Latest ArticlesIncreasing interests of difluorinated amino acids (DFAAs) have been raised in recent years due to their widespread bio-organic and medical applications. However, to date, only few investigations focused on their asymmetric synthesis. Exploring difluoromethyl reagent to tailor a novel pathway and developing efficient catalytic system are highly desirable for constructing structurally diverse chiral DFAAs. Herein, a copper-catalyzed asymmetric difluorobenzylation of aldimine esters is described. By using α,α-difluorinated benzyltriflones as difluoromethyl reagents, this protocol allows the asymmetric synthesis of α-quaternary DFAAs with wide scope, good yields and excellent enantioselectivities (90%-98% ee). Control experiments and DESI-MS analysis demonstrate the reaction probably proceeds via a key difluorocarbocation intermediate. Moreover, polyfluoroarenes are found efficient candidates to polyfluoroaryl amino acids via C-F activation. Gram-scale experiment, late-stage functionalization, synthesis of difluorinated dipeptides and bioactive molecular analogues revealed the utility of the protocol, thereby largely enriching the structural diversity of FAAs and providing more potential opportunities in drug discovery.
Sonodynamic therapy (SDT) exhibits noninvasive and accuracy in cancer treatment, and has aroused widespread attention. However, the low quantum yield of inorganic sonosensitizers under ultrasound (US) stimulation leads to unsatisfactory efficacy. In this work, an urchin-like piezoelectric ZnSnO3/Cu3P p-n heterojunction was constructed as an efficient sonosensitizer for enhanced SDT. The p-n heterojunction formation narrows the band bandgap and increases the piezoelectric property, which contribute to the promotion of carrier separation and suppression of carrier recombination, resulting in enhanced SDT. Moreover, under tumor microenvironment (TME) with over produced H2O2 and glutathione (GSH), Cu3P NNs induce chemodynamic therapy (CDT) by initiating a Fenton-like reaction and depleting GSH, leading to increased cellular oxidative damage. With the combination effect, the ZnSnO3/Cu3P heterojunction demonstrates a 70% tumor growth inhibition rate in 4T1 tumor mice model. This piezoelectric heterojunction achieves the combined treatment of SDT and CDT, and opens new possibilities for the application of SDT in tumor therapy.
To efficiently remove perfluorooctanoic acid (PFOA), we developed a composite of magnetic Fe3O4 nanocrystals and MIL-101 (an iron-based metal organic framework). Because of its high surface area, porous structure, and complexation between PFOA as confirmed by experimental results and density functional theory simulation, the magnetic composite showed a Langmuir adsorption capacity of 415 mg/g in the presence of various groundwater components, and thus adsorbed PFOA at environment-relevant concentration within 20 min. The catalyst loaded with PFOA can then be magnetically separated from the synthetic groundwater. This adsorption step concentrated PFOA near MIL-101 and resulted in a fast decomposition rate in the decomposition step, where MIL-101 served as an efficient Fenton agent due to its abundant Fe3+/Fe2+ sites. Meanwhile, the alternative magnetic field was introduced to change the production pathway of reactive oxygen species and superoxide radical anions were produced, which was critical for PFOA degradation. In addition, the inductive heating effect heat the magnetic particles to 445 K through an in-situ approach, which thus further accelerated Fenton reactions rate. In addition, and achieved a complete degradation of PFOA within 30 min. This newly developed Fenton catalyst demonstrates advantages over conventionally heterogeneous and homogeneous catalysts, and thus is promising for practical applications.
The chemical investigation into the EtOAc extract of the deep-sea-derived fungus Penicillium citrinum W22 yielded three unprecedented citrinin dimers, neo-Dicitrinols A–C (1–3) and a known one, penicitrinone A (4). Their structures were elucidated by extensive analysis of spectroscopic data, electronic circular dichroism (ECD) calculation, X-ray diffraction, and biogenetic consideration. neo-Dicitrinols A–C (1–3), bearing a tetramic acid unit, represent the first example of citrinin analogues as hybrid polyketide synthase-nonribosomal peptide synthase (PKS-NRPS) products. neo-Dicitrinol C (3) significantly inhibited renin-angiotensin system-selective lethal 3 (RSL3)-induced ferroptosis with a half maximal effective concentration (EC50) value of 21.6 µmol/L.
Owing to the high spatiotemporal resolution, the second near-infrared (NIR-Ⅱ) imaging window can provide high imaging contrast with diminished tissue autofluorescence and suppressed photon scattering to pinpoint the locations for tumor surgery. Due to the unique optical properties and excellent fluorescence performance, quantum dots (QDs) are regarded as ideal nanoprobes for fluorescence-guided surgery (FGS). Moreover, QDs can be excited by a variety of light sources owing to the continuous and wide absorption ranges. Herein, light-emitting diode (LED) was used as the excitation source of QDs-based nanoprobes to realize FGS of tumor with high resolution. Since the LED light could irradiate a large region with consistent light intensity, signal distortion at the edge of imaging field was avoided. The signal intensity of the view edges under LED excitation can be improved by about 5 times compared to laser excitation. Therefore, more micro-vessels and smaller tumors (Vtumor < 5 mm2) could be detected, thus providing more precise guidance for tumor resection surgery.
Lymphoma is a hematological malignancy with an increasing mortality rate. Nevertheless, the treatment strategy against lymphoma remains limited. Doxorubicin (DOX) is a broad-spectrum anti-tumor chemotherapeutic drug, the clinical application of which is limited by serious adverse effects and drug resistance. In this work, biodegradable methoxy poly(ethylene glycol)-block-poly(lactic acid) (mPEG-PLA) nanomicelles co-delivering of DOX and apatinib (AP) (DOX-AP/m) was developed for lymphoma therapy. The average particle size of the self-assembled drug-loaded nano-micelle was 31.94 nm. It is revealed that AP can enhance the uptake of DOX by tumor cells. The in vivo and in vitro experimental results revealed that DOX-AP/m combination therapy could inhibit proliferation and promote apoptosis of lymphoma cells, and greatly suppress tumor growth. Our study indicated that DOX-AP/m might provide new insight and hold great potential in the treatment of lymphoma.
2-Deoxy-α-C-Glycosides are a significant class of carbohydrates found in numerous bioactive molecules and medicines. Developing a concise strategy for the assembly of these α-configured C-glycosides is crucial in the field of carbohydrate chemistry. However, current methods are restricted to the utilization of glycosyl radical precursors, which are required for pre-syntheses. Herein, we present a novel approach for the synthesis of 2-deoxy-α-C-glycosides using a nickel-catalyzed stereoselective coupling reaction with commercially available glycals. Notably, this method circumvents the preparation for diverse glycosyl radical precursors. The developed protocol exhibits a broad substrate scope and remarkable stereoselectivity under mild reaction conditions. Furthermore, the raw materials required for this process are readily accessible, eliminating the necessity for pre-functionalization modifications of the glycosyl substrates and ensuring high atomic economy.
The catalytic asymmetric dipolar cycloaddition reaction is efficient for the construction of various chiral valuable carbo- and heterocycles. Thus, the design and exploration of new dipoles and the subsequent control of their reactivity for various stereoselective cycloadditions are significant aspects of modern organic synthesis. Herein, we have developed a series of vinyl cyclic carbamates containing an oxazolidine-2,4–dione fragment and used them as reactive precursors for in situ generation of amide-based aza-π-allylpalladium 1,3-dipoles, which could be applied to asymmetric decarboxylative 1,3-dipolar cycloaddition with different types of dipolarophiles containing C=C, C=N, and C=O double bonds. This strategy provides an opportunity for the synthesis of previously unusual structures, such as highly functionalized optically pure pyrrolidin-2-ones, imidazolidin-4-ones, and oxazolidin-4-ones. This protocol also has significant features including wide substrate scope, mild reaction conditions, simple operation, and good to excellent results (70 examples, up to 99% yield, >20:1 dr and 99% ee). This unique method significantly expands the reaction range of the amide-based aza-π-allylpalladium 1,3-dipoles compared to the precedents.
The combination of nucleic acid and small-molecule drugs in tumor treatment holds significant promise; however, the precise delivery and controlled release of drugs within the cytoplasm encounter substantial obstacles, impeding the advancement of formulations. To surmount the challenges associated with precise drug delivery and controlled release, we have developed a multi-level pH-responsive co-loaded drug lipid nanoplatform. This platform first employs cyclic cell-penetrating peptides to exert a multi-level pH response, thereby enhancing the uptake efficiency of tumor cells and endow the nanosystem with effective endosomal/lysosomal escape. Subsequently, small interferring RNA (siRNA) complexes are formed by compacting siRNA with stearic acid octahistidine, which is capable of responding to the lysosome-to-cytoplasm pH gradient and facilitate siRNA release. The siRNA complexes and docetaxel are simultaneously encapsulated into liposomes, thereby creating a lipid nanoplatform capable of co-delivering nucleic acid and small-molecule drugs. The efficacy of this platform has been validated through both in vitro and in vivo experiments, affirming its significant potential for practical applications in the co-delivery of nucleic acids and small-molecule drugs.
Fenton-like process based on metal oxide presents one of the most hoping strategies to generate reactive oxygen species to treat refractory pollutants. The introduction of oxygen vacancies (OVs) can enhance the catalytic performance of metal oxides in Fenton-like reaction. In this paper, a one-step all solid-state synthesis strategy is proposed to induce oxygen defects in V2O5, which uses graphene to engineer the crystallization process of V-based crystals. Such approach employs graphene as a solid-catalyst to promote growth of V-based crystals owing to the ions-π interactions between graphene and VCl3. The electron-donor OVs in V2O5@graphene can not only active H2O2 for the •OH generation, but also accelerate the reduction of V5+ and V4+, thereby ensuring defective V2O5@graphene/H2O2 system is 14.3, 28.2, and 17.3 times higher than that of graphene/H2O2, pure V2O5/H2O2 and graphene+V2O5/H2O2 (mechanical mixed system), respectively. Our study provides a novel synthetic strategy to design and prepare OVs-riched transition metal catalysts for developing advanced oxidation technologies toward higher sustainability and practicality.
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