Latest ArticlesAerobic oxidation using pure dioxygen gas as the oxidant has attracted much attention, but its application in synthetic chemistry has been significantly hampered by the complexity of catalytic system and potential risk of high-energy dioxygen gas. By employing 1, 2-diethoxyethane as a catalyst and ambient air as an oxidant, an efficient protocol for the construction of various aryl-alkyl and diaryl ketones through oxidative cleavage of gem-disubstituted aromatic alkenes under minimal solvent conditions has been achieved.
Photodynamic therapy (PDT) is a promising alternative approach for effective cancer treatment, which can directly destroy local tumor cells due to the generation of cytotoxic singlet oxygen and reactive oxygen species (ROS) in the tumor cells. Intriguingly, PDT-mediated cell death is also associated with anti-tumor immune response. However, immunosuppression of tumor microenvironment is able to limit the immune response induced by PDT, it is therefore necessary to combine with immunocheckpoint inhibitor and immunoadjuvant for synergistic treatment of tumors. Herein, the recent advances of PDT, immunotherapy, and photodynamic immunotherapy are reviewed.
A Lewis base catalyzed ring expansion of isatin with 2, 2, 2-trifluorodiazoethane (CF3CHN2) is developed. It is characterized that the merge of tetramethylethylenediamine and CF3CHN2 generates reactive triazene intermediates, which construct substituted 3-hydroxy-4-(trifluoromethyl)quinolinones with high efficiency. Synthetic application of the procedure is broadened by 3-trifluormethylpyrazole fused 3-hydroxy-4-(trifluoromethyl)quinolinone synthesis.
TEMPO (2, 2, 6, 6-tetramethylpiperidine-1-oxyl) is well-established in orangocatalysis that usually work in synergy with transition-metal catalysis or semiconductor photocatalysis. Here, TEMPO was turned into a visible light photocatalyst to conduct the selective aerobic oxidation of thiols into disulfides. With O2 as an oxidant, a mild and efficient protocol for the selective oxidation of thiols into disulfides including symmetrical and unsymmetrical ones with 5 mol% of TEPMO as a photocatalyst was developed at room temperature under the irradiation of 460 nm blue LEDs. It was found that a complex formed between TEMPO and thiols underpinned the visible light activity and disulfides were obtained in very high isolated yields. This work suggests that TEMPO takes diverse roles in for photocatalytic selective oxidative transformations with O2 as the oxidant.
With the emergence of multidrug-resistant tuberculosis and extensive drug-resistant tuberculosis strains, there is an urgent need to develop novel drugs for the treatment of tuberculosis. The respiratory chain is a promising target for the development of new antimycobacterial agents, and a growing number of compounds have been reported and some have entered clinical trials. In this review, we summarize the main features and the electron transfer process of the mycobacterial respiratory chain, and the recent progress in the search for new small molecule inhibitors targeting the three main potential targets in the respiratory chain of Mycrobacterium tuberculosis. Our emphasis is on the optimization strategy of QcrB inhibitors and the challenges of developing QcrB inhibitors as antituberculosis drugs due to the alternate bd-type oxidase oxidative compensation pathway are discussed.
Four pillar[5]arene based [3]rotaxanes (1-4) involving two 1,4-diethoxypillar[5]arene (DEP5) rings and a dumbbell-shaped component were successfully synthesized. The dumbbell-shape molecules contain one longer bridge, two triazole sites and two multicomponent stoppers. After threading DEP5 rings with linear guests (G1-G4) which contain two benzaldehyde units, the base catalyzed three-component reaction of dimedone, malononitrile and benzaldehyde was performed to construct the stoppers and connected the pseudorotaxanes with stoppers to generate 1–4. The structures of [3]rotaxanes and their self-assembly behaviors were characterized by 1H NMR, 13C NMR, NOESY, HR-ESI-MS, DLS and TEM technologies. We hope that pillar[5]arene based [3]rotaxanes may have potential applications in drug delivery systems and molecular devices.
Sodium taurocholate cotransporting polypeptide (NTCP) is identified as the functional receptor for HBV entry, which is responsible for upregulated HBV transcription in the HBV life cycle. Besides, NTCP is also implicated in the progression of HBV-induced hepatocellular carcinoma (HCC). Thereby, NTCP-targeting entry inhibitors are proposed to suppress HBV infection and replication in HBV-induced hepatoma therapy. Herein, we integrated in silico screening and chemical synthesis to obtain a small-molecule NTCP inhibitor B7, which exhibited moderate anti-proliferative activities against HepG2 cells and anti-HBV activity in vitro. Additionally, CETSA assay, molecular docking, and MD simulation validated that B7 could bind to NTCP. Furthermore, western blot analysis demonstrated that B7 induced apoptosis with an increased expression of Bax and caspase 3 cleaving as well as a decreasing expression of Bcl-2 in HepG2 cells. Taken together, our study identified B7 as a novel NTCP inhibitor with anti-proliferation activities which might provide a new opportunity for HCC therapy.
The removal of ciprofloxacin (CIP) in sulfur-mediated bioprocesses, e.g., sulfate-reducing bacteria (SRB)-mediated process and sulfur-oxidizing bacteria (SOB)-mediated process, was examined for the first time. The results showed that the SRB-mediated process had more efficient CIP removal than that in SOB-mediated process. Adsorption was the primary removal pathway of CIP in SRB-mediated process and SOB-mediated process with the specific adsorption removal rate of 131.4±1.1 μg/g-SS/d and 30.1±1.4 μg/g-SS/d, respectively, at influent CIP concentration of 500 μg/L. In addition, extracellular polymeric substances (EPS) also played an important role on CIP migration and removal in both types of sludge. Further study was conducted to specify the different adsorption of CIP in these two sludge systems from the perspective of sludge properties. The results indicated that there are more potential adsorption sites exist on the SRB-mediated sludge for CIP adsorption than SOB-mediated sludge since the higher protein (PN) content and more kinds of aromatic amino acid substances in EPS, more negative zeta-potential and stronger and more numbers of functional groups in SRB-mediated sludge compared to SOB-mediated sludge. The findings of this study provide insights into the sludge properties affecting CIP removal in sulfur-mediated bioprocesses, and are of guiding significance to employ sulfur-mediated biological systems for treating CIP-containing wastewaters.
The effects of bisulfite-activated permanganate technology (PM/BS) as a pre-oxidation process on enhancing Microcystis aeruginosa (M. aeruginosa) removal by post coagulation were investigated. The results demonstrated that pretreatment with PM/BS process effectively promoted the algae removal by coagulation with Al2(SO4)3 as the coagulant and this phenomenon was more obvious with the increase of water hardness. Compared to the sole coagulation, PM/BS pre-oxidation combing with coagulation could neutralize the zeta potential of algal cells effectively, decrease the algal cell size, and lead to the formation of more compact flocs due to the in-situ generated MnO2. The effect of oxidant dosages on algal organic matter (AOM) was also studied and no obvious release of macromolecular substances was observed with the dosage of KMnO4 increasing from 3.0 mg/L to 7.0 mg/L, suggesting the integrity of algal cells at a high KMnO4 dosage. Moreover, PM/BS pre-oxidation could lead to the decrease of most analyzed disinfection by-products (DBPs) at a Al2(SO4)3 dosage of 40.0 mg/L. The algae removal efficiency was also significantly enhanced by PM/BS pre-oxidation in the test using real algae-laden water. This study indicated that PM/BS process might be a potential assistant technology for algae removal by subsequent coagulation.
Electrocatalytic CO2 reduction (CO2ER) into formate is a desirable route to achieve efficient transformation of CO2 to value-added chemicals, however, it still suffers from limited catalytic activity and poor selectivity. Herein, we develop a hybrid electrocatalyst composed of bismuth and bismuth oxide nanoparticles (NPs) supported on nitrogen-doped reduced graphene oxide (Bi/Bi2O3/NrGO) nanosheets prepared by a combined hydrothermal with calcination treatment. Thanks to the combination of undercoordinated sites and strong synergistic effect between Bi and Bi2O3, Bi/Bi2O3/NrGO-700 hybrid displays a promoted CO2ER catalytic performance and selectivity for formate production, as featured by a small onset potential of -0.5 V, a high current density of -18 mA/cm2, the maximum Faradaic efficiency of 85% at -0.9 V, and a low Tafel slope of 166 mV/dec. Experimental results reveal that the higher CO2ER performance of Bi/Bi2O3/NrGO-700 than that of Bi NPs supported on NrGO (Bi/NrGO) can be due to the partial reduction of Bi2O3 NPs into Bi, which significantly increases undercoordinated active sites on Bi NPs surface, thus boosting its CO2ER performance. Furthermore, a two-electrode device with Ir/C anode and Bi/Bi2O3/NrGO-700 cathode could be integrated with two alkaline batteries or a planar solar cell to achieve highly active water splitting and CO2ER.
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