Asymmetric triplex metallohelices stabilise DNA G-quadruplexes in promoter oncogene sequences and efficiently reduce their expression in cancer cells.

Some metallo-supramolecular helical assemblies with size, shape, charge and amphipathic architectures similar to short cationic α-helical peptides have been shown to target and stabilise DNA G-quadruplexes (G4s) in vitro and downregulate the expression of G4-regulated genes in human cells. To expand the library of metallohelical structures that can act as efficient DNA G4 binders and downregulate genes containing G4-forming sequences in their promoter regions, we investigated the interaction of the two enantiomeric pairs of asymmetric Fe(II) triplex metallohelices with a series of five different DNA G4s formed by the human telomeric sequence (hTelo) and in the promoter regions of c-MYC, c-KIT, and k-RAS oncogenes. The metallohelices display preferential binding to G4s over duplex DNA in all investigated G4-forming sequences and induced arrest of DNA polymerase on template strands containing G4-forming sequences. Moreover, the investigated metallohelices suppressed the expression of c-MYC and k-RAS genes at mRNA and protein levels in HCT116 human cancer cells, as revealed by RT-qPCR analysis and western blotting.

Impact of salinity on anaerobic ceramic membrane bioreactor for textile wastewater treatment: Process performance, membrane fouling and machine learning models.

Anaerobic membrane bioreactor (AnMBR) shows great potential for textile wastewater treatment, but high salinity in the influent may undermine its performance. This study evaluated the impact of salinity on the treatment performance of an upflow anaerobic sludge blanket (UASB) configured AnMBR using a flat sheet ceramic membrane. The salinity was stepwise increased (0, 5, 10 and 20 g/L) in four phases of the AnMBR operation. Results indicated that increased salinity jeopardized the COD removal efficiency of AnMBR from 92% to 73%, but had a marginal effect on dye removal efficacy (90-96%). Low salinity (5 g/L) boosted the biogas production whilst high salinity (>10 g/L) had a negative impact. Additionally, the increase of salinity resulted in the soluble microbial production (SMP) concentration soar and membrane fouling rate increase, peaking at a salinity of 10 g/L (Phase III) and recovering back to a lower level at a salinity of 20 g/L (Phase IV). This indicated a transition occurrence at a salinity of 10 g/L (Phase III). The microbial diversity analyses further suggested a transition from salinity-sensitive microbes (Aminiphilus, Caldatribacterium, Mesotoga, Methanobrevibacter, Methanobacterium, Methanosaeta) to salinity-tolerant microbes (Longilinea, Ignavibacterium, Rhodovarius, Bosea and Flexilinea). This transition can be associated with the increase SMP concentration and more severe membrane fouling in Phase III, which were mitigated after a new equilibrium was reached when the microbial consortium acclimatized to the high salinity. Finally, a machine learning model of the Adaboost algorithm was established to predict COD removal under different salinities. Importantly, this study revealed that AnMBR process performance and membrane operation can be maintained for high salinity textile wastewater treatment with a halophilic microbial community growth under high-salinity selection pressure.

Glycoconjugated Metallohelices have Improved Nuclear Delivery and Suppress Tumour Growth In Vivo.

Monosaccharides are added to the hydrophilic face of a self-assembled asymmetric FeII metallohelix, using CuAAC chemistry. The sixteen resulting architectures are water-stable and optically pure, and exhibit improved antiproliferative selectivity against colon cancer cells (HCT116 p53+/+ ) with respect to the non-cancerous ARPE-19 cell line. While the most selective compound is a glucose-appended enantiomer, its cellular entry is not mainly glucose transporter-mediated. Glucose conjugation nevertheless increases nuclear delivery ca 2.5-fold, and a non-destructive interaction with DNA is indicated. Addition of the glucose units affects the binding orientation of the metallohelix to naked DNA, but does not substantially alter the overall affinity. In a mouse model, the glucose conjugated compound was far better tolerated, and tumour growth delays for the parent compound (2.6 d) were improved to 4.3 d; performance as good as cisplatin but with the advantage of no weight loss in the subjects.

Mirror-Image Dependence: Targeting Enantiomeric G-Quadruplex DNA Using Triplex Metallohelices.

Natural d-DNA and l-DNA are mirror-image counterparts. However, because of the inherent flexibility and conformation diversity of DNA, it is still not clear how enantiomeric compounds recognize d-DNA and l-DNA. Herein, taking G-quadruplex (G4) DNA as an example that has diverse conformations and distinct biofunctions, the binding of ten pairs of iron triplex metallohelices to d- and l-G4 DNA were evaluated. The Δ-enantiomer binds to d-DNA and the Λ-enantiomer binds to l-DNA, exhibiting almost the same stabilization effect and binding affinity. The binding affinity of the Δ-metallohelix with d-G4 is nearly 70-fold higher than that of Λ-metallohelix binding d-G4. Δ-Metallohelix binding to d-G4 follows a two-step binding process driven by a favorable enthalpy contribution to compensate for the associated unfavorable entropy.

Synthesis and evaluation of novel alkannin and shikonin oxime derivatives as potent antitumor agents.

A set of forty alkannin and shikonin oxime derivatives were firstly designed and synthesized. Their cytotoxicities against three kinds of tumor cells and a normal cell line were tested and compared with alkannin and shikonin. The cell-based investigation demonstrated that some oxime derivatives were more or comparatively effective to the lead compounds, especially their selective and excellent antitumor activities towards K562 cells with no toxicity in normal cells. We may conclude that oximate modification to the mother nucleus of alkannin and shikonin is an available approach to acquire potent antitumor agents.

Analyzing urinary hippuric acid as a metabolic health biomarker through a supramolecular architecture.

The prevalence of metabolic disorders has been found to increase concomitantly with alternations in habitual diet and lifestyle, indicating the importance of metabolic health monitoring for early warning of high-risk status and suggesting effective intervention strategies. Hippuric acid (HA), as one of the most abundant metabolites from the gut microbiota, holds potential as a regulator of metabolic health. Accordingly, it is imperative to establish an efficient, sensitive, and affordable method for large-scale population monitoring, revealing the association between HA level and metabolic disorders. Upon systematic screening of macrocycle•dye reporter pair, a supramolecular architecture (guanidinomethyl-modified calix[5]arene, GMC5A) was employed to sense urinary HA by employing fluorescein (Fl), whose complexation behavior was demonstrated by theoretical calculations, accomplishing quantification of HA in urine from 249 volunteers in the range of 0.10 mM and 10.93 mM. Excitedly, by restricted cubic spline, urinary HA concentration was found to have a significantly negative correlation with the risk of metabolic disorders when it exceeded 0.76 mM, suggesting the importance of dietary habits, especially the consumption of fruits, coffee, and tea, which was unveiled from a simple questionnaire survey. In this study, we accomplished a high throughput and sensitive detection of urinary HA based on supramolecular sensing with the GMC5A•Fl reporter pair, which sheds light on the rapid quantification of urinary HA as an indicator of metabolic health status and early intervention by balancing the daily diet.

Exercise ameliorates chronic inflammatory response induced by high-fat diet via Sestrin2 in an Nrf2-dependent manner.

Chronic inflammation is a major contributor to the development of metabolic disorders and is commonly seen in studies of diet-induced obesity in humans and rodents. Exercise has been shown to have anti-inflammatory properties, though the exact mechanisms are still not fully understood. Sestrins and Nrf2 are of interest to researchers as they are known to protect against inflammation and oxidative stress. In this study, we aim to explore the interconnection between Sestrin2 (SESN2) and Nrf2 and their roles in exercise benefits on chronic inflammation. Our data showed that SESN2 knockout aggravated the abnormalities of body weight, fat mass, and serum lipid that were induced by a high-fat diet (HFD), and a concomitant increase of TNF-α, IL-1ß and IL-6 in both serum and skeletal muscle. Notably, exercise was found to reverse these changes, and SESN2 was found to be necessary for exercise to reduce the inflammatory response in skeletal muscles, though not in serum. Immunoprecipitation and bioinformatics prediction experiments further revealed that SESN2 directly binds to Nrf2, indicating a protein-protein interaction between the two. Furthermore, our data demonstrated that SESN2 protein is necessary for exercise-induced effects on Nrf2 pathway in HFD-fed mice, and Nrf2 protein is necessary to enable SESN2 to reduce the inflammation caused by palmitic acid (PA)+ oleic acid (OA) treatment in vitro. Our findings indicate that exercise mitigates chronic inflammation induced by HFD through SESN2 in an Nrf2-dependent manner. Our study reveals a novel molecular mechanism whereby the SESN2/Nrf2 pathway mediates the positive impact of exercise on chronic inflammation.

In vivo visualization of enantioselective targeting of amyloid and improvement of cognitive function by clickable chiral metallohelices.

The pathogenesis of Alzheimer's disease (AD) is closely related to several contributing factors, especially amyloid-ß (Aß) aggregation. Bioorthogonal reactions provide a general, facile, and robust route for the localization and derivatization of Aß-targeted agents. Herein, a pair of chiral alkyne-containing metallohelices (ΛA and ΔA) were demonstrated to enantioselectively target and modulate Aß aggregation, which has been monitored in triple-transgenic AD model mice and proved to improve cognitive function. Compared with its enantiomer ΔA, ΛA performed better in blocking Aß fibrillation, relieving Aß-triggered toxicity, and recovering memory deficits in vivo. Moreover, clickable ΛA could act as a functional module for subsequent visualization and versatile modification of amyloid via bioorthogonal reaction. As a proof-of-concept, thioflavin T, tacrine, and magnetic nanoparticles were conjugated with ΛA to realize Aß photo-oxygenation, acetylcholinesterase inhibition, and Aß clearance, respectively. This proof-of-principle work provided new insights into the biolabeling and bioconjugation of multifunctional metallosupramolecules through click reactions for AD therapy.

Enantioselective Degrader for Elimination of Extracellular Aggregation-Prone Proteins hIAPP Associated with Type 2 Diabetes.

Targeted protein degradation has demonstrated the power to modulate protein homeostasis. For overcoming the limitation to intracellular protein degradation, lysosome targeting chimeras have been recently developed and successfully utilized to degrade a range of disease-relevant extracellular and membrane proteins. Inspired by this strategy, here we describe our proof-of-concept studies using metallohelix-based degraders to deliver the extracellular human islet amyloid polypeptide (hIAPP) into the lysosomes for degradation. Our designed metallohelix can bind and inhibit hIAPP aggregation, and the conjugated tri-GalNAc motif can target macrophage galactose-type lectin 1 (MGL1), yielding chimeric molecules that can both inhibit hIAPP aggregation and direct the bound hIAPP for lysosomal degradation in macrophages. Further studies demonstrate that the enhanced hIAPP clearance has been through the endolysosomal system and depends on MGL1-mediated endocytosis. Intriguingly, Λ enantiomers show even better efficiency in preventing hIAPP aggregation and promoting internalization and degradation of hIAPP than Δ enantiomers. Moreover, metallohelix-based degraders also faciltate the clearance of hIAPP through asialoglycoprotein receptor in liver cells. Overall, our studies demonstrate that chiral metallohelix can be employed for targeted degradation of extracellular misfolded proteins and possess enantioselectivity.

Current approaches and strategies to identify Hedgehog signaling pathway inhibitors for cancer therapy.

The Hedgehog signaling pathway plays a vital role in embryonic development and tissue patterning. Aberrant regulation of this pathway is commonly associated with the occurrence, development and progression of various types of malignancies. The development of inhibitors targeting Hedgehog pathway has attracted significant interests in cancer therapy and led to the discovery of three drugs Vismodegib, Sonidegib and Glasdegib. However, their clinical application has been hampered due to adverse effects and resistance issues, highlighting the urgent need for new inhibitors. Herein we give a systematic overview of the current status and characteristics of various approaches to developing the Hedgehog pathway inhibitors, including library screening, natural product-oriented approach, analogue approach, drug repositioning, in silico tools and others. The future prospects are also discussed for the discovery and development of next-generation inhibitors.

Recycling sludge-derived hydrochar to facilitate advanced denitrification of secondary effluent: Role of extracellular electron transfer.

Sludge-derived hydrochar (SDHC) was recycled to enhance the denitrification of secondary effluent. Under different carbon to nitrogen (C/N) ratios, the nitrogen removal efficiency (NRE) and carbon source efficiency (CSE) of denitrification coupled with SDHC (DN-SDHC) were distinctly higher than that of denitrification alone (DN). Moreover, at the C/N ratios of 3.0-3.2 and 5.8-5.9, the nitrogen removal rate (NRR) of DN-SDHC was 3.6- and 1.5-fold that of DN, respectively. The characterization of SDHC before and after used in denitrification indicated that the metal ions and functional groups did not participate in denitrification. Although SDHC has no redox capacity to donate electron for denitrification, its higher conductivity enabled the acceleration of extracellular electron transfer from carbon source to denitrifiers. The abundance of denitrifying community and functional genes was synchronously promoted by SDHC. Especially, the significant increase of nosZ gene encoding nitrous oxide reductase was conducive to mitigating the emission of N2O greenhouse gas.

Metallohelices emulate the properties of short cationic α-helical peptides.

Naturally occurring peptides in many living systems perform antimicrobial and anticancer host defence roles, but their potential for clinical application is limited by low metabolic stability and relatively high costs of goods. Self-assembled helical metal complexes provide an attractive synthetic platform for non-peptidic architectures that can emulate some of the properties of short cationic α-helical peptides, with tuneable charge, shape, size and amphipathicity. Correspondingly there is a growing body of evidence demonstrating that these supramolecular architectures exhibit bioactivity that emulates that of the natural systems. We review that evidence in the context of synthetic advances in the area, driven by the potential for biomedical applications. We note some design considerations for new biologically-relevant metallohelices, and give our outlook on the future of these compounds as therapeutic peptidomimetics.

Triazole-based, optically-pure metallosupramolecules; highly potent and selective anticancer compounds.

Functionalised triazole aldehydes are used in the highly selective self-assembly of water-compatible, optically pure, low symmetry Fe(ii)- and Zn(ii)-based metallohelices. Sub-micromolar antiproliferative activity is observed against various cancerous cell lines, accompanied by excellent selectivity versus non-cancerous cells and potential for synergistic combinatorial therapy with cisplatin.

Discovery of selective, antimetastatic and anti-cancer stem cell metallohelices via post-assembly modification.

Helicates and related metallofoldamers, synthesised by dynamic self-assembly, represent an area of chemical space inaccessible by traditional organic synthesis, and yet with potential for discovery of new classes of drug. Here we report that water-soluble, optically pure Fe(ii)- and even Zn(ii)-based triplex metallohelices are an excellent platform for post-assembly click reactions. By these means, the in vitro anticancer activity and most importantly the selectivity of a triplex metallohelix Fe(ii) system are dramatically improved. For one compound, a remarkable array of mechanistic and pharmacological behaviours is discovered: inhibition of Na+/K+ ATPase with potency comparable to the drug ouabain, antimetastatic properties (including inhibition of cell migration, re-adhesion and invasion), cancer stem cell targeting, and finally colonosphere inhibition competitive with the drug salinomycin.

Metallohelices that kill Gram-negative pathogens using intracellular antimicrobial peptide pathways.

A range of new water-compatible optically pure metallohelices - made by self-assembly of simple non-peptidic organic components around Fe ions - exhibit similar architecture to some natural cationic antimicrobial peptides (CAMPs) and are found to have high, structure-dependent activity against bacteria, including clinically problematic Gram-negative pathogens. A key compound is shown to freely enter rapidly dividing E. coli cells without significant membrane disruption, and localise in distinct foci near the poles. Several related observations of CAMP-like mechanisms are made via biophysical measurements, whole genome sequencing of tolerance mutants and transcriptomic analysis. These include: high selectivity for binding of G-quadruplex DNA over double stranded DNA; inhibition of both DNA gyrase and topoisomerase I in vitro; curing of a plasmid that contributes to the very high virulence of the E. coli strain used; activation of various two-component sensor/regulator and acid response pathways; and subsequent attempts by the cell to lower the net negative charge of the surface. This impact of the compound on multiple structures and pathways corresponds with our inability to isolate fully resistant mutant strains, and supports the idea that CAMP-inspired chemical scaffolds are a realistic approach for antimicrobial drug discovery, without the practical barriers to development that are associated with natural CAMPS.

Stereochemistry and amyloid inhibition: Asymmetric triplex metallohelices enantioselectively bind to Aß peptide.

Stereochemistry is vital for pharmaceutical development and can determine drug efficacy. Herein, 10 pairs of asymmetric triplex metallohelix enantiomers as a library were used to screen inhibitors of amyloid ß (Aß) aggregation via a fluorescent cell-based high-throughput method. Intriguingly, Λ enantiomers show a stronger inhibition effect than Δ enantiomers. In addition, the metallohelices with aromatic substituents are more effective than those without, revealing that these groups play a key role in the Aß interaction. Fluorescence stopped-flow kinetic studies indicate that binding of the Λ enantiomer to Aß is much faster than that of the Δ enantiomer. Furthermore, studies in enzyme digestion, isothermal titration calorimetry, nuclear magnetic resonance, and computational docking demonstrate that the enantiomers bind to the central hydrophobic α-helical region of Aß13-23, although with different modes for the Λ and Δ enantiomers. Finally, an in vivo study showed that these metallohelices extend the life span of the Caenorhabditis elegans CL2006 strain by attenuating Aß-induced toxicity. Our work will shed light on the design and screening of a metal complex as an amyloid inhibitor against Alzheimer's disease.

Design, synthesis, and biological evaluation of shikonin and alkannin derivatives as potential anticancer agents via a prodrug approach.

To minimize the cytotoxicity of shikonin and alkannin that arises through the generation of reactive oxygen species (ROS) and alkylation of the naphthazarin ring, two series of novel core-scaffold-modified shikonin and alkannin derivatives were designed. These derivatives, which differ in their configurational and positional isomerism (R-, S-, and 2- and 6-isomers) were synthesized in high enantiomeric excess (>99 % ee). The selectivity of the dimethylated derivatives was significantly higher than the parent shikonin in vitro, but some side effects were still observed in vivo. Surprisingly, the dimethylated diacetyl derivatives with poor anticancer activity in vitro showed tumor-inhibiting effects similar to paclitaxel without any toxicity in vivo. The anticancer activity of these derivatives is in agreement with their low ROS generation and alkylating capacity, emphasizing their potential as prodrugs. This strategy provides means to address the nonspecific cytotoxicity of naphthazarin analogues toward normal cells.

Kinesin spindle protein (KSP) inhibitors in combination with chemotherapeutic agents for cancer therapy.

A diverse group of proteins, the activities of which are precisely orchestrated during mitosis, have emerged as targets for cancer therapeutics; these include the Aurora kinases (AKs), Polo-like kinases (PLKs), and the kinesin spindle protein (KSP). KSP is essential for the proper separation of spindle poles during mitosis. Agents that target KSP selectively act on cells undergoing cell division, which means that KSP inhibitors are mitosis-specific drugs, and have demonstrated remarkable activities in vitro. However, a significant obstacle to the success of KSP inhibitors is that these compounds, with tremendous efficacy in vitro, have demonstrated little or even no antitumor activity in vivo. Accumulated data suggest that a combination of KSP inhibitors with various cytostatic drugs will result in a more powerful tumor-killing effect than monotherapy. Combination therapies might predominate and represent the next frontier in the discovery research of KSP inhibitors as potential anticancer drugs. Few published studies have reviewed combination therapy using KSP inhibitors. Herein we provide a comprehensive review of the literature on KSP inhibitor monotherapy and therapeutic combinations. The current state and problems are also discussed.

Synthesis and antibacterial activity of novel 11,12-cyclic carbonate azithromycin 4''-O-carbamate derivatives.

A series of novel 11,12-cyclic carbonate azithromycin 4''-O-carbamate derivatives were designed, synthesized and evaluated for their in vitro antibacterial activities. Compounds 7b and 7d were the most effective (0.5 and 0.5 microg ml(-1)) against two strains of erythromycin-resistant Streptococcus pneumoniae whose resistance was encoded by the erm gene and the erm and mef genes, respectively. Compounds 7a, 7e and 7g showed significantly potent activity against erythromycin-susceptible strains such as Staphylococcus aureus and S. pyogenes. These results suggest that the introduction of the prolonged arylalkylcarbamoyl group to the C-4'' position can dramatically enhance the activity against erythromycin-resistant bacteria encoded by the erm gene or the erm and mef genes.