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1.
Sensors (Basel) ; 24(11)2024 May 23.
Artículo en Inglés | MEDLINE | ID: mdl-38894113

RESUMEN

This study presents a novel method for the nighttime detection of waterborne individuals using an enhanced YOLOv5s algorithm tailored for infrared thermal imaging. To address the unique challenges of nighttime water rescue operations, we have constructed a specialized dataset comprising 5736 thermal images collected from diverse aquatic environments. This dataset was further expanded through synthetic image generation using CycleGAN and a newly developed color gamut transformation technique, which significantly improves the data variance and model training effectiveness. Furthermore, we integrated the Convolutional Block Attention Module (CBAM) at the end of the last encoder's feedforward network. This integration maximizes the utilization of channel and spatial information to capture more intricate details in the feature maps. To decrease the computational demands of the network while maintaining model accuracy, Ghost convolution was employed, thereby boosting the inference speed as much as possible. Additionally, we applied hyperparameter evolution to refine the training parameters. The improved algorithm achieved an average detection accuracy of 85.49% on our proprietary dataset, significantly outperforming its predecessor, with a prediction speed of 23.51 FPS. The experimental outcomes demonstrate the proposed solution's high recognition capabilities and robustness, fulfilling the demands of intelligent lifesaving missions.

2.
Int J Mol Sci ; 25(12)2024 Jun 14.
Artículo en Inglés | MEDLINE | ID: mdl-38928262

RESUMEN

Cancer is a significant global public health issue with increasing morbidity and mortality rates. To address this challenge, novel drug carriers such as nano-materials, liposomes, hydrogels, fibers, and microspheres have been extensively researched and utilized in oncology. Among them, polymer microspheres are gaining popularity due to their ease of preparation, excellent performance, biocompatibility, and drug-release capabilities. This paper categorizes commonly used materials for polymer microsphere preparation, summarizes various preparation methods (emulsification, phase separation, spray drying, electrospray, microfluidics, and membrane emulsification), and reviews the applications of polymer microspheres in cancer diagnosis, therapy, and postoperative care. The current status and future development directions of polymer microspheres in cancer treatment are analyzed, highlighting their importance and potential for improving patient outcomes.


Asunto(s)
Microesferas , Neoplasias , Polímeros , Humanos , Neoplasias/diagnóstico , Neoplasias/terapia , Polímeros/química , Portadores de Fármacos/química , Animales , Antineoplásicos/uso terapéutico , Sistemas de Liberación de Medicamentos/métodos
3.
Molecules ; 29(10)2024 May 13.
Artículo en Inglés | MEDLINE | ID: mdl-38792156

RESUMEN

Vitamin C (VC), also known as ascorbic acid, plays a crucial role as a water-soluble nutrient within the human body, contributing to a variety of metabolic processes. Research findings suggest that increased doses of VC demonstrate potential anti-tumor capabilities. This review delves into the mechanisms of VC absorption and its implications for cancer management. Building upon these foundational insights, we explore modern delivery systems for VC, evaluating its use in diverse cancer treatment methods. These include starvation therapy, chemodynamic therapy (CDT), photothermal/photodynamic therapy (PTT/PDT), electrothermal therapy, immunotherapy, cellular reprogramming, chemotherapy, radiotherapy, and various combination therapies.


Asunto(s)
Ácido Ascórbico , Neoplasias , Ácido Ascórbico/uso terapéutico , Ácido Ascórbico/farmacología , Humanos , Neoplasias/tratamiento farmacológico , Neoplasias/metabolismo , Fotoquimioterapia/métodos , Animales , Antineoplásicos/uso terapéutico , Antineoplásicos/farmacología , Terapia Combinada
4.
Cardiovasc Diabetol ; 22(1): 267, 2023 09 29.
Artículo en Inglés | MEDLINE | ID: mdl-37775767

RESUMEN

BACKGROUND: Evidence regarding the neutrophil-lymphocyte ratio (NLR) and mortality risk in diabetes patients is scarce. This study investigated the relationship of the NLR with all-cause and cardiovascular mortality risk in diabetes patients. METHODS: Diabetes patients (n = 3251) from seven National Health and Nutrition Examination Survey (NHANES) cycles (2003-2016) were included in this study. The cause of death and mortality status of the participants were obtained from National Death Index records. Restricted cubic spline (RCS) was used to visualize the association of the NLR with mortality risk. The maximally selected rank statistics method (MSRSM) was used to determine the optimal NLR cutoff value corresponding to the most significant association with survival outcomes. Weighted multivariable Cox regression models and subgroup analyses were adopted to assess the association of the NLR with all-cause and cardiovascular mortality. Time-dependent receiver operating characteristic curve (ROC) analysis was conducted to evaluate the accuracy of the NLR in predicting survival outcomes. RESULTS: During a median follow-up of 91 months (interquartile range, 55-131 months), 896 (27.5%) of the 3251 diabetes patients died, including 261 (8.0%) with cardiovascular deaths and 635 (19.5%) with noncardiovascular deaths. The RCS regression analysis showed a positive linear association between the NLR and all-cause and cardiovascular mortality (both p > 0.05 for nonlinearity) in diabetes patients. Participants were divided into higher (> 3.48) and lower (≤ 3.48) NLR groups according to the MSRSM. In the multivariable-adjusted model, compared with participants with a lower NLR, those with a higher NLR had a significantly higher risk of both all-cause (HR 2.03, 95% confidence interval (CI) 1.64-2.51, p < 0.0001) and cardiovascular mortality (HR 2.76, 95% CI 1.84-4.14, p < 0.0001). The association was consistent in subgroup analyses based on age, sex, smoking status, drinking status, and hypertension, with no significant interaction between the aforementioned characteristics and the NLR (p interaction > 0.05). The time-dependent ROC curve showed that the areas under the curve of the 1-, 3-, 5-, and 10-year survival rates were 0.72, 0.66, 0.64, and 0.64 for all-cause mortality and 0.69, 0.71, 0.69 and 0.65, respectively, for cardiovascular mortality. CONCLUSION: An elevated NLR is independently associated with increased all-cause and cardiovascular mortality in diabetes patients.


Asunto(s)
Diabetes Mellitus , Hipertensión , Humanos , Neutrófilos , Encuestas Nutricionales , Pronóstico , Linfocitos , Factores de Riesgo , Diabetes Mellitus/diagnóstico , Estudios Retrospectivos
5.
Phys Chem Chem Phys ; 25(18): 12783-12790, 2023 May 10.
Artículo en Inglés | MEDLINE | ID: mdl-37128988

RESUMEN

Ag(I) is able to mediate single-crystal-to-single-crystal transformation through [2+2] photocycloaddition to prepare high-conductivity materials. However, the intrinsic mechanism of Ag(I) mediation, the detailed photophysical and photochemical processes as well as the origin of the enhanced conductivity of nanocrystals are still unclear. In this work, the comprehensive kinetic scheme and regulation mechanism are established by the accurate QM/MM calculations at the CASPT2//CASSCF/AMBER level of theory with consideration of the crystal environment. We find that the argentophilic interaction and through space electronic interaction are the key factors that promote Ag(I)-mediated [2+2] PCA reactions and may account for the enhancement of conductivity. These mechanistic insights into the Ag(I)-regulated photo-dimerization in the crystal surrounding are beneficial for the design of the structurally and electrically favorable skeletons of a metal-organic coordination polymer.

6.
Int J Mol Sci ; 25(1)2023 Dec 28.
Artículo en Inglés | MEDLINE | ID: mdl-38203609

RESUMEN

Metabolic disorders present a significant public health challenge globally. The intricate relationship between the gut microbiome, particularly Bacteroides spp. (BAC), and obesity, including their specific metabolic functions, remains partly unresolved. This review consolidates current research on BAC's role in obesity and lipid metabolism, with three objectives: (1) To summarize the gut microbiota's impact on obesity; (2) To assess BAC's efficacy in obesity intervention; (3) To explore BAC's mechanisms in obesity and lipid metabolism management. This review critically examines the role of BAC in obesity, integrating findings from clinical and preclinical studies. We highlight the changes in BAC diversity and concentration following successful obesity treatment and discuss the notable differences in BAC characteristics among individuals with varying obesity levels. Furthermore, we review recent preclinical studies demonstrating the potential of BAC in ameliorating obesity and related inflammatory conditions, providing detailed insights into the methodologies of these in vivo experiments. Additionally, certain BAC-derived metabolites have been shown to be involved in the regulation of host lipid metabolism-related pathways. The enhanced TNF production by dendritic cells following BAC administration, in response to LPS, also positions BAC as a potential adjunctive therapy in obesity management.


Asunto(s)
Manejo de la Obesidad , Obesidad , Humanos , Inflamación , Atención Odontológica , Bacteroides
7.
Angew Chem Int Ed Engl ; 62(9): e202215891, 2023 Feb 20.
Artículo en Inglés | MEDLINE | ID: mdl-36596721

RESUMEN

Trifluoromethyl-bearing 5-membered rings are prevalent in bioactive molecules, but modular approaches to these compounds by functionalization of robust C(sp3 )-H bonds in a direct and selective manner are extremely challenging. Herein we report the rhodium-catalyzed α-CF3 -α-alkyl carbene insertion into C(sp3 )-H bonds of a broad range of substrates to access 7 types of CF3 -bearing saturated 5-membered carbo- and heterocycles. The reaction is particularly effective for benzylic C-H insertion exerting good site-, diastereo- and enantiocontrol, and applicable to the synthesis of chiral CF3 analogues of bioactive molecules. Ruthenium α-CF3 -α-alkyl carbene complexes underwent stoichiometric reactions to give C-H insertion products, lending evidence for the involvement of metal α-CF3 -α-alkyl carbene species in the catalytic cycle. DFT calculations revealed that the π⋅⋅⋅π attraction and intra-carbene C-H⋅⋅⋅F hydrogen bond elucidate the origin of selectivity of the benzylic C-H insertion reactions.

8.
Metab Eng ; 72: 107-115, 2022 07.
Artículo en Inglés | MEDLINE | ID: mdl-35296429

RESUMEN

(+)-Nootkatone is a valuable, functional sesquiterpene that is widely used in food, cosmetics, pharmaceutical, agriculture, and other fields. However, only traces of it accumulate in plants, which is insufficient to meet the market demand. Therefore, commercial (+)-nootkatone is currently synthesized from (+)-valencene. Here, we engineered Saccharomyces cerevisiae to achieve high production of (+)-valencene. Employing gene screening, protein engineering and biosynthetic pathway optimization, we achieved 12.4 g/L (+)-valencene production with the mutant strain. This titer was further increased to 16.6 g/L, the highest titer reported to date, by coupling critical factors for cell growth and biochemical pathway induction. Subsequently, (+)-nootkatone was chemically synthesized from bio-fermented (+)-valencene with a yield of 80%. This study achieved efficient microbial synthesis of (+)-valencene, which may be utilized in industrial production and stabilize the supply of (+)-nootkatone.


Asunto(s)
Saccharomyces cerevisiae , Sesquiterpenos , Ingeniería Metabólica , Sesquiterpenos Policíclicos , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Sesquiterpenos/metabolismo
9.
Haematologica ; 107(7): 1655-1668, 2022 07 01.
Artículo en Inglés | MEDLINE | ID: mdl-34407604

RESUMEN

Platelets play an essential role in thrombosis and hemostasis. Abnormal hemostasis can cause spontaneous or severe post-traumatic bleeding. Bernard-Soulier syndrome (BSS) is a rare inherited bleeding disorder caused by a complete quantitative deficiency in the GPIb-IX-V complex. Multiple mutations in GP9 lead to the clinical manifestations of BSS. Understanding the roles and underlying mechanisms of GP9 in thrombopoiesis and establishing a proper animal model of BSS would be valuable to understand the disease pathogenesis and to improve its medical management. Here, by using CRISPR-Cas9 technology, we created a zebrafish gp9SMU15 mutant to model human BSS. Disruption of zebrafish gp9 led to thrombocytopenia and a pronounced bleeding tendency, as well as an abnormal expansion of progenitor cells. The gp9SMU15 zebrafish can be used as a BSS animal model as the roles of GP9 in thrombocytopoiesis are highly conserved from zebrafish to mammals. Utilizing the BSS model, we verified the clinical GP9 mutations by in vivo functional assay and tested clinical drugs for their ability to increase platelets. Thus, the inherited BSS zebrafish model could be of benefit for in vivo verification of patient-derived GP9 variants of uncertain significance and for the development of potential therapeutic strategies for BSS.


Asunto(s)
Síndrome de Bernard-Soulier , Animales , Síndrome de Bernard-Soulier/genética , Plaquetas/patología , Mamíferos , Mutación , Complejo GPIb-IX de Glicoproteína Plaquetaria/genética , Pez Cebra/genética
10.
Angew Chem Int Ed Engl ; 61(23): e202201739, 2022 06 07.
Artículo en Inglés | MEDLINE | ID: mdl-35302709

RESUMEN

Due to the linear coordination nature of gold(I) catalysts, achieving high enantiocontrol in asymmetric gold catalysis is a great challenge. To improve the enantiocontrol of gold catalysis, an ion-pairing strategy was therefore proposed. A series of bifunctional P,N ligands based on chiral spirocyclic and biaryl scaffolds were synthesized and applied in the gold(I)-catalyzed desymmetric lactonization of alkynylmalonic acids. A wide range of chiral lactones containing an α-position quaternary stereocenter were synthesized with high yields, excellent regioselectivity and enantioselectivity under mild reaction conditions. The synthetic utilities of the current reaction were demonstrated by gram-scale synthesis and transformations of chiral lactones. The origin of enantioselectivity and the role of the alcohol additive were elucidated via control experiments and DFT calculations.


Asunto(s)
Oro , Lactonas , Catálisis , Ligandos , Estereoisomerismo
11.
Angew Chem Int Ed Engl ; 61(21): e202200748, 2022 May 16.
Artículo en Inglés | MEDLINE | ID: mdl-35183066

RESUMEN

Metal-free and metal-containing molecular trefoil knots are fascinating ensembles that are usually covalently assembled, the latter requiring the rational design of di- or multidentate/multipodal ligands as connectors. In this work, we describe the self-assembly of pentadecanuclear AuI trefoil knots [Au15 (C≡CR)15 ] from monoalkynes HC≡CR (R=9,9-X2 -fluorenyl with X=nBu, n-hexyl) and [AuI (THT)Cl]. Hetero-bimetallic counterparts [Au9 M6 (C≡CR)15 ] (M=Cu/Ag) were self-assembled by reactions of [Au15 (C≡CR)15 ] with [Cu(MeCN)4 ]+ /AgNO3 and HC≡CR. The type of pentadecanuclear trefoil knots described herein is characterized by X-ray crystallography, 2D NMR and HR-ESI-MS. [Au9 Cu6 (C≡CR)15 ] is relatively stable in hexane; its excited state properties were investigated. DFT calculations revealed that non-covalent metal-metal and metal-ligand interactions, together with longer alkyl chain-strengthened inter-ligand dispersion interactions, govern the stability of the trefoil knot structures.

12.
Nanotechnology ; 33(7)2021 Nov 24.
Artículo en Inglés | MEDLINE | ID: mdl-34171849

RESUMEN

Transition metal carbides and nitrides (MXenes), as a large family of emerging two-dimensional materials, have demonstrated extraordinary performance in many fields such as electronics, optics and energy storage. However, their susceptibility to oxidation during preparation and storage in ambient air environment is undesirable for long-term and stable applications. Here, we have demonstrated that the spontaneous oxidation of Ti3C2Txcan be harnessed ingeniously to prepare Ti3C2Tx/TiO2in situformed heterojunctions. Furthermore, a self-powered ultraviolet photodetector was constructed based on the photoelectrochemical performance of Ti3C2Tx/TiO2heterojunctions. Since the highly conductive Ti3C2Txcan promote the separation and transfer of photogenerated carriers in TiO2, the prepared photodetector exhibits high responsivity (2.06 mA W-1), short rise and decay times (45 and 69 ms) and long-term stability. This work demonstrates the controllable synthesis of Ti3C2Tx/TiO2heterojunctions and provides a new promising potential of MXenes for photodetection applications.

13.
BMC Infect Dis ; 21(1): 662, 2021 Jul 08.
Artículo en Inglés | MEDLINE | ID: mdl-34238251

RESUMEN

BACKGROUND: Granulicatella adiacens is facultative anaerobic Gram-positive bacteria, which mainly involve bacterial endocarditis and bacteremia, but there are few reports of local suppurative infection. A case of lung abscess with a coinfection of Granulicatella adiacens and other bacteria in a lung cancer patient will be reported in this paper. To our knowledge, this is the first case report describing lung abscess due to G.adiacens. CASE PRESENTATION: A 52-year-old Chinese woman was admitted to the hospital, She complained of coughing and expectoration for 1 month, shortness of breath for half a month, and dyspnea for 1 day. After a series of examinations, she was diagnosed with lung abscess, pleural effusion, and bronchogenic carcinoma. Draining pus culture demonstrated Granulicatella adiacens. After more than 5 weeks of antibiotic therapies in total, she gradually recovered to fight against lung cancer. CONCLUSION: This is the first reported lung abscess caused by G.adiacens. In immunosuppressed hosts, G.adiacens is a virulent pathogen associated with a spectrum of intrathoracic suppurative. Earlier diagnosis and proper drainage surgery with effective antibiotics treatment are very important, and antimicrobial treatment should be more than 5 weeks. When complex pulmonary infection interferes with the CT diagnosis, clinical suspicion of lung cancer should be increased if G.adiacens or Eikenella corrodens is detected from a pulmonary infection.


Asunto(s)
Carnobacteriaceae/patogenicidad , Coinfección/etiología , Absceso Pulmonar/etiología , Neoplasias Pulmonares/complicaciones , Antibacterianos/uso terapéutico , Carnobacteriaceae/aislamiento & purificación , Coinfección/diagnóstico , Coinfección/tratamiento farmacológico , Eikenella corrodens/aislamiento & purificación , Eikenella corrodens/patogenicidad , Femenino , Humanos , Absceso Pulmonar/diagnóstico , Absceso Pulmonar/tratamiento farmacológico , Neoplasias Pulmonares/diagnóstico , Neoplasias Pulmonares/tratamiento farmacológico , Persona de Mediana Edad , Resultado del Tratamiento
14.
J Clin Lab Anal ; 35(12): e24003, 2021 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-34676904

RESUMEN

BACKGROUND: Circular RNA (circRNA) affects the occurrence and development of human cancers, but the specific mechanism of hepatocellular carcinoma (HCC) has not yet been fully understood. METHODS: CircRNAs were determined by human circRNA array analysis and quantitative reverse transcription polymerase chain reaction (qRT-PCR). Cell viability, migration, invasion, and other indicators were used for cell function analysis. Knockdown and overexpression techniques were used to explore the mechanism of circCORO1C in the occurrence and development of HCC by RNA sequencing, qRT-PCR, western blot, and other methods. RESULTS: Among the thousands of circRNAs, 1238 circRNAs were significantly changed. As for the top 10 upregulated circRNAs, the expression of circRNAs, hsa_circ_0036412, hsa_circ_0036411, hsa_circ_0028071, hsa_circ_0036409, hsa_circ_0000437, hsa_circ_0021427, hsa_circ_0097182, hsa_circ_0028067, hsa_circ_0006852, and hsa_circ_0003620 were significantly increased. In regard to the top 10 downregulated circRNAs, the expression of hsa_circ_0123629, hsa_circ_0096121, hsa_circ_0038932, hsa-circRNA3310-44, hsa_circ_0045746, hsa_circ_0016836, hsa-circRNA10899-9, hsa_circ_0050116, hsa_circ_0035543, and hsa_circ_0092118 decreased significantly. About these circRNAs, the downregulation of hsa_circ_0006852 (circCORO1C) can inhibit the tumorigenesis of HCC cells in vivo and in vitro, and the overexpression of circCORO1C can enhance the proliferation and metastasis ability of HCC cells. Mechanistically, circCORO1C activated the NF-κB signaling pathway, increased P65 phosphorylation and upregulation of c-Myc and COX-2, leading to increased PD-L1 expression. CONCLUSION: CircCORO1C upregulates c-Myc and COX-2 through NF-κB signaling pathway, leading to the upregulation of PD-L1, which jointly promotes the development of HCC, suggesting that circCORO1C is a promising biomarker and therapeutic target for HCC.


Asunto(s)
Antígeno B7-H1/genética , Carcinoma Hepatocelular/patología , Neoplasias Hepáticas/patología , FN-kappa B/genética , ARN Circular/genética , Animales , Antígeno B7-H1/metabolismo , Carcinoma Hepatocelular/genética , Proliferación Celular/genética , Regulación Neoplásica de la Expresión Génica , Humanos , Neoplasias Hepáticas/genética , Masculino , Ratones Endogámicos BALB C , FN-kappa B/metabolismo , Análisis de Secuencia de ARN , Ensayos Antitumor por Modelo de Xenoinjerto
15.
J Clin Lab Anal ; 35(12): e24054, 2021 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-34708890

RESUMEN

BACKGROUND: mRNAs have been shown to be critical biomarkers or therapeutic targets for human diseases. However, only a few of them have been studied as blood-based biomarkers for gastric carcinoma (GC) detection. METHODS: mRNA expression profiles for GC were screened using plasma samples from 10 GC patients with different TNM stages and 5 healthy individuals as controls. One candidate tumor-related mRNA named HTRA2 was then evaluated in GC samples with quantitative real-time polymerase chain reaction (qRT-PCR). TCGAportal, UALCAN, and TISCH database were used to explore the function of HTRA2 in GC. Finally, the effect generated by HTRA2 expression on cell proliferating, invading, and migrating processes was assessed in vitro with knockdown and over-expression strategies. RESULTS: HTRA2 displayed noticeable increase inside GC plasma compared with control cases. Higher expression of HTRA2 displayed a correlation to higher clinicopathological stage and worse prognosis. HTRA2 knocking down down-regulated GC cells' proliferating, invading, and migrating states, while HTRA2 over-expression exerted the inconsistent influence. HTRA2 protein, which may interact with PINK1, PARL, and CYCS, was mainly located in the mitochondria of cells and primarily involved cellular response and metabolic signaling pathway. Immune factors may interact with HTRA2 in GC, and HTRA2 was found noticeably linked with immunosuppressor such as CD274, IDO1, and TIGIT. CONCLUSION: One plasma HTRA2 can be an emerging diagnosis-related biomarker to achieve GC detecting process, but the particular regulatory effect still needs to be further explored.


Asunto(s)
Ácidos Nucleicos Libres de Células/sangre , Serina Peptidasa A2 que Requiere Temperaturas Altas/genética , Neoplasias Gástricas/genética , Biomarcadores de Tumor/genética , Estudios de Casos y Controles , Regulación Neoplásica de la Expresión Génica , Estudio de Asociación del Genoma Completo , Humanos , Análisis de Secuencia por Matrices de Oligonucleótidos/métodos , ARN Mensajero/sangre , Transducción de Señal/genética , Neoplasias Gástricas/inmunología , Neoplasias Gástricas/patología
16.
Angew Chem Int Ed Engl ; 60(9): 4796-4803, 2021 02 23.
Artículo en Inglés | MEDLINE | ID: mdl-33205509

RESUMEN

High-valent iron-nitrido species are nitrogen analogues of iron-oxo species which are versatile reagents for C-H oxidation. Nonetheless, C-H activation by iron-nitrido species has been scarcely explored, as this is often hampered by their instability and short lifetime in solutions. Herein, the hydrogen atom transfer (HAT) reactivity of an Fe porphyrin nitrido species (2 c) toward C-H substrates was studied in solutions at room temperature, which was achieved by nanosecond laser flash photolysis (LFP) of its FeIII -azido precursor (1 c) supported by a bulky bis-pocket porphyrin ligand. C-H bonds with bond dissociation enthalpies (BDEs) of up to ≈84 kcal mol-1 could be activated, and the second-order rate constants (k2 ) are on the order of 102 -104  s-1 m-1 . The Fe-amido product formed after HAT could further release ammonia upon protonation.

17.
Angew Chem Int Ed Engl ; 60(34): 18619-18629, 2021 08 16.
Artículo en Inglés | MEDLINE | ID: mdl-33847064

RESUMEN

Metal-catalyzed C-N bond formation reactions via acylnitrene transfer have recently attracted much attention, but direct detection of the proposed acylnitrenoid/acylimido M(NCOR) (R=aryl or alkyl) species in these reactions poses a formidable challenge. Herein, we report on Ru(NCOR) intermediates in C-N bond formation catalyzed by [RuIV (Por)Cl2 ]/N3 COR, a catalytic method applicable to aziridine/oxazoline formation from alkenes, amination of substituted indoles, α-amino ketone formation from silyl enol ethers, amination of C(sp3 )-H bonds, and functionalization of natural products and carbohydrate derivatives (up to 99 % yield). Experimental studies, including HR-ESI-MS and EPR measurements, coupled with DFT calculations, lend evidence for the formulation of the Ru(NCOR) acylnitrenoids as a RuV -imido species.

18.
J Comput Chem ; 41(4): 305-316, 2020 02 05.
Artículo en Inglés | MEDLINE | ID: mdl-31713255

RESUMEN

Density functional theory has been used to study the biologically important coenzyme NADPH and its oxidized form NADP+ . It was found that free NADPH prefers a compact structure in gas phase and exists in more extended geometries in aqueous solution. Ultraviolet-visible absorption spectra in aqueous solution were calculated for NADPH with an explicit treatment of 100 surrounding water molecules in combination with the COSMO solvation model for bulk hydration effects. The obtained spectra using the B3LYP hybrid density functional agree quite well with experimental data. The changes of Gibbs free energies ΔG in reactions of NADPH with O2 observed experimentally in cardiovascular and in chemical systems, that is, NADPH + 2 3 O2 → NADP+ + 2 O2- + H+ and NADPH + 1 O2 + H+ → NADP+ + H2 O2 , respectively, were calculated. The NADPH oxidation reaction in the cardiovascular system cannot proceed without activation since the obtained ΔG is positive. The reaction of NADPH in the chemical system with singlet oxygen was found to proceed in two ways, each consisting of two steps, that is, NADPH firstly reacts with 1 O2 barrierlessly to form NADP+ and HO2- , from which H2 O2 is formed in a spontaneous reaction with H+ , or 1 O2 and H+ initially form 1 HO2+ , which further reacts with NADPH to yield NADP+ and H2 O2 . © 2019 The Authors. Journal of Computational Chemistry published by Wiley Periodicals, Inc.


Asunto(s)
Teoría Funcional de la Densidad , NADP/metabolismo , Estructura Molecular , NADP/química , Oxidación-Reducción , Espectrofotometría Ultravioleta , Estereoisomerismo
19.
Angew Chem Int Ed Engl ; 59(37): 16202-16208, 2020 Sep 07.
Artículo en Inglés | MEDLINE | ID: mdl-32558142

RESUMEN

A transition-metal-free C(sp2 )-C(sp2 ) bond formation reaction by the cross-coupling of diazo quinones with catechol boronic esters was developed. With this protocol, a variety of biaryls and alkenyl phenols were obtained in good to high yields under mild conditions. The reaction tolerates various functionalities and is applicable to the derivatization of pharmaceuticals and natural products. The synthetic utility of the method was demonstrated by the short synthesis of multi-substituted triphenylenes and three bioactive natural products, honokiol, moracin M, and stemofuran A. Mechanistic studies and density functional theory (DFT) calculations revealed that the reaction involves attack of the boronic ester by a singlet quinone carbene followed by a 1,2-rearrangement through a stepwise mechanism.

20.
Angew Chem Int Ed Engl ; 59(38): 16561-16571, 2020 09 14.
Artículo en Inglés | MEDLINE | ID: mdl-32500643

RESUMEN

Reliable methods for enantioselective cis-dihydroxylation of trisubstituted alkenes are scarce. The iron(II) complex cis-α-[FeII (2-Me2 -BQPN)(OTf)2 ], which bears a tetradentate N4 ligand (Me2 -BQPN=(R,R)-N,N'-dimethyl-N,N'-bis(2-methylquinolin-8-yl)-1,2-diphenylethane-1,2-diamine), was prepared and characterized. With this complex as the catalyst, a broad range of trisubstituted electron-deficient alkenes were efficiently oxidized to chiral cis-diols in yields of up to 98 % and up to 99.9 % ee when using hydrogen peroxide (H2 O2 ) as oxidant under mild conditions. Experimental studies (including 18 O-labeling, ESI-MS, NMR, EPR, and UV/Vis analyses) and DFT calculations were performed to gain mechanistic insight, which suggested possible involvement of a chiral cis-FeV (O)2 reaction intermediate as an active oxidant. This cis-[FeII (chiral N4 ligand)]2+ /H2 O2 method could be a viable green alternative/complement to the existing OsO4 -based methods for asymmetric alkene dihydroxylation reactions.

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