Half-maximal Effective Concentration Research Articles

Evaluating alternative compounds for strongyloidiasis therapy: Novel insights from larval migration inhibition test.

Strongyloidiasis is a neglected tropical disease estimated to affect more than 600 million people worldwide. Recently, the World Health Organization road map on neglected tropical diseases 2021-2030 has put the focus on strongyloidiasis, including this disease within its mass drug administration campaigns. With the use of ivermectin in extensive treatment of all populations at-risk, identifying effective therapeutic alternatives is crucial in case ivermectin resistance arises. The objective of the present study was the development of a larval migration inhibition assay to evaluate the anthelmintic efficacy of commercial drugs and diamine and aminoalcohol derivatives against infective Strongyloides ratti third stage larvae. Through this technique, we successfully screened and estimated the in vitro anthelmintic efficacy of six commercial drugs, seven diamine derivatives and eight aminoalcohol derivatives. Unexpectedly, the half-maximal effective concentration of ivermectin and moxidectin (2.21 and 2.34 μM, respectively) were observed as the highest value obtained among all commercial drugs tested by this in vitro technique. Moreover, some diamine and aminoalcohol derivatives showed superior efficacy inhibiting S. ratti motility compared to ivermectin, with five compounds (AA23, AA34, AO2 AO7 and AO14b) also displaying selectivity indexes on HepG2 and Caco2 higher than 1. These findings underscore the potential of these derivatives as promising alternatives for strongyloidiasis treatment, warranting further investigation and in vivo efficacy assessment.

Mps1-Targeted Molecular Design of Melatonin for Broad-Spectrum Antifungal Agent Discovery.

Melatonin, a multifunctional class of natural products, has demonstrated antifungal activity, making it a promising candidate for developing antifungal agents. The mitogen-activated protein kinase (Mps1) within fungal pathogens has a target inhibitory effect of melatonin in fungi. We use a virtual screening strategy to design melatonin derivatives based on the melatonin-Mps1 targeting model. Of these, a multiflorane-substitution compound M-12 emerges as a potent antifungal agent, exhibiting broad-spectrum efficacy against eight phytopathogenic fungal species, and effectively reduces the severity of tomato gray mold, Fusarium head blight in wheat, Sclerotinia stem rot in rape, and peach brown rot. M-12 half-maximal effective concentration values (5.50 μM against Botrytis cinerea, 5.21 μM against Fusarium graminearum, 10.6 μM against Rhizoctonia solani, and 9.02 μM against Sclerotinia sclerotiorum) are better than those of commercial broad-spectrum fungicide azoxystrobin (55.0, 23.2, 46.5, and 17.7 μM, respectively). Antifungal activity of enantiomer (S)-M-12 (5.02 μM) is significantly greater than its (R)-enantiomer (23.6 μM) against B. cinerea. Molecular docking and transcriptome analysis reveal that M-12 achieves its antifungal effects by inhibiting Mps1 kinase, thereby suppressing fungal growth and virulence.

Design, synthesis, and structure–activity relationships of xanthine derivatives as broad-spectrum inhibitors of coronavirus replication

Illuminated by insights into the hijacking of host cellular metabolism by coronaviruses, we identified an initial hit compound 7030B-C5, characterized by a xanthine scaffold, via a cellular-level phenotypic screening from a domestic repertoire of lipid-modulating agents. A series of derivatives were synthesized and optimized through comprehensive structure–activity relationship (SAR) studies focusing on the N-1, C-8, and N-7 positions of xanthine and preliminary exploration on the N-3 position and parent nucleus. Compounds 10e, 10f and 10o, featuring modifications at the N-7 position, showed inhibitory activity with half maximal effective concentration (EC50) values in the three-digit nanomolar range against human coronavirus-229Ehuman coronavirus-229E (HCoV-229E). In particular, compound 10o exerted superior potency across various coronavirus strains, including HCoV-229E, HCoV-OC43, and the Omicron variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Further investigations revealed that 10o acted on the post-entry stages of virus replication and exhibited a distinctive antiviral mechanism from that of clinically approved nirmatrelvir and molnupiravir. Moreover, drug combination study indicates that 10o operates additively with nirmatrelvir, molnupiravir or omicsynin B4, a dual inhibitor of host proteases for S protein priming. Additionally, in vivo assessments show that 10o has favorable pharmacokinetic and safety profiles compared to its parent compound 7030B-C5. These findings underscore the potential of 10o as a promising antiviral candidate for the treatment of current and potential future coronavirus infections.

Differential Selection for Survival and for Growth in Adaptive Laboratory Evolution Experiments With Benzalkonium Chloride.

Biocides are used to control microorganisms across different applications, but emerging resistance may pose risks for those applications. Resistance to biocides has commonly been studied using adaptive laboratory evolution (ALE) experiments with growth at subinhibitory concentrations linked to serial subculturing. It has been shown recently that Escherichia coli adapts to repeated lethal stress imposed by the biocide benzalkonium chloride (BAC) by increased survival (i.e., tolerance) and not by evolving the ability to grow at increased concentrations (i.e., resistance). Here, we investigate the contributions of evolution for tolerance as opposed to resistance for the outcome of ALE experiments with E. coli exposed to BAC. We find that BAC concentrations close to the half maximal effective concentration (EC50, 4.36 μg mL-1) show initial killing (~40%) before the population resumes growth. This indicates that cells face a two-fold selection pressure: for increased survival and for increased growth. To disentangle the effects of both selection pressures, we conducted two ALE experiments: (i) one with initial killing and continued stress close to the EC50 during growth and (ii) another with initial killing and no stress during growth. Phenotypic characterization of adapted populations showed that growth at higher BAC concentrations was only selected for when BAC was present during growth. Whole genome sequencing revealed distinct differences in mutated genes across treatments. Treatments selecting for survival-only led to mutations in genes for metabolic regulation (cyaA) and cellular structure (flagella fliJ), while treatments selecting for growth and survival led to mutations in genes related to stress response (hslO and tufA). Our results demonstrate that serial subculture ALE experiments with an antimicrobial at subinhibitory concentrations can select for increased growth and survival. This finding has implications for the design of ALE experiments to assess resistance risks of antimicrobials in different scenarios such as disinfection, preservation, and environmental pollution.

Structure-activity optimization of ryanodine receptor modulators for the treatment of catecholaminergic polymorphic ventricular tachycardia

BackgroundCatecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited arrhythmia disorder associated with potentially lethal arrhythmias. Most CPVT cases are caused by inherited variants in the gene encoding ryanodine receptor type 2 (RYR2). ObjectiveThe goal of this study was to investigate the structure-activity relationship of tetracaine derivatives and to test a lead compound in a mouse model of CPVT. MethodsWe synthesized >200 tetracaine derivatives and characterized 11 of those. The effects of these compounds on Ca2+ handling in cardiomyocytes from R176Q/+ mice was tested with confocal microscopy. The effects of lead compound MSV1302 on arrhythmia inducibility and cardiac contractility were tested by programmed electrical stimulation and echocardiography, respectively. Plasma and microsomal stability and cytotoxicity assays were also performed. ResultsCa2+ imaging revealed that 4 of 11 compounds suppressed sarcoplasmic reticulum Ca2+ leak through mutant RyR2. Two compounds selected for further testing exhibited a half-maximal effective concentration of 146 nM (MSV1302) and 49 nM (MSV1406). Whereas neither compound altered baseline electrocardiogram intervals, only MSV1302 suppressed stress- and pacing-induced ventricular tachycardia in vivo in R176Q/+ mice. Echocardiography revealed that the lead compound MSV1302 did not negatively affect cardiac inotropy and chronotropy. Finally, compound MSV1302 did not block INa, ICa,L, or IKr; it exhibited excellent stability in plasma and microsomes, and it was not cytotoxic. ConclusionStructure-activity relationship studies of second-generation tetracaine derivatives identified lead compound MSV1302 with a favorable pharmacokinetic profile. MSV1302 normalized aberrant RyR2 activity in vitro and in vivo, without altering cardiac inotropy, chronotropy, or off-target effects on other ion channels. This compound may be a strong candidate for future clinical studies to determine its efficacy in CPVT patients.

In vitro and in vivo Evaluations of the Antifungal Activity of Salicylic Acid and Silicon Against Ganoderma Boninense

Basal stem rot disease (BSR) in oil palms is one of the primary diseases that has led to the wide use of fungicides. This increased the development of fungal isolates resistant to fungicides and led to the search for alternative strategies to replace the use of fungicides. This study aimed to evaluate in vitro antifungal activity of salicylic acid (SA) and silicon (Si) in inhibiting mycelial growth of Ganoderma boninense using Poison Food Technique and to evaluate the in vivo efficacy of Si treatment on oil palm seedlings growth and resistance towards G. boninense. Percentage inhibition of radial mycelial growth (PIRG) was assessed, and Si treatment significantly reduced mycelial radial growth of G. boninenseup to 100% inhibition at concentrations of 200 and 250 mg/L. The half-maximal effective concentration (EC50) for Si was 68.57 mg/L, while for SiO2, it was 273.95 mg/L. The EC50 for salicylic acid was 381.33 mg/L. For in vivo evaluation, oil palm seedlings treated with Si at 150, 200, and 250 mg/L showed the lowest severity of leaf chlorosis and necrotic symptoms, which were 7.36%, 6.49%, and 4.05%, respectively. In contrast, the seedlings without Si showed the highest severity of leaf symptoms. Examination of internal bole tissues of oil palm seedlings treated with Si at a concentration of 250 mg/L also recorded a 3.0% mean percentage of disease severity compared to the untreated infected seedlings, which showed 35.0% disease severity. Our findings demonstrated the potential of Si application in controlling the BSR disease caused by Ganoderma boninense.

Antimicrobial mechanisms and antifungal activity of compounds generated by banana rhizosphere Pseudomonas aeruginosa Gxun-2 against fusarium oxysporum f. sp. cubense.

Fusarium wilt of banana, also recognized as Panama disease, is caused by the soil-borne fungus Fusarium oxysporum f. sp. cubense tropical race 4 (FOC TR4). In recent years, strategies utilizing biocontrol agents, comprising antifungal microorganisms and their associated bioactive compounds from various environments, have been implemented to control this destructive disease. Our previous study showed that Pseudomonas aeruginosa Gxun-2 had significant antifungal effects against FOC TR4. However, there has been little scientific investigation of the antibacterial or antifungal activity. The aim of this study was to isolate, identify and evaluate the inhibition strength of active compounds in P. aeruginosa Gxun-2, so as to explain the mechanism of the strain inhibition on FOC TR4 from the perspective of compounds. The main antibacterial compounds of strain Gxun-2 were isolated, purified and identified using by fermentation extraction, silica gel column chromatography, thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC), and nuclear magnetic resonance (NMR) techniques. The effect of the compounds on the mycelial growth, morphology and spore germination of strain FOC TR4 was observed by 96-well plate method and AGAR diffusion method. Among the metabolites produced by the strain, four antifungal compounds which were identified phenazine (C12H8N2), phenazine-1-carboxylic acid (PCA) (C13H8N2O2), 2-acetamidophenol (C8H9NO2) and aeruginaldehyde (C10H7NO2S) were identified through HPLC and NMR. Of these compounds, phenazine and PCA exhibited the most pronounced inhibitory effects on the spore germination and mycelial growth of FOC TR4. Phenazine demonstrated potent antifungal activity against FOC TR4 with a minimum inhibitory concentration (MIC) of 6.25 mg/L. The half-maximal effective concentration (EC50) was calculated to be 26.24 mg/L using the toxicity regression equation. PCA exhibited antifungal activity against FOC TR4 with an MIC of 25 mg/L and an EC50 of 89.63 mg/L. Furthermore, phenazine and PCA triggered substantial morphological transformations in the mycelia of FOC TR4, encompassing folding, bending, fracturing, and diminished spore formation. These findings indicate that strain Gxun-2 plays a crucial role in controlling FOC TR4 pathogenesis, predominantly through producing the antifungal compounds phenazine and PCA, and possesses potential as a cost-efficient and sustainable biocontrol agent against Fusarium wilt of banana in forthcoming times.

Exploration of compounds to inhibit the Panton-Valentine leukocidin of Staphylococcus aureus

The Panton-Valentine leukocidin (PVL) of Staphylococcus aureus is associated with necrotizing infections. After binding to complement 5a receptor (C5aR/CD88) and CD45 it causes cytolysis in polymorphonuclear neutrophils (PMNs) as well as inflammasome activation in monocytes. The objective of this study was to test if (ant)agonists of C5aR and CD45 can attenuate the effect of PVL on PMNs and monocytes. We tested the effect of various concentrations of six C5aR (ant)agonists (avacopan, BM213, DF2593A, JPE-1375, PMX205 and W-54011) and one CD45 antagonist (NQ301) to attenuate the cytotoxic effect of PVL on human PMNs and monocytes in vitro. Shifts in the half-maximal effective concentration (EC50) of PVL to achieve a cytotoxic effect on PMNs and modulation of inflammatory cytokine response from monocytes were determined by flow cytometry and IL-1β detection. Pre-treatment of PMNs with avacopan, PMX205 and W-54,011 resulted in 3.6- to 4.3-fold shifts in the EC50 for PVL and were able to suppress IL-1β secretion by human monocytes in the presence of PVL. BM213, DF2593A and NQ301 were unable to change the susceptibility of PMNs towards PVL or reduce inflammasome activation in monocytes. Avacopan, PMX205 and W-54,011 showed protection against PVL-induced cytotoxicity and suppressed IL-1β secretion by monocytes. Clinical studies are needed to prove whether these substances can be used therapeutically as repurposed drugs.

SAR Analysis of Novel Coxsackie virus A9 Capsid Binders.

Enterovirus infections are common in humans, yet there are no approved antiviral treatments. In this study we concentrated on inhibition of one of the Enterovirus B (EV-B), namely Coxsackievirus A9 (CVA9), using a combination of medicinal chemistry, virus inhibition assays, structure determination from cryogenic electron microscopy and molecular modeling, to determine the structure activity relationships for a promising class of novel N-phenylbenzylamines. Of the new 29 compounds synthesized, 10 had half maximal effective concentration (EC50) values between 0.64-10.46 μM, and of these, 7 had 50% cytotoxicity concentration (CC50) values higher than 200 μM. In addition, this new series of compounds showed promising physicochemical properties and act through capsid stabilization, preventing capsid expansion and subsequent release of the genome.

Development, Pharmacokinetics and Antimalarial Evaluation of Dose Flexible 3D Printlets of Dapsone for Pediatric Patients.

The focus of current studies was to fabricate dose flexible printlets of dapsone (DDS) for pediatric patients by selective laser sintering (SLS) 3D printing method, and evaluate its physicochemical, patient in-use stability, and pharmacokinetic attributes. Eight formulations were fabricated using Kollicoat® IR, Eudragit® L-100-55 and StarCap®as excipients and evaluated for hardness, disintegration, dissolution, amorphous phase by differential scanning calorimetry and X-ray powder diffraction, in-use stability at 30 oC/75% RH for a month, and pharmacokinetic study in Sprague Dawley rats. The hardness, and disintegration of the printlets varied from 2.6±1.0 (F4) to 7.7±0.9 (F3) N and 2.0±0.4 (F2) to 7.6±0.6 (F3) sec, respectively. The drug was partially present as an amorphous form in the printlets. The drug was completely (>85%) dissolved in 20 min. No change in drug form or dissolution extent was observed after storage at in use condition. Pharmacokinetic profiles of both formulations (tablets and printlets) were almost superimposable with no statistical difference in pharmacokinetic parameters (Tmax, Cmax, and AUC0-¥)between formulations (p>0.05). Values of EC50 (half maximal effective concentration) and EC90 (maximal concentration inducing 90% maximal response) were 0.50±0.15 and 1.32±0.26 mM, 0.41±0.06 and 1.11±0.21, and 0.42±0.13 and 1.36±0.19 mM for DDS, printlet and tablet formulations, respectively, and differences were statistically insignificant (p>0.05). In conclusion, tablet and printlet formulations are expected to be clinical similar, thus clinically interchangeable.

Antiviral activity of Nigella sativa oil against two SARS-CoV-2surrogates in vitro as a dietary product

Background: Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is primarily transmitted via aerosol and droplets, but environmental surfaces or potentially contaminated foods may contribute to further viral transmission. Nigella sativa seed (black cumin seed) oil possesses various biological activities against bacteria, fungi, parasites, orviruses. Objectives: This study aimed to explore black cumin seed oil (BSO) with anti-SARS-CoV-2 activities using bovine coronavirus (BCoV) and human coronavirus (HCoV) OC43 as surrogates. Methods and Results: BSO was tested at 1-100 mL/L concentrations for cytotoxicity towards human rectal tumor (HRT-18G) cells and 0.1-10 mL/L for efficacy against BCoV and HCoV OC43 in suspension. Two coronaviruses were separately mixed with BSO suspension and incubated for various times (0, 15, 30, 45, and 60 min) at 4, 23, and 37°C. The virus titerreduction was determined by median tissue culture infectious dose (TCID50) assay with HRT-18G cells as the host. BSO concentrations of 1-20 mL/L exhibited low cytotoxicity (<10%) towards HRT-18G cells. The inactivation of coronaviruses by BSO was concentration-, temperature-, and exposure time-dependent. At 37°C, BSO reduced 2.0 logs of BCoV and3.0 logs of HCoV OC43 in 60 min, respectively. Specifically, half maximal effective concentration (EC50) of BSO at 4, 23, and 37°C after the 1-h exposure was 4.28, 3.06, and 0.87 mL/L against BCoV, respectively, and 0.61, 0.61 and 0.48 mL/L against HCoV OC43, respectively. Moreover, BSO didn’t affect the attachment of BCoV and HCoV OC43 into host cells. Conclusion: Our findings on the inhibition activity of BSO against SARS-CoV-2 surrogates suggested the potential use of this natural product in mitigating SARS-CoV-2 infection. Our results also suggest that HCoV OC43 may be a more appropriate surrogate for SARS-CoV-2 to screen antiviral dietary products. Keywords: Nigella sativa, SARS-CoV-2 surrogates, antiviral activity, quantitative suspension test, dietary supplement

A new brown rot disease of plum caused by Mucor xinjiangensis sp. nov. and screening of its chemical control.

A novel species of Mucor was identified as the causal agent of a brown rot of Prunus domestica (European plum), widely grown in the south of Xinjiang, China. This disease first appears as red spots after the onset of the fruits. With favorable environmental conditions, fruit with infected spots turn brown, sag, expand, wrinkle, and harden, resulting in fruit falling. Fungal species were isolated from infected fruits. A phylogenetic analysis based on internal transcribed spacer (ITS) regions and the large subunit (LSU) of the nuclear ribosomal RNA (rRNA) gene regions strongly supported that these isolates made a distinct evolutionary lineage in Mucor (Mucoromycetes, Mucoraceae) that represents a new taxonomic species, herein named as Mucor xinjiangensis. Microscopic characters confirmed that these strains were morphologically distinct from known Mucor species. The pathogenicity of M. xinjiangensis was confirmed by attaching an agar disk containing mycelium on fruits and re-isolation of the pathogen from symptomatic tissues. Later, fourteen fungicides were selected to determine the inhibitory effect on the pathogen. Further, results showed that difenoconazole had the best effect on the pathogen and the strongest toxicity with the smallest half maximal effective concentration (EC50) value, followed by a compound fungicide composed of difenoconazole with azoxystrobin, mancozeb, prochloraz with iprodione, pyraclostrobin with tebuconazole, and trifloxystrobin with tebuconazole and ethhylicin. Present study provides the basis for the prevention and control of the novel plum disease and its pathogen.

Identification and characterization of a small molecule BFstatin inhibiting BrpR, the transcriptional regulator for biofilm formation of Vibrio vulnificus.

Many pathogenic bacteria form biofilms that are resistant to not only host immune defenses but also antibiotics, posing a need for the development of strategies to control biofilms. In this study, to prevent biofilm formation of the fulminating foodborne pathogen Vibrio vulnificus, chemical libraries were extensively screened to identify a small molecule inhibiting the activity of BrpR, a transcriptional regulator for biofilm genes. Accordingly, the BrpR inhibitor BFstatin [N1-(2-chloro-5-fluorophenyl)-N3-propylmalonamide], with a half-maximal effective concentration of 8.01 μM, was identified. BFstatin did not interfere with bacterial growth or exhibit cytotoxicity to the human epithelial cell line. BFstatin directly bound to BrpR and interrupted its binding to the target promoter DNAs of the downstream genes. Molecular dynamics simulation of the interaction between BFstatin and BrpR proposed that BFstatin modifies the structure of BrpR, especially the DNA-binding domain. Transcriptomic analyses revealed that BFstatin reduces the expression of the BrpR regulon including the cabABC operon and brp locus which contribute to the production of biofilm matrix of V. vulnificus. Accordingly, BFstatin diminished the biofilm levels of V. vulnificus by inhibiting the matrix development in a concentration-dependent manner. Altogether, BFstatin could be an anti-biofilm agent targeting BrpR, thereby rendering V. vulnificus more susceptible to host immune defenses and antibiotics.

TAK-861, a potent, orally available orexin receptor 2-selective agonist, produces wakefulness in monkeys and improves narcolepsy-like phenotypes in mouse models

Narcolepsy type 1 (NT1) is associated with severe loss of orexin neurons and characterized by symptoms including excessive daytime sleepiness and cataplexy. Current medications indicated for NT1 often show limited efficacy, not addressing the full spectrum of symptoms, demonstrating a need for novel drugs. We discovered a parenteral orexin receptor 2 (OX2R) agonist, danavorexton, and an orally available OX2R agonist, TAK-994; both improving NT1 phenotypes in mouse models and individuals with NT1. However, danavorexton has limited oral availability and TAK-994 has a risk of off-target liver toxicity. To avoid off-target-based adverse events, a highly potent molecule with low effective dose is preferred. Here, we show that a novel OX2R-selective agonist, TAK-861 [N-{(2S,3R)-4,4-Difluoro-1-(2-hydroxy-2-methylpropanoyl)-2-[(2,3′,5′-trifluoro[1,1′-biphenyl]-3-yl)methyl]pyrrolidin-3-yl}ethanesulfonamide], activates OX2R with a half-maximal effective concentration of 2.5 nM and promotes wakefulness at 1 mg/kg in mice and monkeys, suggesting ~ tenfold higher potency and lower effective dosage than TAK-994. Similar to TAK-994, TAK-861 substantially ameliorates wakefulness fragmentation and cataplexy-like episodes in orexin/ataxin-3 and orexin-tTA;TetO DTA mice (NT1 mouse models). Compared with modafinil, TAK-861 induces highly correlated brain-wide neuronal activation in orexin-tTA;TetO DTA mice, suggesting efficient wake-promoting effects. Thus, TAK-861 has potential as an effective treatment for individuals with hypersomnia disorders including narcolepsy, potentially with a favorable safety profile.

Flavonol derivatives containing piperazine and quinoxaline fragments: synthesis and antifungal activity.

A series of flavonol derivatives containing piperazine and quinoxaline had been designed and synthesized. The biological activity test results showed that some of the target compounds had good antifungal activity against various fungi. N5 had the best antifungal activity against Phomopsis sp (P.s.) and Phytophthora capsica (P.c.). The half maximal effective concentration (EC50) was 12.9 and 25.8μg/mL against P.s. and P.c., respectively, which were better than azoxystrobin (Az, 25.4 and 71.1μg/mL). In addition, the protective and curative activities of N5 against kiwifruit were 85.9 and 67.0% at 200μg/mL in vivo, which were better than that of Az (65.9 and 57.0%). The protective and curative activities against chili leaves were 80.6 and 66.5% at 200μg/mL, which were better than that of Az (77.6 and 60.0%). The scanning electron microscopy (SEM) experiment showed that the action of N5 caused the mycelium to bend and fold, changed its morphology and caused damaged to the mycelium. Through the measurement of relative conductivity, leakage of cytoplasmic contents and determination of malondialdehyde (MDA) content indicated that N5 could damage the integrity of pathogenic fungal cell membranes, change the permeability of cell membranes, and affect the normal growth of mycelium.

Acute and Chronic Ecotoxicity of Daphnia magna Exposed to Ash Leachate from the Cotopaxi Volcano, Ecuador.

Ecuador's wetlands and aquatic ecosystems are chronically exposed to ash contamination due to the frequent volcanoes' eruptions in the country. Still, the short and long-term effects of ash contamination on the aquatic biota are not well understood. We used ashes released by the Cotopaxi volcano in 2016 to investigate their acute and chronic effects in Daphna magna. We calculated the half maximal effective concentration (EC50) after 2 and 21 days of exposure, the non-observed effect concentration (NOEC), and the lowest observed effect concentration (LOEC) on offspring production. We also analyzed the metal concentration present in the ashes. The EC50 values at 2 and 21 days were found at 80% and 5% ash leachate concentrations, respectively. After 21 days of exposure, high mortality and low neonatal production were observed in all leachate concentrations (NOEC was at 15%, and LOEC was at 20% leachate concentration). Our results suggest that the ashes from the Cotopaxi volcano can cause acute and chronic toxicity to aquatic life and should be classified as hazardous waste, depending on the dose. There is an urgent need for further studies that assess toxicity caused by the intense volcanic activity in Ecuador.

Virulence, structure, and triadimefon sensitivity of the Puccinia striiformis f. sp. tritici population in Shaanxi Province, China.

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is the most destructive fungal disease affecting wheat in China, especially in Shaanxi Province, an important epidemiological region connecting the western Pst over-summer regions and the central and eastern spring epidemic regions in the country. In the present study, 291 Pst isolates from Shaanxi Province were studied for their virulence using two sets of wheat differentials, population structure using single-nucleotide polymorphism (SNP) markers, and sensitivity to fungicide. When the isolates were tested on the Chinese differentials of 19 wheat cultivars, 72 races were identified, which belonged to three groups, including the Guinong 22 group (48.45%), Hybrid 46 group (31.62%), and Suwon 11 group (19.93%). The three most predominant races were CYR34 (15.46%), G22-14 (11.68%), and CYR32 (10.65%). When the isolates were tested on the 18 Yr single-gene differentials, 95 races were identified, but none of the isolates were virulent to either Yr5 or Yr15. Cluster analyses of the virulence data based on the two sets of differentials and the SNP marker data consistently separated the Shaanxi Pst population into two clusters in the central part and southern part of the Province. Triadimefon sensitivity testing across different concentrations showed a broad range of half-maximal effective concentration (EC50) values, from 0.03 to 5.99 μg mL-1, with a mean EC50 of 0.46 μg mL-1. The majority of isolates (90.72%) were sensitive to the fungicide. The correlation analyses of the virulence, SNP marker, and the triadimefon sensitivity data showed no significant correlations, except a logarithmic relationship between the EC50 value and the number of avirulence factors. This study is the first to determine the relationship of virulence and SNP markers with triadimefon sensitivity in a regional Pst population.The findings provide valuable insights for breeding resistant wheat cultivars and integrated management of stripe rust.

Identification of a new retigabine derivative with improved photostability for selective activation of neuronal Kv7 channels and antiseizure activity.

Pharmacological activation of neuronal Kv7 channels by the antiepileptic drug retigabine (RTG; ezogabine) has been proven effective in treating partial epilepsy. However, RTG was withdrawn from the market due to the toxicity caused by its phenazinium dimer metabolites, leading to peripheral skin discoloration and retinal abnormalities. To address the undesirable metabolic properties of RTG and prevent the formation of phenazinium dimers, we made chemical modifications to RTG, resulting in a new RTG derivative, 1025c, N,N'-{4-[(4-fluorobenzyl) (prop-2-yn-1-yl)amino]-1,2-phenylene}bis(3,3-dimethylbutanamide). Whole-cell recordings were used to evaluate Kv7 channel openers. Site-directed mutagenesis and molecular docking were adopted to investigate the molecular mechanism underlying 1025c and Kv7.2 interactions. Mouse seizure models of maximal electroshock (MES), subcutaneous pentylenetetrazol (scPTZ), and PTZ-induced kindling were utilized to test compound antiepileptic activity. The novel compound 1025c selectively activates whole-cell Kv7.2/7.3 currents in a concentration-dependent manner, with half-maximal effective concentration of .91 ± .17 μmol·L-1. The 1025c compound also causes a leftward shift in Kv7.2/7.3 current activation toward a more hyperpolarized membrane potential, with a shift of the half voltage of maximal activation (ΔV1/2) of -18.6 ± 3.0 mV. Intraperitoneal administration of 1025c demonstrates dose-dependent antiseizure activities in assays of MES, scPTZ, and PTZ-induced kindling models. Moreover, through site-directed mutagenesis combined with molecular docking, a key residue Trp236 has been identified as critical for 1025c-mediated activation of Kv7.2 channels. Photostability experiments further reveal that 1025c is more photostable than RTG and is unable to dimerize. Our findings demonstrate that 1025c exhibits potent and selective activation of neuronal Kv7 channels without being metabolized to phenazinium dimers, suggesting its developmental potential as an antiseizure agent for therapy.

Single nucleotide and copy number variants of cancer driver genes inform drug response in multiple cancers.

Due to the heterogeneity of cancer, precision medicine has been a major challenge for cancer treatment. Determining medication regimens based on patient genotypes has become a research hotspot in cancer genomics. In this study, we aim to identify key biomarkers for targeted therapies based on single nucleotide variants (SNVs) and copy number variants (CNVs) of genes. The experiment is carried out on 7 cancers on the Encyclopedia of Cancer Cell Lines (CCLE) dataset. Considering the high mutability of driver genes which result in abundant mutated samples, the effect of data sparsity can be eliminated to a large extent. Therefore, we focus on discovering the relationship between driver mutation patterns and three measures of drug response, namely area under the curve (AUC), half maximal effective concentration (EC50), and log2-fold change (LFC). First, multiple statistical methods are applied to assess the significance of difference in drug response between sample groups. Next, for each driver gene, we analyze the extent to which its mutations can affect drug response. Based on the results of multiple hypothesis tests and correlation analyses, our main findings include the validation of several known drug response biomarkers such as BRAF, NRAS, MAP2K1, MAP2K2, and CDKN2A, as well as genes with huge potential to infer drug responses. It is worth emphasizing that we identify a list of genes including SALL4, B2M, BAP1, CCDC6, ERBB4, FOXA1, GRIN2A, and PTPRT, whose impact on drug response spans multiple cancers and should be prioritized as key biomarkers for targeted therapies. Furthermore, based on the statistical p-values and correlation coefficients, we construct gene-drug sensitivity maps for cancer drug recommendation. In this work, we show that driver mutation patterns could be used to tailor therapeutics for precision medicine.

Development of a 213Bi-Labeled Pyridyl Benzofuran for Targeted α-Therapy of Amyloid-β Aggregates.

Alzheimer disease is a neurodegenerative disorder with limited treatment options. It is characterized by the presence of several biomarkers, including amyloid-β aggregates, which lead to oxidative stress and neuronal decay. Targeted α-therapy (TAT) has been shown to be efficacious against metastatic cancer. TAT takes advantage of tumor-localized α-particle emission to break disease-associated covalent bonds while minimizing radiation dose to healthy tissues due to the short, micrometer-level, distances traveled. We hypothesized that TAT could be used to break covalent bonds within amyloid-β aggregates and facilitate natural plaque clearance mechanisms. Methods: We synthesized a 213Bi-chelate-linked benzofuran pyridyl derivative (BiBPy) and generated [213Bi]BiBPy, with a specific activity of 120.6 GBq/μg, dissociation constant of 11 ± 1.5 nM, and logP of 0.14 ± 0.03. Results: As the first step toward the validation of [213Bi]BiBPy as a TAT agent for the reduction of Alzheimer disease-associated amyloid-β, we showed that brain homogenates from APP/PS1 double-transgenic male mice (6-9 mo old) incubated with [213Bi]BiBPy exhibited a marked reduction in amyloid-β plaque concentration as measured using both enzyme-linked immunosorbent and Western blotting assays, with a half-maximal effective concentration of 3.72 kBq/pg. Conclusion: This [213Bi]BiBPy-concentration-dependent activity shows that TAT can reduce amyloid plaque concentration invitro and supports the development of targeting systems for invivo validations.