Mannich-Type Condensation and Domino Quinazolinone-Amidine Rearrangement Affords Ring-Fused Mackinazolinones with Anti-Amoebic Activity.

A three-step synthesis of anti-amoebic, ring-fused mackinazolinones has been developed. A Mannich-type reaction between quinazolin-4-ones and -Cbz propanal in the presence of AgOTf afforded quinazolinones (19-94% isolated yield) bearing a newly formed heterocycle with an alkylamine appendage that, upon -Cbz deprotection and basification, triggered a domino rearrangement to afford 45 separable, ring-fused products. Several compounds inhibited growth of parasites that can cause a lethal human brain infection.

Pharmacophore Establishment and Optimization of Saturated 1,6-Naphthyridine-Fused Quinazolinones that Inhibit Meningoencephalitis-Causing .

Primary amoebic meningoencephalitis (PAM) is a human brain infection caused by with a 97% mortality rate. Quinazolinones resulting from a Mannich-coupled domino rearrangement were recently identified as inhibitors of the amoeba. Herein, we resolved the effective concentrations for 25 pilot compounds and then, using the Mannich protocol and a key late-stage, -demethylation/functionalization, we synthesized 53 additional analogs to improve potency, solubility and microsomal stability.

Synthesis and Evaluation of Benzylamine Inhibitors of Neuropathogenic "Brain-Eating" Amoeba.

Current therapy for primary amoebic meningoencephalitis (PAM), a highly lethal brain infection in humans caused by amoeba, is restricted to repurposed drugs with limited efficacy and success. Discovery of an antiamoebic benzylamine scaffold precipitated a medicinal chemistry effort to improve potency, cytotoxicity profile, and drug-like properties. Thirty-four compounds were prepared, leading to compound with significant gains in potency (EC = 0.

Clinical and Translational Pharmacology Considerations for Anti-infectives Approved Under the FDA Animal Rule.

The US Food and Drug Administration's Animal Rule provides a pathway for approval of drugs and biologics aimed to treat serious or life-threatening conditions wherein traditional clinical trials are either not ethical or feasible. In such a scenario, determination of safety and efficacy are based on integration of data on drug disposition and drug action collected from in vitro models, infected animals, and healthy volunteer human studies. The demonstration of clinical efficacy and safety in humans based on robust, well-controlled animal studies is filled with challenges.

Efficacy of a brain-penetrant antiviral in lethal Venezuelan and eastern equine encephalitis mouse models.

Venezuelan and eastern equine encephalitis viruses (VEEV and EEEV, respectively) are mosquito-borne, neuroinvasive human pathogens for which no FDA-approved therapeutic exists. Besides the biothreat posed by these viruses when aerosolized, arthropod transmission presents serious health risks to humans, as demonstrated by the 2019 outbreak of EEE disease in the United States that resulted in 38 confirmed cases, 19 deaths, and neurological effects in survivors. Here, we describe the discovery of a 2-pyrrolidinoquinazolinone scaffold, efficiently synthesized in two to five steps, whose structural optimization resulted in profound antiviral activity.

Dihydropyrazinoquinazolinones via S2 Sulfamidate Ring-Opening and a Sequential Quinazolinone-Amidine Rearrangement Strategy (SQuAReS).

A synthesis of dihydropyrazino-[2,1-]-quinazolinones is described using a 2-alkylaminoquinazolinone-mediated ring opening of a-/chiral sulfamidates, followed by a tandem quinazolinone-amidine rearrangement termed SQuAReS. This approach takes advantage of sulfamidates whose regioselective ring opening, after hydrolysis, appends an optimally distanced nucleophilic amine to a quinazolinone such that subsequent domino rearrangements are favored, integrating unique substitution patterns on a privileged core. This three-step protocol integrated five telescoped transformations and generated 20 pyrazinoquinazolinones in up to 74% yield with high enantiomeric fidelity and diastereoselectivity.

Characterization of Glucokinases from Pathogenic Free-Living Amoebae.

Infection with pathogenic free-living amoebae, including Naegleria fowleri, spp., and Balamuthia mandrillaris, can lead to life-threatening illnesses, primarily because of catastrophic central nervous system involvement. Efficacious treatment options for these infections are lacking, and the mortality rate due to infection is high.

Piperazinobenzodiazepinones: New Encephalitic Alphavirus Inhibitors via Ring Expansion of 2-Dichloromethylquinazolinones.

Venezuelan and eastern equine encephalitis viruses are disease-causing, neuropathic pathogens with no approved treatment options in humans. While expanding the pharmacophoric model of antialphaviral amidines prepared via a quinazolinone rearrangement, we discovered that diamine-treated, 2-dihalomethylquinolinones unexpectedly afforded ring-expanded piperazine-fused benzodiazepinones. Notably, this new chemotype (19 examples) showed potent, submicromolar inhibition of virus-induced cell death, >7-log reduction of viral yield, and tractable structure-activity relationships across both viruses.

An Innovation 10 Years in the Making: The Stories in the Pages of .

Innovation in medicinal chemistry has been at the heart of since the journal's founding 10 years ago. In his inaugural editorial, Editor-in-Chief Dennis Liotta laid out a vision for the journal to become the "premier international journal for rapid communication of cutting-edge studies," and, after 10 years, it has become exactly that. The great hope of drug discovery scientists is that their innovations will lead to new therapeutics to treat unmet medical needs.

Engineering Selectivity for Reduced Toxicity of Bacterial Kinase Inhibitors Using Structure-Guided Medicinal Chemistry.

Tuberculosis is a major global public health concern, and new drugs are needed to combat both the typical form and the increasingly common drug-resistant form of this disease. The essential tuberculosis kinase PknB is an attractive drug development target because of its central importance in several critical signaling cascades. A major hurdle in kinase inhibitor development is the reduction of toxicity due to nonspecific kinase activity in host cells.

Time to 'Mind the Gap' in novel small molecule drug discovery for direct-acting antivirals for SARS-CoV-2.

A pipeline of effective direct-acting antivirals (DAAs) remains a critical gap in addressing the current pandemic given vaccination hesitancy, the emergence of viral variants of concern, susceptible populations for which vaccination is ineffective or unavailable, and the possibility that coronavirus disease 2019 (COVID-19) is here to stay. Since the start of the pandemic, global efforts in small molecule drug discovery have focused largely on testing of FDA-approved drugs to accelerate evaluation in clinical trials in hospitalized patients. With 80% of the population who test positive for SARS-CoV-2 having asymptomatic to mild COVID-19, early stage, DAAs would be of enormous benefit to reduce spread, duration of symptoms and quarantine length.

Diastereoselective, Multicomponent Synthesis of Pyrrolopyrazinoquinazolinones via a Tandem Quinazolinone Rearrangement/Intramolecular Ring Closure of Tautomeric ()-Benzamidines.

An expedient route to enantiopure, diastereomeric pyrrolopyrazinoquinazolinones was developed following the discovery of a domino quinazolinone rearrangement-intramolecular cyclization of N-H benzamidines. A Ugi-Mumm-Staudinger sequence employing an optically pure proline derivative gave quinazolinones that, upon -Boc deprotection, rearranged to tautomeric -benzamidines. Subsequent spontaneous cyclization afforded 15 diastereomeric pyrazinoquinazolinone pairs in up to 83% overall yield and 89:11 d.

Construction of -Boc-2-Alkylaminoquinazolin-4(3)-Ones via a Three-Component, One-Pot Protocol Mediated by Copper(II) Chloride that Spares Enantiomeric Purity.

Chiral 2-alkylquinazolinones are key synthetic intermediates, but their preparation in high optical purity is challenging. Thus, a multicomponent procedure integrating anthranilic acids, -Boc-amino acids, and amines in the presence of methanesulfonyl chloride, -methylimidazole, and copper(II) chloride was developed to mildly afford -Boc-2-alkylaminoquinazolin-4(3)-ones with excellent preservation of enantiomeric purity (>99% ee). Copper(II) chloride was essential to retaining enantiopurity, and reaction component structural changes were well tolerated, resulting in an efficient, all-in-one procedure that promotes sequential coupling, lactonization, aminolysis, and cyclization in good yields.

Dual-Stage Picolinic Acid-Derived Inhibitors of .

causes a prevalent human infection for which only the acute stage has an FDA-approved therapy. To find inhibitors of both the acute stage parasites and the persistent cyst stage that causes a chronic infection, we repurposed a compound library containing known inhibitors of parasitic hexokinase, the first step in the glycolysis pathway, along with a larger collection of new structural derivatives. The focused screen of 22 compounds showed a 77% hit rate (>50% multistage inhibition) and revealed a series of aminobenzamide-linked picolinic acids with submicromolar potency against both parasite forms.

Emergence and Magnitude of ML336 Resistance in Venezuelan Equine Encephalitis Virus Depend on the Microenvironment.

Venezuelan equine encephalitis virus (VEEV) is a New World that can cause neurological disease and death in humans and equines following transmission from infected mosquitoes. Despite the continued epidemic threat of VEEV, and its potential use as a bioterrorism agent, there are no FDA-approved antivirals or vaccines for treatment or prevention. Previously, we reported the discovery of a small molecule, ML336, with potent antiviral activity against VEEV.

Divergent 2-Chloroquinazolin-4(3H)-one Rearrangement: Twisted-Cyclic Guanidine Formation or Ring-Fused N-Acylguanidines via a Domino Process.

A highly efficient 2-chloroquinazolin-4(3H)-one rearrangement was developed that predictably generates either twisted-cyclic or ring-fused guanidines in a single operation, depending on the presence of a primary versus secondary amine in the accompanying diamine reagent. Exclusive formation of twisted-cyclic guanidines results from pairing 2-chloroquinazolinones with secondary diamines. Use of primary amine-containing diamines permits a domino quinazolinone rearrangement/intramolecular cyclization, gated through (E)-twisted-cyclic guanidines, to afford ring-fused N-acylguanidines.

Discovery of Selective Inhibitors of Endoplasmic Reticulum Aminopeptidase 1.

ERAP1 is an endoplasmic reticulum-resident zinc aminopeptidase that plays an important role in the immune system by trimming peptides for loading onto major histocompatibility complex proteins. Here, we report discovery of the first inhibitors selective for ERAP1 over its paralogues ERAP2 and IRAP. Compound (-(-(2-(1-indol-3-yl)ethyl)carbamimidoyl)-2,5-difluorobenzenesulfonamide) and compound (1-(1-(4-acetylpiperazine-1-carbonyl)cyclohexyl)-3-(-tolyl)urea) are competitive inhibitors of ERAP1 aminopeptidase activity.

Benzamidine ML336 inhibits plus and minus strand RNA synthesis of Venezuelan equine encephalitis virus without affecting host RNA production.

Venezuelan equine encephalitis virus (VEEV) is an alphavirus that is endemic to the Americas. VEEV outbreaks occur periodically and cause encephalitis in both humans and equids. There are currently no therapeutics or vaccines for treatment of VEEV in humans.

Synthesis of Ring-Fused, N-Substituted 4-Quinolinones Using p-Guided, Base-Promoted Annulations with Isatoic Anhydrides: Total Synthesis of Penicinotam.

An anionic annulation strategy employing isatoic anhydrides and a wide assortment of enolizable partners was developed to afford over 80 novel ring-fused, N-substituted 4-quinolinones, an underrepresented privileged template. Multiple factors governing the efficiency of the transformation were determined, resulting in a reliable and tunable synthetic platform applicable for a broad range of substrates with variable deprotonation susceptibility, such as tetramic and tetronic acids, cyclic 1,3-diketones, and cycloalkanones. Application to the synthesis of bioactive, pyrrolizine-fused 4-quinolinone, penicinotam , resulted in the most brief and highest yielding total synthesis of the alkaloid in three steps and a 36% overall yield.

Efficacy of a ML336 derivative against Venezuelan and eastern equine encephalitis viruses.

Currently, there are no licensed human vaccines or antivirals for treatment of or prevention from infection with encephalitic alphaviruses. Because epidemics are sporadic and unpredictable, and endemic disease is common but rarely diagnosed, it is difficult to identify all populations requiring vaccination; thus, an effective post-exposure treatment method is needed to interrupt ongoing outbreaks. To address this public health need, we have continued development of ML336 to deliver a molecule with prophylactic and therapeutic potential that could be relevant for use in natural epidemics or deliberate release scenario for Venezuelan equine encephalitis virus (VEEV).

Enzymatic and Structural Characterization of the Glucokinase.

Infection with the free-living amoeba leads to life-threatening primary amoebic meningoencephalitis. Efficacious treatment options for these infections are limited, and the mortality rate is very high (∼98%). Parasite metabolism may provide suitable targets for therapeutic design.

Telescoped synthesis of C3-functionalized (E)-arylamidines using Ugi-Mumm and regiospecific quinazolinone rearrangements.

An efficient four-step, six-transformation protocol was developed to afford bioactive N-alkyl- or N-arylamide (E)-arylamidines featuring strategic amidine C3 modifications which were inaccessible or low yielding by previous methods. This synthetic approach, exemplified with 24 amidines and requiring only a single purification, highlights a multicomponent Ugi-Mumm rearrangement to afford highly diversified quinazolinones which undergo regiospecific rearrangement to afford new amidines. The method extensively broadens the structural scope of this new class of trisubstituted amidines and demonstrates the tolerance of regional C3 amidine steric bulk, visualized with X-ray crystallographic analysis.

Editing N-Glycan Site Occupancy with Small-Molecule Oligosaccharyltransferase Inhibitors.

The oligosaccharyltransferase (OST) is a multisubunit enzyme complex that N-glycosylates proteins in the secretory pathway and is considered to be constitutive and unregulated. However, small-molecule OST inhibitors such as NGI-1 provide a pharmacological approach for regulating N-linked glycosylation. Herein we design cell models with knockout of each OST catalytic subunit (STT3A or STT3B) to screen the activity of NGI-1 and its analogs.

Palladium-Catalyzed Cyclocarbonylation of Pyridinylated Vinylogous Amides and Ureas to Generate Ring-Fused Pyridopyrimidinones.

As part of a program aimed at generating new heterocyclic frameworks for medicinal chemistry exploration, an efficient approach to the assembly of novel ring-fused pyridopyrimidinones was undertaken. Specifically, a collection of 11 H-pyrido[2,1- b]quinazoline-1,11(2 H)-diones and 2,3-dihydropyrido[1,2- a]pyrrolo[3,4- d]pyrimidine-1,10-diones was generated via a palladium-catalyzed, pyridine-directed, cyclocarbonylation of 2-pyridyl-linked vinylogous amides and ureas in yields of up to 90%.