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ACS Catalysis Jan 2023In the context of copper-catalyzed nitrene transfer to olefins, many systems operate upon mixing a CuX salt (X = halide, OTf) and a polydentate N-based ligand, assuming...
In the context of copper-catalyzed nitrene transfer to olefins, many systems operate upon mixing a CuX salt (X = halide, OTf) and a polydentate N-based ligand, assuming that the X ligand is displaced from the coordination sphere toward a counterion position. Herein, we demonstrated that such general assumption should be in doubt since studies carried out with the well-defined copper(I) complexes (TTM)CuCl and [(TTM)Cu(NCMe)]PF (TTM = tris(triazolyl)methane ligand) demonstrate a dual behavior from a catalytic and mechanistic point of view that exclusively depends on the presence or absence of the chloride ligand bonded to the metal center. When coordinated, the turnover-limiting step corresponds to the formation of the carbon-nitrene bond, whereas in its absence, the highest barrier corresponds to the formation of the copper-nitrene intermediate.
PubMed: 37808365
DOI: 10.1021/acscatal.2c05069 -
Chemical Science Oct 2023Terminal Ru(v)-imido species are thought to be as reactive to group transfer reactions as their Ru(v)-oxo homologues, but are less studied. With the electron-rich...
Terminal Ru(v)-imido species are thought to be as reactive to group transfer reactions as their Ru(v)-oxo homologues, but are less studied. With the electron-rich corrole ligand, relatively stable and isolable Ru(v)-arylimido complexes [Ru(Bu-Cor)(NAr)] (H(Bu-Cor) = 5,15-diphenyl-10-(-butylphenyl)corrole, Ar = 2,4,6-MeCH (Mes), 2,6-(Pr)CH (Dipp), 2,4,6-(Pr)CH (Tipp), and 3,5-(CF)CH (BTF)) can be prepared from [Ru(Bu-Cor)] under strongly reducing conditions. This type of Ru(v)-monoarylimido corrole complex with = ½ was characterized by high-resolution ESI mass spectrometry, X-band EPR, resonance Raman spectroscopy, magnetic susceptibility, and elemental analysis, together with computational studies. Under heating/light irradiation (xenon lamp) conditions, the complexes [Ru(Bu-Cor)(NAr)] (Ar = Mes, BTF) could undergo aziridination of styrenes and amination of benzylic C(sp)-H bonds with up to 90% product yields.
PubMed: 37800003
DOI: 10.1039/d3sc02266h -
Blood Advances Jan 2024Allogeneic hematopoietic stem cell transplantation (HSCT) is highly effective for treating pediatric high-risk or relapsed acute lymphoblastic leukemia (ALL). For young...
Allogeneic hematopoietic stem cell transplantation (HSCT) is highly effective for treating pediatric high-risk or relapsed acute lymphoblastic leukemia (ALL). For young children, total body irradiation (TBI) is associated with severe late sequelae. In the FORUM study (NCT01949129), we assessed safety, event-free survival (EFS), and overall survival (OS) of 2 TBI-free conditioning regimens in children aged <4 years with ALL. Patients received fludarabine (Flu), thiotepa (Thio), and either busulfan (Bu) or treosulfan (Treo) before HSCT. From 2013 to 2021, 191 children received transplantation and were observed for ≥6 months (median follow-up: 3 years). The 3-year OS was 0.63 (95% confidence interval [95% CI], 0.52-0.72) and 0.76 (95% CI, 0.64-0.84) for Flu/Thio/Bu and Flu/Thio/Treo (P = .075), respectively. Three-year EFS was 0.52 (95% CI, 0.41-0.61) and 0.51 (95% CI, 0.39-0.62), respectively (P = .794). Cumulative incidence of nonrelapse mortality (NRM) and relapse at 3 years were 0.06 (95% CI, 0.02-0.12) vs 0.03 (95% CI: <0.01-0.09) (P = .406) and 0.42 (95% CI, 0.31-0.52) vs 0.45 (95% CI, 0.34-0.56) (P = .920), respectively. Grade >1 acute graft-versus-host disease (GVHD) occurred in 29% of patients receiving Flu/Thio/Bu and 17% of those receiving Flu/Thio/Treo (P = .049), whereas grade 3/4 occurred in 10% and 9%, respectively (P = .813). The 3-year incidence of chronic GVHD was 0.07 (95% CI, 0.03-0.13) vs 0.05 (95% CI, 0.02-0.11), respectively (P = .518). In conclusion, both chemotherapeutic conditioning regimens were well tolerated and NRM was low. However, relapse was the major cause of treatment failure. This trial was registered at www.clinicaltrials.gov as #NCT01949129.
Topics: Child; Child, Preschool; Humans; Busulfan; Graft vs Host Disease; Hematopoietic Stem Cell Transplantation; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Recurrence; Thiotepa; Transplantation Conditioning
PubMed: 37738088
DOI: 10.1182/bloodadvances.2023010591 -
ACS Omega Aug 2023-2-iminothiazolidines and -thiazolidine-2-iminium tetrafluoroborates were successfully produced from --alkyl aziridine-2-carboxylates and phenyl/alkyl isothiocyanates...
Zinc Tetrafluoroborate-Mediated Ring Expansion of -Aziridine-2-carboxylates to -2-Iminothiazolidines and -Thiazolidine-2-iminium Tetrafluoroborates and Evaluation of Antimicrobial Activity.
-2-iminothiazolidines and -thiazolidine-2-iminium tetrafluoroborates were successfully produced from --alkyl aziridine-2-carboxylates and phenyl/alkyl isothiocyanates mediated by zinc tetrafluoroborate in refluxing DCE. Reactions were performed via a complete regio- and stereoselective process to give the title iminothiazolidines and -thiazolidine-2-iminium salts in moderate to good yields (35 to 82%) with a wide substrate scope. In addition, the antibacterial activity evaluation of these compounds, as well as the minimum inhibitory concentration (MIC) determination, revealed that only four -thiazolidine-2-iminium salts showed growth inhibition against .
PubMed: 37636906
DOI: 10.1021/acsomega.3c03531 -
ACS Omega Aug 2023Pesticides are widely used, resulting in continuing human exposure with potential health impacts. Some exposures related to agricultural works have been associated with...
Research of Pesticide Metabolites in Human Brain Tumor Tissues by Chemometrics-Based Gas Chromatography-Mass Spectrometry Analysis for a Hypothetical Correlation between Pesticide Exposure and Risk Factor of Central Nervous System Tumors.
Pesticides are widely used, resulting in continuing human exposure with potential health impacts. Some exposures related to agricultural works have been associated with neurological disorders. Since the 2000s, the hypothesis of the role of pesticides in the occurrence of central nervous system (CNS) tumors has been better documented in the literature. However, the etiology of childhood brain cancers still remains largely unknown. The major objective of this work was to assess the potential role of pesticide exposure as a risk factor for CNS tumors based on questionnaires and statistical analysis of information collected from patients hospitalized in the Neurosurgery Department of the Habib Bourguiba Hospital Medium in Sfax, Tunisia, during the period from January 1, 2022, to May 31, 2023. It also aimed to develop a simple and rapid analytical method by the gas chromatography-mass spectrometry technique for the research traces of pesticide metabolites in some collected human brain tumor tissues in order to more emphasize our hypothesis for such a correlation between pesticide exposure and brain tumor development. Patients with a history of high-risk exposure were selected to conduct further analysis. Chemometric methods were adapted to discern intrinsic variation between pathological and control groups and ascertain effective separation with the identification of differentially expressed metabolites accountable for such variations. Three samples revealed traces of pesticide metabolites that were mostly detected at an early age. The histopathological diagnosis was medulloblastoma for a 10-year-old child and high-grade gliomas for 27- and 35-year-old adults. The bivariate analyses (odds ratio >1 and value <5%) confirmed the great probability of developing cancer by an exposure case. The Cox proportional hazards model revealed the risk of carcinogenicity beyond the age of 50 as a long-term effect of pesticide toxicity. Our study supports the correlation between pesticide exposure and the risk of development of human brain tumors, suggesting that preconception pesticide exposure, and possibly exposure during pregnancy, is associated with an increased childhood brain tumor risk. This hypothesis was enhanced in identifying traces of metabolites from the carbamate insecticide class known for their neurotoxicity and others from pyridazinone, organochlorines (OCs), triazole fungicide, and N-nitroso compounds known for their carcinogenicity. The 2D-OXYBLOT analysis confirmed the neurotoxicity effect of insecticides to induce oxidative damage in CNS cells. Aldicarb was implicated in brain carcinogenicity confirmed by the identification of oxime metabolites in a stress degradation study. Revealing "aziridine" metabolites from the OC class may better emphasize the theory of detecting traces of pesticide metabolites at an early age. Overall, our findings lead to the recommendation of limiting the residential use of pesticides and the support of public health policies serving this objective that we need to be vigilant in the postmarketing surveillance of human health impacts.
PubMed: 37599976
DOI: 10.1021/acsomega.3c04592 -
BioRxiv : the Preprint Server For... Aug 2023Nitriles are uncommon in nature and are typically constructed from oximes via the oxidative decarboxylation of amino acid substrates or from the derivatization of...
Nitriles are uncommon in nature and are typically constructed from oximes via the oxidative decarboxylation of amino acid substrates or from the derivatization of carboxylic acids. Here we report a third strategy of nitrile biosynthesis featuring the cyanobacterial nitrile synthase AetD. During the biosynthesis of the 'eagle-killing' neurotoxin, aetokthonotoxin, AetD converts the alanyl side chain of 5,7-dibromo-L-tryptophan to a nitrile. Employing a combination of structural, biochemical, and biophysical techniques, we characterized AetD as a non-heme diiron enzyme that belongs to the emerging Heme Oxygenase-like Diiron Oxidase and Oxygenase (HDO) superfamily. High-resolution crystal structures of AetD together with the identification of catalytically relevant products provide mechanistic insights into how AetD affords this unique transformation that we propose proceeds via an aziridine intermediate. Our work presents a new paradigm for nitrile biogenesis and portrays a substrate binding and metallocofactor assembly mechanism that may be shared among other HDO enzymes.
PubMed: 37577561
DOI: 10.1101/2023.08.03.551874 -
Journal of the American Society For... Sep 2023Characterization of nonpolar lipids is crucial due to their essential biological functions and ability to exist in various isomeric forms. In this study, we introduce...
Characterization of nonpolar lipids is crucial due to their essential biological functions and ability to exist in various isomeric forms. In this study, we introduce the N-H aziridination method to target carbon-carbon double bonds (C═C bonds) in nonpolar sterol lipids. The resulting fragments are readily dissociated upon collision-induced dissociation, generating specific fragment ions for C═C bond position determination and fingerprint fragments for backbone characterization. This method significantly enhances lipid ionization efficiency, thereby improving the sensitivity and accuracy of nonpolar lipid analysis. We demonstrated that aziridination of sterols leads to distinctive fragmentation pathways for chain and ring C═C bonds, enabling the identification of sterol isomers such as desmosterol and 7-dehydrocholesterol. Furthermore, aziridination can assist in identifying the sterol backbone by providing fingerprint tandem mass spectra. We also demonstrated the quantitative capacity of this approach with a limit of detection of 10 nM in the solvent mixture of methanol and water. To test the feasibility of this method in complex biological samples, we used mouse prostate cancerous tissues and found significant differences in nonpolar lipid profiles between healthy and cancerous samples. The high efficiency and specificity of aziridination-assisted mass spectrometric analysis, as well as its quantitative analysis ability, make it highly suitable for broad applications in nonpolar lipid research.
Topics: Male; Mice; Animals; Sterols; Isomerism; Tandem Mass Spectrometry; Phytosterols; Carbon; Spectrometry, Mass, Electrospray Ionization
PubMed: 37523498
DOI: 10.1021/jasms.3c00161 -
Molecules (Basel, Switzerland) Jul 2023The efficient one-pot halofluorination of a -enaminophosphonate/-iminophosphonate tautomeric mixture resulting in ,-halofluorinated -iminophosphonates is reported....
The efficient one-pot halofluorination of a -enaminophosphonate/-iminophosphonate tautomeric mixture resulting in ,-halofluorinated -iminophosphonates is reported. Subsequent imine reduction gave the corresponding -aminophosphonates as a racemic mixture or with high diastereoselectivity. The proposed protocol is the first example of a synthesis of -inactivated aziridines substituted by a fluorine and phosphonate moiety on the same carbon atom. Based on spectroscopic and theoretical studies, we determined the / geometry of the resulting fluorinated aziridine-2-phosphonate. Our procedure, involving the reduction of -fluoroaziridine mixture , allows us to isolate chiral aziridines as well as aziridines that do not contain a fluorine atom. We also investigated the influence of the fluorine atom on the reactivity of aziridine through an acid-catalyzed regioselective ring-opening reaction. The results of DFT calculations, at the PCM/ωB97x-D/def2-TZVPD level of theory, are in good agreement with the experiments. The transition states of the S2 intramolecular cyclization of vicinal haloamines have been modeled.
PubMed: 37513451
DOI: 10.3390/molecules28145579 -
Cells Jul 2023Tumor therapy escape due to undesired side effects induced by treatment, such as prosurvival autophagy or cellular senescence, is one of the key mechanisms of resistance...
Tumor therapy escape due to undesired side effects induced by treatment, such as prosurvival autophagy or cellular senescence, is one of the key mechanisms of resistance that eventually leads to tumor dormancy and recurrence. Glioblastoma is the most frequent and practically incurable neoplasm of the central nervous system; thus, new treatment modalities have been investigated to find a solution more effective than the currently applied standards based on temozolomide. The present study examined the newly synthesized compounds of aziridine-hydrazide hydrazone derivatives to determine their antineoplastic potential against glioblastoma cells in vitro. Although the output of our investigation clearly demonstrates their proapoptotic activity, the cytotoxic effect appeared to be blocked by treatment-induced autophagy, the phenomenon also detected in the case of temozolomide action. The addition of an autophagy inhibitor, chloroquine, resulted in a significant increase in apoptosis triggered by the tested compounds, as well as temozolomide. The new aziridine-hydrazide hydrazone derivatives, which present cytotoxic potential against glioblastoma cells comparable to or even higher than that of temozolomide, show promising results and, thus, should be further investigated as antineoplastic agents. Moreover, our findings suggest that the combination of an apoptosis inducer with an autophagy inhibitor could optimize chemotherapeutic efficiency, and the addition of an autophagy inhibitor should be considered as an optional adjunctive therapy minimizing the risk of tumor escape from treatment.
Topics: Humans; Glioblastoma; Temozolomide; Chloroquine; Hydrazones; Hydrazines; Antineoplastic Agents; Autophagy; Aziridines
PubMed: 37508570
DOI: 10.3390/cells12141906 -
ACS Omega Jun 2023A divergent two-step process has provided access to optically pure enantiomers of MDMA and MDA, clinically relevant phenylisopropylamine entactogens. Target compounds...
A divergent two-step process has provided access to optically pure enantiomers of MDMA and MDA, clinically relevant phenylisopropylamine entactogens. Target compounds were synthesized from commercially available alanine-derived aziridines. Critical process parameters were identified, and the reactions were optimized to avoid chromatographic purifications toward gram-scale isolations, providing ()-(-)-MDMA, ()-(+)-MDMA, ()-(-)-MDA, and ()-(+)-MDA each in greater than 98% purity by UPLC, >99% enantiomeric excess, and net yields between 50 and 60% for the complete process.
PubMed: 37360440
DOI: 10.1021/acsomega.3c02358