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

Synthesis, Herbicidal Activity, and Molecular Mode of Action Evaluation of Novel Aryloxyphenoxypropionate/Amide Derivatives Containing a Quinazolinone Moiety

To develop aryloxyphenoxypropionate herbicides with a novel structure and improved activity, a total of 39 aryloxyphenoxypropionate/amide derivatives containing quinazolinone moiety were synthesized and further bioevaluated. The bioassay results in the greenhouse showed that most of the target compounds had good herbicidal activity under postemergence conditions, of which, QPP-I-6 displayed excellent herbicidal activity against Echinochloa crusgalli, Digitaria sanguinalis, Spartina alterniflora, Eleusine indica, and Pennisetum alopecuroides with inhibition rates >90% at a dosage of 187.5 g ha-1. More importantly, QPP-I-6 displayed higher crop safety to Gossypium hirsutum, Glycine max, and Arachis hypogaea than the commercial herbicide quizalofop-p-ethyl. Studying the molecular mode of action by phenotypic observation, membrane permeability evaluation, transcriptomic analysis, and in vivo ACCase activity evaluation reveals that QPP-I-6 is a novel ACCase inhibitor. The present work demonstrates that QPP-I-6 can serve as a lead compound for further developing novel ACCase-inhibiting herbicides.

Design, synthesis, anticancer, and antibacterial evaluation of some quinazolinone-based derivatives as DHFR inhibitors

Two series of quinazolinone derivatives were designed and synthesized as dihydrofolate reductase (DHFR) inhibitors. All compounds were evaluated for their antibacterial and antitumor activities. Antibacterial activity was evaluated against three strains of Gram-positive and Gram-negative bacteria. Compound 3d exhibited the highest inhibitory activity against Staphylococcus aureus DHFR (SaDHFR) with IC50 of 0.769 ± 0.04 μM compared to 0.255 ± 0.014 μM for trimethoprim. Compound 3e was also more potent than trimethoprim against Escherichia coli DHFR (EcDHFR) with IC50 of 0.158 ± 0.01 μM and 0.226 ± 0.014 μM, respectively. Compound 3e exhibited a promising antiproliferative effect against most of the tested cancer cells. It also showed potent activity against leukemia (CCRF-CEM, and RPMI-8226); lung NCI-H522, and CNS U251 with GI% of 65.2, 63.22, 73.28, and 97.22, respectively. The cytotoxic activity of compound 3e was almost half the activity of doxorubicin against CCRF-CEM cell line with IC50 of 1.569 ± 0.06 μM and 0.822 ± 0.03 µM, respectively. In addition, compound 3e inhibited human DHFR with IC50 value of 0.527 ± 0.028 µM in comparison to methotrexate (IC50  = 0.118 ± 0.006 µM). Compound 3e caused an arrest of the cell cycle mainly at the S phase and caused a rise in the overall apoptotic percentage from 2.03% to 48.51%. (23.89-fold). Treatment of CCRF-CEM cells with compound 3e produced a significant increase in the active caspase-3 level by 6.25-fold compared to untreated cells. Molecular modeling studies were performed to evaluate the binding pattern of the most active compounds in the bacterial and human DHFR.

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. The lead quinazolinone, BDGR-49, potently reduced cellular VEEV and EEEV titers by >7 log at 1 μM and exhibited suitable intravenous and oral pharmacokinetic profiles in BALB/c mice to achieve excellent brain exposure. Outstanding in vivo efficacy was observed in several lethal, subcutaneous infection mouse models using an 8-day dosing regimen. Prophylactically administered BDGR-49 at 25 mg kg^-1 per day fully protected against a 10× LD₅₀ VEEV Trinidad donkey (TrD) challenge in BALB/c mice. Similarly, we observed 70% protection when 10× LD₅₀ EEEV FL93-939-infected C57BL/6 mice were treated prophylactically with BDGR-49 at 50 mg kg^-1 per day. Last, we observed 100% therapeutic efficacy when mice, challenged with 10× LD₅₀ VEEV TrD, were dosed at 48 hours after infection with BDGR-49 at 25 mg kg^-1 per day. Mouse brain viral titers at 96 hours after infection were reduced to values near the limit of detection. Collectively, these results underscore the substantial development potential of a well-tolerated, brain-penetrant lead compound that shows promise in preventing and treating encephalitic alphavirus disease.

Antibacterial activity evaluation of pleuromutilin derivatives with 4(3H)-quinazolinone scaffold against methicillin-resistant Staphylococcusaureus

Growing antibiotic resistance is causing a health care crisis, leading to an urgent need for new antibiotics to tackle serious hospital and community infections. Pleuromutilin, a naturally occurring product with moderate antibacterial activity, has a unique structure that has attracted great efforts to modify its scaffold to obtain lead compounds. Herein, we report the synthesis of a series of novel pleuromutilin derivatives with a scaffold of 4(3H)-quinazolinone or its analogues at the C-14 side chain and investigated their in vitro activity against Staphylococcus aureus and Staphylococcus epidermidis as well as Gram-negative bacteria (Escherichia coli and Salmonella enterica subsp. enterica serovar pullorum). Structure-activity relationship (SAR) studies showed that the substituents on the benzene ring of 4(3H)-quinazolinone was not as important as the substituted position to improve antibacterial activity while the substituted groups on the N-3 position of 4(3H)-quinazolinone had strong impact on the efficacy. The replacement of the benzene moiety of 4(3H)-quinazolinone with other rings (pyridine, pyrrole, thiophene, or cyclopentyl) also showed high antibacterial efficacy, meaning the benzene ring was dispensable for exerting powerful antibacterial properties. In vitro pharmacokinetics investigations and cytotoxicity assays indicated that 2-mercapto-4(3H)-quinazolinone scaffold was superior to 2-(piperazin-1-yl)quinazolin-4(3H)-one. Among this series of pleuromutilin analogues, compound 23 with a structure of 2-mercapto-3H-pyrrolo[2,3-d]pyrimidin-4(7H)-one displayed the best in vitro antibacterial activity against MRSA (MIC = 0.063 μg/mL) and low cytotoxicity to RAW 264.7 cells (IC50＞100 μM) and was demonstrated to inhibit MRSA effectively in a mouse thigh infection model, outperforming the comparator, tiamulin.

Divergent Approach for Regioselective Synthesis of Linearly and Angularly Fused Benzoimidazoquinazolinones from Isatoic Anhydrides

Ph₃P-I₂-mediated condensation reactions of isatoic anhydrides and o-phenylenediamines have been developed for the regioselective syntheses of a wide range of linearly and angularly fused benzoimidazoquinazolinones. The selectivity of the products relies on the generation of either highly electrophilic oxyphosphonium or less reactive imidate intermediates. A direct amine attack at the C-2 position of the oxyphosphonium intermediate presumably drives the reaction toward the linearly fused products, whereas an attack of the diamine at the C-4 position of the in situ generated cyclic imidate leads to the angularly fused derivatives. This strategy serves as a practical handle for the efficient synthesis of other related heterocycles.

Design and synthesis of novel quinazolinone-based derivatives as EGFR inhibitors with antitumor activity

Nineteen new quinazolin-4(3H)-one derivatives 3a–g and 6a–l were designed and synthesised to inhibit EGFR. The antiproliferative activity of the synthesised compounds was tested in vitro against 60 different human cell lines. The most potent compound 6d displayed superior sub-micromolar antiproliferative activity towards NSC lung cancer cell line NCI-H460 with GI₅₀ = 0.789 µM. It also showed potent cytostatic activity against 40 different cancer cell lines (TGI range: 2.59–9.55 µM). Compound 6d potently inhibited EGFR with IC₅₀ = 0.069 ± 0.004 µM in comparison to erlotinib with IC₅₀ value of 0.045 ± 0.003 µM. Compound 6d showed 16.74-fold increase in total apoptosis and caused cell cycle arrest at G1/S phase in breast cancer HS 578T cell line. Moreover, the most potent derivatives were docked into the EGFR active site to determine their binding mode and confirm their ability to satisfy the pharmacophoric features required for EGFR inhibition.

Regioselective Access to 2-Iminoimidazolidines via AgF-Mediated Cascade Reactions

A convergent access to substituted 2-iminoimidazolidines from aromatic amines and N-propargyl S-methylthiourea is developed via Ag(I)-mediated cascade guanylation-cyclization reactions. This method features high regioselectivity, excellent efficiency, and mild reaction conditions. Subsequent deprotection of the Boc (tert-butyloxycarbonyl) group under acidic conditions provides expedient access to aryl 2-aminoimidazole derivatives in a convenient manner.

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. Antiviral activity was confirmed in primary human neuronal cells. A mechanistic rationale for product formation is proposed, and key structural elements were comparatively modeled between a similarly substituted antiviral amidine and piperazinobenzodiazepinone prototypes to guide future antiviral development.

Direct synthesis for N2-unprotected five-membered cyclic guanidines by regioselective [3+2] annulation of aziridines and cyanamides

A novel and efficient [3+2] annulation of 2-substituted aziridines and N-tosyl cyanamides via domino regioselective ring-opening/5-exo-dig cyclization procedure has been developed, allowing the direct preparation for N2-unprotected five-membered cyclic guanidines...