Inhibitors of the protein–protein interaction (PPI) between the SARS-CoV-2 spike protein and human ACE2 (hACE2), which acts as a ligand–receptor pair that initiates the viral attachment and cellular entry of this coronavirus causing the ongoing COVID-19 pandemic, are of considerable interest as potential antiviral agents. While blockade of such PPIs with small molecules is more challenging than that with antibodies, small-molecule inhibitors (SMIs) might offer alternatives that are less strain- and mutation-sensitive, suitable for oral or inhaled administration, and more controllable/less immunogenic. Here, we report the identification of SMIs of this PPI by screening our compound library focused around the chemical space of organic dyes. Among promising candidates identified, several dyes (Congo red, direct violet 1, Evans blue) and novel druglike compounds (DRI-C23041, DRI-C91005) inhibited the interaction of hACE2 with the spike proteins of SARS-CoV-2 as well as SARS-CoV with low micromolar activity in our cell-free ELISA-type assays (IC50's of 0.2–3.0 μM), whereas control compounds, such as sunset yellow FCF, chloroquine, and suramin, showed no activity. Protein thermal shift assays indicated that the SMIs of interest identified here bind SARS-CoV-2-S and not hACE2. While dyes seemed to be promiscuous inhibitors, DRI-C23041 showed some selectivity and inhibited the entry of two different SARS-CoV-2-S expressing pseudoviruses into hACE2-expressing cells in a concentration-dependent manner with low micromolar IC50's (6–7 μM). This provides proof-of-principle evidence for the feasibility of small-molecule inhibition of PPIs critical for SARS-CoV-2 attachment/entry and serves as a first guide in the search for SMI-based alternative antiviral therapies for the prevention and treatment of diseases caused by coronaviruses in general and COVID-19 in particular.

We report the design, synthesis, and testing of novel small-molecule compounds targeting the CD40–CD154 (CD40L) costimulatory interaction for immunomodulatory purposes. This protein-protein interaction (PPI) is a TNF-superfamily (TNFSF) costimulatory interaction that is an important therapeutic target since it plays crucial roles in the activation of T cell responses, and there is resurgent interest in its modulation with several biologics in development. However, this interaction, just as all other PPIs, is difficult to target by small molecules. Following up on our previous work, we have now identified novel compounds such as DRI-C21091 or DRI-C21095 that show activity (IC50) in the high nanomolar to low micromolar range in the binding inhibition assay and more than thirty-fold selectivity versus other TNFSF PPIs including OX40–OX40L, BAFFR-BAFF, and TNF-R1-TNFα. Protein thermal shift (differential scanning fluorimetry) assays indicate CD154 and not CD40 as the binding partner. Activity has also been confirmed in cell assays and in a mouse model (alloantigen-induced T cell expansion in a draining lymph node). Our results expand the chemical space of identified small-molecule CD40–CD154 costimulatory inhibitors and provide lead structures that have the potential to be developed as orally bioavailable immunomodulatory therapeutics that are safer and less immunogenic than corresponding biologics.

Abstract The Notch signaling pathway has been found to play an important role in multiple human cancers by regulating transcriptional programs. However, the mechanism by which Notch drives target gene transcription is still elusive. In our previous study, we have identified and characterized a novel Notch activation complex kinase, NACK, which acts as a Notch transcriptional co-activator and an essential regulator of Notch-mediated tumorigenesis and development. In this regard, NACK could become a putative drug target in anti-cancer therapies. The lack of three-dimensional (3D) structure of NACK hinders the designing of potential drug inhibitors. Therefore, computational methods are adopted to elucidate the structural and functional features of NACK, which further aid in designing new NACK inhibitors. Molecule docking (Glide) is utilized to obtain potential hit inhibitors for NACK, which will be validated using in-vitro and in-vivo assays. This will open avenues for the development of new therapies for Notch-dependent cancers. Citation Format: Xiaoxia Zhu, Zhiqiang Wang, Ke Jin, Luisana Astudillo, Wen Zhou, Jinshui Chen, Peter Buchwald, Stephan C. Schürer, Anthony J. Capobianco. Discovery of novel anti-cancer therapeutic agents for Notch activation complex kinase (NACK) targeting the Notch pathway. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Targeting the Vulnerabilities of Cancer; May 16-19, 2016; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(1_Suppl):Abstract nr A33.

Costimulatory interactions are required for T cell activation and development of an effective immune response; hence, they are valuable therapeutic targets for immunomodulation. However, they, as all other protein-protein interactions, are difficult to target by small molecules. Here, we report the identification of novel small-molecule inhibitors of the CD40-CD40L interaction designed starting from the chemical space of organic dyes. For the most promising compounds such as DRI-C21045, activity (IC50) in the low micromolar range has been confirmed in cell assays including inhibition of CD40L-induced activation in NF-κB sensor cells, THP-1 myeloid cells, and primary human B cells as well as in murine allogeneic skin transplant and alloantigen-induced T cell expansion in draining lymph node experiments. Specificity versus other TNF-superfamily interactions (TNF-R1-TNF-α) and lack of cytotoxicity have also been confirmed at these concentrations. These novel compounds provide proof-of-principle evidence for the possibility of small-molecule inhibition of costimulatory protein-protein interactions, establish the structural requirements needed for efficient CD40-CD40L inhibition, and serve to guide the search for such immune therapeutics.

AbstractA wide range of aromatic aldehydes and an aliphatic one react with allenyltrichlorosilane to afford propargylic alcohols with high yields and enantioselectivities.

In this paper, in situ Fourier Transform Infrared Spectroscopy (FTIRS) is used to study the electro-catalytic oxidation mechanism of shikimic acid (SA) at a copper electrode in H2O and D2O solution, respectively. As the potential is applied between 0.1 V and 0.2 V vs. SCE, SA is oxidized to 3-dehydroshikimic acid (DHS). Then a significant change appeared when the potential is scanned from 0.3 V to 0.8 V, DHS is decomposed to transaconitate and formate. As the potential is over 0.9 V, formate is further oxidized to CO2. Density functional theory (DFT) calculation of the IR spectra is in good agreement with the experimental observation. The adsorption of transaconitate through carboxyl on copper electrode is also evidenced by p- and s-polarized radiation in FTIRS.

We report a new application of gold nanoparticles for visual detection of copper ions with high sensitivity and selectivity based on the colorimetric difference due to the strong and specific inhibition of Cu(NH3)(6)(2+) to the corrosion of gold nanoparticles at low concentration.

A highly enantioselective synthesis of homopropargylic alcohols is achieved by using the new helical chiral 2,2'-bipyridine N-monoxide catalyst and allenyltrichlorosilane. This method can be further extended to the enantio- and regioselective propargylation of N-acylhydrazones.

A simple, low cost, stable and environmentally friendly gold plating electrolyte containing hypoxanthine as a complexing agent is introduced. Bright and compact gold deposits could be obtained by using PEI-1800 and SUNO (a compound that contains the element sulfur) as additives for electrodepositing gold on a nickel substrate.

Helical chiral 2-aminopyridinium ions were designed as a significantly more acidic (active) dual hydrogen-bonding catalyst than commonly used (thio)urea-based systems. The helicene framework was specifically utilized to position an inherently chiral barrier on the hydrogen-bonding side of the catalyst. The catalyst reactivity and enantioselectivity were successfully demonstrated in additions of 4,7-dihydroindoles to nitroalkenes (0.5-2 mol % catalyst loadings, up to 98:2 er).

Through intramolecular activation, highly stable aryl[2-(hydroxymethyl)phenyl]dimethylsilanes can selectively transfer their aryl groups to effect a cross-coupling reaction with various aryl bromides and chlorides in the presence of a weak non-fluoride base and a palladium/copper catalyst. This reaction tolerates a wide range of functional groups, producing the corresponding functionalized biaryls in high yields with excellent chemoselectivity. Newly disclosed reaction conditions allow the recovery of a cyclic silyl ether in modest-to-good yields and reuse for the synthesis of the arylsilanes. The introduction of two isopropyl groups on the silicon center instead of methyl groups improves the stability and allows quantitative recovery of the silicon residue. Finally, aryl halides having an O-protected [2-(hydroxymethyl)phenyl]dimethylsilyl group cross-couple with the arylsilane reagents to give silyl-functionalized biaryls. Upon deprotection, the biaryls further react with the silylated electrophiles. The iterative cross-coupling deprotection sequences allow rapid assembly of silylated oligoarenes. Syntheses of di- and trisilyloligoarenes are also achieved by use of orthogonal O-protecting groups.

Optically active chiral alkyl chlorides are valuable compounds because of their bioactivity and versatile synthetic utility. Accordingly, the ring opening of epoxides with a chloride nucleophile stands as an important goal in asymmetric catalysis. We describe herein recent advances in the design and development of chiral pyridine N-oxide catalysts for the enantioselective synthesis of chlorohydrins.

The initial stage of silver electrodeposition on a glassy carbon electrode from a cyanide-free bath with 2-hydroxypyridine (2-HP) as the complexing agent is studied. The influence of polyethyleneimine (PEI) as an additive on the nucleation and growth of silver are also examined. Progressive nucleation mechanism is found for silver deposition according to Scharifker–Hills’ model with three-dimensional diffusion- controlled growth nucleation. This mechanism cannot be influenced by adding PEI. However, the diffusion coefficient of the silver–2-HP complexes and the density of nuclei exhibit a remarkable decrease with the addition of PEI. Smoother and brighter silver deposits with progressive nucleation features were obtained in the presence of PEI from the images of scanning electron microscopy.

The title reaction was found to proceed in the presence of a rhodium/1,2-bis(diphenylphosphino)benzene catalyst. Variously substituted arylethenes and 1,3-dienes were obtained in good yields.

Highly efficient synthesis of silyl-substituted oligoarenes with defined structures is achieved by an iterative cross-coupling reaction and deprotection sequence using organo[(2-hydroxymethyl)phenyl]dimethylsilanes. The excellent stability of the tetraorganosilicon compounds as well as mild and divergent conditions for cross-coupling and deprotection steps allows preparation of highly conjugated oligoarenylsilanes such as unsymmetrically disilylated quinquethiophenes.

The title reaction is found to proceed in the presence of a rhodium/diene catalyst. Variously substituted diarylmethylamines and allylamines having an N-arenesulfonyl protection are obtained in good yields, which are important building blocks in organic synthesis.

A new synthetic method of chiral allylsilanes has been developed through a rhodium-catalyzed asymmetric 1,4-addition of alkenyl[2-(hydroxymethyl)phenyl]dimethylsilanes to beta-silyl alpha,beta-unsaturated ketones. By employing (S,S)-Ph-bod* as a ligand, a range of alkenyl nucleophiles have been installed to these substrates in high yield and enantiomeric excess. The resulting allylsilanes can be used for stereoselective intramolecular allylation reactions to control two contiguous tertiary and quaternary stereocenters.

Highly stable alkenyl[2-(hydroxymethyl)phenyl]dimethylsilanes are prepared by stereo- and regioselective hydrosilylation of alkynes catalyzed either by a platinum or ruthenium catalyst using protected [2-(hydroxymethyl) phenyl]dimethylsilanes. Cyclic silyl ether, 1,1-dimethyl-2-oxa-1-silaindan, also serves as a starting material for the alkenylsilanes by the ring-opening reaction with alkenyl Grignard reagents. The resulting alkenylsilanes undergo cross-coupling reaction with various aryl and alkenyl iodides under reaction conditions employing K2CO3 as a base at 35-50 degrees C in highly regio- and stereospecific manners. The reaction tolerates a diverse range of functional groups including silyl protections. The silicon residue is readily recovered and reused on a gram-scale synthesis. Intramolecular coordination of a proximal hydroxyl group is considered to efficiently form pentacoordinate silicates having a transferable group possibly at an axial position and, thus, responsible for the cross-coupling reaction under conditions significantly milder than those reported for the silicon-based reactions. (c) 2006 Elsevier B.V. All rights reserved.