Synthase Inhibitor Research Articles

Discovery and Characterization of Chitin Synthase Inhibitors with Novel Mechanism for Control of Tetranychus urticae.

Tetranychus urticae, a highly destructive global pest, infests a wide range of plant species, including crucial food crops and ornamental plants. Effective control methods for this pest remain limited. Chitin synthase (CHS) is a key enzyme in the biosynthesis of chitin, which is essential for the growth and development of arthropods. However, the lack of detailed research on arthropod CHS proteins has hindered the development of targeted pesticides. In this study, we successfully expressed and purified the full-length TuCHS protein, which exhibited significant enzymatic activity in vitro. Utilizing this protein, we developed a reliable screening method to identify inhibitors targeting TuCHS. Two inhibitors, ZHZ-ZI-11 and SUY-SC-15, were identified. These compounds interfere with chitin translocation within the cell rather than inhibiting CHS enzyme activity. Both inhibitors demonstrated significant acaricidal efficacy, with improved performance when formulated as nanoemulsions. This study presents the first use of arthropod CHS protein for screening potential insecticides targeting chitin biosynthesis during mite development. Our findings provide a solid foundation for the development of novel, environmentally friendly pesticides aimed at CHS.

Pro-197-Ser mutation combinations in acetolactate synthase (ALS) homoeologous genes affect ALS inhibitor herbicide resistance levels in Monochoria korsakowii.

Monochoria korsakowii is a common broadleaf weed found in rice (Oryza sativa) fields. Acetolactate synthase (ALS) inhibitor herbicides are commonly used to control broadleaf weeds in rice fields. However, prolonged herbicide use has exacerbated resistance issues. In this study, we evaluated the resistance to ALS inhibitors in populations where the same mutation occurred separately and simultaneously in the two ALS homoeologous genes (ALS1 and ALS2) and investigated the resistance mechanisms in M. korsakowii. Monochoria korsakowii exhibited high resistance to bensulfuron-methyl, low resistance to penoxsulam, and sensitivity to imazethapyr. Three resistant populations were identified: M-1 and M-2, which independently evolved the Pro-197-Ser mutation in ALS1 and ALS2, respectively, and M-3, which harbored this mutation in both ALS1 and ALS2. The sensitivity of ALS isolated from these populations to herbicide inhibition corresponded to the whole-plant resistance levels. Subsequently, we cloned and transformed Pro-197-Ser-mutated ALS1 and ALS2 into Arabidopsis thaliana. The resistance of homozygous A. thaliana to bensulfuron-methyl and penoxsulam aligned with bioassay trends. Furthermore, we measured the ploidy, relative expression, and copy number of ALS1 and ALS2, and found no significant differences, suggesting that the evolution of resistance was primarily attributed to the Pro-197-Ser mutation. Finally, we developed a derived cleaved amplified polymorphic sequence marker for detecting Pro-197-Ser mutation in ALS. The same mutation occurring separately in homoeologous genes resulted in similar resistance levels, whereas simultaneous mutations in homoeologous genes led to increased resistance levels. © 2024 Society of Chemical Industry.

Mutations on the A and C genomes of Brassica napus confer herbicide resistance to acetohydroxyacid synthase inhibitors

ABSTRACT The point mutations conferring resistance to the sulfonylurea herbicide, chlorsulfuron, are reported for two Brassica napus lines (19c and 30a) developed by seed mutagenesis using ethyl methanesulfonate. Crosses with the herbicide-susceptible wild-type line generated F2 and backcrossed progeny and confirmed that chlorsulfuron resistance was inherited as a dominant mutation at a single locus in both lines. F2 progeny from crossing 19c and 30a segregated in a 15 resistant: 1 susceptible ratio, establishing that the two herbicide-resistant loci are independently inherited and that the mutations for resistance occur at different loci. PCR amplification and DNA sequencing of regions from the acetohydroxyacid synthase gene revealed two separate point mutations at different nucleotides in the same codon. This results in the substitution of proline-197 for leucine in 19c and proline-197 for serine in 30a. The different amino acid substitutions in the acetohydroxyacid synthase enzyme explain the differing responses of 19c and 30a to sulfonylurea and imidazolinone herbicides. Based on attempts at introgression of chlorsulfuron resistance to a wide range of forage brassicas, we conclude that the 19c mutation resides in the Brassica C genome, whereas the 30a mutation is in the Brassica A genome.

Aldosterone synthase inhibitors: a potential revival for treatment of renal and cardiovascular diseases.

Inappropriate aldosterone excess plays a key role in the pathophysiology of various cardiovascular, endocrine and renal diseases. Mineralocorticoid receptor (MR) antagonists (MRAs) such as spironolactone block of the harmful effects of aldosterone and are recommended treatment in these various conditions. However, the sexual adverse effects of spironolactone due to its lack of specificity for the MR and the risk of hyperkalemia in patients with decreased renal function, limit its use. While eplerenone is a more selective MRA, it is less potent than spironolactone. Newer nonsteroidal MRAs, though promising, are either unavailable globally or still under development. Moreover, aldosterone exerts both genomic and nongenomic effects, the latter not fully blocked by MRAs. Aldosterone synthase inhibitors (ASIs) have thus emerged as potential alternatives to MRAs, though the development of selective ASIs has been challenging. This is due to the close homology between the final step of aldosterone synthesis, mediated by CYP11B2 in the zona glomerulosa of the adrenal cortex, and cortisol synthesis, mediated by CYP11B1 in the zona fasciculata. Despite these challenges, new ASIs have demonstrated high in vitro as well as in vivo selectivity for CYP11B2, effectively reducing aldosterone production without affecting cortisol synthesis in humans across large dose ranges. Early phase II trials demonstrated that these ASIs decrease 1) blood pressure in uncontrolled hypertension, and (2) urinary albumin excretion in proteinuric chronic kidney disease. Further longer-term trials will evaluate their efficacy in lowering blood pressure as well as in reducing kidney disease progression and cardiovascular outcomes in heart failure when given alone or in combination with SGLT2 inhibitors.

Mycobacterium tuberculosis F-ATP Synthase Inhibitors and Targets

Mycobacteria tuberculosis (Mtb) infection causes tuberculosis (TB). TB is one of the most intractable infectious diseases, causing over 1.13 million deaths annually. Under harsh growing conditions, the innate response of mycobacteria is to shut down its respiratory metabolism to a basal level, transit into a dormant, non-replicating phase to preserve viability, and establish latent infection. Mtb utilizes non-canonical regulatory mechanisms, such as alternative oxidase pathways, to survive in low oxygen/nutrient conditions. The bacterium’s survival in its native microenvironmental niches is aided by its ability to evolve mutations to drug binding sites, enhance overexpression of various enzymes that activate β-lactam antibiotics hydrolysis, or stimulate efflux pathways to ward off the effect of antibiotics. Bedaquiline and its 3,5-dialkoxypyridine analogs, sudapyridine and squaramide S31f, have been shown to be potent Mtb F1FO-ATP synthase inhibitors of replicating and non-replicating Mtb and have brought oxidative phosphorylation into focus as an anti-TB target. In this review, we attempt to highlight non-canonical structural and regulatory pathogen-specific epitopes of the F1-domain, ligand development on such sites, structural classes of inhibitors targeting the Fo-domain, and alternative respiratory metabolic responses that Mtb employs in response to bedaquiline to ensure its survival and establish latent infection.

Novel Benzimidazole Derivatives as Potent Inhibitors of Microsomal Prostaglandin E2 Synthase 1 for the Potential Treatment of Inflammation, Pain, and Fever.

Microsomal prostaglandin E2 synthase 1 (mPGES-1) is a promising target for treating inflammatory diseases and pain. This study introduces a novel series of benzimidazoles, with the most potent analogs exhibiting IC50 values of 0.27-7.0 nM in a cell-free assay for prostaglandin (PG)E2 production. Compound 44 (AGU654) demonstrated remarkable selectivity for mPGES-1 (IC50 = 2.9 nM) over COX-1, COX-2, 5-LOX, and FLAP, along with excellent bioavailability. Metabololipidomics analysis with activated human monocyte-derived macrophages and human whole blood revealed that AGU654 selectively suppresses PGE2 production triggered by bacterial exotoxins while sparing other prostaglandins. Furthermore, in vivo studies showed that AGU654 significantly alleviated fever, inflammation, and inflammatory pain in preclinical guinea pig models, suggesting that it could be an effective strategy for managing inflammatory diseases. In conclusion, these benzimidazole derivatives warrant further exploration into new and alternative analogs, potentially uncovering novel compounds with a favorable pharmacological profile possessing significant anti-inflammatory and analgesic properties.

Pasteurized Akkermansia muciniphila Ameliorates Preeclampsia in Mice by Enhancing Gut Barrier Integrity, Improving Endothelial Function, and Modulating Gut Metabolic Dysregulation

Preeclampsia (PE) is a serious complication of pregnancy linked to endothelial dysfunction and an imbalance in the gut microbiota. While Akkermansia muciniphila (AKK) has shown promise in alleviating PE symptoms, the use of live bacteria raises safety concerns. This study explored the potential of pasteurized A. muciniphila (pAKK) as a safer alternative for treating PE, focusing on its effects on endothelial function and metabolic regulation. A PE mouse model was induced via the nitric oxide synthase inhibitor L-NAME, followed by treatment with either pAKK or live AKK. Fecal metabolomic profiling was performed via liquid chromatography–tandem mass spectrometry (LC-MS/MS), and in vivo and in vitro experiments were used to assess the effects of pAKK on endothelial function and metabolic pathways. pAKK exhibited therapeutic effects comparable to those of live AKK in improving L-NAME-induced PE-like phenotypes in mice, including enhanced gut barrier function and reduced endotoxemia. pAKK also promoted placental angiogenesis by restoring endothelial nitric oxide synthase (eNOS) activity and nitric oxide (NO) production. The in vitro experiments further confirmed that pAKK alleviated L-NAME-induced NO reduction and endothelial dysfunction in human umbilical vein endothelial cells (HUVECs). Metabolomic analysis revealed that both pAKK and live AKK reversed metabolic disturbances in PE by modulating key metabolites and pathways related to unsaturated fatty acid biosynthesis, folate, and linoleic acid metabolism. As a postbiotic, pAKK may support existing treatments for preeclampsia by improving gut barrier function, restoring endothelial function, and regulating metabolic dysregulation, offering a safer alternative to live bacteria. These findings highlight the potential clinical value of pAKK as an adjunctive therapy in managing PE.

Prolonged L-NAME exposure changes the vasodilator factor from NO to H2O2 in human arterioles in response to A23187

The Ca2+ ionophore A23187 induces endothelium-dependent and non-receptor-mediated vasodilation in human adipose arterioles (HAAs). The purpose of this study was to determine the mechanism of A23187-induced dilation in HAAs from patients with and without coronary artery disease (CAD). HAAs were freshly isolated from adipose tissues obtained from non-CAD (n = 25) and CAD (n = 14) patients, and vascular reactivity was studied by videomicroscopy. No difference in baseline dose response to A23187 was observed between non-CAD and CAD subjects. However, acute (30 min) incubation with N(omega)-nitro-l-arginine methyl ester (L-NAME), NO synthase inhibitor strongly reduced A23187-induced dilation in non-CAD arterioles, while catalase, an H2O2 scavenger, largely abolished dilation in CAD. Surprising, prolonged (90 min) incubation with L-NAME restored A23187 response in non-CAD subjects, which was subsequently inhibited by catalase. The action of prolonged L-NAME exposure was not reversible after washing with Krebs while the effect of acute L-NAME exposure was largely reversible. To further determine the role of mitochondria-derived ROS in A23187-induced dilation, arterioles were treated with rotenone, an inhibitor of complex I of the electron transport chain. Rotenone abolished A23187 response in CAD patients and in non-CAD arterioles after prolonged L-NAME, but not in non-CAD controls. These data indicate that NO contributes to A23187-induced dilation in HAAs from non-CAD patients and H2O2 contributes to the dilation in CAD patients. Prolonged L-NAME exposure induces a NO-H2O2 switch in the mechanism of dilation in non-CAD subjects. Moreover, the effect of prolonged L-NAME exposure is not readily reversible, while the action of acute L-NAME exposure is reversible.

Computational Studies on Diospyros Ebenum and Oldenlandia Umbellata Phytochemicals as Novel Fatty Acid Synthase Inhibitors

Computational Studies on Diospyros Ebenum and Oldenlandia Umbellata Phytochemicals as Novel Fatty Acid Synthase Inhibitors

Therapeutic landscape of metabolic dysfunction-associated steatohepatitis (MASH).

Metabolic dysfunction-associated steatotic liver disease (MASLD)and its severe subgroup metabolic dysfunction-associated steatohepatitis (MASH) have become a global epidemic and are driven by chronic overnutrition and multiple genetic susceptibility factors. The physiological outcomes include hepatocyte death, liver inflammation and cirrhosis. The first therapeutic for MASLD and MASH, resmetirom, has recently been approved for clinical use and has energized this therapeutic space. However, there is still much to learn in clinical studies of MASH, such as the scale of placebo responses, optimal trial end points, the time required for fibrosis reversal and side effect profiles. This Review introduces aspects of disease pathogenesis related to drug development and discusses two main therapeutic approaches. Thyroid hormone receptor-β agonists, such as resmetirom, as well as fatty acid synthase inhibitors, target the liver and enable it to function within a toxic metabolic environment. In parallel, incretin analogues such as semaglutide improve metabolism, allowing the liver to self-regulate and reversing many aspects of MASH. We also discuss how combinations of therapeutics could potentially be used to treat patients.

Cadmium exposure triggers alveolar epithelial cell pyroptosis by inducing mitochondrial oxidative stress and activating the cGAS-STING pathway

BackgroundCadmium is a ubiquitous toxic metal and environmental pollutant. More and more studies have shown that cadmium exposure can damage lung function. Alveolar epithelial cells (AECs) are structural cells that maintain the stability of lung function. The injury of AECs is an essential determinant of many lung diseases. In the lung, cadmium accumulation can cause damage to AECs. However, the specific mechanism is still unclear. This study aimed to explore the key mechanism underlying the injury of AECs caused by cadmium exposure.MethodsThe main modes of death of AECs induced by cadmium exposure were evaluated in vivo and in vitro. Transcriptomic changes of AECs induced by cadmium exposure were analyzed using RNA-sequence. Mitochondrial ROS scavengers (mitoQ), voltage-dependent anion channel 1 (VDAC1) oligomer inhibitor (VBIT4), and cyclic GMP-AMP synthase (cGAS) inhibitor (RU.521) were used to assess whether cadmium exposure triggered pyroptosis of AECs by inducing mitochondrial stress to activate the cGAS-STING-NLRP3 axis.ResultsIn this study, the expression of pyroptosis-related proteins was significantly up-regulated in the cadmium-exposed AECs, while the expression of apoptosis, necroptosis, and ferroptosis-related proteins had no significant up-regulated. The pan-caspase inhibitor ZVAD-FMK significantly reduced cell death. Thus, our research indicates that pyroptosis is the primary type of AEC death exported to cadmium. Mechanistically, RNA-seq and Western Blot results showed that cadmium exposure activated the cGAS-STING pathway in AECs and promoted pyroptosis by activating the NLRP3 inflammasome. Further investigation of the mechanism found that cadmium exposure caused mitochondrial oxidative stress, which led to mtDNA leakage into the cytoplasm and activated the cGAS-STING pathway. In addition, inhibition of the cGAS-STING pathway significantly alleviated lung injury induced by cadmium exposure in mice.ConclusionOur study confirmed that pyroptosis of AECs was a vital mechanism of lung injury after cadmium exposure in a cGAS-STING-dependent manner, which may provide a new target for the treatment of lung diseases induced by cadmium exposure.

Herbicide resistance is complex: a global review of cross-resistance in weeds within herbicide groups

Abstract Herbicides have been placed in global Herbicide Resistance Action Committee (HRAC) herbicide groups based on their sites of action (e.g., acetolactate synthase–inhibiting herbicides are grouped in HRAC Group 2). A major driving force for this classification system is that growers have been encouraged to rotate or mix herbicides from different HRAC groups to delay the evolution of herbicide-resistant weeds, because in theory, all active ingredients within a herbicide group physiologically affect weeds similarly. Although herbicide resistance in weeds has been studied for decades, recent research on the biochemical and molecular basis for resistance has demonstrated that patterns of cross-resistance are usually quite complicated and much more complex than merely stating, for example, a certain weed population is Group 2-resistant. The objective of this review article is to highlight and describe the intricacies associated with the magnitude of herbicide resistance and cross-resistance patterns that have resulted from myriad target-site and non–target site resistance mechanisms in weeds, as well as environmental and application timing influences. Our hope is this review will provide opportunities for students, growers, agronomists, ag retailers, regulatory personnel, and research scientists to better understand and realize that herbicide resistance in weeds is far more complicated than previously considered when based solely on HRAC groups. Furthermore, a comprehensive understanding of cross-resistance patterns among weed species and populations may assist in managing herbicide-resistant biotypes in the short term by providing growers with previously unconsidered effective control options. This knowledge may also inform agrochemical company efforts aimed at developing new resistance-breaking chemistries and herbicide mixtures. However, in the long term, nonchemical management strategies, including cultural, mechanical, and biological weed management tactics, must also be implemented to prevent or delay increasingly problematic issues with weed resistance to current and future herbicides.

Integrated machine learning and physics-based methods assisted de novo design of Fatty Acyl-CoA synthase inhibitors

ABSTRACT Background Tuberculosis is an infectious disease that has become endemic worldwide. The causative bacteria Mycobacterium tuberculosis (Mtb) is targeted via several exciting drug targets. One newly discovered target is the Fatty Acyl-CoA synthase, which plays a significant role in activating the long-chain fatty acids. Research design & methods This study aims to generate novel compounds using Machine Learning (ML) algorithms to inhibit this synthase. Experimentally derived bioactive compounds were chosen from ChEMBL and used as inputs for effective molecule generation by Reinvent4. The library of new molecules generated was subjected to a two-tiered molecular docking protocol, and the results were further studied to obtain a binding free energy check. Results The ML-based de novo drug design (DNDD) approach successfully generated a diverse library of novel molecules targeting Fatty Acyl-CoA synthase. After rigorous molecular docking and binding free energy analysis, four new compounds were identified as potential lead candidates with promising inhibitory effects on Mtb lipid metabolism. Conclusions The study demonstrated the effectiveness of a machine-learning approach in generating novel drug candidates against Mtb. The identified hit compounds show potential as inhibitors of Fatty Acyl-CoA synthase, offering a new avenue for developing treatments for tuberculosis, particularly in combating drug-resistant strains.

Differential participation of CaMKII/ROCK and NOS pathways in the cholinergic inhibitory drive operated by nicotinic α7 receptors in perisynaptic Schwann cells

Nicotinic α7 receptors (α7 nAChRs) present in perisynaptic Schwann cells (PSCs) control acetylcholine (ACh) spillover from the neuromuscular synapse by transiently increasing intracellular Ca2+, which fosters adenosine release via type 1 equilibrative nucleoside transporters (ENT1) and retrograde activation of presynaptic A1 inhibitory receptors. The putative Ca2+-dependent pathways downstream α7 nAChRs involved in the sensing inhibitory drive operated by PSCs is unknown. Herein, we used phrenic nerve-hemidiaphragm preparations from Wistar rats. Time-lapse video-microscopy was instrumental to assess nerve-evoked (50-Hz bursts) transmitter exocytosis and intracellular NO oscillations in nerve terminals and PSCs loaded with FM4-64 and DAF-FM diacetate fluorescent dyes, respectively. Selective activation of α7 nAChRs with PNU 282987 reduced transmitter exocytosis (FM4-64 dye unloading) during 50-Hz bursts. Inhibition of calmodulin activity (with W-7), Ca2+/calmodulin-dependent protein kinase II (CaMKII; with KN-62) and Rho-kinase (ROCK; with H1152) all prevented the release inhibitory effect of PNU 282987. The α7 nAChR agonist transiently increased NO inside PSCs; the same occurred during phrenic nerve stimulation with 50-Hz bursts in the presence of the cholinesterase inhibitor, neostigmine. The nitric oxide synthase (NOS) inhibitor, L-NOARG, but not with the guanylylcyclase (GC) inhibitor, ODQ, prevented inhibition of transmitter exocytosis by PNU 282987. Inhibition of adenosine kinase with ABT 702 favors the intracellular accumulation and translocation of the nucleoside to the synaptic cleft, thus overcoming prevention of the PNU 282987 effect caused by H1152, but not by L-NOARG. In conclusion, the α7nAChR-mediated cholinergic inhibitory drive operated by PSCs involves two distinct Ca2+-dependent intracellular pathways: a CaMKII/ROCK cascade along with a GC-independent NO pathway with divergent end-effects concerning ADK inhibition.

Increased potentiation of 5-fluorouracil induced thymidylate synthase inhibition by 5,10-methylenetetrahydrofolate (arfolitixorin) compared to leucovorin in patients with colorectal liver metastases; The Modelle-001 Trial

Background5-Fluorouracil (5-FU) is a cornerstone in treatment of colorectal cancer (CRC) and is usually combined with leucovorin (LV) to enhance the antitumour effect by increase thymidylate synthase (TS) inhibition, the key target enzyme for 5-FU. Arfolitixorin (Arfo) is an active form of the reduced folate, [6 R]-5,10-methylenetetrahydrofolate ([6 R]-MeTHF and in contrast to LV, does not need to be metabolized. The Modelle-001 was designed to explore whether a single intravenous bolus injection of Arfo as compared to LV, together with 5-FU increases the inhibition of TS, levels of folate concentrations and polyglutamylation in CRC liver metastases (CRLM) and liver parenchyma.Patients and methodsThirty patients with CRLM received either LV (60 mg/m2) or Arfo (30 mg/m2 or 120 mg/m2) in combination with 5-FU preoperatively. Levels of folates and and TS inhibition were measured.ResultsSignificantly higher MeTHF levels and higher TS inhibition were measured in the Arfo groups compared to LV60, and there was a difference in folate poly-glutamylation between the groups.ConclusionThe Modelle-001 Trial demonstrated significantly higher levels of MeTHF in metastases following Arfo compared to LV. This resulted in a greater increase TS inhibition in metastases although not statistically significant.

Structure-based virtual screening to identify hypocholesterolemic phytochemicals as potent inhibitors of squalene synthase a potential target for hypercholesterolemia

Squalene synthase (SQS) plays a crucial role in the cholesterol biosynthetic pathway. Its distinctive strategic position makes it a promising candidate for targeting and developing new anti-hypercholesterolemic agents. To uncover novel phytochemical scaffolds as potential inhibitors of SQS, we employed a structure-based virtual screening approach that involves screening 545 phytochemicals collected from Moroccan aromatic and medicinal plants and filtering them based on RMSD values and their affinity towards the target enzyme. Furthermore, we visualized the interacting amino acid residues to gain insight into the 2D and 3D interactions. The docking process was validated through the re-docking method with the reference co-crystallized complex (PDB id = 3v66, SQS-D3A). The screening resulted in the identification of two phytochemicals, Apigenin 7-O-rutinoside, and Apigenin 7-O-glucuronide, with high affinity for SQS binding sites. Both phytochemicals interact with functionally essential residues of SQS. The drug-likeness and toxicity of the phytochemicals were assessed through ADME-Tox analysis. Later, molecular dynamics simulations were performed by GROMACS software for 100 ns to evaluate the stability and fluctuations of protein-ligand complexes. By examining the trajectories produced by the MD simulations, we monitored complex stability, fluctuation, atomic gyration, H-bond, PCA, and FES. The simulations demonstrated that the interaction between the target and the compounds was stable and consistent. Binding free energy calculations indicated that Apigenin 7-O-rutinoside and Apigenin 7-O-glucuronide exhibited higher binding free energy than the co-crystallized inhibitor (D3A), providing a basis for further research in vitro and in vivo to develop potent SQS inhibitors for the treatment of hypercholesterolemia.

Antioxidant Therapy in Neonatal Hypoxic Ischemic Encephalopathy: Adjuvant or Future Alternative to Therapeutic Hypothermia?

Oxidative stress-related diseases in newborns arise from pro-oxidant/antioxidant imbalance in both term and preterm neonates. Pro-oxidant/antioxidant imbalance has shown to be present in different pathological conditions such as hypoxic ischemic encephalopathy (HIE), retinopathy of prematurity (ROP), bronchopulmonary dysplasia (BPD), necrotizing enterocolitis (NEC), and patent ductus arteriosus (PDA). We performed a narrative review according to the most recent available literature (2012-2024), using Scopus and PubMed as electronic databases. Many observational and experimental studies in vitro and in vivo have evaluated the effectiveness of antioxidant therapies such as melatonin, erythropoietin (EPO), allopurinol, N-acetylcisteine (NAS), and nitric oxide synthase (NOS) inhibitors in these diseases. Perinatal asphyxia is one of the most important causes of mortality and morbidity in term and near-term newborns. Therapeutic hypothermia (TH) is the gold standard treatment for neonates with moderate-severe perinatal asphyxia, resulting in a reduction in the mortality and neurodevelopmental disability rates. According to the most recent literature and clinical trials, melatonin, allopurinol, NAS, NOS inhibitors, magnesium sulfate, and stem cells stand out as promising as both adjuvants and future probable alternatives to TH in the treatment of HIE.

The alarmin, interleukin-33, increases vascular tone via extracellular signal regulated kinase-mediated Ca2+ sensitization and endothelial nitric oxide synthase inhibition.

Alarmins are classified by their release from damaged or ruptured cells. Many alarmins have been found to increase vascular tone and oppose endothelium-dependent dilatation (EDD). Interleukin (IL)-33 plays a prominent role in lung injury and can be released during vascular injury and in chronic studies found to be cardioprotective. Our recent work has implicated IL-33 in acute vascular dysfunction following inhalation of engineered nanomaterials (ENM). However, the mechanisms linking IL-33 to vascular tone have not been interrogated. We therefore aimed to determine whether IL-33 directly influenced microvascular tone and endothelial function. Isolated feed arteries and in vivo arterioles from male and female Sprague-Dawley rats were used to determine direct vascular actions of IL-33. Mesenteric feed arteries and arterioles demonstrated reduced intraluminal diameters when treated with increasing concentrations of recombinant IL-33. IL-33 activated extracellular signal regulated kinase (ERK)1/2 of rat aortic smooth muscle cells but not phosphorylation of myosin light chain kinase. This suggested IL-33may sensitize arterioles to Ca2+-mediated responses. Indeed, IL-33 augmented the myogenic- and phenylephrine-induced vasoconstriction. Additionally, incubation of arterioles with 1ng IL-33 attenuated ACh-mediated EDD. Mechanistically, in human aortic endothelial cells, we demonstrate that IL-33-mediated ERK1/2 activation leads to inhibitory phosphorylation of serine 602 on endothelial nitric oxide synthase. Finally, we demonstrate that IL-33-ERK1/2 contributes to vascular tone following two known inducers of IL-33; ENM inhalation and the rupture endothelial cells. The present study provides novel evidence that IL-33 increases vascular tone via canonical ERK1/2 activation in microvascular smooth muscle and endothelium. Altogether, it is suggested IL-33 plays a critical role in microvascular homeostasis following barrier cell injury. KEY POINTS: Interleukin (IL)-33 causes a concentration-dependent reduction in feed artery diameter. IL-33 acts on vascular smooth muscle cells to augment Ca2+-mediated processes. IL-33 causes inhibitory phosphorylation of endothelial nitric oxide synthase and opposes endothelium-dependent dilatation. Engineered nanomaterial-induced lung injury and endothelial cell rupture in part act through IL-33 to mediate increased vascular tone.

Catalase activity deficiency sensitizes multidrug-resistant Mycobacterium tuberculosis to the ATP synthase inhibitor bedaquiline

Multidrug-resistant tuberculosis (MDR-TB), defined as resistance to the first-line drugs isoniazid and rifampin, is a growing source of global mortality and threatens global control of tuberculosis disease. The diarylquinoline bedaquiline has recently emerged as a highly efficacious drug against MDR-TB and kills Mycobacterium tuberculosis by inhibiting mycobacterial ATP synthase. However, the mechanisms underlying bedaquiline’s efficacy against MDR-TB remain unknown. Here we investigate bedaquiline hyper-susceptibility in drug-resistant Mycobacterium tuberculosis using systems biology approaches. We discovered that MDR clinical isolates are commonly sensitized to bedaquiline. This hypersensitization is caused by several physiological changes induced by deficient catalase activity. These include enhanced accumulation of reactive oxygen species, increased susceptibility to DNA damage, induction of sensitizing transcriptional programs, and metabolic repression of several biosynthetic pathways. In this work we demonstrate how resistance-associated changes in bacterial physiology can mechanistically induce collateral antimicrobial drug sensitivity and reveal druggable vulnerabilities in antimicrobial resistant pathogens.

Medicinal Chemistry Insights in Neuronal Nitric Oxide Synthase Inhibitors Containing Nitrogen Heterocyclic Compounds: A Mini Review.

Many scientific reports over the last two decades have focused on the discovery and development of novel nNOS inhibitors. The structural identity of isoforms, bioavailability, pharmacokinetic, and safety profile issues remain major obstacles in the discovery of more potent and selective nNOS inhibitors. This review aims to provide an in-depth overview of the molecular interaction patterns between nNOS active site and inhibitors containing structurally diverse nitrogen heterocyclic compounds and highlight the structural properties needed to develop selective nNOS inhibitors. Previously published data allowed the usage of the structure-driven approach in the designing of selective nNOS inhibitors, which relies on the specific structural features required to achieve isoform-selectivity towards nNOS. The incorporation of chiral pyrrolidine ring, two aminopyridine heads, or a specific amino tail group, along with the inhibitor's capacity to adopt the curled conformation in the nNOS environment significantly strengthens the molecular interaction between the inhibitor and nNOS residues by forming specific electrostatic interactions and non-bonded contacts that are vital for isoform selectivity. Additional structure-activity relationship investigations are necessary to elucidate more structural characteristics that will ultimately resolve the exact structural basis required for isoform-selective inhibition of nNOS.