Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 29
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Org Lett ; 26(20): 4297-4301, 2024 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-38739778

RESUMO

A three-component reaction for the synthesis of dihydropyrrolo[3,4-e][1,3]thiazines has been developed. Elemental sulfur, maleimides, and 1,3,5-triazinanes are assembled together through sulfuration/nucleophilic attack in N-methylpyrrolidin-2-one (NMP) under mild conditions. A small amount of NaHCO3 is important for the activation of the reaction. In this method, sulfur plays a dual role in thiazine ring formation, while triazinanes are utilized as three-atom synthons in the annulation reaction.

2.
Am J Transl Res ; 16(1): 163-178, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38322569

RESUMO

OBJECTIVE: To investigate the relationships of multiple lipid metabolism indicators and bone turnover markers (BTMs) with bone mineral density (BMD) and osteoporosis, in order to identify high-risk populations. METHODS: A total of 380 patients were recruited and their general information was collected. Linear and logistic regression models were used to analyze the correlation of these indicators with BMD and osteoporosis. RESULTS: Lipid metabolism indices and BTMs exhibited varying degrees of positive or negative correlation with BMD. Elevated levels of triglycerides (r = -0.204, P = 0.004), total cholesterol (TC) (r = -0.244, P < 0.001), low-density lipoprotein cholesterol (LDL-C) (r = -0.256, P < 0.001), apoprotein B (r = -0.292, P < 0.001) and lipoprotein-associated phospholipase A2 (Lp-PLA2) (r = -0.221, P = 0.002) in women were associated with a reduction in BMD. This relationship persisted even after adjusting for confounding factors and in the subgroup analysis of elderly women. In males, TC (r = 0.159, P = 0.033), LDL-C (r = 0.187, P = 0.012), apoprotein B (r = 0.157, P = 0.035), and Lp-PLA2 (r = 0.168, P = 0.024) exhibited a positive correlation with BMD, while free fatty acid (FFA) (r = -0.153, P = 0.041) was negatively correlated with BMD. However, after adjusting for confounding factors, only FFA remained negatively correlated with BMD, which was not observed in the age subgroup analysis. Furthermore, elevated levels of TC and LDL-C in elderly women were positively associated with the risk of osteoporosis or low bone mass. CONCLUSION: Elevated levels of TC and LDL-C not only indicate a decrease in BMD in females but also positively correlate with the occurrence of osteoporosis and low bone mass in elderly females.

3.
RSC Adv ; 14(1): 364-372, 2024 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-38173623

RESUMO

Oxidative transformation of benzylic C-H bonds into functional carbonyl groups under mild conditions represents an efficient method for the synthesis of aromatic carboxylic acids and ketones. Here we report a high-efficiency catalyst system constructed from an Anderson-type polyoxometalate-based metal-Organic framework (POMOF-1) and N-hydroxyphthalimide (NHPI) for selective oxidation of methylarenes and alkylarenes under 1 atm O2 atmosphere. POMOF-1 exerted a synergistic effect originating from the well-aligned Anderson {CrMo6} clusters and Cu centers within the framework, and this entailed good cooperation with NHPI to catalyze the selective oxidation. Accordingly, the reactions exhibit good tolerance and chemical selectivity for a wide range of substrates bearing diverse substituent groups, and the corresponding carboxylic acids and ketones were harvested in good yields under mild conditions. Mechanism study reveals that POMOF-1 worked synergistically with NPHI to activate the benzylic C-H bonds of substrates, which are sequentially oxidized by oxygen and HOO˙ to give rise to the products. This work may pave a way to design high-efficiency catalysts by integration of polyoxometalate-based materials with NPHI for challenging C-H activation.

4.
Int J Nanomedicine ; 18: 7583-7603, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38106447

RESUMO

Introduction: Osteoporosis is a common bone disease in which the bone loses density and strength and is prone to fracture. Bone marrow mesenchymal stem cells (BMSCs) are important in bone-related diseases. Exosomes, as mediators of cell communication, have potential in cell processes. Previous studies have focused on muscle factors' regulation of bone remodeling, but research on exosomes is lacking. Methods:  In order to confirm the therapeutic effect of mechanically stimulated myocytes (C2C12) derived exosomes (Exosome-MS) on the Glucocorticoid-induced osteoporosis(GIOP) compared with unmechanically stimulated myocytes (C2C12) derived exosomes (Exosomes), we established a dexamethasone-induced osteoporosis model in vivo and in vitro. Cell viability and proliferation were assessed using CCK8 and EDU assays. Osteogenic potential was evaluated through Western blotting, real-time PCR, alkaline phosphatase activity assay, and alizarin red staining. Differential expression of miRNAs was determined by high-throughput sequencing. The regulatory mechanism of miR-92a-3p on cell proliferation and osteogenic differentiation via the PTEN/AKT pathway was investigated using real-time PCR, luciferase reporter gene assay, Western blotting, and immunofluorescence. The therapeutic effects of exosomes were evaluated in vivo using microCT, HE staining, Masson staining, and immunohistochemistry. Results:  In this study, we found that exosomes derived from mechanical stress had a positive impact on the proliferation and differentiation of bone marrow mesenchymal stem cells (BMSCs). Importantly, we demonstrated that miR-92a-3p mimics could reverse dexamethasone-induced osteoporosis in vitro and in vivo, indicating that mechanical stress-induced mouse myoblast-derived exosomes could promote osteogenesis and prevent the occurrence and progression of osteoporosis in mice through miR-92a-3p/PTEN/AKT signaling pathway. Conclusion:  Exosomes derived from mechanical stress-induced myoblasts can promote the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells through miR-92a-3p/PTEN/AKT signaling pathway, and can have a therapeutic effect on glucocorticoid-induced osteoporosis in mice in vivo.


Assuntos
Exossomos , MicroRNAs , Osteoporose , Camundongos , Animais , Proteínas Proto-Oncogênicas c-akt/metabolismo , Glucocorticoides , Osteogênese , Exossomos/metabolismo , Estresse Mecânico , Transdução de Sinais , MicroRNAs/genética , MicroRNAs/metabolismo , Diferenciação Celular , Osteoporose/induzido quimicamente , Osteoporose/tratamento farmacológico , Osteoporose/genética , Dexametasona/farmacologia
5.
J Am Chem Soc ; 145(47): 25545-25552, 2023 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-37962982

RESUMO

Herein, we report a manganese-catalyzed three-component coupling of ß-H containing alcohols, methanol, and phosphines for the synthesis of γ-hydroxy phosphines via a borrowing hydrogen strategy. In this development, methanol serves as a sustainable C1 source. A variety of aromatic and aliphatic substituted alcohols and phosphines could undergo the dehydrogenative cross-coupling process efficiently and deliver the corresponding ß-phosphinomethylated alcohol products in moderate to good yields. Mechanistic studies suggest that this transformation proceeds in a sequential manner including catalytic dehydrogenation, aldol condensation, Michael addition, and catalytic hydrogenation.

6.
Dalton Trans ; 52(45): 17019-17029, 2023 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-37933953

RESUMO

Incorporating catalytic units into a crystalline porous matrix represents a facile way to build high-efficiency heterogeneous catalysts, and by rational design of the porous skeleton with appropriate building blocks the catalytic performance can be significantly enhanced for a series of organic transformations owing to the synergistic effect from the multicomponent and confined porous microenvironment around catalytically active sites. Herein, we demonstrate that the design and synthesis of a porous polyoxometalate-based metal-organic framework YL2(H2O)2[CrMo6O18(PET)2]·4H2O (POMOF-1) constructed from Anderson-type [CrMo6O18(PET)2] (PET = pentaerythritol), which can be employed as a multifunctional platform for synthesis of N-containing compounds via selective oxidative coupling with amines. POMOF-1 features microporous 1D channels defined by Y3+ and L, with [CrMo6O18(PET)2] arranged orderly between adjacent Lvia electrostatic interactions. Upon using POMOF-1 as a catalyst and H2O2 as an oxidant, a variety of amines could be effectively converted to value-added amides, imines and azobenzenes via the oxidative cross-coupling with alcohols or homo-coupling. In particular, POMOF-1 showed dramatically improved activity for the N-formylation reaction owing to the synergistic and confinement effect, with the yield of amides up to 95% and 4 times higher than that of homogeneous [CrMo6O18(PET)2]. Meanwhile, the oxidative homo-coupling of arylmethylamines and arylamines can be facilely tuned by adjustment of the amount of oxidant, solvent and additive, affording imines and azobenzenes in high selectivity and yield, respectively. POMOF-1 is robust and can be reused for 5 cycles with little loss of catalytic activity and structural integrity. The work demonstrates that the combination of catalytically active POMs with crystalline porous MOFs holds great potential to build robust and recyclable heterogeneous systems with enhanced activity and selectivity for multifunctional catalysis.

7.
Angew Chem Int Ed Engl ; 62(32): e202305925, 2023 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-37264744

RESUMO

It is challenging to achieve stable and efficient radical emissions under ambient conditions. Herein, we present a rational design strategy to protect photoinduced carbonyl free radical emission through electrostatic interaction and spin delocalization effects. The host-guest system is constructed from tricarbonyl-substituted benzene molecules and a series of imidazolium ionic liquids as the guest and host, respectively, whereby the carbonyl anion radical emission can be in situ generated under the light irradiation and further stabilized by electrostatic interaction. More importantly, the anion species and the alkyl chain length of imidazolium ionic liquids show a noticeable effect on luminescence efficiency, with the highest radical emission efficiency is as high as 53.3 % after optimizing the imidazole ionic liquid's structure, which is about four times higher than the polymer-protected radical system. Theoretical calculations confirm the synergistic effect of strong electrostatic interactions and that the spin delocalization effect significantly stabilizes the radical emission. Moreover, such a radical emission system also could be integrated with a fluorescent dye to induce multi-color or even white light emission with reversible temperature-responsive characteristics. The radical emission system can also be used to detect different amine compounds on the basis of the emission changes and photoactivation time.

8.
J Org Chem ; 88(11): 7489-7497, 2023 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-37114576

RESUMO

A designed method for the preparation of 3-aminomethylated maleimides via Morita-Baylis-Hillman (MBH) reaction was developed. This phosphine-catalyzed coupling adopted maleimides and 1,3,5-triazinanes as the substrate, giving a series of 3-aminomethylated maleimide derivatives with a double bond retained on the maleimide ring in 41-90% yield. Acylation, isomerization, and Michael addition of the obtained products demonstrated the synthetic application of the present protocol. The results of control experiments indicated that phosphorus ylide formation and elimination take place during the reaction pathway.

9.
Angew Chem Int Ed Engl ; 62(17): e202215882, 2023 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-36847452

RESUMO

Herein, we report a manganese-catalyzed three-component coupling of secondary alcohols, primary alcohols and methanol for the synthesis of ß,ß-methylated/alkylated secondary alcohols. Using our method, a series of 1-arylethanol, benzyl alcohol derivatives, and methanol undergo sequential coupling efficiently to construct assembled alcohols with high chemoselectivity in moderate to good yields. Mechanistic studies suggest that the reaction proceeds via methylation of a benzylated secondary alcohol intermediate to generate the final product.

10.
J Org Chem ; 87(22): 15661-15669, 2022 11 18.
Artigo em Inglês | MEDLINE | ID: mdl-36317696

RESUMO

By employing Cu(CH3CN)4PF6 as the catalyst and tert-butyl hydroperoxide as the oxidant, we realized a three-component radical selenosulfonation of substituted maleimides, sulfonyl hydrazides, and diphenyl diselenides, providing a series of 3,4-selenosulfonylated succinimides in moderate to good yields. This reaction features broad substrate scopes, high functional-group tolerability, and feasibility of gram-scale synthesis, enabling one-step construction of C-SO2 and C-Se bonds under mild reaction conditions. Preliminary mechanistic studies support the free-radical-induced pathway.


Assuntos
Cobre , Iodo , Cobre/química , Maleimidas , Estrutura Molecular , Hidrazinas/química , Catálise
11.
J Org Chem ; 87(5): 3762-3769, 2022 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-35168325

RESUMO

A convenient and practical hydrosulfonylation and disulfonylation of substituted maleimides was realized using sulfonyl hydrazides as the sulfur reagent and tert-butyl hydroperoxide as the oxidant. The advantages of the reactions include mild and transition-metal-free reaction conditions, good functional group tolerance, and readily available starting materials. The radical species-induced pathway is also demonstrated by mechanistic studies.

12.
J Org Chem ; 87(5): 2711-2720, 2022 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-35018783

RESUMO

An efficient annulation method for the synthesis of polysubstituted dihydrofurans from 1,3-dicarbonyl compounds and maleimides is described. The reactions can afford furo[2,3-c]pyrrole derivatives with satisfactory yields. The developed strategy realizes the direct oxidative double C(sp3)-H functionalization in the presence of copper(I) salts and 2-(tert-butylperoxy)-2-methylpropane. Meanwhile, this protocol features a mild reaction condition and simple catalytic system. A reaction mechanism involving a single electron oxidation is also proposed.

13.
Biomacromolecules ; 22(12): 4988-4999, 2021 12 13.
Artigo em Inglês | MEDLINE | ID: mdl-34724615

RESUMO

Autograft is currently the gold standard in the clinical treatment of peripheral nerve injury (PNI), which, however, is limited by the availability of a donor nerve and secondary injuries. Nerve guidance conduits (NGC) provide a suitable microenvironment to promote the regeneration of injured nerves, which could be the substitutes for autografts. In this study, nerve growth factor (NGF) encapsulated chitosan nanoparticles (CSNPs) were first constructed in situ in an oxidized bacterial cellulose (OBC) conduit using the ion gel method after the introduction of a CS/NGF solution under pressure to enable a sustainable release of NGF. A novel NGF@CSNPs/OBC nanocomposite with antibacterial activity, biodegradability, and porous microstructure was successfully developed. In vitro experiments showed that the nanocomposite promoted the adhesion and proliferation of Schwann cells. When the nanocomposite was applied as NGC to repair the sciatic nerve defect of rats, a successful repair of the 10 mm nerve defect was observed after 4 weeks. At week 9, the diameter, morphology, histology, and functional recovery of the regenerated nerve was comparable to the autografts, indicating that the NGC effectively promoted the regeneration and function recovery of the nerve. In summary, the NGF@CSNPs/OBC as a novel NGC provides great potential in the treatment of PNI.


Assuntos
Quitosana , Nanopartículas , Fator de Crescimento Neural , Regeneração Nervosa , Animais , Quitosana/química , Nanopartículas/química , Fator de Crescimento Neural/farmacologia , Ratos , Nervo Isquiático/lesões , Nervo Isquiático/fisiologia
14.
J Org Chem ; 84(17): 11032-11041, 2019 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-31333030

RESUMO

A regioselective synthesis of polysubstituted dihydropyrazoles and pyrazoles through an iodine-catalyzed oxidative cyclization strategy of aldehyde hydrazones with electron-deficient olefins is described. The protocol adopts very mild reaction conditions and provides desirable yields. The reaction is supposed to proceed via a cascade C-H functionalization, C-N bond formation, and oxidation sequential processes. The overall simplicity and regioselectivity of the catalytic system make this approach a valuable and step-economical tool to construct a C-C bond for the synthesis of Mefenpyr-Diethyl.

15.
Org Lett ; 21(16): 6270-6274, 2019 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-31348662

RESUMO

A reductive radical relay strategy for the construction of fused benzo[e]isoindole-1,3,5-trione through a reaction of α-bromo ketones with maleimides in the presence of Ir(ppy)3 under visible-light irradiation is described. The protocol employs very mild reaction conditions and offers satisfactory yields. Moreover, the reaction proceeds through a cascade C(sp3)-Br/C(sp2)-H functionalization, double C-C bond formation, and oxidative aromatization sequence.

16.
Org Lett ; 21(13): 5046-5050, 2019 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-31247786

RESUMO

A variety of pyrrolo[3,4- c]pyrazole derivatives from readily available aldehyde hydrazones and maleimides via direct oxidative coupling under radical cascade reaction have been reported. This method offers satisfactory chemical yields and good functional group compatibility. Moreover, this practical approach is catalyzed by CuCl utilizing air as the oxidant and some control experiments were performed to elaborate the mechanism.

17.
Org Lett ; 19(22): 6044-6047, 2017 11 17.
Artigo em Inglês | MEDLINE | ID: mdl-29087716

RESUMO

An efficient and practical Cu(I)-catalyzed oxidative cyclization cascade reaction of diverse amines, alkyne esters and maleimides has been developed. The reactions can afford 4,6-dioxopyrrolo[3,4-b]pyrrole-2,3-dicarboxylates and related derivatives with satisfactory yields by altering the reaction conditions slightly. The substrate scope highlights the flexibility of the catalyst, and a reaction mechanism is also proposed.

18.
Org Lett ; 18(2): 152-5, 2016 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-26709531

RESUMO

An efficient Pd(II)-catalyzed approach for the direct synthesis of indolo[3,2-a]pyrrolo[3,4-c]carbazole-6,8-diones has been developed from both free and protected (NH) indoles and maleimides via a regioselective tandem oxidative coupling reaction. The yields are moderate to excellent. In addition, 2-substituted indoles are suitable substrates in this protocol, leading to the formation of indolylmaleimides. The present methodology provides a concise route to highly functionalized indolopyrrolocarbazole derivatives.


Assuntos
Carbazóis/síntese química , Compostos Heterocíclicos de 4 ou mais Anéis/síntese química , Indóis/síntese química , Maleimidas/química , Paládio/química , Carbazóis/química , Catálise , Compostos Heterocíclicos de 4 ou mais Anéis/química , Indóis/química , Maleimidas/síntese química , Estrutura Molecular , Acoplamento Oxidativo , Estereoisomerismo
19.
Chem Biol ; 20(6): 796-805, 2013 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-23790490

RESUMO

Kosinostatin (KST), an antitumor antibiotic, features a pyrrolopyrrole moiety spirally jointed to a five-membered ring of an anthraquinone framework glycosylated with a γ-branched octose. By a combination of in silico analysis, genetic characterization, biochemical assay, and precursor feeding experiments, a biosynthetic pathway for KST was proposed, which revealed (1) the pyrrolopyrrole moiety originates from nicotinic acid and ribose, (2) the bicyclic amidine is constructed by a process similar to the tryptophan biosynthetic pathway, and (3) a discrete adenylation enzyme and a peptidyl carrier protein (PCP) are responsible for producing a PCP-tethered building block parallel to type II polyketide synthase (PKS) rather than for the PKS priming step by providing the starter unit. These findings provide an opportunity to further explore the inexplicable enzymatic logic that governs the formation of pyrrolopyrrole moiety and the spirocyclic skeleton.


Assuntos
Aminoglicosídeos/biossíntese , Antibacterianos/biossíntese , Antineoplásicos/metabolismo , Pirróis/química , Aminoglicosídeos/química , Antibacterianos/química , Antineoplásicos/química , Sequência de Bases , Clonagem Molecular , Espectroscopia de Ressonância Magnética , Micromonospora/genética , Micromonospora/metabolismo , Conformação Molecular , Dados de Sequência Molecular , Família Multigênica , Peptídeo Sintases/metabolismo , Policetídeo Sintases/genética , Policetídeo Sintases/metabolismo
20.
Fitoterapia ; 83(8): 1548-52, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22981505

RESUMO

Three new xanthones, garcinolic acid (1), 10α-ethoxy-9,10-dihydromorellic acid (2), and 10α-ethoxy-9,10-dihydrogambogenic acid (3), along with six known compounds were isolated from the resin of Garcinia hanburyi. These compounds were tested for their cytotoxicities against A549, HCT116, SK-BR-3 and HepG2, and showed high inhibitory effects on the cell lines.


Assuntos
Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/farmacologia , Garcinia/química , Resinas Vegetais/química , Xantonas/química , Linhagem Celular Tumoral , Humanos , Estrutura Molecular
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...