Isoxazole-3-hydroxamic acid derivatives as peptide deformylase inhibitors and potential antibacterial agents

A Study on Synthesis of Chalcone Derived -5- Membered Isoxazoline and Isoxazole Scaffolds

Chalcone-derived Isoxazole scaffolds remain the central focus because of their greater biological, clinical, and pharmacological properties. The present study reviews the synthesis of various chalcone derived - 5- Membered Isoxazoline and Isoxazole Scaffolds with the available literature until 2021. Keywords: Chalcones, Isoxazoles, Isoxazolines, Biological and Pharmacological properties.

Design, synthesis, and biological evaluation of N-(4-substituted)-3-phenylisoxazolo[5,4-d]pyrimidin-4-amine derivatives as apoptosis-inducing cytotoxic agents

A library of new 3-phenylisoxazolo[5,4-d]pyrimidines (8-10) was designed based on a scaffold hybridization technique incorporating the important pharmacophoric features of 4-aminopyrimidine and phenyl isoxazole scaffold which is renowned for its BET inhibition activity. The designed molecules were synthesized and evaluated with the NCI-60 cell line panel. Examination by NCI-60 cell lines at single-dose and the five-dose study showed that compound 10h exhibited promising growth inhibitory effects with GI₅₀ values on various cancer cell lines such as HCT-15 (Colon Cancer)-0.0221 μM, MDA-MB-435 (Melanoma) - 0.0318 μM, SNB-75(CNS Cancer)-0.0263 μM, and MCF7 (Breast Cancer)-0.0372 μM. Further studies to know the mechanism of action of 10h based on the phase-contrast microscopic evaluation, DAPI, acridine orange/ethidium bromide (AO/EB) staining, and annexin V-FITC assays revealed that elevation in the intracellular ROS leads to alteration in mitochondrial membrane potential which in turn induced the apoptosis in BT-474 cancer cells, which could be the plausible mechanism of action for compound 10h.

Synthesis and biological evaluation of fluoro-substituted spiro-isoxazolines as potential anti-viral and anti-cancer agents

Electrophilic fluorine-mediated dearomative spirocyclization has been developed to synthesize a range of fluoro-substituted spiro-isoxazoline ethers and lactones. The in vitro biological assays of synthesized compounds were probed for anti-viral activity against human cytomegalovirus (HCMV) and cytotoxicity against glioblastomas (GBM6) and triple negative breast cancer (MDA MB 231). Interestingly, compounds 4d and 4n showed significant activity against HCMV (IC50 ∼ 10 μM), while 4l and 5f revealed the highest cytotoxicity with IC50 = 36 to 80 μM. The synthetic efficacy and biological relevance offer an opportunity to further drug-discovery development of fluoro-spiro-isoxazolines as novel anti-viral and anti-cancer agents.

Crystal structure of (R)-5-[(R)-3-(4-chloro-phen-yl)-5-methyl-4,5-di-hydro-isoxazol-5-yl]-2-methyl-cyclo-hex-2-enone

The title compound, C17H18ClNO2, was prepared and isolated as a pure diastereoisomer, using column chromatography followed by a succession of fractional crystallizations. Its exact structure was fully identified via 1H NMR and confirmed by X-ray diffraction. It is built up from a central five-membered di-hydro-isoxazole ring to which a p-chloro-phenyl group and a cyclo-hex-2-enone ring are attached in the 3 and 5 positions. The cyclo-hex-2-one and isoxazoline rings each exhibit an envelope conformation. The crystal packing features C-H⋯O, C-H⋯N and C-H⋯π inter-actions, which generate a three-dimensional network.

Synthesis of carbohydrate-substituted isoxazoles and evaluation of their antitubercular activity

Eight new sugar-substituted isoxazoles were synthesized by a 1,3-dipolar cycloaddition reaction of aromatic nitrile oxides with carbohydrate-substituted alkynes. Products were screened for antimycobacterial activity against the Mycobacterium tuberculosis H37Rv strain. Four compounds, 5e–h, significantly inhibit growth of the bacterial strain with a minimum inhibitory concentration (MIC) of 3.125 μg/mL.

Isoxazole ring as a useful scaffold in a search for new therapeutic agents

Due to its relatively easy synthesis, isoxazole ring has been as an object of interest for chemists and pharmacologists from research groups all over the world. Its chemical modifications include both connection of isoxazole with other aromatic, heteroaromatic or non aromatic rings and substitution with different alkyl groups. Thanks to their usually low cytotoxicity, isoxazole derivatives are still popular scaffolds for the development of new agents with variable biological activities, such as antimicrobial, antiviral, anticancer, anti-inflammatory, immunomodulatory, anticonvulsant or anti-diabetic properties. This review discusses the chemical structure of recently developed isoxazole derivatives with regards to their activity and potential therapeutic use.

Copper-catalyzed aerobic oxidative C–O bond formation for the synthesis of 3,5-disubstituted isoxazoles from enone oximes

An efficient copper-catalyzed aerobic oxidative C–O bond formation for the synthesis of 3,5-disubstituted isoxazoles from enone oximes is presented.

A unique peptide deformylase platform to rationally design and challenge novel active compounds

Peptide deformylase (PDF) is considered an excellent target to develop antibiotics. We have performed an extensive characterization of a new PDF from the pathogen Streptococcus agalactiae, showing properties similar to other known PDFs. S. agalactiae PDF could be used as PDF prototype as it allowed to get complete sets of 3-dimensional, biophysical and kinetic data with virtually any inhibitor compound. Structure-activity relationship analysis with this single reference system allowed us to reveal distinct binding modes for different PDF inhibitors and the key role of a hydrogen bond in potentiating the interaction between ligand and target. We propose this protein as an irreplaceable tool, allowing easy and relevant fine comparisons between series, to design, challenge and validate novel series of inhibitors. As proof-of-concept, we report here the design and synthesis of effective specific bacterial PDF inhibitors of an oxadiazole series with potent antimicrobial activity against a multidrug resistant clinical isolate.

Oxyboration with and without a Catalyst: Borylated Isoxazoles via B-O σ-Bond Addition

Herein we report an oxyboration reaction with activated substrates that employs B–O σ bond additions to C–C π bonds to form borylated isoxazoles, which are potential building blocks for drug discovery. Although this reaction can be effectively catalyzed by gold, it is the first example of uncatalyzed oxyboration of C–C π bonds by B–O σ bonds—and only the second example that is catalyzed. This oxyboration reaction is tolerant of groups incompatible with alternative lithiation/borylation and palladium-catalyzed C–H activation/borylation technologies for the synthesis of borylated isoxazoles.

A Multilayer Network Approach for Guiding Drug Repositioning in Neglected Diseases

Drug development for neglected diseases has been historically hampered due to lack of market incentives. The advent of public domain resources containing chemical information from high throughput screenings is changing the landscape of drug discovery for these diseases. In this work we took advantage of data from extensively studied organisms like human, mouse, E. coli and yeast, among others, to develop a novel integrative network model to prioritize and identify candidate drug targets in neglected pathogen proteomes, and bioactive drug-like molecules. We modeled genomic (proteins) and chemical (bioactive compounds) data as a multilayer weighted network graph that takes advantage of bioactivity data across 221 species, chemical similarities between 1.7 10⁵ compounds and several functional relations among 1.67 10⁵ proteins. These relations comprised orthology, sharing of protein domains, and shared participation in defined biochemical pathways. We showcase the application of this network graph to the problem of prioritization of new candidate targets, based on the information available in the graph for known compound-target associations. We validated this strategy by performing a cross validation procedure for known mouse and Trypanosoma cruzi targets and showed that our approach outperforms classic alignment-based approaches. Moreover, our model provides additional flexibility as two different network definitions could be considered, finding in both cases qualitatively different but sensible candidate targets. We also showcase the application of the network to suggest targets for orphan compounds that are active against Plasmodium falciparum in high-throughput screens. In this case our approach provided a reduced prioritization list of target proteins for the query molecules and showed the ability to propose new testable hypotheses for each compound. Moreover, we found that some predictions highlighted by our network model were supported by independent experimental validations as found post-facto in the literature.

Neglected tropical diseases are human infectious diseases that are often associated with poverty. Historically, lack of interest from the pharmaceutical industry resulted in the lack of good drugs to combat the majority of the pathogens that cause these diseases. Recently, the availability of open chemical information has increased with the advent of public domain chemical resources and the release of data from high throughput screening assays. Our aim in this work was to make use of data from extensively studied organisms like human, mouse, E. coli and yeast, among others, to prioritize and identify candidate drug targets in neglected pathogen proteomes, and drug-like bioactive molecules to foster drug development against neglected diseases. Our approach to the problem relied on applying bioinformatics and computational biology strategies to model large datasets spanning complete proteomes and extensive chemical information from publicly available sources. As a result, we were able to prioritize drug targets and identify potential targets for orphan bioactive drugs.

Synthesis of 3,4,5-trisubstituted isoxazoles via 1,3-dipolar cycloaddition/SO2 extrusion of benzoisothiazole-2,2-dioxide-3-ylidenes with nitrile oxides

An straightforward synthesis of 3,4,5-trisubstituted isoxazole derivatives via 1,3-dipolar cycloaddtion/SO₂ extrusion of benzoisothiazole-2,2-dioxide-3-ylidenes with nitrile oxides is reported using 4 Å molecular sieves as dehydrochlorinating agent.

Direct synthesis of 4-fluoroisoxazoles through gold-catalyzed cascade cyclization-fluorination of 2-alkynone O-methyl oximes

A tandem protocol for the synthesis of fluorinated isoxazoles has been developed via catalytic intramolecular cyclizations of 2-alkynone O-methyl oximes and ensuing fluorination. The reactions proceed smoothly at room temperature in the presence of 5 mol % of (IPr)AuCl, 5 mol % of AgOTs, 2.5 equiv of Selectfluor, and 2 equiv of NaHCO3. This process features an efficient one-pot cascade route to fluoroisoxazoles with high yields and high selectivity under mild reaction conditions.

Design, synthesis, computational and biological evaluation of some new hydrazino derivatives of DHA and pyranopyrazoles

Two series of compounds namely, 4-aryl/heteroaryl hydrazino-3-acetyl-6-methyl-2H-pyran-2-ones (4a-4j) and pyrano[4,3-c]pyrazoles (6a-6e and 6g) were synthesized starting from 3-acetyl-4-chloro-6-methyl-2H-pyran-2-one (2). Estimation of pharmacotherapeutic potential, possible molecular mechanism of action, toxic/side effects and interaction with drug-metabolizing enzymes were made for the synthesized compounds on the basis of prediction of activity spectra for substances (PASS) prediction results and their analysis by PharmaExpert software. COX inhibition predicted by PASS was confirmed by experimental evaluation and validated via docking studies. Out of all the compounds, compounds 4h, 4j, 6e, 6g exhibited good anti-inflammatory activity, whereas compounds 4b, 4c, 4h, 4i, 4j, 6b, 6e, 6g showed excellent analgesic activity compared with standard drug Diclofenac sodium.