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Biomedicine & Pharmacotherapy =... May 2024Naringenin is a flavonoid found in many fruits and herbs, most notably in grapefruits. In recent years, this compound and its derivatives have been of great interest due...
Naringenin is a flavonoid found in many fruits and herbs, most notably in grapefruits. In recent years, this compound and its derivatives have been of great interest due to their high biological activity, including fungicidal and bactericidal effects, also in relation to multidrug-resistant bacteria. Membrane interactions of naringenin oxime (NO) and its 7-O-alkyl (7-alkoxy) derivatives, such as methyl (7MENO), ethyl (7ETNO), isopropyl (7IPNO), n-butyl (7BUNO) and n-pentyl (7PENO) were studied. Thermotropic properties of model membranes were investigated via differential scanning calorimetry (DSC), the influence on lipid raft mimicking giant unilamellar vesicles (GUVs) via fluorescence microscopy, and membrane permeability via measuring calcein leakage from liposomes. Molecular calculations supplemented the study. The influence of naringenin oximes on two strains of multidrug resistant bacteria: Staphylococcus aureus KJ and Enterococcus faecalis 37VRE was also investigated. In DSC studies all compounds reduced the temperature and enthalpy of main phase transition and caused disappearing of the pretransition. NO was the least active. The reduction in the area of surface domains in GUVs was observed for NO. Compounds NO and 7BUNO resulted in very low secretion of calcein from liposomes (permeability < 3 %). The highest results were observed for 7MENO (88.4 %) and 7IPNO (78.5 %). When bacterial membrane permeability was investigated all compounds caused significant release of propidium iodide from S. aureus (31.6-87.0 % for concentration 128 μg/mL). In the case of E. faecalis, 7ETNO (75.7 %) and NO (28.8 %) were the most active. The rest of the tested compounds showed less activity (permeability < 13.9 %). The strong evidence was observed that antibacterial activity of the tested compounds may be associated with their interaction with bacterial membrane.
Topics: Flavanones; Oximes; Staphylococcus aureus; Cell Membrane; Enterococcus faecalis; Anti-Bacterial Agents; Unilamellar Liposomes; Calorimetry, Differential Scanning; Cell Membrane Permeability; Microbial Sensitivity Tests
PubMed: 38636394
DOI: 10.1016/j.biopha.2024.116581 -
Molecules (Basel, Switzerland) Apr 2024The Beckmann rearrangement of ketoximes to their corresponding amides, using a Brønsted acid-mediated fragmentation and migration sequence, has found wide-spread...
The Beckmann rearrangement of ketoximes to their corresponding amides, using a Brønsted acid-mediated fragmentation and migration sequence, has found wide-spread industrial application. We postulated that the development of a methodology to access ylideneamino sulfates using tributylsulfoammonium betaine (TBSAB) would afford isolable Beckmann-type intermediates and competent partners for subsequent rearrangement cascades. The ylideneamino sulfates generated, isolated as their tributylammonium salts, are sufficiently activated to undergo Beckmann rearrangement without additional reagent activation. The generation of sulfuric acid in situ from the ylideneamino sulfate giving rise to a routine Beckmann rearrangement and additional amide bond cleavage to the corresponding aniline was detrimental to reaction success. The screening of bases revealed inexpensive sodium bicarbonate to be an effective additive to prevent classic Brønsted acid-mediated fragmentation and achieve optimal conversions of up to 99%.
PubMed: 38611947
DOI: 10.3390/molecules29071667 -
Biomedicine & Pharmacotherapy =... May 2024Human adenovirus (HAdV) infection is a major cause of respiratory disease, yet no antiviral drugs have been approved for its treatment. Herein, we evaluated the...
Human adenovirus (HAdV) infection is a major cause of respiratory disease, yet no antiviral drugs have been approved for its treatment. Herein, we evaluated the antiviral and anti-inflammatory effects of cyclin-dependent protein kinase (CDK) inhibitor indirubin-3'-monoxime (IM) against HAdV infection in cells and a transgenic mouse model. After evaluating its cytotoxicity, cytopathic effect reduction, antiviral replication kinetics, and viral yield reduction assays were performed to assess the anti-HAdV activity of IM. Quantitative real-time polymerase chain reaction (qPCR), quantitative reverse transcription PCR (qRT-PCR), and western blotting were used to assess the effects of IM on HAdV DNA replication, transcription, and protein expression, respectively. IM significantly inhibited HAdV DNA replication as well as E1A and Hexon transcription, in addition to significantly suppressing the phosphorylation of the RNA polymerase II C-terminal domain (CTD). IM mitigated body weight loss, reduced viral burden, and lung injury, decreasing cytokine and chemokine secretion to a greater extent than cidofovir. Altogether, IM inhibits HAdV replication by downregulating CTD phosphorylation to suppress viral infection and corresponding innate immune reactions as a promising therapeutic agent.
Topics: Indoles; Animals; Oximes; Humans; Antiviral Agents; Adenoviruses, Human; Virus Replication; Anti-Inflammatory Agents; Mice; Mice, Transgenic; Adenovirus Infections, Human; A549 Cells; Cytokines; Phosphorylation
PubMed: 38603887
DOI: 10.1016/j.biopha.2024.116558 -
Cellular & Molecular Biology Letters Apr 2024Melanoma is the most lethal skin cancer characterized by its high metastatic potential. In the past decade, targeted and immunotherapy have brought revolutionary...
BACKGROUND
Melanoma is the most lethal skin cancer characterized by its high metastatic potential. In the past decade, targeted and immunotherapy have brought revolutionary survival benefits to patients with advanced and metastatic melanoma, but these treatment responses are also heterogeneous and/or do not achieve durable responses. Therefore, novel therapeutic strategies for improving outcomes remain an unmet clinical need. The aim of this study was to evaluate the therapeutic potential and underlying molecular mechanisms of RC48, a novel HER2-target antibody drug conjugate, either alone or in combination with dabrafenib, a V600-mutant BRAF inhibitor, for the treatment of advanced BRAF-mutant cutaneous melanoma.
METHODS
We evaluated the therapeutic efficacy of RC48, alone or in combination with dabrafenib, in BRAF-mutant cutaneous melanoma cell lines and cell-derived xenograft (CDX) models. We also conducted signaling pathways analysis and global mRNA sequencing to explore mechanisms underlying the synergistic effect of the combination therapy.
RESULTS
Our results revealed the expression of membrane-localized HER2 in melanoma cells. RC48 effectively targeted and inhibited the growth of HER2-positive human melanoma cell lines and corresponding CDX models. When used RC48 and dabrafenib synergically induced tumor regression together in human BRAF-mutant melanoma cell lines and CDX models. Mechanically, our results demonstrated that the combination therapy induced apoptosis and cell cycle arrest while suppressing cell motility in vitro. Furthermore, global RNA sequencing analysis demonstrated that the combination treatment led to the downregulation of several key signaling pathways, including the PI3K-AKT pathway, MAPK pathway, AMPK pathway, and FOXO pathway.
CONCLUSION
These findings establish a preclinical foundation for the combined use of an anti-HER2 drug conjugate and a BRAF inhibitor in the treatment of BRAF-mutant cutaneous melanoma.
Topics: Humans; Melanoma; Skin Neoplasms; Proto-Oncogene Proteins B-raf; Phosphatidylinositol 3-Kinases; Antineoplastic Agents; Immunoconjugates; Mutation; Imidazoles; Oximes
PubMed: 38594618
DOI: 10.1186/s11658-024-00555-z -
Protein Science : a Publication of the... May 2024Chemical warfare nerve agents and pesticides, known as organophosphorus compounds inactivate cholinesterases (ChEs) by phosphorylating the serine hydroxyl group located...
Disentangling the formation, mechanism, and evolvement of the covalent methanesulfonyl fluoride acetylcholinesterase adduct: Insights into an aged-like inactive complex susceptible to reactivation by a combination of nucleophiles.
Chemical warfare nerve agents and pesticides, known as organophosphorus compounds inactivate cholinesterases (ChEs) by phosphorylating the serine hydroxyl group located at the active site of ChEs. Over the course of time, phosphorylation is followed by loss of an organophosphate-leaving group and the bond with ChEs becomes irreversible, a process known as aging. Differently, structurally related irreversible catalytic poisons bearing sulfur instead of phosphorus convert ChEs in its aged form only by covalently binding to the key catalytic serine. Kinetic and crystallographic studies of the interaction between Torpedo californica acetylcholinesterase (TcAChE) and a small organosulfonate, methanesulfonyl fluoride (MSF), indeed revealed irreversibly methylsulfonylated serine 200, to be isosteric with the bound aged sarin/soman analogues. The potent bulky reversible inhibitor 7-bis-tacrine (BTA) adopts, in the active site of the crystal structure of the MSF-enzyme adduct, a location and an orientation that closely resemble the one being found in the crystal structure of the BTA-enzyme complex. Remarkably, the presence of BTA accelerates the rate of methanesulfonylation by a factor of two. This unexpected result can be explained on the basis of two facts: i) the steric hindrance exerted by BTA to MSF in accessing the active site and ii) the acceleration of the MSF-enzyme adduct formation as a consequence of the lowering of the rotational and translational degrees of freedom in the proximity of the catalytic serine. It is well known that pralidoxime (2-Pyridine Aldoxime Methyl chloride, 2-PAM) alone or in the presence of the substrate acetylcholine cannot reactivate the active site serine of the TcAChE-MSF adduct. We show that the simultaneous presence of 2-PAM and the additional neutral oxime, 2-[(hydroxyimino)methyl]-l-methylimidazol (2-HAM), triggers the reactivation process of TcAChE within the hour timescale. Overall, our results pave the way toward the likely use of a cocktail of distinctive oximes as a promising recipe for an effective and fast reactivation of aged cholinesterases.
Topics: Cholinesterase Inhibitors; Acetylcholinesterase; Oximes; Serine; Pralidoxime Compounds; Sulfones; Taurine
PubMed: 38591646
DOI: 10.1002/pro.4977 -
Journal of the American Chemical Society Apr 2024Lysine dimethylation (Kme) is a crucial post-translational modification (PTM) that regulates biological processes and is implicated in diseases. There is significant...
Lysine dimethylation (Kme) is a crucial post-translational modification (PTM) that regulates biological processes and is implicated in diseases. There is significant interest in globally identifying these methylation marks. Unfortunately, this remains challenging due to the lack of robust technologies for selectively labeling Kme. To address this, we present a chemical method named tertiary amine coupling by oxidation (TACO). This method selectively modifies Kme to aldehydes using Selectfluor and a base. The resulting aldehydes from Kme were then functionalized using reductive amination, thiolamine, and oxime chemistry. We successfully demonstrated the versatility of TACO in selectively labeling Kme peptides and proteins in complex cell lysate mixtures with varying payloads, including affinity tags and fluorophores. We further showed the application of TACO chemistry for the identification of Kme sites at a single-molecule level by fluorosequencing. We discovered novel 30 Kme sites, in addition to previously known 5 Kme sites, by proteomics analysis of TACO-modified nuclear extracts. Our work establishes a unique strategy for covalently modifying Kme, facilitating the global identification of low-abundance Kme-PTMs and their sites within complex cell lysate mixtures.
Topics: Lysine; Protein Processing, Post-Translational; Proteins; Amines; Aldehydes
PubMed: 38584362
DOI: 10.1021/jacs.4c00253 -
PloS One 2024Quantitative values derived from PET brain images are of high interest for neuroscientific applications. Insufficient DT correction (DTC) can lead to a systematic bias...
OBJECTIVE
Quantitative values derived from PET brain images are of high interest for neuroscientific applications. Insufficient DT correction (DTC) can lead to a systematic bias of the output parameters obtained by a detailed analysis of the time activity curves (TACs). The DTC method currently used for the Siemens 3T MR BrainPET insert is global, i.e., differences in DT losses between detector blocks are not considered, leading to inaccurate DTC and, consequently, to inaccurate measurements masked by a bias. However, following careful evaluation with phantom measurements, a new block-pairwise DTC method has demonstrated a higher degree of accuracy compared to the global DTC method.
APPROACH
Differences between the global and the block-pairwise DTC method were studied in this work by applying several radioactive tracers. We evaluated the impact on [11C]ABP688, O-(2-[18F]fluoroethyl)-L-tyrosine (FET), and [15O]H2O TACs.
RESULTS
For [11C]ABP688, a relevant bias of between -0.0034 and -0.0053 ml/ (cm3 • min) was found in all studied brain regions for the volume of distribution (VT) when using the current global DTC method. For [18F]FET-PET, differences of up to 10% were observed in the tumor-to-brain ratio (TBRmax), these differences depend on the radial distance of the maximum from the PET isocenter. For [15O]H2O, differences between +4% and -7% were observed in the GM region. Average biases of -4.58%, -3.2%, and -1.2% for the regional cerebral blood flow (CBF (K1)), the rate constant k2, and the volume of distribution VT were observed, respectively. Conversely, in the white matter region, average biases of -4.9%, -7.0%, and 3.8% were observed for CBF (K1), k2, and VT, respectively.
CONCLUSION
The bias introduced by the global DTC method leads to an overestimation in the studied quantitative parameters for all applications compared to the block-pairwise method.
SIGNIFICANCE
The observed differences between the two DTC methods are particularly relevant for research applications in neuroscientific studies as they affect the accuracy of quantitative Brain PET images.
Topics: Positron-Emission Tomography; Brain; Phantoms, Imaging; Head; Magnetic Resonance Imaging; Oximes; Pyridines
PubMed: 38578749
DOI: 10.1371/journal.pone.0296357 -
Chemico-biological Interactions May 2024The first organophosphorus nerve agent was discovered accidently during the development of pesticides, shortly after the first use of chemical weapons (chlorine,... (Review)
Review
The first organophosphorus nerve agent was discovered accidently during the development of pesticides, shortly after the first use of chemical weapons (chlorine, phosgene) on the battlefield during World War I. Despite the Chemical Weapons Convention banning these substances, they have still been employed in wars, terrorist attacks or political assassinations. Characterised by their high lethality, they target the nervous system by inhibiting the acetylcholinesterase (AChE) enzyme, preventing neurotransmission, which, if not treated rapidly, inevitably leads to serious injury or the death of the person intoxicated. The limited efficacy of current antidotes, known as AChE reactivators, pushes research towards new treatments. Numerous paths have been explored, from modifying the original pyridinium oximes to developing hybrid reactivators seeking a better affinity for the inhibited AChE. Another crucial approach resides in molecules more prone to cross the blood-brain barrier: uncharged compounds, bio-conjugated reactivators or innovative formulations. Our aim is to raise awareness on the threat and toxicity of organophosphorus nerve agents and to present the main synthetic efforts deployed since the first AChE reactivator, to tackle the task of efficiently treating victims of these chemical warfare agents.
Topics: Humans; Nerve Agents; Organophosphorus Compounds; Animals; Cholinesterase Reactivators; Medical Countermeasures; Acetylcholinesterase; Cholinesterase Inhibitors; Chemical Warfare Agents; Antidotes; Oximes
PubMed: 38574837
DOI: 10.1016/j.cbi.2024.110973 -
ACS Omega Mar 2024A metal-free, user-friendly photochemical transformation of nitroalkanes to oximes, nitrones, and hydroxylamines has been developed. The visible-light-induced reactions...
A metal-free, user-friendly photochemical transformation of nitroalkanes to oximes, nitrones, and hydroxylamines has been developed. The visible-light-induced reactions are catalyzed by the readily available photoredox organocatalyst 4CzIPN and use inexpensive amines as reductants. Broad in scope and tolerant of multiple functional groups and heterocycles, the transformation proceeds under mild conditions. Its synthetic potential was demonstrated in the formal total synthesis of amathaspiramide F. A basic insight into the reaction mechanism was gained with the help of an NMR study.
PubMed: 38559917
DOI: 10.1021/acsomega.3c10041 -
Archives of Toxicology Jun 2024Poisoning with the organophosphorus nerve agent VX can be life-threatening due to limitations of the standard therapy with atropine and oximes. To date, the underlying...
Poisoning with the organophosphorus nerve agent VX can be life-threatening due to limitations of the standard therapy with atropine and oximes. To date, the underlying pathomechanism of VX affecting the neuromuscular junction has not been fully elucidated structurally. Results of recent studies investigating the effects of VX were obtained from cells of animal origin or immortalized cell lines limiting their translation to humans. To overcome this limitation, motor neurons (MN) of this study were differentiated from in-house feeder- and integration-free-derived human-induced pluripotent stem cells (hiPSC) by application of standardized and antibiotic-free differentiation media with the aim to mimic human embryogenesis as closely as possible. For testing VX sensitivity, MN were initially exposed once to 400 µM, 600 µM, 800 µM, or 1000 µM VX and cultured for 5 days followed by analysis of changes in viability and neurite outgrowth as well as at the gene and protein level using µLC-ESI MS/HR MS, XTT, IncuCyte, qRT-PCR, and Western Blot. For the first time, VX was shown to trigger neuronal cell death and decline in neurite outgrowth in hiPSC-derived MN in a time- and concentration-dependent manner involving the activation of the intrinsic as well as the extrinsic pathway of apoptosis. Consistent with this, MN morphology and neurite network were altered time and concentration-dependently. Thus, MN represent a valuable tool for further investigation of the pathomechanism after VX exposure. These findings might set the course for the development of a promising human neuromuscular test model and patient-specific therapies in the future.
Topics: Humans; Induced Pluripotent Stem Cells; Motor Neurons; Organothiophosphorus Compounds; Nerve Agents; Cell Differentiation; Cell Survival; Neuronal Outgrowth; Chemical Warfare Agents; Dose-Response Relationship, Drug; Cells, Cultured
PubMed: 38555327
DOI: 10.1007/s00204-024-03708-3