Diversified strategy for the synthesis of DNA-encoded oxindole libraries.

DNA-encoded library technology (DELT) employs DNA as a barcode to track the sequence of chemical reactions and enables the design and synthesis of libraries with billions of small molecules through combinatorial expansion. This powerful technology platform has been successfully demonstrated for hit identification and target validation for many types of diseases. As a highly integrated technology platform, DEL is capable of accelerating the translation of synthetic chemistry by using on-DNA compatible reactions or off-DNA scaffold synthesis.

Construction of Thiazole-Fused Dihydropyrans via Formal [4 + 2] Cycloaddition Reaction on DNA.

An efficient and facile formal [4 + 2] cycloaddition reaction was developed to synthesize diverse thiazole-fused dihydropyrans (TFDP) on DNA. Mild reaction conditions, broad substrate scope, and compatibility with subsequent enzymatic ligation demonstrated the utility of this methodology in DNA-encoded library synthesis.

Fragment-Based Computational Method for Designing GPCR Ligands.

G protein-coupled receptors (GPCRs) are the largest family of cell surface receptors, which is arguably the most important family of drug target. With the technology breakthroughs in X-ray crystallography and cryo-electron microscopy, more than 300 GPCR-ligand complex structures have been publicly reported since 2007, covering about 60 unique GPCRs. Such abundant structural information certainly will facilitate the structure-based drug design by targeting GPCRs.

Palladium-Promoted DNA-Compatible Heck Reaction.

Optimal conditions for palladium-promoted Heck reaction on DNA were developed with good to excellent conversions. Versatility with either DNA-conjugated styrene/acrylamide or aryl iodide and a broad substrate scope of the corresponding coupling partners were established. Furthermore, robustness of the Heck reaction conditions on single-strand DNA and feasibility for DNA-encoded library production were demonstrated.

A potent Lassa virus antiviral targets an arenavirus virulence determinant.

Arenaviruses are a significant cause of hemorrhagic fever, an often-fatal disease for which there is no approved antiviral therapy. Lassa fever in particular generates high morbidity and mortality in West Africa, where the disease is endemic, and a recent outbreak in Nigeria was larger and more geographically diverse than usual. We are developing LHF-535, a small-molecule viral entry inhibitor that targets the arenavirus envelope glycoprotein, as a therapeutic candidate for Lassa fever and other hemorrhagic fevers of arenavirus origin.

Inverse-Electron-Demand Diels-Alder Reactions for the Synthesis of Pyridazines on DNA.

The synthesis of pyridazines on DNA has been developed on the basis of inverse-electron-demand Diels-Alder (IEDDA) reactions of 1,2,4,5-tetrazines. The broad substrate scope is explored. Functionalized pyridazine products are selected for subsequent DNA-compatible Suzuki-Miyaura coupling, acylation, and SAr substitution reactions, demonstrating the feasibility and versatility of IEDDA reactions for DNA-encoded library synthesis.

Ruthenium-Promoted C-H Activation Reactions between DNA-Conjugated Acrylamide and Aromatic Acids.

The first example of DNA-compatible C-H activation reaction between DNA-conjugated acrylamides and aromatic acids has been developed. This new transformation enables aromatic acid, previously considered as monofunctional building block, to act like a bifunctional building block for the DNA encoded library synthesis. The general scope of aromatic acid was established for this new on-DNA C-H activation, which paved the way for its application in combinatorial library preparation.

Lead optimization of an acylhydrazone scaffold possessing antiviral activity against Lassa virus.

Previously we reported the optimization of antiviral scaffolds containing benzimidazole and related heterocycles possessing activity against a variety of arenaviruses. These series of compounds were discovered through an HTS campaign of a 400,000 small molecule library using lentivirus-based pseudotypes incorporated with the Lassa virus envelope glycoprotein (LASV GP). This screening also uncovered an alternate series of very potent arenavirus inhibitors based upon an acylhydrazone scaffold.

Novel benzoxazole inhibitor of dengue virus replication that targets the NS3 helicase.

Dengue virus (DENV) is the predominant mosquito-borne viral pathogen that infects humans with an estimated 50 to 100 million infections per year worldwide. Over the past 50 years, the incidence of dengue disease has increased dramatically and the virus is now endemic in more than 100 countries. Moreover, multiple serotypes of DENV are now found in the same geographic region, increasing the likelihood of more severe forms of disease.

Discovery and optimization of potent broad-spectrum arenavirus inhibitors derived from benzimidazole and related heterocycles.

A series of potent arenavirus inhibitors sharing a benzimidazole core were previously reported by our group. SAR studies were expanded beyond the previous analysis, which involved the attached phenyl rings and methylamino linker portion, to include modifications focused on the benzimidazole core. These changes included the introduction of various substituents to the bicyclic benzimidazole ring system along with alternate core heterocycles.

Discovery and optimization of potent broad-spectrum arenavirus inhibitors derived from benzimidazole.

A chemically diverse library of about 400,000 small molecules was screened for antiviral activity against lentiviral pseudotypes with the Lassa virus envelope glycoprotein (LASV GP) gene incorporated. High-throughput screening resulted in discovery of a hit compound (ST-37) possessing a benzimidazole core which led to a potent compound series. Herein, we report SAR studies which involved structural modifications to the phenyl rings and methylamino linker portion attached to the benzimidazole core.

A novel inhibitor of dengue virus replication that targets the capsid protein.

Dengue viruses (DENV) infect 50 to 100 million people worldwide per year, of which 500,000 develop severe life-threatening disease. This mosquito-borne illness is endemic in most tropical and subtropical countries and has spread significantly over the last decade. While there are several promising vaccine candidates in clinical trials, there are currently no approved vaccines or therapeutics available for treatment of dengue infection.

SAR analysis of a series of acylthiourea derivatives possessing broad-spectrum antiviral activity.

A series of acylthiourea derivatives were designed, synthesized, and evaluated for broad-spectrum antiviral activity with selected viruses from Poxviridae (vaccinia virus) and two different genera of the family Bunyaviridae (Rift Valley fever and La Crosse viruses). A compound selected from a library screen, compound 1, displayed submicromolar antiviral activity against both vaccinia virus (EC(50)=0.25 μM) and La Crosse virus (EC(50)=0.

Evaluation of Lassa antiviral compound ST-193 in a guinea pig model.

Lassa virus (LASV), a member of the Arenaviridae family, causes a viral hemorrhagic fever endemic to West Africa, where as many as 300,000 infections occur per year. Presently, there are no FDA-approved LASV-specific vaccines or antiviral agents, although the antiviral drug ribavirin has shown some efficacy. A recently identified small-molecule inhibitor of arenavirus entry, ST-193, exhibits submicromolar antiviral activity in vitro.

A specific interaction of small molecule entry inhibitors with the envelope glycoprotein complex of the Junín hemorrhagic fever arenavirus.

Arenaviruses are responsible for acute hemorrhagic fevers worldwide and are recognized to pose significant threats to public health and biodefense. Small molecule compounds have recently been discovered that inhibit arenavirus entry and protect against lethal infection in animal models. These chemically distinct inhibitors act on the tripartite envelope glycoprotein (GPC) through its unusual stable signal peptide subunit to stabilize the complex against pH-induced activation of membrane fusion in the endosome.

pH-induced activation of arenavirus membrane fusion is antagonized by small-molecule inhibitors.

The arenavirus envelope glycoprotein (GPC) mediates viral entry through pH-induced membrane fusion in the endosome. This crucial process in the viral life cycle can be specifically inhibited in the New World arenaviruses by the small-molecule compound ST-294. Here, we show that ST-294 interferes with GPC-mediated membrane fusion by targeting the interaction of the G2 fusion subunit with the stable signal peptide (SSP).

Identification of a broad-spectrum arenavirus entry inhibitor.

Several arenaviruses, including Lassa virus (LASV), are causative agents of hemorrhagic fever, for which effective therapeutic options are lacking. The LASV envelope glycoprotein (GP) gene was used to generate lentiviral pseudotypes to identify small-molecule inhibitors of viral entry. A benzimidazole derivative with potent antiviral activity was identified from a high-throughput screen utilizing this strategy.

Discovery of small molecule inhibitors of ubiquitin-like poxvirus proteinase I7L using homology modeling and covalent docking approaches.

Essential for viral replication and highly conserved among poxviridae, the vaccinia virus I7L ubiquitin-like proteinase (ULP) is an attractive target for development of smallpox antiviral drugs. At the same time, the I7L proteinase exemplifies several interesting challenges from the rational drug design perspective. In the absence of a published I7L X-ray structure, we have built a detailed 3D model of the I7L ligand binding site (S2-S2' pocket) based on exceptionally high structural conservation of this site in proteases of the ULP family.

N-(3,3a,4,4a,5,5a,6,6a-Octahydro-1,3-dioxo-4,6- ethenocycloprop[f]isoindol-2-(1H)-yl)carboxamides: Identification of novel orthopoxvirus egress inhibitors.

A series of novel, potent orthopoxvirus egress inhibitors was identified during high-throughput screening of the ViroPharma small molecule collection. Using structure--activity relationship information inferred from early hits, several compounds were synthesized, and compound 14 was identified as a potent, orally bioavailable first-in-class inhibitor of orthopoxvirus egress from infected cells. Compound 14 has shown comparable efficaciousness in three murine orthopoxvirus models and has entered Phase I clinical trials.