Parecoxib decreases cellular growth and Bcl-2 protein levels in primary cultures of keloid fibroblasts.

Keloids seem to overexpress cyclo-oxygenase-2 (COX-2), suggesting a role in its deregulated pathway in inducing an altered epithelial-mesenchymal interaction, which may be responsible for the overgrowth of dermal components resulting in scars or keloid lesions. This study aimed to evaluate the effect of Parecoxib, a COX-2 inhibitor, on cell growth in fibroblast primary cultures obtained from human keloid tissues. Tissue explants were obtained from patients who underwent intralesional excision of untreated keloids; central fractions were isolated from keloid tissues and used for establishing distinct primary cultures. Appropriate aliquots of Parecoxib, a COX-2 inhibitor were diluted to obtain the concentration used in the experimental protocols in vitro (1, 10 or 100 µM). Treatment with Parecoxib (at all concentrations) caused a significant decrease in cellular growth from 24 hours onwards, and with a maximum at 72 hours (P < .02). Moreover, at 72 hours Parecoxib significantly reduced cellular vitality. Parecoxib treatment also induced an increase in fragmented nuclei with a maximum effect at 100 µM and a significant decrease in Bcl-2 and an increase in activated caspase-3 protein levels at 72 hours compared with control untreated cultures. Our findings suggest a potential use of the COX-2 inhibitor, Parecoxib, as the therapy for keloids.

Accumulation and metabolism of pyroxasulfone in tomato seedlings.

Pyroxasulfone (PYS) is an isoxazole herbicide favored for its high activity. However, the metabolic mechanism of PYS in tomato plants and the response mechanism of tomato to PYS are still lacking. In this study, it was found that tomato seedlings had a strong ability to absorb and translocate PYS from roots to shoots. The highest accumulation of PYS was in the apex tissue of the tomato shoots. Using UPLC-MS/MS, five metabolites of PYS were detected and identified in tomato plants, and their relative contents in different parts of tomato plants varied greatly. The serine conjugate, DMIT [5, 5-dimethyl-4, 5-dihydroisoxazole-3-thiol (DMIT)] &Ser, was the most abundant metabolites of PYS in tomato plants. In tomato plants, the conjugation of thiol-containing metabolic intermediates of PYS to serine may mimic the cystathionine ß-synthase-catalyzed condensation of serine and homocysteine (in the pathway sly00260 sourced from KEGG database). This study ground breakingly proposed that serine may play an important role in plant metabolism of PYS and fluensulfone (whose molecular structure is similar to PYS). PYS and atrazine (whose toxicity profile is similar to PYS but not conjugate with serine) produced different regulatory outcomes for endogenous compounds in the pathway sly00260. Differential metabolites in tomato leaves exposed to PYS compared with the control, including amino acids, phosphates, and flavonoids, may play important roles in tomato response to PYS stress. This study provides inspiration for the biotransformation of sulfonyl-containing pesticides, antibiotics and other compounds in plants.

The Trisubstituted Isoxazole MMV688766 Exerts Broad-Spectrum Activity against Drug-Resistant Fungal Pathogens through Inhibition of Lipid Homeostasis.

Candida species are among the most prevalent causes of systemic fungal infection, posing a growing threat to public health. While Candida albicans is the most common etiological agent of systemic candidiasis, the frequency of infections caused by non-albicans Candida species is rising. Among these is Candida auris, which has emerged as a particular concern. Since its initial discovery in 2009, it has been identified worldwide and exhibits resistance to all three principal antifungal classes. Here, we endeavored to identify compounds with novel bioactivity against C. auris from the Medicines for Malaria Venture's Pathogen Box library. Of the five hits identified, the trisubstituted isoxazole MMV688766 emerged as the only compound displaying potent fungicidal activity against C. auris, as well as other evolutionarily divergent fungal pathogens. Chemogenomic profiling, as well as subsequent metabolomic and phenotypic analyses, revealed that MMV688766 disrupts cellular lipid homeostasis, driving a decrease in levels of early sphingolipid intermediates and fatty acids and a concomitant increase in lysophospholipids. Experimental evolution to further probe MMV688766's mode of action in the model fungus Saccharomyces cerevisiae revealed that loss of function of the transcriptional regulator HAL9 confers resistance to MMV688766, in part through the upregulation of the lipid-binding chaperone HSP12, a response that appears to assist in tolerating MMV688766-induced stress. The novel mode of action we have uncovered for MMV688766 against drug-resistant fungal pathogens highlights the broad utility of targeting lipid homeostasis to disrupt fungal growth and how screening structurally-diverse chemical libraries can provide new insights into resistance-conferring stress responses of fungi. IMPORTANCE As widespread antimicrobial resistance threatens to propel the world into a postantibiotic era, there is a pressing need to identify mechanistically distinct antimicrobial agents. This is of particular concern when considering the limited arsenal of drugs available to treat fungal infections, coupled with the emergence of highly drug-resistant fungal pathogens, including Candida auris. In this work, we demonstrate that existing libraries of drug-like chemical matter can be rich resources for antifungal molecular scaffolds. We discovered that the small molecule MMV688766, from the Pathogen Box library, displays previously undescribed broad-spectrum fungicidal activity through perturbation of lipid homeostasis. Characterization of the mode of action of MMV688766 provided new insight into the protective mechanisms fungi use to cope with the disruption of lipid homeostasis. Our findings highlight that elucidating the genetic circuitry required to survive in the presence of cellular stress offers powerful insights into the biological pathways that govern this important phenotype.

Structural insight into the molecular mechanism of cilofexor binding to the farnesoid X receptor.

Farnesoid X receptor (FXR) is a bile acid-related nuclear receptor and is considered a promising target to treat several liver disorders. Cilofexor is a selective FXR agonist and has already entered phase III trials in primary sclerosing cholangitis (PSC) patients. Pruritis caused by cilofexor treatment is dose dependent. The binding characteristics of cilofexor with FXR and its pruritogenic mechanism remain unclear. In our research, the affinity of cilofexor bound to FXR was detected using an isothermal titration calorimetry (ITC) assay. The binding mechanism between cilofexor and FXR-LBD is explained by the cocrystal structure of the FXR/cilofexor complex. Structural models indicate the possibility that cilofexor activates Mas-related G protein-coupled receptor X4 (MRGPRX4) or G protein-coupled bile acid receptor 1 (GPBAR1), leading to pruritus. In summary, our analyses provide a molecular mechanism of cilofexor binding to FXR and provide a possible explanation for the dose-dependent pruritis of cilofexor.

Inhibition of AMPA (α-Amino-3-Hydroxy-5-Methyl-4-Isoxazole Propionate) Receptor Reduces Acute Blood-Brain Barrier Disruption After Subarachnoid Hemorrhage in Mice.

Activation of α-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptor (AMPAR) is thought to cause acute brain injury, but the role remains poorly understood in subarachnoid hemorrhage (SAH). This study was conducted to evaluate if AMPAR activation induces acute blood-brain barrier (BBB) disruption after SAH. C57BL/6 male adult mice (n = 117) underwent sham or filament perforation SAH modeling, followed by a random intraperitoneal injection of vehicle or two dosages (1 mg/kg or 3 mg/kg) of a selective noncompetitive AMPAR antagonist perampanel (PER) at 30 min post-modeling. The effects were evaluated by mortality, neurological scores, and brain water content at 24-48 h and video electroencephalogram monitoring, immunostaining, and Western blotting at 24 h post-SAH. PER significantly suppressed post-SAH neurological impairments, brain edema, and BBB disruption. SAH developed epileptiform spikes without obvious convulsion, which were also inhibited by PER. Western blotting showed that the expression of AMPAR subunits GluA1 and GluA2 was unchanged after SAH, but they were significantly activated after SAH. PER prevented post-SAH activation of GluA1/2, associated with the suppression of post-SAH induction of tenascin-C, a causative mediator of post-SAH BBB disruption. Meanwhile, an intracerebroventricular injection of a subtype-selective GluA1/2 agonist augmented the activation of GluA1/2 and the induction of tenascin-C in brain capillary endothelial cells and aggravated post-SAH BBB disruption without increases in epileptiform spikes. Neurological impairments and brain edema were not correlated with the occurrence of epileptiform spikes. This study first showed that AMPAR plays an important role in the development of post-SAH BBB disruption and can be a novel therapeutic target against it.

Simultaneous determination of isoxaflutole and its two metabolites in corn under field conditions by LC-MS/MS.

OBJECTIVE: An improved QuEChERS method was established and verified for simultaneous determination of isoxaflutole and its metabolites diketonitrile and benzoic acid analogue residues in corn and plants. This method was mainly used to study the digestion rule and final residue level of isoxaflutole and its metabolites in corn and plants. It was hoped that the safe use of isoxaflutole in corn can be achieved eventually. METHOD: The method was completed by means of ultra-performance liquid chromatography with triple quadrupole mass spectrometry. The extraction of the target substance was through acetonitrile solution containing 1% acetic acid, and the purification was through primary secondary amine, octadecylsilane and graphitized carbon black sorbent. RESULTS: In the method, the quantitative limits and detection limits of the three analytes were 0.005-0.01 and 0.001-0.003 mg kg-1 respectively. The half-life of isoxaflutole in the plants in Shandong and Anhui was 36.4 and 42.1 days respectively, and the digestion dynamics all conformed to the first-order kinetics. The final residues of isoxaflutole in green corn and mature corn were less than 0.02 mg kg-1 of the maximum residue limit set by the Codex Alimentarius Commission. CONCLUSIONS: The residual amount of isoxaflutole in corn and plants at harvest time was acceptable when isoxaflutole was applied once at a dose of 121.5 g a.i. ha-1 . © 2021 Society of Chemical Industry.

Marine Brominated Tyrosine Alkaloids as Promising Inhibitors of SARS-CoV-2.

There have been more than 150 million confirmed cases of SARS-CoV-2 since the beginning of the pandemic in 2019. By June 2021, the mortality from such infections approached 3.9 million people. Despite the availability of a number of vaccines which provide protection against this virus, the evolution of new viral variants, inconsistent availability of the vaccine around the world, and vaccine hesitancy, in some countries, makes it unreasonable to rely on mass vaccination alone to combat this pandemic. Consequently, much effort is directed to identifying potential antiviral treatments. Marine brominated tyrosine alkaloids are recognized to have antiviral potential. We test here the antiviral capacity of fourteen marine brominated tyrosine alkaloids against five different target proteins from SARS-CoV-2, including main protease (Mpro) (PDB ID: 6lu7), spike glycoprotein (PDB ID: 6VYB), nucleocapsid phosphoprotein (PDB ID: 6VYO), membrane glycoprotein (PDB ID: 6M17), and non-structural protein 10 (nsp10) (PDB ID: 6W4H). These marine alkaloids, particularly the hexabrominated compound, fistularin-3, shows promising docking interactions with predicted binding affinities (S-score = -7.78, -7.65, -6.39, -6.28, -8.84 Kcal/mol) for the main protease (Mpro) (PDB ID: 6lu7), spike glycoprotein (PDB ID: 6VYB), nucleocapsid phosphoprotein (PDB ID: 6VYO), membrane glycoprotein (PDB ID: 6M17), and non-structural protein 10 (nsp10) (PDB ID: 6W4H), respectively, where it forms better interactions with the protein pockets than the native interaction. It also shows promising molecular dynamics, pharmacokinetics, and toxicity profiles. As such, further exploration of the antiviral properties of fistularin-3 against SARS-CoV-2 is merited.

Brain Distribution of Berzosertib: An Ataxia Telangiectasia and Rad3-Related Protein Inhibitor for the Treatment of Glioblastoma.

The effective treatment of brain tumors is a considerable challenge in part because of the presence of the blood-brain barrier (BBB) that limits drug delivery. Glioblastoma multiforme (GBM) is an aggressive and infiltrative primary brain tumor with an extremely poor prognosis after standard-of-care therapy with surgery, radiotherapy (RT), and chemotherapy. DNA damage response (DDR) pathways play a critical role in DNA repair in cancer cells, and inhibition of these pathways can potentially augment RT and chemotherapy tumor cell toxicity. The ataxia telangiectasia and Rad3-related protein (ATR) kinase is a key regulator of the DDR network and is potently and selectively inhibited by the ATR inhibitor berzosertib. Although in vitro studies demonstrate a synergistic effect of berzosertib in combination with temozolomide, in vivo efficacy studies have yet to recapitulate this observation using intracranial tumor models. In the current study, we demonstrate that delivery of berzosertib to the brain is restricted by efflux at the BBB. Berzosertib has a high binding affinity to brain tissue compared with plasma, thereby leading to low free drug concentrations in the brain. Berzosertib distribution is heterogenous within the tumor, wherein concentrations are substantially lower in normal brain and invasive tumor rim (wherein the BBB is intact) when compared with those in the tumor core (wherein the BBB is leaky). These results demonstrate that high tissue binding and limited and heterogenous brain distribution of berzosertib may be important factors that influence the efficacy of berzosertib therapy in GBM. SIGNIFICANCE STATEMENT: This study examined the brain delivery and efficacy of berzosertib in patient-derived xenograft models of glioblastoma multiforme (GBM). Berzosertib is actively effluxed at the blood-brain barrier and is highly bound to brain tissue, leading to low free drug concentrations in the brain. Berzosertib is heterogeneously distributed into different regions of the brain and tumor and, in this study, was not efficacious in vivo when combined with temozolomide. These factors inform the future clinical utility of berzosertib for GBM.

Effect of immature tick-borne encephalitis virus particles on antiviral activity of 5-aminoisoxazole-3-carboxylic acid adamantylmethyl esters.

Tick-borne encephalitis virus (TBEV), a member of the genus Flavivirus, is common in Europe and Asia and causes a severe disease of the central nervous system. A promising approach in the development of therapy for TBEV infection is the search for small molecule antivirals targeting the flavivirus envelope protein E, particularly its ß-n-octyl-d-glucoside binding pocket (ß-OG pocket). However, experimental studies of candidate antivirals may be complicated by varying amounts and different forms of the protein E in the virus samples. Viral particles with different conformations and arrangements of the protein E are produced during the replication cycle of flaviviruses, including mature, partially mature, and immature forms, as well as subviral particles lacking genomic RNA. The immature forms are known to be abundant in the viral population. We obtained immature virion preparations of TBEV, characterized them by RT-qPCR, and assessed in vivo and in vitro infectivity of the residual mature virions in the immature virus samples. Analysis of the ß-OG pocket structure on the immature virions confirmed the possibility of binding of adamantylmethyl esters of 5-aminoisoxazole-3-carboxylic acid in the pocket. We demonstrated that the antiviral activity of these compounds in plaque reduction assay is significantly reduced in the presence of immature TBEV particles.

Pan-3C Protease Inhibitor Rupintrivir Binds SARS-CoV-2 Main Protease in a Unique Binding Mode.

Rupintrivir targets the 3C cysteine proteases of the picornaviridae family, which includes rhinoviruses and enteroviruses that cause a range of human diseases. Despite being a pan-3C protease inhibitor, rupintrivir activity is extremely weak against the homologous 3C-like protease of SARS-CoV-2. In this study, the crystal structures of rupintrivir were determined bound to enterovirus 68 (EV68) 3C protease and the 3C-like main protease (Mpro) from SARS-CoV-2. While the EV68 3C protease-rupintrivir structure was similar to previously determined complexes with other picornavirus 3C proteases, rupintrivir bound in a unique conformation to the active site of SARS-CoV-2 Mpro splitting the catalytic cysteine and histidine residues. This bifurcation of the catalytic dyad may provide a novel approach for inhibiting cysteine proteases.

Evolution of kinase polypharmacology across HSP90 drug discovery.

Most small molecules interact with several target proteins but this polypharmacology is seldom comprehensively investigated or explicitly exploited during drug discovery. Here, we use computational and experimental methods to identify and systematically characterize the kinase cross-pharmacology of representative HSP90 inhibitors. We demonstrate that the resorcinol clinical candidates ganetespib and, to a lesser extent, luminespib, display unique off-target kinase pharmacology as compared with other HSP90 inhibitors. We also demonstrate that polypharmacology evolved during the optimization to discover luminespib and that the hit, leads, and clinical candidate all have different polypharmacological profiles. We therefore recommend the computational and experimental characterization of polypharmacology earlier in drug discovery projects to unlock new multi-target drug design opportunities.

Y06014 is a selective BET inhibitor for the treatment of prostate cancer.

Bromodomain and extra-terminal proteins (BETs) are potential targets for the therapeutic treatment of prostate cancer (PC). Herein, we report the design, the synthesis, and a structure-activity relationship study of 6-(3,5-dimethylisoxazol-4-yl)benzo[cd]indol-2(1H)-one derivative as novel selective BET inhibitors. One representative compound, 19 (Y06014), bound to BRD4(1) in the low micromolar range and demonstrated high selectivity for BRD4(1) over other non-BET bromodomain-containing proteins. This molecule also potently inhibited cell growth, colony formation, and mRNA expression of AR-regulated genes in PC cell lines. Y06014 also shows stronger activity than the second-generation antiandrogen enzalutamide. Y06014 may serve as a new small molecule probe for further validation of BET as a molecular target for PC drug development.

Screening of Synthetic Isoxazolone Derivative Role in Alzheimer's Disease: Computational and Pharmacological Approach.

Alzheimer's disease (AD) is age-dependent neurological disorder with progressive loss of cognition and memory. This multifactorial disease is characterized by intracellular neurofibrillary tangles, beta amyloid plaques, neuroinflammation, and increased oxidative stress. The increased cellular manifestations of these markers play a critical role in neurodegeneration and pathogenesis of AD. Therefore, reducing neurodegeneration by decreasing one or more of these markers may provide a potential therapeutic roadmap for the treatment of AD. AD causes a devastating loss of cognition with no conclusive and effective treatment. Many synthetic compound containing isoxazolone nucleus have been reported as neuroprotective agents. The aim of this study was to explore the anti-Alzheimer's potential of a newly synthesized 3,4,5-trimethoxy isoxazolone derivative (TMI) that attenuated the beta amyloid (Aß1-42) and tau protein levels in streptozotocin (STZ) induced Alzheimer's disease mouse model. Molecular analysis revealed increased beta amyloid (Aß1-42) protein levels, increased tau protein levels, increased cellular oxidative stress and reduced antioxidant enzymes in STZ exposed mice brains. Furthermore, ELISA and PCR were used to validate the expression of Aß1-42. Pre-treatment with TMI significantly improved the memory and cognitive behavior along with ameliorated levels of Aß1-42 proteins. TMI treated mice further showed marked increase in GSH, CAT, SOD levels while decreased levels of acetylcholinesterase inhibitors (AChEI's) and MDA intermediate. The multidimensional nature of isoxazolone derivatives and its versatile affinity towards various targets highpoint its multistep targeting nature. These results indicated the neuroprotective potential of TMI which may be considered for the treatment of neurodegenerative disease specifically in AD.

Synthesis, Antimicrobial Evaluation and Docking Study of Novel 3,5-Disubstituted-2-Isoxazoline and 1,3,5-Trisubstituted-2-Pyrazoline Derivatives.

BACKGROUND: The frequent use of antibacterial agents leads to antimicrobial resistance, which is one of the biggest threats to global health today. Therefore, the discovery of novel antimicrobial agents is still urgently needed to overcome the severe infections caused by these putative pathogens resistant to currently available drugs. OBJECTIVE: The present work was aimed to synthesize and investigate the preliminary structureactivity relationships (SARs) of isoxazoline and pyrazoline derivatives as antimicrobial agent. METHODS: Target compounds were obtained in a multistep reaction synthesis and the antimicrobial activity was investigated in several species; two-gram negative (Escherichia coli and Pseudomonas aeruginosa), two-gram positive (Staphylococcus aureus and Bacillus subtilis) and one fungi (Candida albicans), using cup-plate agar diffusion method. The most potent compounds were docked into glucosamine-6-phosphate synthase (GlcN-6-P), the molecular target enzyme for antimicrobial agents, using Autodock 4.2 program. RESULTS: Herein, thirteen novel target compounds were synthesized in moderate to good isolated yield. Based on the SARs, two compounds (2c and 5c) were found to be potent antimicrobial agents on all tested targets, recording potency higher than amoxicillin, the standard antimicrobial drug. Compound 2b identified as selective for gram-negative, while compound 7a found to be selective for gram-positive. The hit compounds (2c, 5a, 5c and 5d) were subjected to a docking study on glucosamine-6-phosphate synthase (GlcN-6-P). All hits were found to bind to the orthosteric (active) site of the enzyme, which might represent a competitive mechanism of inhibition. CONCLUSION: The newly synthesized heterocyclic compounds could serve as potent leads for the development of novel antimicrobial agents.

New series of isoxazole derivatives targeting EGFR-TK: Synthesis, molecular modeling and antitumor evaluation.

New series of isoxazole derivatives were synthesized and evaluated for in vitro antitumor activity against HepG2, MCF-7 and HCT-116 cancer cells. Results showed that 4b and 25a are the most potent members against the three cancer cells (IC50 = 6.38-9.96 µM). Further, 4a, 8a and 16b showed strong activity against the three cancer cells, whereas 6b, 10a, 10b and 16a exhibited moderate activity against the three cancer cells. Moreover, 25a showed low cytotoxicity against WISH and WI38 normal cells (IC50 = 53.19 ± 3.1 and 38.64 ± 2.8 µM, respectively), and it might be used as a potent and safe antitumor agent. The nine active compounds 4a, 4b, 6b, 8a, 10a, 10b, 16a, 16b and 25a were studied for EGFR-TK inhibitory activity, where 10a, 10b and 25a showed the highest inhibitory activity (IC50 = 0.064 ± 0.001, 0.066 ± 0.001 and 0.054 ± 0.001 µM, respectively). Compound 25a was also assessed against other four target proteins, and it showed promising inhibitory activities against VEGFR-2, CK2α and topoisomerase IIß, and acceptable inhibitory activity against tubulin polymerization. Cell cycle analysis of cancer cells treated with 25a proved that it induces cell cycle arrest at G2/M and pre-G1 phases. Furthermore, it was confirmed that 25a induces cancer cell death through apoptosis, supported by increased caspases 3/9 levels and increased Bax/Bcl-2 ratio in the three cancer cells. In addition, docking studies proved the exact fit of 25a into the active site of EGFR-TK, VEGFR-2, CK2α, topoisomerase IIß and tubulin. Lipinski's rule and Veber's standards were also analyzed, and results illustrated that 25a is expected to be well absorbed orally.

Computational modeling and target synthesis of monomethoxy-substituted o-diphenylisoxazoles with unexpectedly high antimitotic microtubule destabilizing activity.

The ability of monomethoxy-substituted o-diphenylisoxazoles 2a-d to interact with the colchicine site of tubulin was predicted using computational modeling, docking studies, and calculation of binding affinity. The respective molecules were synthesized in high yields by three steps reaction using easily available benzaldehydes, acetophenones, and arylnitromethanes as starting material. The calculated antitubulin effect was confirmed in vivo in a sea urchin embryo model. Compounds 2a and 2c showed high antimitotic microtubule destabilizing activity compared to that of CA4. Isoxazole 2a also exhibited significant cytotoxicity against human cancer cells in NCI60 screen. For the first time, isoxazole-linked CA4 derivatives 2a and 2c with only one methoxy substituent were identified as potent antimitotic microtubule destabilizing agents. These molecules could be considered as promising structures for further optimization.

Design, synthesis and biological evaluation of 3,5-diaryl isoxazole derivatives as potential anticancer agents.

The present study was carried out in the attempt to synthesize a new class of potential anticancer agents comprising eleven compounds (24-34) sharing the 3,5-diarylisoxazole as a core. The chemical structure of the new synthesized compounds was established by IR, 1H NMR, 13C NMR and elemental analysis. Their biological potential towards prostate cancer was evaluated by using cancer PC3 cells and non-tumorigenic PNT1a cells. Interestingly, compound 26 distinguished from others with a quite high selectivity value that is comparable to 5-FU. The binding mode of 26 towards Ribosomal protein S6 kinase beta-1 (S6K1) was investigated at a molecular level of detail by employing docking simulations based on GLIDE standard precision as well as MM-GBSA calculations.

Visual High-Throughput Screening for Developing a Fatty Acid Amide Hydrolase Natural Inhibitor Based on an Enzyme-Activated Fluorescent Probe.

Fatty acid amide hydrolase (FAAH) is an important drug target for the treatment of many disease related conditions such as pain, inflammation, and mood disorders due to its vital role in the metabolism of endocannabinoid. In our present work, a FAAH-activated fluorescent probe named THPO was developed, which possessed high selectivity and excellent sensitivity for FAAH in complex systems. Critically, its metabolite 7-amino-3H-phenoxazin-3-one (AHPO) has long excitation and emission wavelengths and high fluorescence quantum yield, which are necessary for monitoring the activity of FAAH in living systems. In addition, a visual high-throughput screening method for FAAH inhibitors was established using THPO, which resulted in the discovery of an efficient natural inhibitor Neobavaisoflavone that was identified from 68 traditional herbal medicines. These results indicated that THPO can be used as a molecular tool for the rapid evaluation of FAAH activity in complex systems as well as providing an effective approach to screen FAAH inhibitors and providing a boost for the discovery of therapeutic agents toward FAAH related diseases.

Enantioselective Detection, Bioactivity, and Metabolism of the Novel Chiral Insecticide Fluralaner.

Fluralaner, a veterinary drug, is a potential chiral isoxazoline insecticide possessing high insecticidal and acaricidal activity. However, there is little information regarding the enantioselective effect of fluralaner. In this work, a promising chiral detection method was established with liquid chromatography-mass spectrometry in agricultural products and animal organs to investigate enantioselective metabolism and bioactivity. The optical rotation and absolute configuration of fluralaner enantiomers were confirmed with S-(+)-fluralaner and R-(-)-fluralaner. The bioactivity assay indicated that S-fluralaner was 33-39 times more active than the R-enantiomer against Chilo suppressalis and Laodelphax striatellus. This finding suggests that the application of pure S-fluralaner instead of racemate in agricultural management could reduce risk. Homology modeling and molecular docking showed that S-fluralaner, with a lower energy of -6.90 kcal/mol, possessed better binding affinity to the γ-aminobutyric acid receptor. The stereoselective metabolism in rat liver microsomes was explored, and slight enantioselectivity was observed with R-fluralaner that was preferentially metabolized. The enantiomer fraction values ranged from 0.43 to 0.49. The results provide reference for residue detection, risk assessment, and the scientific use of fluralaner in agricultural applications.

Simultaneous Determination of Parecoxib and Its Metabolite Valdecoxib Concentrations in Beagle Plasma by UPLC-MS/MS and Application for Pharmacokinetics Study.

A method for the simultaneous determination of parecoxib and its metabolite valdecoxib in beagle plasma by UPLC-MS/MS was developed and validated. After the plasma was extracted by acetonitrile precipitation, the analytes were separated on an Acquity UPLC BEH C18 column (2.1 mm × 50 mm, 1.7 µm) using acetonitrile-formic acid as the mobile phase in gradient mode. The analytes were monitored by multiple reaction monitoring (MRM) in electrospray negative ion mode. The mass transfer pairs were m/z 368.97→119.01 for parecoxib, m/z 312.89→118.02 for valdecoxib, and m/z 379.98→316.02 for celecoxib (internal standard, IS). The correlation coefficients of parecoxib and valdecoxib ranged from 5 to 4000 ng/mL were greater than 0.9998. The recovery of parecoxib and valdecoxib was greater than 82.54%. The inter- and intra-day precision RSD values were 1.36~3.65% and 2.28~5.91%, respectively. The accuracy of RE values were -1.38%~1.96%. Finally, the matrix effect (ME) and stability were also within acceptable criteria. This method had been successfully applied to the pharmacokinetics of parecoxib and valdecoxib in beagle plasma after injection of parecoxib (1.33 mg/kg, intramuscular injection).