug targets within molecular docking, molecular quantum similarity, and chemical reactivity indices frameworks

The study focused on drug discovery for COVID-19, emphasizing the challenges posed by the pandemic and the importance of understanding the virus’s biology. The research utilized molecular docking and quantum similarity analyses to explore potential ligands for SARS-CoV-2 RNA-dependent RNA polymerase. Docking Results Docking outcomes for various ligands, including Oseltamivir, Prochloraz, Valacyclovir, Baricitinib, Molnupiravir, Penciclovir, Famciclovir, Lamivudine, and Nitazoxanide, were presented. Interactions between ligands and specific residues in the RNA-dependent RNA polymerase were analyzed. Reactivity Descriptors Global parameters, such as electronic chemical potential, chemical hardness, global softness, and global electrophilicity, were computed for the ligands. For the local reactivity descriptors, the Fukui Functions were used. Fukui functions, representing electrophilic and nucleophilic sites, were calculated for selected ligands (Valacyclovir and Penciclovir). Nucleophilic character assignments for specific molecular regions were discussed, providing insights into potential charge-donating interactions. Results and Discussion Challenges in COVID-19 drug discovery, such as virus mutability, rapid evolution, and resource limitations, were summarized. Progress in vaccine development and the need for ongoing research to address variants and breakthrough cases were emphasized. Overlap Operator Analysis Higher MQSM between Lamivudine and Molnupiravir (0.5742) indicates structural and electronic similarity. Lowest MQSM between Oseltamivir and Prochloraz (0.2233) implies structural dissimilarity. Coulomb Operator Analysis Higher MQSM between Lamivudine and Molnupiravir (0.9178) suggests both structural and electronic similarity. Lowest MQSM between Baricitinib and Famciclovir (0.6001) indicates greater structural diversity. Measurements above 0.5 in Table 3 suggest electronic similarity, emphasizing the electronic aspects in molecular analysis. In this sense, it study employed a multi-faceted approach combining molecular docking, quantum similarity analyses, and chemical reactivity assessments to explore potential drug candidates for COVID-19. The findings provide valuable insights into ligand interactions, reactivity patterns, and the challenges associated with drug discovery in the context of the global pandemic.

Sterol Derivatives Specifically Increase Anti-Inflammatory Oxylipin Formation in M2-like Macrophages by LXR-Mediated Induction of 15-LOX.

The understanding of the role of LXR in the regulation of macrophages during inflammation is emerging. Here, we show that LXR agonist T09 specifically increases 15-LOX abundance in primary human M2 macrophages. In time- and dose-dependent incubations with T09, an increase of 3-fold for ALOX15 and up to 15-fold for 15-LOX-derived oxylipins was observed. In addition, LXR activation has no or moderate effects on the abundance of macrophage marker proteins such as TLR2, TLR4, PPARγ, and IL-1RII, as well as surface markers (CD14, CD86, and CD163). Stimulation of M2-like macrophages with FXR and RXR agonists leads to moderate ALOX15 induction, probably due to side activity on LXR. Finally, desmosterol, 24(S),25-Ep cholesterol and 22(R)-OH cholesterol were identified as potent endogenous LXR ligands leading to an ALOX15 induction. LXR-mediated ALOX15 regulation is a new link between the two lipid mediator classes sterols, and oxylipins, possibly being an important tool in inflammatory regulation through anti-inflammatory oxylipins.

Cinnamic Acid: A Low-Toxicity Natural Bidentate Ligand for Uranium Decorporation.

Uranium accumulation in the kidneys and bones following internal contamination results in severe damage, emphasizing the pressing need for the discovery of actinide decorporation agents with efficient removal of uranium and low toxicity. In this work, cinnamic acid (3-phenyl-2-propenoic acid, CD), a natural aromatic carboxylic acid, is investigated as a potential uranium decorporation ligand. CD demonstrates markedly lower cytotoxicity than that of diethylenetriaminepentaacetic acid (DTPA), an actinide decorporation agent approved by the FDA, and effectively removes approximately 44.5% of uranyl from NRK-52E cells. More importantly, the results of the prompt administration of the CD solution remove 48.2 and 27.3% of uranyl from the kidneys and femurs of mice, respectively. Assessments of serum renal function reveal the potential of CD to ameliorate uranyl-induced renal injury. Furthermore, the single crystal of CD and uranyl compound (C9H7O2)2·UO2 (denoted as UO2-CD) reveals the formation of uranyl dimers as secondary building units. Thermodynamic analysis of the solution shows that CD coordinates with uranyl to form a 2:1 molar ratio complex at a physiological pH of 7.4. Density functional theory (DFT) calculations further show that CD exhibits a significant 7-fold heightened affinity for uranyl binding in comparison to DTPA.

A dual-target SPR screening system for simultaneous ligand discovery of SARS-CoV-2 spike protein and its receptor ACE2 from Chinese herbs

Traditional Chinese Medicine (TCM) is a supremely valuable resource for the development of drug discovery. Few methods are capable of hunting for potential molecule ligands from TCM towards more than one single protein target. In this study, a novel dual-target surface plasmon resonance (SPR) biosensor was developed to perform targeted compound screening of two key proteins involved in the cellular invasion process of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2): the spike (S) protein receptor binding domain (RBD) and the angiotensin-converting enzyme 2 (ACE2). The screening and identification of active compounds from six Chinese herbs were conducted taking into consideration the multi-component and multi-target nature of Traditional Chinese Medicine (TCM). Puerarin from Radix Puerariae Lobatae was discovered to exhibit specific binding affinity to both S protein RBD and ACE2. The results highlight the efficiency of the dual-target SPR system in drug screening and provide a novel approach for exploring the targeted mechanisms of active components from Chinese herbs for disease treatment.

Understanding the Molecular Landscape of Endometriosis: A Bioinformatics Approach to Uncover Signaling Pathways and Hub Genes.

Endometriosis is a chronic gynecological disorder characterized by the ectopic growth of endometrial tissue outside the uterus, leading to debilitating pain and infertility in affected women. Despite its prevalence and clinical significance, the molecular mechanisms underlying the progression of endometriosis remain poorly understood. This study employs bioinformatics tools and molecular docking simulations to unravel the intricate genetic and molecular networks associated with endometriosis progression. The primary objectives of this research are to identify differentially expressed genes (DEGs) linked to endometriosis, elucidate associated biological pathways using the Database for Annotation, Visualization, and Integrated Discovery (DAVID), construct a Protein-Protein Interaction (PPI) network to identify hub genes, and perform molecular docking simulations to explore potential ligand-protein interactions associated with endometriosis. Microarray data from Homo sapiens, specifically Accession: GDS3092 Series = GSE5108 (Platform: GPL2895), were retrieved from the NCBI Gene Expression Omnibus (GEO). The data underwent rigorous preprocessing and DEG analysis using NCBI GEO2. Database for Annotation, Visualization, and Integrated Discovery analysis was employed for functional annotation, and a PPI network was constructed using the STITCH database and Cytoscape 3.8.2. Molecular docking simulations against target proteins associated with endometriosis were conducted using MVD 7.0. A total of 1 911 unique elements were identified as DEGs associated with endometriosis from the microarray data. Database for Annotation, Visualization, and Integrated Discovery analysis revealed pathways and biological characteristics positively and negatively correlated with endometriosis. Hub genes, including BCL2, CCNA2, CDK7, EGF, GAS6, MAP3K7, and TAB2, were identified through PPI network analysis. Molecular docking simulations highlighted potential ligands, such as Quercetin-3-o-galactopyranoside and Kushenol E, exhibiting favorable interactions with target proteins associated with endometriosis. This study provides insights into the molecular signatures, pathways, and hub genes associated with endometriosis. Utilizing DAVID in this study clarifies biological pathways associated with endometriosis, revealing insights into intricate genetic networks. Molecular docking simulations identified ligands for further exploration in therapeutic interventions. The consistent efficacy of these ligands across diverse targets suggests broad-spectrum effectiveness, encouraging further exploration for potential therapeutic interventions. The study contributes to a deeper understanding of endometriosis pathogenesis, paving the way for targeted therapies and precision medicine approaches to improve patient outcomes. These findings advance our understanding of the molecular mechanisms in endometriosis (EMS), offering promising avenues for future research and therapeutic development in addressing this complex condition.

Similar Binding Modes of cGMP Analogues Limit Selectivity in Modulating Retinal CNG Channels via the Cyclic Nucleotide-Binding Domain.

In treating retinitis pigmentosa, a genetic disorder causing progressive vision loss, selective inhibition of rod cyclic nucleotide-gated (CNG) channels holds promise. Blocking the increased Ca2+-influx in rod photoreceptors through CNG channels can potentially delay disease progression and improve the quality of life for patients. To find inhibitors for rod CNG channels, we investigated the impact of 16 cGMP analogues on both rod and cone CNG channels using the patch-clamp technique. Although modifications at the C8 position of the guanine ring did not change the ligand efficacy, modifications at the N1 and N2 positions rendered cGMP largely ineffective in activating retinal CNG channels. Notably, PET-cGMP displayed selective potential, favoring rod over cone, whereas Rp-cGMPS showed greater efficiency in activating cone over rod CNG channels. Ligand docking and molecular dynamics simulations on cyclic nucleotide-binding domains showed comparable binding energies and binding modes for cGMP and its analogues in both rod and cone CNG channels (CNGA1 vs CNGA3 subunits). Computational experiments on CNGB1a vs CNGB3 subunits showed similar binding modes albeit with fewer amino acid interactions with cGMP due to an inactivated conformation of their C-helix. In addition, no clear correlation could be observed between the computational scores and the CNG channel efficacy values, suggesting additional factors beyond binding strength determining ligand selectivity and potency. This study highlights the importance of looking beyond the cyclic nucleotide-binding domain and toward the gating mechanism when searching for selective modulators. Future efforts in developing selective modulators for CNG channels should prioritize targeting alternative channel domains.

Constitutive activity of ionotropic glutamate receptors via hydrophobic substitutions in the ligand-binding domain

Neurotransmitter ligands electrically excite neurons by activating ionotropic glutamate receptor (iGluR) ion channels. Knowledge of the iGluR amino acid residues that dominate ligand-induced activation would enable the prediction of function from sequence. We therefore explored the molecular determinants of activity in rat N-methyl-D-aspartate (NMDA)-type iGluRs (NMDA receptors), complex heteromeric iGluRs comprising two glycine-binding GluN1 and two glutamate-binding GluN2 subunits, using amino acid sequence analysis, mutagenesis, and electrophysiology. We find that a broadly conserved aspartate residue controls both ligand potency and channel activity, to the extent that certain substitutions at this position bypass the need for ligand binding in GluN1 subunits, generating NMDA receptors activated solely by glutamate. Furthermore, we identify a homomeric iGluR from the placozoan Trichoplax adhaerens that has utilized native mutations of this crucial residue to evolve into a leak channel that is inhibited by neurotransmitter binding, pointing to a dominant role of this residue throughout the iGluR superfamily.

Diosmetin derivatives as multifunctional anti-AD ligands: Design, synthesis, and biological evaluation.

With the increasing aging population, rational design of drugs for Alzheimer's disease (AD) treatment has become an important research area. Based on the multifunctional design strategy, four diosmetin derivatives (1-4) were designed, synthesized, and characterized by 1H NMR, 13C NMR, and MS. Docking study was firstly applied to substantiate the design strategies and then the biological activities including cholinesterase inhibition, metal chelation, antioxidation and β-amyloid (Aβ) aggregation inhibition invitro were evaluated. The results showed that 1-4 had good acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibition, metal chelation (selective chelation of Cu2+ ions), antioxidation, self-induced, Cu2+-induced, and AChE-induced Aβ aggregation inhibition activities, and suitable blood-brain barrier (BBB) permeability. Especially, compound 3 had the strongest inhibitory effect on AChE (10-8 M magnitude) and BuChE (10-7 M magnitude) and showed the best inhibition on AChE-induced Aβ aggregation with 66.14% inhibition ratio. Furthermore, compound 3 could also reduce intracellular reactive oxygen species (ROS) levels in Caenorhabditis elegans and had lower cytotoxicity. In summary, 3 might be considered as a potential multifunctional anti-AD ligand.

Optimizing cryopreservation conditions for use of fucosylated human mesenchymal stromal cells in anti-inflammatory/immunomodulatory therapeutics.

Mesenchymal stem/stromal cells (MSCs) are being increasingly used in cell-based therapies due to their broad anti-inflammatory and immunomodulatory properties. Intravascularly-administered MSCs do not efficiently migrate to sites of inflammation/immunopathology, but this shortfall has been overcome by cell surface enzymatic fucosylation to engender expression of the potent E-selectin ligand HCELL. In applications of cell-based therapies, cryopreservation enables stability in both storage and transport of the produced cells from the manufacturing facility to the point of care. However, it has been reported that cryopreservation and thawing dampens their immunomodulatory/anti-inflammatory activity even after a reactivation/reconditioning step. To address this issue, we employed a variety of methods to cryopreserve and thaw fucosylated human MSCs derived from either bone marrow or adipose tissue sources. We then evaluated their immunosuppressive properties, cell viability, morphology, proliferation kinetics, immunophenotype, senescence, and osteogenic and adipogenic differentiation. Our studies provide new insights into the immunobiology of cryopreserved and thawed MSCs and offer a readily applicable approach to optimize the use of fucosylated human allogeneic MSCs as immunomodulatory/anti-inflammatory therapeutics.

Investigating the impact of solvation on p-Phenylenediamine - 2-Amino pyrimidine - Formaldehyde Terpolymer (P2APF) ligand's reactivity and drug suitability for malaria treatment: Insights from experimental and quantum calculations

This study aims at investigating the drug potential of p-Phenylenediamine – 2-Amino Pyrimidine – Formaldehyde terpolymer (P2APF) ligand against drug resistant Plasmodium falciparum. Plasmodium falciparum, an embodiment of cunning among malaria parasites, thrives in regions plagued by rampant mosquito transmission, subpar vector control, and limited access to effective treatments. To this end, this study explored the structural properties of the p-Phenylenediamine – 2-Amino Pyrimidine – Formaldehyde terpolymer (P2APF) ligand, (comprising p-Phenylenediamine, 2-Aminopyrimidine, and Formaldehyde) as a drug potent ligand against the common proteins coding for malaria infection. Various spectroscopic techniques such as FT-IR, UV–visible, and NMR (1H & 13C) spectroscopy were employed both experimentally and theoretically. Additionally, the ligand's surface morphology was investigated using scanning electron microscopy. To comprehend the influence of solvation, theoretical investigations utilizing density functional theory (DFT) at the B3LYPD(BJ)/6-311G++G (2d,2p) level were conducted in DMSO, water, and methanol solvents. The results from the frontier molecular orbital (FMO) analysis provided valuable insights into the electronic properties and solvation effects of P2APF. Specifically, the calculated energy gap of 3.671 eV for P2APF_methanol and 3.672 eV for P2APF_DMSO suggested these solvents as promising environments for reactivity and interactions. Molecular docking studies unveiled the most notable binding affinity between P2APF and the 5UMB chaperone protein receptor, exhibiting a binding affinity of -7.3 kcal/mol on serine and aspartic acid residues, with an average bond distance of 2.25 Å. This robust protein-ligand interaction signifies the promising potential of the P2APF ligand in targeting this specific receptor, thereby combating drug-resistant strains of Plasmodium falciparum for the present and the future.

Role of UDP-N-acetylmuramic acid in the regulation of MurA activity revealed by molecular dynamics simulations.

The peptidoglycan biosynthesis pathway plays a vital role in bacterial cells, and facilitates peptidoglycan layer formation, a fundamental structural component of the bacterial cell wall. The enzymes in this pathway are candidates for antibiotic development, as most do not have mammalian homologues. The UDP-N-acetylglucosamine (UNAG) enolpyruvyl transferase enzyme (MurA) in the peptidoglycan pathway cytoplasmic step is responsible for the phosphoenolpyruvate (PEP)-UNAG catalytic reaction, forming UNAG enolpyruvate and inorganic phosphate. Reportedly, UDP-N-acetylmuramic acid (UNAM) binds tightly to MurA forming a dormant UNAM-PEP-MurA complex and acting as a MurA feedback inhibitor. MurA inhibitors are complex, owing to competitive binding interactions with PEP, UNAM, and UNAG at the MurA active site. We used computational methods to explore UNAM and UNAG binding. UNAM showed stronger hydrogen-bond interactions with the Arg120 and Arg91 residues, which help to stabilize the closed conformation of MurA, than UNAG. Binding free energy calculations using end-point computational methods showed that UNAM has a higher binding affinity than UNAG, when PEP is attached to Cys115. The unbinding process, simulated using τ-random acceleration molecular dynamics, showed that UNAM has a longer relative residence time than UNAG, which is related to several complex dissociation pathways, each with multiple intermediate metastable states. This prevents the loop from opening and exposing the Arg120 residue to accommodate UNAG and potential new ligands. Moreover, we demonstrate the importance of Cys115-linked PEP in closed-state loop stabilization. We provide a basis for evaluating novel UNAM analogues as potential MurA inhibitors. PUBLIC SIGNIFICANCE: MurA is a critical enzyme involved in bacterial cell wall biosynthesis and is involved in antibiotic resistance development. UNAM can remain in the target protein's active site for an extended time compared to its natural substrate, UNAG. The prolonged interaction of this highly stable complex known as the 'dormant complex' comprises UNAM-PEP-MurA and offers insights into antibiotic development, providing potential options against drug-resistant bacteria and advancing our understanding of microbial biology.