Latest ArticlesNickel/(S)-t-Bu-PHOX complex catalyzed asymmetric arylative cyclization of N-alkynones has been achieved, delivering 1, 2, 3, 6-tetrahydropyridines containing a chiral tertiary alcohol in high yields and excellent enantioselectivities, which provides efficient access to chiral tetrahydropyridine and piperidine analogues.
Tumor-associated carbohydrate antigens (TACAs) are attractive targets for vaccine development. In this context, we described a strategy combining artificial TACA and glycoengineering for cancer vaccine development. A 2, 4-ditrophenyl (DNP)-modified GM3 intermediate was synthesized chemoenzymatically and conjugated to keyhole limpet hemocyanin (KLH), and the resulting bioconjugate was tested for its potential as a vaccine candidate. Mice immunological studies revealed that the DNP-modified GM3 (GM3-NHDNP) analog elicited strong and rapid immune responses by recruiting anti-DNP antibodies to facilitate the targeted delivery of the vaccine construct to antigen processing cells (APCs). Moreover, the endogenously produced anti-DNP antibodies, together with the elicited antibodies against GM3-NHDNP, may synergistically promote tumor binding and cancer cell death when the cancer cell surfaces are glycoengineered to express the GM3-NHDNP antigen.
All-hydrocarbon stapling strategy has been widely applied for enhancing the proteolytic stability of peptides. However, two major technical hurdles to some extent limit the development of stapled peptides for therapeutic usage: rational selection of the stapling sites and the corresponding deletion of the native side chains. Previously we described the development of the olefin-terminated amino acids with the retention of native side chains and successfully applied them in the synthesis of hydrocarbon stapled peptides with single side-chain retention. Here, we explored the feasibility and effectiveness of hydrocarbon stapling strategy characterized as double side-chains retention. Modeled after a lengthy human immunodeficiency virus-1 (HIV-1) fusion inhibitor SC34EK, Leui, Seri+4 and Lysi, Leui+4 stapled peptides with the retention of double side-chains were effectively obtained. Our complementary study provided a convenient alternative to address where to install the staple in sequence for conventional all-hydrocarbon peptide stapling. Furthermore, this method not only conferred conformational reinforcement for SC34EK with high α-helicity and protease resistance, but also preserved the structural characteristic (key peripheral residues, charge and solubility) of the linear peptide to the maximum, which are crucial for anti-HIV-1 activity.
The replacement of the disulfide bridge of CPI-1, a peptide inhibitor of light chain of Botulinum toxin serotype A, with the thioether-containing and biscarba-containing diaminodiacid bridge leads to a significant decrease in the degradation by trypsin and increase in the detoxification activity in vivo, the addition of hydrophobic or positive amino acid at C-terminus of modified peptides further improves the inhibitory activity.
Drug resistance remains to be a serious problem with type I human immunodeficiency virus (HIV-1) non-nucleoside reverse transcriptase inhibitors (NNRTIs). A series of novel boronic acid-containing diarylpyrimidine (DAPY) derivatives were designed via bioisosterism and scaffold-hopping strategies, taking advantage of the ability of a boronic acid group to form multiple hydrogen bonds. The target compounds were synthesized and evaluated for their anti-HIV activities and cytotoxicity in MT-4 cells. Compound 10j yielded the most potent activity and turned out to be a single-digit nanomolar inhibitor towards the HIV-1 IIIB [wild-type (WT) strain], L100I and K103N strains, with 50% effective concentration (EC50) values of 7.19–9.85 nmol/L. Moreover, 10j inhibited the double-mutant strain RES056 with an EC50 value of 77.9 nmol/L, which was 3.3-more potent than that of EFV (EC50 = 260 nmol/L) and comparable to that of ETR (EC50 = 32.2 nmol/L). 10j acted like classical NNRTIs with high affinity for WT HIV-1 reverse transcriptase (RT) with 50% inhibition concentration (IC50) value of 0.1837 μmol/L. Furthermore, molecular dynamics simulation indicated that 10j was proposed as a promising molecule for fighting against HIV-1 infection through inhibiting RT activity. Overall, the results demonstrated that 10j could serve as a lead molecule for further modification to address virus-drug resistance.
Three matrine-derived alkaloids, alopecuroidine A (1), alopecuroidine B (2a) and alopecuroidine C (2b) were isolated from the seeds of Sophora alopecuroides. Their structures were elucidated by extensive spectroscopic analyses and X-ray diffraction. Three compounds possess an unprecedented rearranged fused 7/6/5/6 tetracyclic skeleton with a diazacycloheptane structure. Their plausible biosynthetic pathway was also proposed. The anti-proliferative activities of compounds 1 and 2a were examined by the MTT assay. Compound 1 inhibited the viability of human lung cancer A549 cells, having a half maximal inhibitory concentration (IC50) of 7.58 ± 2.47 µmol/L at 72 h. The flow cytometric analysis suggested that 1 inhibited A549 cell growth by inducing apoptosis and cell-cycle arrest. Additionally, 1 induced the loss of mitochondrial membrane potential, elevated intracellular reactive oxygen species, increased the Bax/Bcl-2 ratio, stimulated cleaved-caspase-3 and P53 protein levels, and suppressed the pro-caspase-3 level. Thus, 1 appeared to induce A549 cells apoptosis through a mitochondria-mediated apoptotic pathway.
More and more attentions have been attracted by lithium-sulfur batteries (Li-S), owing to the high energy density for the increasingly advanced energy storage system. While the poor cycling stability, due to the inherent polysulfide shuttle, seriously hampered their practical application. Recently, some polar hosts, like single metal oxides and sulfides, have been employed as hosts to interact with polysulfide intermediates. However, due to the inherent poor electrical conductivity of these polar hosts, a relatively low specific capacity is obtained. Herein, a spinel-type bimetal sulfide NiCo2S4 through a Prussian blue analogue derived methodology is reported as the novel host of polysulfide, which enables high-performance sulfur cathode with high Coulombic efficiency and low capacity decay. Notably, the Li-S battery with NiCo2S4-S composites cathode still maintains a capacity of 667 mAh/g at 0.5 C after 300 cycles, and 399 mAh/g at 1 C after 300 cycles. Even after 300 cycles at the current density of 0.5 C, the capacity decays by 0.138% per cycle at high sulfur loading about 3 mg/cm2. And the capacity decays by 0.026% per cycle after 1000 cycles, when the rate is 1 C. More importantly, the cathode of NiCo2S4-S composite shows the outstanding discharge capacity, owing to its good conduction, high catalytic ability and the strong confinement of polysulfides.
The efficient utilization of solar energy through photocatalysis is ideal for solving environmental issues and the development sustainable future. BiOBr-based semiconductors possess unique narrowed bandgaps and layered structures, thereby widely studied as photocatalysts for environmental remediation. However, a little has been focused on the comprehensive reviewing of BiOBr despite its extensive and promising applications. In this review, the state-of-the-art developments of BiOBr-based photocatalysts for environmental remediation are summarized. Particular focus is paid to the synthetic strategies for the control of the resulting morphologies, as well as efficient modification strategies for improving the photocatalytic activities. These include boosting the bulk phase by charge separation, enhancing the spatial charge separation, and engineering the surface states. The environmental uses of BiOBr-based photocatalysts are also reviewed in terms of purification of pollutants and CO2 reduction. Finally, future challenges and opportunities of BiOBr-based materials in photocatalysis are discussed. Overall, this review provides a good basis for future exploration of high-efficiency solar-driven photocatalysts for environmental sustainability.
Air batteries are promising energy storage technologies that have gained continuous attraction due to their high energy densities. At present, investigations on anodes of air batteries are usually focused on various metals such as Li, Zn, Al. In contrast, the semiconductor anodes like Si and Ge are less investigated. Si-air battery possesses a high theoretical energy density and Ge-air battery has a high actual power density and ideal safety. Besides anodes, air cathodes where oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are also the key components in air batteries. To further promote the discharging performance and facilitate energy conversion/storage, semiconductor materials have been introduced in electrochemical cells like Li-O2 and Zn-air batteries. This review briefly summarizes semiconductor materials utilized in various air batteries, including the progress of Si-air and Ge-air batteries and recent advances in semiconductor cathodes catalysts. Finally, the remaining challenges and further perspective are discussed.
Heterogeneous nanostructures that are defined as a hybrid structure consisting of two or more nanoscale domains with distinct chemical compositions or physical characteristics have attracted intense efforts in recent years. In this review, we focus on the introduction of a number of heterogeneous nanostructures derived using core-shell Ag-Pt nanoparticles as starting materials, including hollow, dimeric and composite structures and also highlight their application in catalyzing electrochemical reactions, e.g., methanol oxidation reaction and oxygen reduction reaction. This review not only shows the capability of core-shell Ag-Pt nanoparticles in producing various heterogeneous nanostructures as starting templates, but also highlights the structural design or electronic interaction that endows the heterogeneous nanostructures with enhanced catalytic properties either in methanol oxidation or in oxygen reduction. Further, we also make some perspectives for more heterogeneous nanostructures that may be prepared by using core-shell Ag-Pt particles or their derivatives so as to offer the readers the opportunities and challenges in this field.
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