Inspired by bis-ß-carboline alkaloids: Construction and antitumor evaluation of a novel bis-ß-carboline scaffold as potent antitumor agents.

Bis-ß-carboline alkaloids are widely distributed in natural products and represent a promising drug-like scaffold for discovering drugs and bioactive molecules. In this study, we utilized the structural simplification strategy to construct a novel bis-ß-carboline scaffold via "one-pot" condensation-Mannich reaction. The simplified bis-ß-carboline derivatives were obtained in good yield. Antitumor evaluation revealed most compounds, especially 3m, displayed potent antitumor activity (IC50 values for 3m: 0.96 µM âˆ¼ 1.52 µM). More importantly, 3m displayed valuable antitumor properties including anti-migration and anti-invasion activity against cancer cells, antiangiogenic and vascular-disrupting properties. Mechanistic studies revealed 3m potently inhibited both Top1 and Top2 activity, thus interfering with DNA synthesis in cancer cells. Taken together, this study developed a new synthetic methodology to construct a novel bis-ß-carboline scaffold, which represents a promising lead structure for antitumor drug discovery.

Discovery of potent tubulin inhibitors targeting the colchicine binding site via structure-based lead optimization and antitumor evaluation.

The colchicine binding site of tubulin is a promising target for discovering novel antitumour agents. Previously, we identified 2-aryl-4-amide-quinoline derivatives displayed moderate tubulin polymerisation inhibitory activity and broad-spectrum in vitro antitumour activity. In this study, structure based rational design and systematic structural optimisation were performed to obtain analogues C1∼J2 bearing diverse substituents and scaffolds. Among them, analogue G13 bearing a hydroxymethyl group displayed good tubulin polymerisation inhibitory activity (IC50 = 13.5 µM) and potent antiproliferative activity (IC50 values: 0.65 µM∼0.90 µM). G13 potently inhibited the migration and invasion of MDA-MB-231 cells, and displayed potent antiangiogenic activity. It efficiently increased intracellular ROS level and decreased MMP in cancer cells, and obviously induced the fragmentation and disassembly of the microtubules network. More importantly, G13 exhibited good in vivo antitumour efficacy in MDA-MB-231 xenograft model (TGI = 38.2%; i.p., 30 mg/kg).

Crystal Growth, Structural Transition, and Magnetic Properties of Ho5Pd4Sn12.

Single crystals and polycrystalline samples of Ho5Pd4Sn12 have been synthesized using flux and arc-melting methods, respectively. Single-crystal X-ray diffraction studies indicate that Ho5Pd4Sn12 crystallizes in a tetragonal structure (I4/m) at room temperature and transforms into a monoclinic structure (C2/m) below ∼194 K. This structural transition is further supported by a transmission electron microscopy study and an anomaly at ∼194 K in the specific heat data. Temperature-dependent resistivity data also show a kink around the structural transition temperature. Ho5Pd4Sn12 is antiferromagnetically ordered below 7 K. Ho5Pd4Sn12 shows magnetic anisotropy, and the isothermal magnetization curve (H⊥c) at 2 K exhibits a field-induced magnetic phase transition around 22.8 kOe.

The cytoplasmic tail of rhodopsin triggers rapid rod degeneration in kinesin-2 mutants.

Photoreceptor degeneration can lead to blindness and represents the most common form of neural degenerative disease worldwide. Although many genes involved in photoreceptor degeneration have been identified, the underlying mechanisms remain to be elucidated. Here we examined photoreceptor development in zebrafish kif3a and kif3b mutants, which affect two subunits of the kinesin-2 complex. In both mutants, rods degenerated quickly, whereas cones underwent a slow degeneration process. Notably, the photoreceptor defects were considerably more severe in kif3a mutants than in kif3b mutants. In the cone photoreceptors of kif3a mutants, opsin proteins accumulated in the apical region and formed abnormal membrane structures. In contrast, rhodopsins were enriched in the rod cell body membrane and represented the primary reason for rapid rod degeneration in these mutants. Moreover, removal of the cytoplasmic tail of rhodopsin to reduce its function, but not decreasing rhodopsin expression levels, prevented rod degeneration in both kif3a and kif3b mutants. Of note, overexpression of full-length rhodopsin or its cytoplasmic tail domain, but not of rhodopsin lacking the cytoplasmic tail, exacerbated rod degeneration in kif3a mutants, implying an important role of the cytoplasmic tail in rod degeneration. Finally, we showed that the cytoplasmic tail of rhodopsin might trigger rod degeneration through activating the downstream calcium signaling pathway, as drug treatment with inhibitors of intracellular calcium release prevented rod degeneration in kif3a mutants. Our results demonstrate a previously unknown function of the rhodopsin cytoplasmic domain during opsin-triggered photoreceptor degeneration and may open up new avenues for managing this disease.

Deeds and Words: Farmers' Attitude-Paradox in Collective Action for Small-Scale Irrigation.

We explore the mechanisms of the attitude-behavior paradox and how multiple stakeholders strategize to compromise their attitudes and behaviors. Through an instrumental variable probit model, we examine the effect of income heterogeneity and social ties on the farmers' attitude-behavior paradox for collective action. The empirical results demonstrate that weak and strong ties, income heterogeneity, interaction terms, education, community environment, and community rules negatively affect the paradox, whereas water stealing and water use conflicts positively affect it. After dividing the paradox into two forms, we find that weak ties, the interaction terms thereof, negatively affect the paradox for "having negative attitude but do have behavior", while income heterogeneity negatively affects the paradox for "having positive attitude but no behavior". We contribute to the understanding of mechanisms whereby economic incentives and social structures interplay in addressing the above paradox. We conclude by discussing the implications for policies to overcome this social dilemma.

Co-immobilization of laccase and ABTS onto amino-functionalized ionic liquid-modified magnetic chitosan nanoparticles for pollutants removal.

This work aims to achieve the co-immobilization of laccase and 2,2-binamine-di-3-ethylbenzothiazolin-6-sulfonic acid (ABTS) to improve removal capability of the biocatalyst for pollutants while avoiding potential pollution caused by ABTS. The laccase was immobilized on magnetic chitosan nanoparticles modified with amino-functionalized ionic liquid containing ABTS (MACS-NIL) based on Cu ion chelation (MACS-NIL-Cu-lac). The carrier was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, x-ray diffraction and etc., and electron paramagnetic resonance confirmed the mediator molecule ABTS on the carrier could also play the role of electron transmission. MACS-NIL-Cu-lac presented relatively high immobilization capacity, enhanced activity (1.7-fold that of free laccase), improved pH and temperature adaptability, and increased thermal and storage stability. The removal performance assay found that MACS-NIL-Cu-lac had a good removal efficiency with 100.0 % for 2,4-dichlorophenol in water at 25 °C, even when the concentration reached 50 mg/L. Reusability study showed that after six catalytic runs, the removal efficiency of 2,4-dichlorophenol by MACS-NIL-Cu-lac could still reach 93.2 %. Additionally, MACS-NIL-Cu-lac exhibited higher catalytic efficiencies with 100.0 %, 70.5 % and 93.3 % for bisphenol A, indole, and anthracene, respectively. The high catalytic performance in pure water system obtained by the novel biocatalyst co-immobilizing laccase and electron mediator ABTS showed greater practical application value.