RESUMO
The investigation of the leaves of Pittosporum elevaticostatum Chang et Yan led to the isolation of fifteen pentacyclic triterpenoids (1-15), including five previously undescribed ones (1-5), and nine others (16-24). The structures of compounds 1-5 were elucidated based on comprehensive spectroscopic techniques, including one dimension (1D) and 2D nuclear magnetic resonance (NMR), high resolution electrospray ionization mass spectroscopy (HR-ESI-MS), and other methods. Compounds 2 and 13 demonstrated significant inhibitory activity against Listeria monocytogenes (L. monocytogenes) with minimum inhibitory concentration (MIC) values of 32 µM. Scanning electron microscopy (SEM) observations revealed insights into the antibacterial mechanism, indicating that compounds 2 and 13 either prevent biofilm formation of dispersed the preformed cell membranes. Additionally, compounds 1, 5, 7, and 12 exhibited anti-inflammatory activity on lipopolysaccharide (LPS)-stimulated BV-2 microglial cells with IC50 values ranging from 11.27 to 17.80 µM.
Assuntos
Antibacterianos , Anti-Inflamatórios , Listeria monocytogenes , Testes de Sensibilidade Microbiana , Triterpenos Pentacíclicos , Folhas de Planta , Folhas de Planta/química , Antibacterianos/farmacologia , Antibacterianos/isolamento & purificação , Anti-Inflamatórios/farmacologia , Anti-Inflamatórios/isolamento & purificação , Estrutura Molecular , Camundongos , Animais , Listeria monocytogenes/efeitos dos fármacos , Triterpenos Pentacíclicos/farmacologia , Triterpenos Pentacíclicos/isolamento & purificação , Compostos Fitoquímicos/farmacologia , Compostos Fitoquímicos/isolamento & purificação , Microglia/efeitos dos fármacos , Linhagem Celular , ChinaRESUMO
Interest in electrocatalytic bioconjugation reactions has surged, particularly for modifying tryptophan and tyrosine residues in proteins. We used a cost-effective graphite felt electrode and low-current methodology to achieve selective bioconjugation of tryptophan with thiophenols, yielding up to 92%. This method exclusively labeled tryptophan residues and incorporated fluorinated tryptophan for NMR analysis. Eight polypeptides, including lanreotide and leuprorelin, were effectively coupled, demonstrating the method's versatility and potential for novel diagnostic and therapeutic agents.
Assuntos
Peptídeos , Triptofano , Triptofano/química , Peptídeos/química , Técnicas Eletroquímicas , Estrutura Molecular , Somatostatina/química , Somatostatina/análogos & derivados , Peptídeos Cíclicos/química , EletrodosRESUMO
A highly stereoselective coupling reaction of diazooxindoles with difluoroenoxysilanes catalyzed by Lewis acidic boranes has been developed. The reaction proceeded at ambient temperature under transition metal-free conditions with wide functional group tolerance. By using this simple procedure, a series of tetrasubstituted monofluoroalkenes can be accessed in good yield with high selectivity.
RESUMO
Wound healing is a dynamic and complex process, it's urgent to develop new wound dressings with excellent performance to promote wound healing at the different stages. Here, a novel composite hydrogel dressing composed by silver nanoparticles (AgNPs) impregnated adenine-modified chitosan (CS-A) and octafunctionalized polyhedral oligomeric silsesquioxane (POSS) of benzaldehyde-terminated polyethylene glycol (POSS-PEG-CHO) solution was presented to solve the problem of wound infection. Modification of chitosan with adenine, not only can improve the water solubility of chitosan, but also introduce bioactive substances to promote cell proliferation. CS-A and POSS-PEG-CHO were cross-linked by Schiff-base reaction to form the injectable self-healing hydrogel. On this basis, AgNPs were added into the hydrogel, which endows the hydrogel with better antibacterial activity. Moreover, this kind of hydrogel exhibits excellent cell proliferation properties. Studies demonstrated that the hydrogel can significantly accelerate the closure of infected wounds. The histological analysis and immunofluorescence staining demonstrated that the wounds treated with the composite hydrogel exhibited fewer inflammatory cells, more collagen deposition and angiogenesis, faster regeneration of epithelial tissue. Above all, adenine-modified chitosan composite hydrogel with AgNPs loaded was considered as a dressing material with great application potential for promoting the healing of infected wounds.
Assuntos
Adenina , Antibacterianos , Proliferação de Células , Quitosana , Hidrogéis , Nanopartículas Metálicas , Polietilenoglicóis , Prata , Cicatrização , Quitosana/química , Quitosana/farmacologia , Cicatrização/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Antibacterianos/farmacologia , Antibacterianos/química , Polietilenoglicóis/química , Prata/química , Prata/farmacologia , Hidrogéis/química , Hidrogéis/farmacologia , Animais , Nanopartículas Metálicas/química , Adenina/farmacologia , Adenina/química , Camundongos , Compostos de Organossilício/química , Compostos de Organossilício/farmacologia , Ratos , Humanos , Infecção dos Ferimentos/tratamento farmacológicoRESUMO
Hydroxyl radical (â¢OH), one of the most reactive and deleterious substances in organisms, belongs to a class of reactive oxygen species (ROS), and it has been verified to play an essential role in numerous pathophysiological scenarios. However, due to its extremely high reactivity and short lifetime, the development of a reliable and robust method for tracking endogenous â¢OH remains an ongoing challenge. In this work, we presented the first ratiometric fluorescent nanoprobe NanoDCQ-3 for â¢OH sensing based on oxidative C-H abstraction of dihydroquinoline to quinoline. The study mainly focused on how to modulate the electronic effects to achieve an ideal ratiometric detection of â¢OH, as well as solving the inherent problem of hydrophilicity of the probe, so that it was more conducive to monitoring â¢OH in living organisms. The screened-out probe NanoDCQ-3 exhibited an exceptional ratiometric sensing capability, better biocompatibility, good cellular uptake, and appropriate in vivo retention, which has been reliably used for detecting exogenous â¢OH concentration fluctuation in living cells and zebrafish models. More importantly, NanoDCQ-3 facilitated visualization of â¢OH and evaluation of drug treatment efficacy in diabetic mice. These findings afforded a promising strategy for designing ratiometric fluorescent probes for â¢OH. NanoDCQ-3 emerged as a valuable tool for the detection of â¢OH in vivo and held potential for drug screening for inflammation-related diseases.
Assuntos
Técnicas Biossensoriais , Diabetes Mellitus Experimental , Animais , Camundongos , Radical Hidroxila , Peixe-Zebra , Diabetes Mellitus Experimental/induzido quimicamente , Diabetes Mellitus Experimental/tratamento farmacológico , Espécies Reativas de Oxigênio , Corantes FluorescentesRESUMO
Promoting the healing of diabetic wounds remains a major challenge in scientific research today. A star-like eight-arm cross-linker octafunctionalized POSS of benzaldehyde-terminated polyethylene glycol (POSS-PEG-CHO) was synthesized, and crosslinked with hydroxypropyltrimethyl ammonium chloride chitosan (HACC) via Schiff base reaction to obtain Chitosan-based POSS-PEG hybrid hydrogels. The designed composite hydrogels exhibited strong mechanical strength, injectability, excellent self-healing efficiency, good cytocompatibility and antibacterial properties. Furthermore, the composite hydrogels could accelerate cells migration and proliferation, as expected by remarkably promoting wound healing in diabetic mice. The wounds treated with the composite hydrogels displayed faster regeneration of epithelial tissue, fewer inflammatory cells, more collagen deposition and higher expression level of VEGF. Therefore, Chitosan-based POSS-PEG hybrid hydrogel has great application potential as a dressing for promoting the healing of diabetic wounds.
Assuntos
Quitosana , Diabetes Mellitus Experimental , Animais , Camundongos , Bandagens , Materiais Biocompatíveis , Hidrogéis , CicatrizaçãoRESUMO
In this paper, the mechanism of neutron absorption and common reinforced particles is introduced, and recent research progress on different types of neutron-shielding materials (borated stainless steels, B/Al Alloy, B4C/Al composites, polymer-based composites, and shielding concrete) for transportation and wet or dry storage of spent fuel is elaborated, and critical performance is summarized and compared. In particular, the most widely studied and used borated stainless steel and B4C/Al composite neutron-absorption materials in the field of spent fuel are discussed at length. The problems and solutions in the preparation and application of different types of neutron-shielding materials for spent fuel transportation and storage are discussed, and their research priorities and development trends are proposed.
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A selective arylation of donor-acceptor diazo compounds with aniline derivatives catalyzed by Lewis acidic boranes is developed. This simple reaction protocol provides an efficient method for the synthesis of diarylacetates under metal-free conditions.
Assuntos
Boranos , Compostos Azo , CatáliseRESUMO
A paired electrolysis enabled cascade annulation that enables the efficient synthesis of highly functionalized quinoline-substituted bioactive molecules from readily available starting materials is reported. Using this methodology, two goals, namely, the direct synthesis of quinolines and the introduction of quinoline moieties to bioactive molecules, can be simultaneously achieved in one simple operation. The use of electroreduction for the activation of isatin, together with the further anodic oxidation of KI to catalytically result in a cascade annulation, highlight the unique possibilities associated with electrochemical activation methods. This transformation can tolerate a wide range of functional groups and can also be used as a functionalization tactic in pharmaceutical research as well as other areas.
RESUMO
An unprecedented redox-neutral annulation reaction of tertiary anilines with electron-deficient alkynes was developed that proceeds through a cascade Friedel-Crafts alkylation/[1,5]-hydride transfer/Mannich cyclization sequence. Under B(C6F5)3 catalysis, a range of functionalized 1,2,3,4-tetrahydroquinolines were facilely constructed in moderate to good yields with exclusive 3,4-anti-stereochemistry. The commercial availability of the catalyst and the high atom and step economy of the procedure, together with metal-free and external oxidant-free conditions, make this an attractive method in organic synthesis.
RESUMO
Electrochemical oxygen reduction reaction (ORR) is a powerful tool for introducing oxygen functional groups in synthetic chemistry. However, compared with the well-developed one-electron oxygen reduction process, the applications of two-electron oxygen reduction in electrochemical synthesis have been seldom studied. We present herein our recent progress in the oxidation of α-diazoesters to α-ketoesters by in situ generated hydrogen peroxide via a two-electron oxygen reduction approach. A diverse collection of valuable α-ketoester products was obtained with moderate to high yields under an exogenous-oxidant-free and metal catalyst-free electrochemical conditions.
RESUMO
Injectable and degradable PEG hydrogel was prepared via Michael-type addition between cross-linking monomer 4-arm-PEG-MAL and two cross-linkers of hydrolysis degradable PEG-diester-dithiol and non-degradable PEG-dithiol, and it had a porous structure with the uniform pore size. The biocompatibility assays in vitro indicated that PEG hydrogel had excellent biocompatibility and can be degraded naturally without leading to any negative impact on cells. The results of antibacterial experiments showed that PEG hydrogel can inhibit the growth of bacteria. Furthermore, the Cell Counting Kit-8 (CCK-8) assay, LIVE/DEAD cell staining, and scratch healing experiments proved that PEG hydrogel can promote cell proliferation and migration, which had been further confirmed in in vivo experiments on the rat wound models. All experimental results demonstrated that PEG hydrogel is an injectable antibacterial dressing, which can promote the process of wound healing and has great potential in the field of wound healing.
Assuntos
Antibacterianos/farmacologia , Materiais Biocompatíveis/farmacologia , Hidrogéis/farmacologia , Polietilenoglicóis/farmacologia , Cicatrização/efeitos dos fármacos , Antibacterianos/síntese química , Antibacterianos/química , Materiais Biocompatíveis/síntese química , Materiais Biocompatíveis/química , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Escherichia coli/efeitos dos fármacos , Humanos , Hidrogéis/síntese química , Hidrogéis/química , Teste de Materiais , Testes de Sensibilidade Microbiana , Estrutura Molecular , Tamanho da Partícula , Polietilenoglicóis/síntese química , Polietilenoglicóis/química , Staphylococcus aureus/efeitos dos fármacosRESUMO
Calcification of bioprosthetics is a primary challenge in the field of artificial heart valves and a main reason for biological heart valve prostheses failure. Recent advances in nanomaterial science have promoted the development of polymers with advantageous properties that are likely suitable for artificial heart valves. In this work, we developed a nanocomposite polymeric biomaterial POSS-PEG (polyhedral oligomeric silsesquioxane-polyethylene glycol) hybrid hydrogel, which not only has improved mechanical and surface properties but also excellent biocompatibility. The results of atomic force microscopy and in vivo animal experiments indicated that the content of POSS in the PEG matrix plays an important role on the surface and contributes to its biological properties, compared to the decellularized porcine aortic valve scaffold. Additionally, this modification leads to enhanced protection of the hydrogel from thrombosis. Furthermore, the introduction of POSS nanoparticles also gives the hydrogel a better calcification resistance efficacy, which was confirmed through in vitro tests and animal experiments. These findings indicate that POSS-PEG hybrid hydrogel is a potential material for functional heart valve prosthetics, and the use of POSS nanocomposites in artificial valves may offer potential long-term performance and durability advantages.
Assuntos
Materiais Biocompatíveis/química , Próteses Valvulares Cardíacas , Hidrogéis/química , Compostos de Organossilício/química , Polietilenoglicóis/química , Animais , Materiais Biocompatíveis/síntese química , Hidrogéis/síntese química , Masculino , Teste de Materiais , Estrutura Molecular , Compostos de Organossilício/síntese química , Tamanho da Partícula , Polietilenoglicóis/síntese química , Ratos , Ratos Sprague-Dawley , Alicerces Teciduais/químicaRESUMO
We report herein a B(C6F5)3-catalyzed redox-neutral ß-functionalization of pyrrolidines with isatins. Under transition-metal- and oxidant-free conditions at ambient temperature, a series of pyrrolidines bearing a functionalized exocyclic alkene are accessed in high efficiency through a borrowing hydrogen process. A simple switch to higher reaction temperature in a one-pot procedure also provides access to a diverse array of C(3)-functionalized pyrroles while liberating water and hydrogen gas as the only byproducts.
RESUMO
Herein, we present the first example of catalytic redox-neutral ß-functionalization of tertiary amines through a borrowing hydrogen process. This B(C6F5)3-catalyzed procedure utilizes commercially or readily available catalysts and substrates and promotes a direct functionalization of the C(sp3)-H bond at the ß-position of acyclic tertiary amines through conjugate addition to para-quinone methides. Compared to previous work on direct ß-functionalization of tertiary amines under oxidative conditions, besides being metal-free, the significant advantage of this method is that neither stoichiometric oxidants nor reductants are needed which may otherwise generate unnecessary waste.
RESUMO
Leucine aminopeptidase (LAP), one of the important cancer-related biomarkers, is significantly over-expressed in many malignant tumor cells. Developing an effective fluorescent probe for high-specificity and in situ trapping of endogenous LAP in living samples is still challenging. In this project, we report a water-soluble near-infrared (NIR) fluorescent probe (CHMC-M-Leu) for specific monitoring of LAP in vitro and in vivo. The novel fluorescent probe (CHMC-M-Leu) contains a NIR-emitting fluorophore (CHMC-M) as the reporter and l-leucine as the enzyme-active trigger moiety which are linked together by a p-aminobenzyl alcohol (PABA) section. Upon exposure to LAP, the fluorescence at 625 nm gets impressively enhanced, which belongs to the near-infrared region and is beneficial for imaging in vivo. Furthermore, the novel fluorescent probe exhibits fast response and highly chemoselective detection of LAP in various bio-related species. In addition, CHMC-M-Leu shows favourable cellular uptake and was successfully used to monitor endogenous LAP in living cells.
Assuntos
Ensaios Enzimáticos/métodos , Corantes Fluorescentes/química , Corantes Fluorescentes/metabolismo , Raios Infravermelhos , Leucil Aminopeptidase/metabolismo , Sobrevivência Celular , Células HeLa , Células Hep G2 , Humanos , Leucina/química , Imagem ÓpticaRESUMO
Currently, chemotherapy is a widely used and important treatment for cancer. However, almost all of the treatments have shortcomings associated with poor specificity and high toxicity, which results in severe side effects to normal cells and tissue. This is a very important problem, and yet, it currently remains unanswered. Therefore, the development of the method for the more effective delivery of anticancer drugs to their targets and real-time monitoring of the localization of the drugs are very important. Herein, we designed a theranostic prodrug: CPT-p-Leu, which was constructed using fluorescent camptothecin (CPT), a self-immolative linker and leucine (Leu) residue. Upon exposure to LAP (leucine aminopeptidase: LAP), the amide bond in CPT-p-Leu will be cleaved, followed by an intramolecular 1,6-elimination, which triggers the active anticancer drug (CPT) release and recovers the fluorescence of CPT. With our design, the anticancer drug, CPT, can be used as both a drug and a fluorescence reporter, making our system suitable to accurately and effectively track the released CPT distribution. Based on this strategy, CPT-p-Leu could achieve the chemoselective detection of LAP and monitoring of the anticancer drug release. Furthermore, it also provides a very convenient way to accurately determine the location of the released drug in living samples. In addition, CPT-p-Leu shows a good cell membrane permeability and enhanced cytotoxicity toward LAP overexpressing cancer cells. We anticipate that our research will facilitate the development of improved theranostic systems for cancer therapy.
RESUMO
Nitroxyl (HNO) is a derivative of nitric oxide (NO) that plays an essential role in various biological and pharmacological events. Until now, the in situ trapping and specific detection of HNO in living samples is still challenging. In this project, we fabricated a novel BODIPY-based micellar nanoprobe for monitoring nitroxyl in vitro and in vivo in ratiometric mode in aqueous solution. The probe (P-BODIPY-N) contains an asymmetrical BODIPY dye for fluorescent signaling and a diphenylphosphinobenzoyl as the trigger moiety; then we encapsulated P-BODIPY-N into the hydrophobic interior of an amphiphilic copolymer (mPEG-DSPE) and prepared a novel BODIPY-based micellar nanoprobe: NP-BODIPY-N. As far as we know, this probe is the first reported ratiometric fluorescent nanoprobe for HNO, which exhibits ultrasensitivity, high selectivity, and good biocompatibility. Above all, this nanoprobe shows favorable cellular uptaken and was successfully used to detect intracellular HNO released by Angeli's salt in living cells and zebrafish larvae. These results indicate that our newly designed nanoprobe will provide a promising tool for the studies of HNO in living system.
Assuntos
Compostos de Boro/química , Corantes Fluorescentes/química , Óxidos de Nitrogênio/análise , Imagem Óptica/métodos , Animais , Células Hep G2 , Humanos , Micelas , Fosfatidiletanolaminas/química , Fosfinas/química , Polietilenoglicóis/química , Peixe-ZebraRESUMO
Leucine aminopeptidase (LAP) is an important cancer-related biomarker, which shows significant overexpression in malignant tumor cells like liver cancer. Developing an effective method to monitor LAP in tumor cells holds great potential for cancer diagnosis, treatment, and management. In this work, we report a novel BODIPY-based fluorescent probe (BODIPY-C-Leu) capable of monitoring LAP in vitro and in vivo in both ratiometric and turn-on model. BODIPY-C-Leu contains an asymmetrical BODIPY dye for fluorescent signaling and a dipeptide (Cys-Leu) as the triggered moiety. Activation occurs by cleavage of the amide bond in dipeptides and subsequently an intramolecular S â N conversion to convert sulfur-substituted BODIPY to amino-substituted BODIPY, resulting in a dramatic fluorescence variation to realize the detection of LAP. Furthermore, we have successfully employed BODIPY-C-Leu to monitor LAP activity in different cancer cells, indicating that HeLa cells have a higher level of LAP activity than A549 cells. Importantly, we demonstrated the capability of the probe for real-time monitoring the drug-induced LAP level changes in zebrafish.