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MethodsX 2021Nitrite and nitrate are present in many foods. Nitrate can be converted into nitrite in human body. Nitrite can react with secondary amines to form secondary amines and...
Nitrite and nitrate are present in many foods. Nitrate can be converted into nitrite in human body. Nitrite can react with secondary amines to form secondary amines and with thiols to form nitrosothiols. Some nitrosamines are cancers suspect. Because of their importance in terms of human health, research on these compounds is still topical and the use of a rapid and reproducible method for determination and quantification of these compounds is necessary. This article presents a method to study the chemical reactivity of nitrite in meat products through the analysis of non-volatile nitrosamines and nitrosothiols based on:•A specific alkaline and heat extraction of nitro-compounds followed by deprotenization by ultrafiltration•NO detection by the Griess reaction•NO released from -NO and -NO bonds by UV light followed by a specific cleavage of S-NO bonds with HgClThis method, validated on cured meat products, could be developed in the same way on all products containing nitrite and nitrate and leading to the formation of nitroso-compounds. The limit of detection for these compounds are of the order of the micromole per liter.
PubMed: 34434809
DOI: 10.1016/j.mex.2021.101289 -
ACS Medicinal Chemistry Letters Aug 2021SARS-CoV-2 entry into host cells relies on the spike (S) protein binding to the human ACE2 receptor. In this study, we investigated the structural dynamics of the viral...
SARS-CoV-2 entry into host cells relies on the spike (S) protein binding to the human ACE2 receptor. In this study, we investigated the structural dynamics of the viral S protein at the fusion peptide (FP) domain and small molecule binding for therapeutics development. Following comparative modeling analysis and docking studies of our previously identified fusion inhibitor chlorcyclizine, we performed a pharmacophore-based virtual screen and identified two novel chemotypes of entry inhibitors targeting the FP. The compounds were evaluated in the pseudoparticle viral entry assay and SARS-CoV-2 cytopathic effect assay and showed single-digital micromole inhibition against SARS-CoV-2 as well as SARS-CoV-1 and MERS. The characterization of the FP binding site of SARS-CoV-2 S protein provides a promising target for the structure-based development of small molecule entry inhibitors as drug candidates for the treatment of COVID-19.
PubMed: 34394844
DOI: 10.1021/acsmedchemlett.1c00263 -
Molecules (Basel, Switzerland) Jul 2021Acridino-diaza-20-crown-6 ether derivatives as new turn-on type fluorescent chemosensors with an excellent functionality and photophysical properties have been designed...
Acridino-diaza-20-crown-6 ether derivatives as new turn-on type fluorescent chemosensors with an excellent functionality and photophysical properties have been designed and synthesized for metal ion-selective optochemical sensing applications. Spectroscopic studies revealed that in an acetonitrile-based semi-aqueous medium, the sensor molecules exhibited a remarkable fluorescence enhancement with high sensitivity only toward Zn, Al and Bi, among 23 different metal ions. Studies on complexation showed a great coordinating ability of log > 4.7 with a 1:1 complex stoichiometry in each case. The detection limits were found to be from 59 nM to micromoles. The new ionophores enabled an optical response without being affected either by the pH in the range of 5.5-7.5, or the presence of various anions or competing metal ions. Varying the -substituents of the new host-backbone provides diverse opportunities in both immobilization and practical applications without influencing the molecular recognition abilities.
PubMed: 34279381
DOI: 10.3390/molecules26134043 -
EJNMMI Radiopharmacy and Chemistry Jul 2021[F]MC225 is a radiotracer for imaging P-glycoprotein (P-gp) function at the blood-brain barrier. The P-gp function can be altered due to different factors, for instance,...
BACKGROUND
[F]MC225 is a radiotracer for imaging P-glycoprotein (P-gp) function at the blood-brain barrier. The P-gp function can be altered due to different factors, for instance, decreased P-gp function has been described in patients with Alzheimer's or Parkinson's Disease. The current applied radiosynthesis of [F]MC225 involves 2 steps, including the distillation of the [F] fluoroethylbromide intermediate. To develop a more robust synthetic procedure, it is of interest to produce the radiotracer via a 1-step synthesis. The present study describes a new synthetic approach to produce [F]MC225 via direct F-fluorination. Moreover, we also provide the appropriate conditions for the automation of the synthesis. A mesylate precursor was synthesized via a multi-step synthetic route and used for the radiolabeling. The nucleophilic substitution of the mesylate group by [F] Fluoride was automated in two different synthesis modules: IBA Synthera and Eckert and Ziegler PharmTracer (E&Z).
RESULTS
The mesylate precursor was synthesized in 7 steps starting with 5-hydroxy-1-tetralone (commercially available) in practical yields. The stability of the precursor was improved via mesylate salt formation method. The radiolabeling was done by adding the mesylate precursor dissolved in DMF to the dried [F]KF/K complex and heating at 140 °C for 30 min. Quality control by UPLC confirmed the production of [F]MC225 with a molar activity (A) higher than 100 GBq/micromole. The synthesis time in Synthera was 106 min and the product was obtained with a radiochemical purity higher than 95% and RCY of 6.5%, while the production in E&Z lasted 120 min and the product had a lower radiochemical purity (91%) and RCY (3.8%).
CONCLUSIONS
[F]MC225 was successfully produced via a 1-step reaction. The procedure is suitable for automation using commercially available synthesis modules. The automation of the radiosynthesis in the Synthera module allows the production of the [F]MC225 by a reliable and simple method.
PubMed: 34264435
DOI: 10.1186/s41181-021-00139-8 -
Aging Jul 2021Ovarian cancer is the third most common cancer and the second most common cause of gynecologic cancer death in women. Its routine clinical management includes surgical...
Ovarian cancer is the third most common cancer and the second most common cause of gynecologic cancer death in women. Its routine clinical management includes surgical resection and systemic therapy with chemotherapeutics. While the first-line systemic therapy requires the combined use of platinum-based agents and paclitaxel, many ovarian cancer patients have recurrence and eventually succumb to chemoresistance. Thus, it is imperative to develop new strategies to overcome recurrence and chemoresistance of ovarian cancer. Repurposing previously-approved drugs is a cost-effective strategy for cancer drug discovery. The antiparasitic drug mebendazole (MBZ) is one of the most promising drugs with repurposing potential. Here, we investigate whether MBZ can overcome cisplatin resistance and sensitize chemoresistant ovarian cancer cells to cisplatin. We first established and characterized two stable and robust cisplatin-resistant (CR) human ovarian cancer lines and demonstrated that MBZ markedly inhibited cell proliferation, suppressed cell wounding healing/migration, and induced apoptosis in both parental and CR cells at low micromole range. Mechanistically, MBZ was revealed to inhibit multiple cancer-related signal pathways including ELK/SRF, NFKB, MYC/MAX, and E2F/DP1 in cisplatin-resistant ovarian cancer cells. We further showed that MBZ synergized with cisplatin to suppress cell proliferation, induce cell apoptosis, and blunt tumor growth in xenograft tumor model of human cisplatin-resistant ovarian cancer cells. Collectively, our findings suggest that MBZ may be repurposed as a synergistic sensitizer of cisplatin in treating chemoresistant human ovarian cancer, which warrants further clinical studies.
Topics: Animals; Antinematodal Agents; Antineoplastic Agents; Apoptosis; Carcinoma, Ovarian Epithelial; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cisplatin; Drug Repositioning; Drug Resistance, Neoplasm; Female; Humans; Mebendazole; Mice; Mice, Nude; Ovarian Neoplasms; Signal Transduction; Tumor Stem Cell Assay; Wound Healing; Xenograft Model Antitumor Assays
PubMed: 34232919
DOI: 10.18632/aging.203232 -
Cell Death & Disease Jul 2021An ultra-large structure-based virtual screening has discovered iKeap1 as a direct Keap1 inhibitor that can efficiently activate Nrf2 signaling. We here tested its...
An ultra-large structure-based virtual screening has discovered iKeap1 as a direct Keap1 inhibitor that can efficiently activate Nrf2 signaling. We here tested its potential effect against hydrogen peroxide (HO)-induced oxidative injury in osteoblasts. In primary murine and human osteoblasts, iKeap1 robustly activated Nrf2 signaling at micromole concentrations. iKeap1 disrupted Keap1-Nrf2 association, causing Nrf2 protein stabilization, cytosol accumulation and nuclear translocation in murine and human osteoblasts. The anti-oxidant response elements (ARE) activity and transcription of Nrf2-ARE-dependent genes (including HO1, NQO1 and GCLC) were increased as well. Significantly, iKeap1 pretreatment largely ameliorated HO-induced reactive oxygen species production, lipid peroxidation and DNA damage as well as cell apoptosis and programmed necrosis in osteoblasts. Moreover, dexamethasone- and nicotine-induced oxidative injury and apoptosis were alleviated by iKeap1. Importantly, Nrf2 shRNA or CRISPR/Cas9-induced Nrf2 knockout completely abolished iKeap1-induced osteoblast cytoprotection against HO. Conversely, CRISPR/Cas9-induced Keap1 knockout induced Nrf2 cascade activation and mimicked iKeap1-induced cytoprotective actions in murine osteoblasts. iKeap1 was ineffective against HO in the Keap1-knockout murine osteoblasts. Collectively, iKeap1 activated Nrf2 signaling cascade to inhibit HO-induced oxidative injury and death of osteoblasts.
Topics: Animals; Antioxidants; Apoptosis; Cells, Cultured; Humans; Hydrogen Peroxide; Kelch-Like ECH-Associated Protein 1; Lipid Peroxidation; NF-E2-Related Factor 2; Osteoblasts; Oxidative Stress; Signal Transduction
PubMed: 34226516
DOI: 10.1038/s41419-021-03962-8 -
Biology Jun 2021Citrus production is facing an unprecedented problem because of huanglongbing (HLB) disease. Presently, no effective HLB-easing method is available when citrus becomes...
Citrus production is facing an unprecedented problem because of huanglongbing (HLB) disease. Presently, no effective HLB-easing method is available when citrus becomes infected. Guanosine 5'-monophosphate synthetase (GMPS) is a key protein in the de novo synthesis of guanine nucleotides. GMPS is used as an attractive target for developing agents that are effective against the patogen infection. In this research, homology modeling, structure-based virtual screening, and molecular docking were used to discover the new inhibitors against Las GMPS. Enzyme assay showed that folic acid and AZD1152 showed high inhibition at micromole concentrations, with AZD1152 being the most potent molecule. The inhibition constant (K) value of folic acid and AZD1152 was 51.98 µM and 4.05 µM, respectively. These results suggested that folic acid and AZD1152 could be considered as promising candidates for the development of Las agents.
PubMed: 34203217
DOI: 10.3390/biology10070594 -
Experimental Biology and Medicine... Aug 2021The ability to predict prediabetes, which affects ∼90 million adults in the US and ∼400 million adults worldwide, would be valuable to public health. Acylcarnitines,...
The ability to predict prediabetes, which affects ∼90 million adults in the US and ∼400 million adults worldwide, would be valuable to public health. Acylcarnitines, fatty acid metabolites, have been associated with type 2 diabetes risk in cross-sectional studies of mostly Caucasian subjects, but prospective studies on their link to prediabetes in diverse populations are lacking. Here, we determined the association of plasma acylcarnitines with incident prediabetes in African Americans and European Americans enrolled in a prospective study. We analyzed 45 acylcarnitines in baseline plasma samples from 70 adults (35 African-American, 35 European-American) with incident prediabetes (progressors) and 70 matched controls (non-progressors) during 5.5-year (mean 2.6 years) follow-up in the Pathobiology of Prediabetes in a Biracial Cohort (POP-ABC) study. Incident prediabetes (impaired fasting glucose/impaired glucose tolerance) was confirmed with OGTT. We measured acylcarnitines using tandem mass spectrometry, insulin sensitivity by hyperinsulinemic euglycemic clamp, and insulin secretion using intravenous glucose tolerance test. The results showed that progressors and non-progressors during POP-ABC study follow-up were concordant for 36 acylcarnitines and discordant for nine others. In logistic regression models, beta-hydroxy butyryl carnitine (C4-OH), 3-hydroxy-isovaleryl carnitine/malonyl carnitine (C5-OH/C3-DC), and octenoyl carnitine (C8:1) were the only significant predictors of incident prediabetes. The combined cut-off plasma levels of <0.03 micromol/L for C4-OH, <0.03 micromol/L for C5-OH/C3-DC, and >0.25 micromol/L for C8:1 acylcarnitines predicted incident prediabetes with 81.9% sensitivity and 65.2% specificity. Thus, circulating levels of one medium-chain and two short-chain acylcarnitines may be sensitive biomarkers for the risk of incident prediabetes among initially normoglycemic individuals with parental history of type 2 diabetes.
Topics: Adult; Blood Glucose; Carnitine; Cross-Sectional Studies; Glucose Intolerance; Humans; Insulin Resistance; Insulin Secretion; Insulins; Male; Middle Aged; Prediabetic State
PubMed: 33926260
DOI: 10.1177/15353702211009493 -
Biochimica Et Biophysica Acta.... Jun 2021Biofilm-producing pathogens, such as Acinetobacter baumannii, have aroused escalating attention. Because these bacteria could secrete mixture with close-knit...
Biofilm-producing pathogens, such as Acinetobacter baumannii, have aroused escalating attention. Because these bacteria could secrete mixture with close-knit architecture and complicated components to resist traditional antibiotics. Here, we reported an amphiphilic peptide denoted as zp3 (GIIAGIIIKIKK-NH), which showed favorable bioactivity against Acinetobacter baumannii ATCC 19606 (minimal inhibitory concentration, MIC = 4 μM) and low cytotoxicity to mammalian cells Vero (half maximal inhibitory concentration, IC > 100 μM). Importantly, zp3 could inhibit the formation of biofilm at micromole level and eliminate around 50% preformed biofilm at 32 μM after 6 h treatment. This peptide was able to bind with biofilm while maintaining a helical structure in a mimic biofilm-rich environment. In vivo test demonstrated that zp3 rescued 33.3% of larvae after 48 h infection and reduced 1 log live bacteria inside the animal body after 6 h treatment. The bactericidal mode for zp3 was attributed to the combination of influencing ions balance at low concentration and inducing permeability alteration and pore formation on the Acinetobacter baumannii membrane at high concentration. Application on medical textiles also proved that zp3 could perform a good antibacterial activity in practice.
Topics: Acinetobacter baumannii; Animals; Anti-Bacterial Agents; Biofilms; Cell Survival; Chlorocebus aethiops; Larva; Membrane Potentials; Microbial Sensitivity Tests; Moths; Peptides; Vero Cells
PubMed: 33675719
DOI: 10.1016/j.bbamem.2021.183600 -
Bio-protocol May 2020Kinases and ATPases perform essential biological functions in metabolism and regulation. Activity of these enzymes is commonly measured by coupling ATP consumption to...
Kinases and ATPases perform essential biological functions in metabolism and regulation. Activity of these enzymes is commonly measured by coupling ATP consumption to the synthesis of a detectable product. For most assay systems the ATP concentration during the reaction is unknown, compromising the precision of the assay. Using the ADP-specific hexokinase (ADP-HK) from the thermophilic archaeon the protocol outlined here allows real time coupling of ATP consumption to downstream signal change enabling accurate kinetic measurements. ADP-HK phosphorylates glucose that is then used by glucose-6-phosphate dehydrogenase to reduce NAD to NADH which can be measured at 340 nm. We have shown this assay to be sensitive to the detection of micromole quantities of ADP with no detectable background from ATP.
PubMed: 33659565
DOI: 10.21769/BioProtoc.3599