Superresolution imaging of antibiotic-induced structural disruption of bacteria enabled by photochromic glycomicelles.

Bacterial evolution, particularly in hospital settings, is leading to an increase in multidrug resistance. Understanding the basis for this resistance is critical as it can drive discovery of new antibiotics while allowing the clinical use of known antibiotics to be optimized. Here, we report a photoactive chemical probe for superresolution microscopy that allows for the in situ probing of antibiotic-induced structural disruption of bacteria. Conjugation between a spiropyran (SP) and galactose via click chemistry produces an amphiphilic photochromic glycoprobe, which self-assembles into glycomicelles in water. The hydrophobic inner core of the glycomicelles allows encapsulation of antibiotics. Photoirradiation then serves to convert the SP to the corresponding merocyanine (MR) form. This results in micellar disassembly allowing for release of the antibiotic in an on-demand fashion. The glycomicelles of this study adhere selectively to the surface of a Gram-negative bacterium through multivalent sugar-lectin interaction. Antibiotic release from the glycomicelles then induces membrane collapse. This dynamic process can be imaged in situ by superresolution spectroscopy owing to the "fluorescence blinking" of the SP/MR photochromic pair. This research provides a high-precision imaging tool that may be used to visualize how antibiotics disrupt the structural integrity of bacteria in real time.

Investigating the self-assembly of 2NapFF and ureido-pyrimidinone multicomponent systems for cell culture.

Low molecular weight gels are formed via the self-assembly of small molecules into fibrous structures. In the case of hydrogels, these networks entrap large volumes of water, yielding soft materials. Such gels tend to have weak mechanical properties and a high permeability for cells, making them particularly appealing for regenerative medicine applications. Ureido-pyrimidinone (UPy) supramolecular gelators are self-assembling systems that have demonstrated excellent capabilities as biomaterials. Here, we combine UPy-gelators with another low molecular weight gelator, the functionalized dipeptide 2NapFF. We have successfully characterized these multicomponent systems on a molecular and bulk scale. The addition of 2NapFF to a crosslinked UPy hydrogel significantly increased hydrogel stiffness from 30 Pa to 1300 Pa. Small-angle X-ray scattering was used to probe the underlying structures of the systems and showed that the mixed UPy and 2NapFF systems resemble the scattering data produced by the pristine UPy systems. However, when a bifunctional UPy-crosslinker was added, the scattering was close to that of the 2NapFF only samples. The results suggest that the crosslinker significantly influences the assembly of the low molecular weight gelators. Finally, we analysed the biocompatibility of the systems using fibroblast cells and found that the cells tended to spread more effectively when the crosslinking species was incorporated. Our results emphasise the need for thorough characterisation at multiple length scales to finely control material properties, which is particularly important for developing novel biomaterials.

Synthesis and Biological Evaluation of Pyrazole-Pyrimidones as a New Class of Correctors of the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR).

Cystic fibrosis (CF) is caused by the functional expression defect of the cystic fibrosis transmembrane conductance regulator (CFTR) protein. Despite the recent success in CFTR modulator development, the available correctors only partially restore the F508del-CFTR channel function, and several rare CF mutations show resistance to available drugs. We previously identified compound 4172 that synergistically rescued the F508del-CFTR folding defect in combination with the existing corrector drugs VX-809 and VX-661. Here, novel CFTR correctors were designed by applying a classical medicinal chemistry approach on the 4172 scaffold. Molecular docking and three-dimensional quantitative structure-activity relationship (3D-QSAR) studies were conducted to propose a plausible binding site and design more potent and effective analogs. We identified three optimized compounds, which, in combination with VX-809 and the investigational corrector 3151, increased the plasma membrane density and function of F508del-CFTR and other rare CFTR mutants resistant to the currently approved therapies.

Scaffold overlay of flavonoid-inspired molecules: Discovery of 2,3-diaryl-pyridopyrimidin-4-imine/ones as dual hTopo-II and tubulin targeting anticancer agents.

Almost half of all medicines approved by the U.S. Food and Drug Administration have been found to be developed based on inspiration from natural products (NPs). Here, we report a novel strategy of scaffold overlaying of scaffold-hopped analogs of bioactive flavones and isoflavones and installation of drug-privileged motifs, which has led to discovery of anticancer agents that surpass the functional efficiency of the original NPs. The analogs, 2,3-diaryl-pyridopyrimidin-4-imine/ones were efficiently synthesized by an approach of a nitrile-stabilized quaternary ammonium ylide as masked synthon and Pd-catalyzed activation-arylation methods. Compared to the NPs, these NP-analogs exhibited differentiated functions; dual inhibition of human topoisomerase-II (hTopo-II) enzyme and tubulin polymerization, and pronounced antiproliferative effect against various cancer cell lines, including numerous drug-resistant cancer cells. The most active compound 5l displayed significant inhibition of migration ability of cancer cells and blocked G1/S phase transition in cell cycle. Compound 5l caused pronounced effect in expression patterns of various key cell cycle regulatory proteins; up-regulation of apoptotic proteins, Bax, Caspase 3 and p53, and down-regulation of apoptosis-inhibiting proteins, BcL-xL, Cyclin D1, Cyclin E1 and NF-κB, which indicates high efficiency of the molecule 5l in apoptosis-signal axis interfering potential. Cheminformatics analysis revealed that 2,3-diaryl-pyridopyrimidin-4-imine/ones occupy a distinctive drug-relevant chemical space that is seldom represented by natural products and good physicochemical, ADMET and pharmacokinetic-relevant profile. Together, the anticancer potential of the investigated analogs was found to be much more efficient compared to the original natural products and two anticancer drugs, Etoposide (hTopo-II inhibitor) and 5-Flurouracile (5-FU).

Discovery of pyrrolo[2,3-d]pyrimidin-4-one derivative YCH3124 as a potent USP7 inhibitor for cancer therapy.

USP7 is one of the most studied deubiquitinating enzymes, which is involved in the regulation of multiple cell signaling pathways and has been shown to be associated with the occurrence and progression of a variety of cancers. Inhibitors targeting USP7 have been studied by several teams, but most of them lack selectivity and have low activities. Herein, we reported a serious of pyrrole[2,3-d]pyrimidin-4-one derivatives through scaffold hopping of recently reported 4-hydroxypiperidine compounds. The representative compound Z33 (YCH3124) exhibited highly potent USP7 inhibition activity as well as anti-proliferative activity against four kinds of cancer cell lines. Further study revealed that YCH3124 effectively inhibited the downstream USP7 pathway and resulted in the accumulation of both p53 and p21 in a dose-dependent manner. Notably, YCH3124 disrupted cell cycle progression through restricting G1 phase and induced significant apoptosis in CHP-212 cells. In summary, our efforts provided a series of novel pyrrole[2,3-d]pyrimidin-4-one analogs as potent USP7 inhibitors with excellent anti-cancer activity.

Design, synthesis, and biological evaluation of Pyrido[1,2-a]pyrimidin-4-one derivatives as novel allosteric SHP2 inhibitors.

SHP2 (Src homology-2-containing protein tyrosine phosphatase 2) plays an important role in cell proliferation, survival, migration by affecting RAS-ERK, PI3K-AKT, JAK-STAT signaling pathways and so on. Overexpression or gene mutation of SHP2 is closely linked with a variety of cancers, making it a potential therapeutic target for cancer disease. In this paper, 30 target compounds bearing pyrido[1,2-a]pyrimidin-4-one core were synthesized via two-round design strategy by means of scaffold hopping protocol. It was evaluated the in vitro enzymatic inhibition and cell antiproliferation assay of these targets. 13a, designed in the first round, presented relatively good inhibitory activity, but its molecular rigidity might limit further improvement by hindering the formation of the desired "bidentate ligand", as revealed by molecular docking studies. In our second-round design, S atom as a linker was inserted into the core and the 7-aryl group to enhance the flexibility of the structure. The screening result revealed that 14i could exhibit high enzymatic activity against full-length SHP2 (IC50 = 0.104 µM), while showing low inhibitory effect on SHP2-PTP (IC50 > 50 µM). 14i also demonstrated high antiproliferative activity against the Kyse-520 cells (IC50 = 1.06 µM) with low toxicity against the human brain microvascular endothelial cells HBMEC (IC50 = 30.75 µM). 14i also displayed stronger inhibitory activities on NCI-H358 and MIA-PaCa2 cells compared to that of SHP099. Mechanistic studies revealed that 14i could induce cell apoptosis, arrest the cell cycle at the G0/G1 phase and downregulate the phosphorylation levels of Akt and Erk1/2 in Kyse-520 cells. Molecular docking and molecular dynamics studies displayed more detailed information on the binding mode and binding mechanism of 14i and SHP2. These data suggest that 14i has the potential to be a promising lead compound for our further investigation of SHP2 inhibitors.

New morpholine-containing pyrimidinones act on α-adrenoceptors.

Drugs that act on α-adrenoceptors may contain morpholine and pyrimidinone heterocycles. The aim of this study was to synthesize a series of pyrimidinones (S6a-e and S8) and characterize their α-adrenoceptor activity. Cytotoxicity assays (MTT and LDH) were performed in A7r5 and HUVECs. Concentration-effect curves to phenylephrine (Phe) were performed in rat aortic rings in the presence of compounds S6a-e and S8 or vehicle. Nitric oxide (NO) production and NO stable metabolic products, nitrite and nitrate, expressed as total nitrogen oxides (NOx) were assessed in HUVECs by confocal microscopy with the DAF-2DA probe and by the Griess reaction, respectively. Molecular docking simulations were performed using the 6a compound and α2A-adrenoceptor. In the evaluated conditions, the percentage of viable cells and the release of LDH were similar between control cells and cells exposed to the tested pyrimidinones. S6d, S6e, S8, and the positive control prazosin (but not S6a, S6b, and S6c) decreased Phe-induced contractions in endothelium-denuded aortic rings. S6a, S6b, and S6c decreased Phe-induced contractions in endothelium-intact aortic rings. The effect of S6a was abolished by L-NAME. NO production and NOx levels were inhibited in the presence of the α2 receptor antagonist yohimbine and the NOS inhibitor L-NAME. The 6a docking simulation estimated that the mean binding free energy of the compound was lower than the estimated value for yohimbine. These data suggest that S6d, S6e, and S8 may be α1-adrenoceptor antagonists while S6a acts as an agonist of α2-adrenoceptors.

Rutaecarpine-inspired scaffold-hopping strategy and Ullmann cross-coupling based synthetic approach: Identification of pyridopyrimidinone-indole based novel anticancer chemotypes.

Natural products as starting templates have shown historically major contribution to development of drugs. Inspired by the structure-function of an anticancer natural alkaloid Rutaecarpine, the Scaffold-hopped Acyclic Analogues of Rutaecarpine (SAAR) with 'N'-atom switch (1°-hop) and ring-opening (2°-hop) were investigated. A new synthetic route was developed for an effective access to the analogues, i.e. 2-indolyl-pyrido[1,2-a]pyrimidinones, which involved preparation of N-Boc-N'-phthaloyltryptamine/mexamine-bromides and pyridopyrmidinon-2-yl triflate, a nickel/palladium-catalysed Ullmann cross-coupling of these bromides and triflate, deprotection of phthalimide followed by N-aroylation, and Boc-deprotection. Fourteen novel SAAR-compounds were prepared, and they showed characteristic antiproliferative activity against various cancer cells. Three most active compounds (11a, 11b, and 11c) exhibited good antiproliferative activity, IC50 7.7-15.8 µM against human breast adenocarcinoma cells (MCF-7), lung cancer cells (A549), and colon cancer cells (HCT-116). The antiproliferative property was also observed in the colony formation assay. The SAAR compound 11b was found to have superior potency than original natural product Rutaecarpine and an anticancer drug 5-FU in antiproliferative activities with relatively lower cytotoxicity towards normal breast epithelial cells (MCF10A) and significantly higher inhibitory effect on cancer cells' migration. The compound 11b was found to possess favourable in silico physicochemical characteristics (lipophilicity-MLOGP, TPSA, and water solubility-ESOL, and others), bioavailability score, and pharmacokinetic properties (GI absorption, BBB non-permeant, P-gp, and CYP2D6). Interestingly, the compound 11b did not show any medicinal chemistry structural alert of PAINS and Brenk filter. The study represents for the first time the successful discovery of new potent anticancer chemotypes using Rutaecarpine natural alkaloid as starting template and reaffirms the significance of natural product-inspired scaffold-hopping technique in drug discovery research.

Design, synthesis, and biological evaluation of pyrido[2,3-d]pyrimidin-7(8H)-one derivatives as potent USP1 inhibitors.

USP1 has emerged as a novel and potential target for drug discovery in single therapeutic agents or combination with chemotherapy and molecular targeted therapy. In this study, based on the disclosed structure of ML323 and KSQ-4279, we designed and synthesized a series of pyrido[2,3-d]pyrimidin-7(8H)-one derivatives as potent USP1 inhibitors by cyclization strategy and the systematic structure-activity relationship exploration was conducted. The representative compounds 1k, 1m and 2d displayed excellent USP1/UAF inhibition and exhibited strong antiproliferation effect in NCI-H1299 cells. Further flow cytometry analysis revealed that they could arrest breast cancer cells MDA-MB-436 in the S phase. Inhibition mechanism study of compound 1m indicated these derivatives acted as reversible and noncompetitive USP1 inhibitors. Of note, the combination of compound 1m with PARP inhibitor olaparib generated enhanced cell killing in olaparib-resistant MDA-MB-436/OP cells, and compound 1m exhibited excellent oral pharmacokinetic properties in mice. Overall, our efforts may provide a reliable basis for the development of novel USP1 inhibitor as a single therapeutic agent and in combination with PARP inhibitors.

Discovery of Pyrido[1,2-α] Pyrimidinone Mesoionic Compounds as Potential Control Agents Against Potato Virus Y.

Potato virus Y (PVY) relies on aphids and tubers to spread in the field and causes serious economic losses in the potato industry. Here, we found that pyrido[1,2-α] pyrimidinone mesoionic compounds with insecticidal activity against aphids possessed a good inhibitory effect on PVY. Among them, compound 35 had the best inhibitory activity against PVY (EC50 = 104 µg/mL), even superior to that of ningnanmycin (125 µg/mL). The fluorescence and qPCR results confirmed that compound 35 could inhibit the proliferation of PVY in Nicotiana benthamiana. Preliminary experiments on the mechanism of action indicated that compound 35 had good binding affinity with the coat protein (CP), which plays an essential role in aphid-PVY interactions. Molecular docking revealed that compound 35 could bind to the pocket of CP formed by Ser52, Glu204, and Arg208. Compound 35 had substantially lower binding affinity (Kd) values with CPS52A (219 µM), CPE204A (231 µM), and CPR208A (189 µM) than those with CPWT (5.80 µM). A luciferase assay confirmed that mutating Ser52, Glu204, and Arg208 significantly affected the expression level of CP and further reduced virus proliferation. Therefore, the broad-spectrum activity of compound 35 provides a unique strategy for the prevention and treatment of PVY.

WLB-87848, a Selective σ1 Receptor Agonist, with an Unusually Positioned NH Group as Positive Ionizable Moiety and Showing Neuroprotective Activity.

The synthesis and pharmacological activity of a new series of thieno[2,3-d]pyrimidin-4(3H)-one derivatives as sigma-1 receptor (σ1R) ligands are reported. A hit from a high-throughput screening program was evolved into a highly potent and selective σ1R agonist (14qR) that contains a free NH group as positive ionizable moiety, not fulfilling the usual pharmacophoric features of the σ1R. The compound shows good physicochemical and ADMET characteristics, displays an agonist profile in the binding immunoglobulin protein/σ1R association assay, induces neuron viability in an in vitro model of ß-amyloid peptide intoxication, and presents positive results against recognition memory impairment induced by hippocampal injection of Aß peptide in rats after oral treatment, altogether making 14qR (WLB-87848) an interesting candidate for neuroprotection.

Discovery of selective TYK2 inhibitors: Design, synthesis, in vitro and in silico studies of promising hits with triazolopyrimidinone scaffold.

The Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway mediates many cytokine and growth factor signals. Tyrosine kinase 2 (TYK2), one of the members of this pathway and the first described member of the JAK family. TYK2 associates with inflammatory and autoimmune diseases, cancer and diabetes. Here, we present novel compounds as selective inhibitors of the canonical kinase domain of TYK2 enzyme. These compounds were rationally designed and synthesized with appropriate reactions. Molecular modeling techniques were used to design and optimize the candidates for TYK2 inhibition and to determine the estimated binding orientations of them inside JAKs. Designed compounds potently inhibited TYK2 with good selectivity against other JAKs as determined by in vitro assays. In order to verify its selectivity properties, compound A8 was tested against 58 human kinases (KinaseProfiler™ assay). The effects of the selected seven compounds on the protein levels of members of the JAK/STAT family were also detected in THP-1 monocytes although the basal level of these proteins is poorly detectable. Therefore, their expression was induced by lipopolysaccharide treatment and compounds A8, A15, A18, and A19 were found to be potent inhibitors of the TYK2 enzyme, (9.7 nM, 6.0 nM, 5.0 nM and 10.3 nM, respectively), and have high selectivity index for the JAK1, JAK2, and JAK3 enzymes. These findings suggest that triazolo[1,5-a]pyrimidinone derivatives may be lead compounds for developing potent TYK2-selective inhibitors targeting enzymes' active site.

Design, synthesis, and bioevaluation of SOS1 PROTACs derived from pyrido[2,3-d]pyrimidin-7-one-based SOS1 inhibitor.

Oncogenic KRAS mutations drive an approximately 25 % of all human cancers. Son of Sevenless 1 (SOS1), a critical guanine nucleotide exchange factor, catalyzes the activation of KRAS. Targeting SOS1 degradation has engaged as a promising therapeutic strategy for KRAS-mutant cancers. Herein, we designed and synthesized a series of novel CRBN-recruiting SOS1 PROTACs using the pyrido[2,3-d]pyrimidin-7-one-based SOS1 inhibitor as the warhead. One representative compound 11o effectively induced the degradation of SOS1 in three different KRAS-mutant cancer cell lines with DC50 values ranging from 1.85 to 7.53 nM. Mechanism studies demonstrated that 11o-induced SOS1 degradation was dependent on CRBN and proteasome. Moreover, 11o inhibited the phosphorylation of ERK and displayed potent anti-proliferative activities against SW620, A549 and DLD-1 cells. Further optimization of 11o may provide us promising SOS1 degraders with favorable drug-like properties for developing new chemotherapies targeting KRAS-driven cancers.

Design, synthesis, docking, and antiviral evaluation of some novel pyrimidinone-based α-aminophosphonates as potent H1N1 and HCoV-229E inhibitors.

Dialkyl/aryl aminophosphonates, 3a-g and 4a-e were synthesized using the LiClO4 catalyzed Kabachnic Fields-type reaction straightforwardly and efficiently. The synthesized phosphonates structures were characterized using elemental analyses, FT-IR, 1H NMR, 13C NMR, and MS spectroscopy. The new compounds were subjected to in-silico molecular docking simulations to evaluate their potential inhibition against Influenza A Neuraminidase and RNA-dependent RNA polymerase of human coronavirus 229E. Subsequently, the compounds were further tested in vitro using a cytopathic inhibition assay to assess their antiviral activity against both human Influenza (H1N1) and human coronavirus (HCoV-229E). Diphenyl ((2-(5-cyano-6-oxo-4-phenyl-1,6-dihydropyrimidin-2-yl) hydrazinyl) (furan-2-yl) methyl) phosphonate (3f) and diethyl ((2-(5-cyano-6-oxo-4-phenyl-1,6-dihydropyrimidin-2-yl) hydrazinyl) (1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl) methyl) phosphonate (4e) were demonstrated direct inhibition activity against Influenza A Neuraminidase and RNA-dependent RNA polymerase. This was supported by their highly favorable binding energies in-silico, with top-ranked values of -12.5 kcal/mol and -14.2 kcal/mol for compound (3f), and -13.5 kcal/mol and -9.89 kcal/mol for compound (4e). Moreover, they also displayed notable antiviral efficacy in vitro against both viruses. These compounds demonstrated significant antiviral activity, as evidenced by selectivity indices (SI) of 101.7 and 51.8, respectively against H1N1, and 24.5 and 5.1 against HCoV-229E, respectively.

The effect of charge and albumin on cellular uptake of supramolecular polymer nanostructures.

Intracellular delivery of functional biomolecules by using supramolecular polymer nanostructures has gained significant interest. Here, various charged supramolecular ureido-pyrimidinone (UPy)-aggregates were designed and formulated via a simple "mix-and-match" method. The cellular internalization of these UPy-aggregates in the presence or absence of serum proteins by phagocytic and non-phagocytic cells, i.e., THP-1 derived macrophages and immortalized human kidney cells (HK-2 cells), was systematically investigated. In the presence of serum proteins the UPy-aggregates were taken up by both types of cells irrespective of the charge properties of the UPy-aggregates, and the UPy-aggregates co-localized with mitochondria of the cells. In the absence of serum proteins only cationic UPy-aggregates could be effectively internalized by THP-1 derived macrophages, and the internalized UPy-aggregates either co-localized with mitochondria or displayed as vesicular structures. While the cationic UPy-aggregates were hardly internalized by HK-2 cells and could only bind to the membrane of HK-2 cells. With adding and increasing the amount of serum albumin in the cell culture medium, the cationic UPy-aggregates were gradually taken up by HK-2 cells without anchoring on the cell membranes. It is proposed that the serum albumin regulates the cellular internalization of UPy-aggregates. These results provide fundamental insights for the fabrication of supramolecular polymer nanostructures for intracellular delivery of therapeutics.

Design, Synthesis, and Biological Evaluation of Pyrido [1,2-α] Pyrimidinone Mesoionic Derivatives Bearing Propenylbenzene as the Vector Control Insecticide.

A series of novel pyrido [1,2-α] pyrimidinone mesoionic derivatives bearing a propenylbenzene group at the 1-position were synthesized on the basis of the structure of mesoionic insecticides triflumezopyrim and dicloromezotiaz via a rationally conceived pharmacophore model and evaluated for their insecticidal activities against three insect vectors. The bioassay results showed that some compounds exerted remarkable insecticidal activities against M. domestica, Ae. albopictus, and B. germanica. Particularly, compound 26l displayed outstanding insecticidal activity against Ae. Albopictus, with an LC50 value of 0.45 µg/mL, far superior to that of imidacloprid (LC50 = 1.82 µg/mL) and equivalent to that of triflumezopyrim (0.35 µg/mL). Meanwhile, compound 34l presented a broad insecticidal spectrum, with LC50 values of 1.51 µg/g sugar, 0.52 µg/mL and 0.14 µg/adult, which were about 2.88, 3.50, and 1.50 times better than that of imidacloprid (LC50 = 4.35 µg/g sugar, 1.82 µg/mL and 0.21 µg/adult against M. domestica, Ae. albopictus, and B. germanica, respectively) and equivalent to that of triflumezopyrim against M. domestica (1.13 µg/g sugar) and Ae. albopictus (0.35 µg/mL) but lower than the potency against B. germanica (0.06 µg/g sugar). The molecular docking study by energy minimizations revealed that introducing propenylbenzene at the 1-position of compounds 26l and 34l could embed into the binding pocket of nicotinic acetylcholine receptors and form pi-alkyl interaction with LEU306. These results demonstrated that compounds 26l and 34l could be promising candidates for vector control insecticides, which deserved further investigation.

Iron Oxide Nanoparticles with Supramolecular Ureido-Pyrimidinone Coating for Antimicrobial Peptide Delivery.

Antimicrobial peptides (AMPs) can kill bacteria by disrupting their cytoplasmic membrane, which reduces the tendency of antibacterial resistance compared to conventional antibiotics. Their possible toxicity to human cells, however, limits their applicability. The combination of magnetically controlled drug delivery and supramolecular engineering can help to reduce the dosage of AMPs, control the delivery, and improve their cytocompatibility. Lasioglossin III (LL) is a natural AMP form bee venom that is highly antimicrobial. Here, superparamagnetic iron oxide nanoparticles (IONs) with a supramolecular ureido-pyrimidinone (UPy) coating were investigated as a drug carrier for LL for a controlled delivery to a specific target. Binding to IONs can improve the antimicrobial activity of the peptide. Different transmission electron microscopy (TEM) techniques showed that the particles have a crystalline iron oxide core with a UPy shell and UPy fibers. Cytocompatibility and internalization experiments were carried out with two different cell types, phagocytic and nonphagocytic cells. The drug carrier system showed good cytocompatibility (>70%) with human kidney cells (HK-2) and concentration-dependent toxicity to macrophagic cells (THP-1). The particles were internalized by both cell types, giving them the potential for effective delivery of AMPs into mammalian cells. By self-assembly, the UPy-coated nanoparticles can bind UPy-functionalized LL (UPy-LL) highly efficiently (99%), leading to a drug loading of 0.68 g g-1. The binding of UPy-LL on the supramolecular nanoparticle system increased its antimicrobial activity against E. coli (MIC 3.53 µM to 1.77 µM) and improved its cytocompatible dosage for HK-2 cells from 5.40 µM to 10.6 µM. The system showed higher cytotoxicity (5.4 µM) to the macrophages. The high drug loading, efficient binding, enhanced antimicrobial behavior, and reduced cytotoxicity makes ION@UPy-NH2 an interesting drug carrier for AMPs. The combination with superparamagnetic IONs allows potential magnetically controlled drug delivery and reduced drug amount of the system to address intracellular infections or improve cancer treatment.

Structure and function analysis of a type III preQ1-I riboswitch from Escherichia coli reveals direct metabolite sensing by the Shine-Dalgarno sequence.

Riboswitches are small noncoding RNAs found primarily in the 5' leader regions of bacterial messenger RNAs where they regulate expression of downstream genes in response to binding one or more cellular metabolites. Such noncoding RNAs are often regulated at the translation level, which is thought to be mediated by the accessibility of the Shine-Dalgarno sequence (SDS) ribosome-binding site. Three classes (I-III) of prequeuosine1 (preQ1)-sensing riboswitches are known that control translation. Class I is divided into three subtypes (types I-III) that have diverse mechanisms of sensing preQ1, which is involved in queuosine biosynthesis. To provide insight into translation control, we determined a 2.30 Å-resolution cocrystal structure of a class I type III preQ1-sensing riboswitch identified in Escherichia coli (Eco) by bioinformatic searches. The Eco riboswitch structure differs from previous preQ1 riboswitch structures because it has the smallest naturally occurring aptamer and the SDS directly contacts the preQ1 metabolite. We validated structural observations using surface plasmon resonance and in vivo gene-expression assays, which showed strong switching in live E. coli. Our results demonstrate that the Eco riboswitch is relatively sensitive to mutations that disrupt noncanonical interactions that form the pseudoknot. In contrast to type II preQ1 riboswitches, a kinetic analysis showed that the type III Eco riboswitch strongly prefers preQ1 over the chemically similar metabolic precursor preQ0. Our results reveal the importance of noncanonical interactions in riboswitch-driven gene regulation and the versatility of the class I preQ1 riboswitch pseudoknot as a metabolite-sensing platform that supports SDS sequestration.

Design, Synthesis, and Insecticidal Activity of Mesoionic Pyrido[1,2-a]pyrimidinone Containing Isoxazole/Isoxazoline Moiety as a Potential Insecticide.

Bean aphid (Aphis craccivora) resistance to commonly used insecticides has made controlling these pests increasingly difficult. In this study, we introduced isoxazole and isoxazoline, which possess insecticidal activity, into pyrido[1,2-a]pyrimidinone through a scaffold hopping strategy. We designed and synthesized a series of novel mesoionic compounds that exhibited a range of insecticidal activities against A. craccivora. The LC50 values of compounds E1 and E2 were 0.73 and 0.88 µg/mL, respectively, better than triflumezopyrim (LC50 = 2.43 µg/mL). Proteomics and molecular docking analyses showed that E1 might influence the A. craccivora nervous system by interacting with neuronal nicotinic acetylcholine receptors (nAChRs). This research offers a new approach to the advancement of novel mesoionic insecticides.

Green and efficient one-pot three-component synthesis of novel drug-like furo[2,3-d]pyrimidines as potential active site inhibitors and putative allosteric hotspots modulators of both SARS-CoV-2 MPro and PLPro.

In this paper, an environmentally benign, convenient, and efficient one-pot three-component reaction has been developed for the regioselective synthesis of novel 5-aroyl(or heteroaroyl)-6-(alkylamino)-1,3-dimethylfuro[2,3-d]pyrimidine-2,4(1H,3H)-diones (4a‒n) through the sequential condensation of aryl(or heteroaryl)glyoxal monohydrates (1a‒g), 1,3-dimethylbarbituric acid (2), and alkyl(viz. cyclohexyl or tert-butyl)isocyanides (3a or 3b) catalyzed by ultra-low loading ZrOCl2•8H2O (just 2 mol%) in water at 50 ˚C. After synthesis and characterization of the mentioned furo[2,3-d]pyrimidines (4a‒n), their multi-targeting inhibitory properties were investigated against the active site and putative allosteric hotspots of both SARS-CoV-2 main protease (MPro) and papain-like protease (PLPro) based on molecular docking studies and compare the attained results with various medicinal compounds which approximately in three past years were used, introduced, and or repurposed to fight against COVID-19. Furthermore, drug-likeness properties of the mentioned small heterocyclic frameworks (4a‒n) have been explored using in silico ADMET analyses. Interestingly, the molecular docking studies and ADMET-related data revealed that the novel series of furo[2,3-d]pyrimidines (4a‒n), especially 5-(3,4-methylendioxybenzoyl)-6-(cyclohexylamino)-1,3-dimethylfuro[2,3-d]pyrimidine-2,4(1H,3H)-dione (4g) as hit one is potential COVID-19 drug candidate, can subject to further in vitro and in vivo studies. It is worthwhile to note that the protein-ligand-type molecular docking studies on the human body temperature-dependent MPro protein that surprisingly contains zincII (ZnII) ion between His41/Cys145 catalytic dyad in the active site, which undoubtedly can make new plans for designing novel SARS-CoV-2 MPro inhibitors, is performed for the first time in this paper, to the best of our knowledge.