Latest ArticlesFungal alkylresorcinols are a class of polyketides, which are commonly synthesized by the hybridization of highly reducing polyketide synthase (hrPKS) with non-reducing polyketide synthase (nrPKS). In this study, we identified and demonstrated a new assembly model for synthesizing alkylresorcinol (scirpilin A, 1), which was accomplished by collaboration of a hrPKS (FscA) and a type Ⅲ PKS (FscB). Furthermore, three post-tailoring enzymes (FscC, FscD, and FscE) act iteratively on 1 skeleton, including successive 14e− oxidation of inert carbons, di-halogenation, and di-methylation, to form highly oxidized and multi-substituted alkylresorcinols. Our work presents an unusual synthesis manner of alkylresorcinols, sheds light on the collaborative mechanism between hrPKS and type Ⅲ PKS and provides three valuable enzymatic catalysts for the tailoring of alkylresorcinol family natural products in future.
Dynamic assembly on time scale is common in biological systems but rare for artificial materials, especially for smart luminescent materials. Programming molecular assembly in a spatio-temporal manner and resulting in white-light-including multicolor fluorescence with time-dynamic features remains challenging. Herein, controlling molecular assembly on time scale is achieved by integrating a pH-responsive motif to a transient alkaline solution which is fabricated by activators (NaOH) and deactivators (esters), leading to automatic assembly on time scale and time-dependent multicolor fluorescence changing from blue to white and yellow. The kinetics of the assembly process is dependent on the ester hydrolysis process, which can be controlled by varying ester concentrations, temperature, initial pH, stirring rate and ester structures. This dynamic fluorescent system can be further developed for intelligent fluorescent materials such as fluorescent ink, three-dimension (3D) codes and even four-dimension (4D) codes, exhibiting a promising potential for information encryption.
Lithium-sulfur (Li-S) batteries with high theoretical capacity and energy density need to solve problems such as the high decomposition energy barrier of Li2S and large volume change of sulfur in the charging process caused by the shuttle effect before practical application. Herein, a green synthesis method is used to prepare polyacrylic acid (PAA) superabsorbent material, and then the pyrolyzed PAA (P/PAA) material is obtained as the positive electrode of Li-S battery. Density functional calculation reveals that the oxygen self-doping pyrolyzed polyacrylic acid (P/PAA) delivered stronger binding energy toward Li2S species in carbonyl C=O than that of graphite powder (GP) which are −1.58 eV and −1.02 eV, respectively. Coupled with the distribution of relaxation time analysis and the in-situ electrochemical impedance approach, it is further demonstrated that the designed P/PAA as sulfur host plays a physical/chemical adsorption dual function in maintaining the stability and rate performance of batteries. With an initial discharge capacity of 1258 mAh/g at 0.1 C and a minimal capacity decline of 0.05% per cycle even after 800 cycles at 0.5 C, the produced cathode demonstrated outstanding electrochemical performance. The average Coulombic efficiency is nearly 100%. The P/PAA electrodes may typically retain 96% of their capacity while declining on average only 0.033% per cycle after 130 cycles at 3 C. This effort provides a new method for the future development of heteroatomic self-doping superabsorbent with promising adsorption properties for polysulfides as cathode materials of Li-S batteries.
Indole is a biologically active compound formed by the fusion of benzene and pyrrole, and it is widely found in natural products and drugs. Due to the unique structure and properties of indole, its derivatives often exhibit distinctive physiological activities, which has led to widespread attention in the field of pesticide development. Analyzing the design strategies and structure-activity relationships (SARs) of compounds is a crucial step in developing novel pesticides. This review mainly summarizes indole compounds with plant growth regulating, antiviral, fungicidal, herbicidal, and insecticidal activities, with the aim of providing new insights into the discovery and mechanism of action of novel indole-based pesticides.
Due to the advantages of renewable, low pollution and wide distribution of biomass resources, it is selected as the electrode material for supercapacitors. For carbon-based electrode materials, specific surface area and pore structure have a great influence. Exploring and summarizing the influence of activation on pore structure will greatly broaden this field. Based on the activation mechanism of activator, this paper summarizes the latest progress of biomass activation applied to supercapacitors, including traditional physical and chemical activation methods and non-traditional methods such as biological activation method, self-activation method, template assisted activation method and green activator activation. Finally, the challenges, strategies and prospects for the future development of biomass-derived carbon material activation are pointed out. In summary, this review will help researchers choose appropriate strategies to design biomass-derived carbon electrode materials for supercapacitors, thereby promoting the application of biomass materials.
Qubit, as the basic unit of quantum operations, has at least two quantum states for superposition. Diamond itself has no superimposable quantum states, but after injecting N atoms, the resulted nitrogen-vacancy centers form excellent-performance qubits. For the same purpose, we can also obtain qubits by modifying the matrix without effective quantum states. HKUST-1 ({Cu3(BTC)2(H2O)3}, BTC = 1,3,5-benzene-tricarboxylate) with S = 0 ground state is electron paramagnetic resonance (EPR) silent, so it is not a qubit candidate. However, the spontaneously hydrolyzed HKUST-1 produces dilute uncoupled CuⅡ ions with S = 1/2. In this paper, we utilized the hydrolysis products of HKUST-1 to obtain qubits and assembled a core-shell structural HKUST-1@ZIF-8 by ZIF-8 ({Zn(mim)2}, mim = 2-methylimidazole) coated over HKUST-1 for controlling the hydrolysis. The experimental results clearly show that the qubits come from hydrolyzed CuⅡ ions. Furthermore, the dilute uncoupled CuⅡ ions in this assembly can effectively reduce the decoherence of qubits. The EPR studies show that the T2 of this compound is 1067 ns at 10 K.
Phomaketals A (1) and B (2), two tropolonic meroterpenoids with the unprecedented pentacyclic skeletons, were isolated from the solid-substrate fermentation cultures of a eupC overexpressed mutant strain of the fungus Phoma sp., together with a biogenetically related secondary metabolite pughiinin B (3), and the known one noreupenifeldin B (4). The structures of 1–3 were elucidated primarily by nuclear magnetic resonance (NMR) experiments. The absolute configurations of 1 and 2 were assigned by electronic circular dichroism calculations and the calculated NMR with DP4+ analysis, while that of 3 was established by single-crystal X-ray diffraction analysis using Cu Kα radiation. Biogenetically, phomaketals A (1) and B (2) could be derived from the hypothetical tropolonic sesquiterpene intermediates neosetophomone B (6) and 9-R-neosetophomone B (6′), respectively, via different reactions cascades. Compound 1 showed antiproliferative effect only against the SUPB15 cells, with an 50% inhibitory concentration (IC50) value of 4.85 µmol/L, while the co-isolated known meroterpenoid 4 displayed potent effects against three tumor cell lines, SUPB15, EL4, and H9, showing IC50 values of 0.36–27.08 µmol/L.
Mercury ion (Hg2+), as one of the most toxic heavy metal ions, accumulates easily in the environment, which can generate potential hazards to the ecosystem and human health. To effectively detect and remove Hg2+, we fabricated four types of carbon dots (CDs) using carboxymethyl nanocellulose as a carbon source doped with different elements using a hydrothermal method. All the CDs exhibited a strong fluorescence emission, excitation-dependent emission and possessed good water dispersibility. Moreover, the four fluorescent CDs were used for Hg2+ recognition in aqueous solution, where the CDs-N exhibited better sensitivity and selectivity for Hg2+ detection, with a low limit of detection of 8.29 × 10−6 mol/L. It was determined that the fluorescence quenching could be ascribed to a photoinduced charge-transfer processes between Hg2+ and the CDs. In addition, the CDs-N were used as a smart invisible ink for anti-counterfeiting, information encryption and decryption. Furthermore, the CDs-N were immersed into a cellulose (CMC)-based hydrogel network to prepare fluorescent hydrogels capable of simultaneously detecting and adsorbing Hg2+. We anticipate that this research will open possibilities for a green method to synthesize fluorescent CDs for metal ion detection and fluorescent ink production.
Anti-inflammatory drugs targeting inflammatory bowel disease (IBD) have attracted considerable attention but still face low therapeutic outcomes and frequent side effects. Astaxanthin (ATX), a natural ketone, possesses potent antioxidant and anti-inflammatory properties. However, it faces problems such as poor water solubility, photothermal instability, and low bioavailability. Here, we employed a supramolecular encapsulation strategy to create a nanoscale oral delivery system for ATX (referred to as FC-ATX NPs) by coupling fucoidan (FUC) with chitosan oligosaccharides (COS). The obtained FC-ATX NPs exhibited a particular "bean pod" structure with uniform size, good encapsulation efficiency, excellent physical and chemical stability, pH-triggered intestinal targeted slow-release properties, and potent antioxidant capacity. In vitro cell culture experiments showed that FC-ATX NPs promoted cellular uptake and scavenged excessive intracellular reactive oxygen species (ROS). In mouse models of colitis, FC-ATX NPs enhanced the drug absorption of intestinal epithelial cells and effectively accumulated at the site of inflammation. This work provides an efficient approach to enhance the bioavailability of ATX and has excellent application potential as an oral targeted delivery system for colitis therapy.
Covalent bioactive compounds are successfully used in clinic and attracted intense research efforts in the fundamental study as well as drug development. The advantageous effects of covalent compounds compared with non-covalent ones are highly dependent on electrophilic warheads. Hence, electrophilic warheads with tunable reactivity and selectivity are highly demanded in fields of medicinal chemistry and chemical biology. Herein, we report a novel electrophilic warhead, chloromethyl group activated by thiol-substituted 1,2,4-triazole. Interestingly, a pair of regioisomers could be simultaneously occurred in the step of alkylation during the synthesis of this unique motif. This is a rare example that the alkylation could simultaneously generate these two separable regioisomers of 1,2,4-triazole at the nitrogen or sulfur atom. The covalent-working mechanism of this new warhead is confirmed by various chemoproteomics experiments including target identification and binding site mapping. Importantly, the reactivity and selectivity of this new electrophilic warhead could be efficiently tuned by virtue of stereo effect. Interestingly, one pair of regioisomers (19S and 19X) induced distinct modes of cell death. Isomer 19S could induce apoptosis of colon cancer cells while 19X could induce both apoptosis and ferroptosis. Together, this study provides pairs of novel electrophilic warheads that could be useful not only in supporting the design of covalent compounds for drug discovery but also in providing chemical probes for the fundamental biological study.
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