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Acute kidney injury (AKI) is a global public health problem with its pathogenesis not fully understood. Excessive apoptosis of renal tubular epithelial cells is an important feature of AKI patients, and therefore an anti-apoptotic approach could be used in the treatment for AKI. Up-regulation of B-cell lymphoma-2 (BCL-2) gene and protein has been found to be correlated with anti-apoptosis of cells. It has been found that the presence of the C-rich sequence on the upstream region of the BCL-2 gene promoter could form DNA secondary i-motif structure, and its stabilization by small molecules could up-regulate gene transcription and translation. In the present study, we constructed AKI models through folic acid (FA) induction. With these in vitro and in vivo models, we demonstrated that the acridone derivative A22 could up-regulate the expression of BCL-2 by targeting its gene promoter i-motif to reduce renal tubular epithelial cell apoptosis and improve renal function in many ways. A22 could alleviate FA-induced oxidative stress injury, inflammatory response, and endoplasmic reticulum stress in mouse kidneys. Our results provided a potentially new anti-apoptotic approach for the treatment of early stages of AKI. Our employed model focused on its short-term effect on AKI, while its long-term efficacy and safety, particularly regarding the regeneration of renal tubular epithelial cells, require further investigation before clinical application. This study further demonstrated that promoter i-motif could be targeted for up-regulating BCL-2 expression for the treatment of important diseases caused by excessive apoptosis. [ABSTRACT FROM AUTHOR]

Aims: Obesity always leads to profound perturbation of metabolome. Metabolome studies enrich the knowledge on associations between endogenous metabolites and obesity, potentially providing innovative strategies for the development of novel anti‐obesity pharmacotherapy. This study aims to identify an endogenous metabolite that regulates energy expenditure and to explore its application for obesity treatment. Materials and Methods: C57BL/6 mice were fed with a high‐fat and high‐cholesterol (HFC) diet, comprising 60% fat and 1.2% cholesterol, for 12 weeks to induce obesity. Significant metabolites were identified in the livers of both health and obese mice through comparative hepatic metabolomics analysis. Correlation between serum or adipose L‐aspartate level and body weight in obese mice, as well as human body mass index (BMI), was evaluated. In addition, saline or 200 mg/kg L‐aspartate was orally administrated to HFC diet mice and HFC diet‐induced obese mice for 6–7 weeks. Body weight, adipose tissue weight, glucose tolerance and liver damage were assessed to evaluate the effect on obesity prevention and treatment. Comprehensive lab animal monitoring system (CLAMS) and seahorse assay were employed to investigate the regulatory effect of L‐aspartate on energy metabolism in vivo and in vitro, respectively. 3T3‐L1 preadipocytes and murine white adipose tissue (WAT) were utilized to examine the impact of L‐aspartate on adipocyte adipogenesis and lipogenesis and cellular signalling pathway in vitro and in vivo. Results: L‐aspartate, an approved drug for liver injury and chronic fatigue, was identified as an endogenous inducer of energy expenditure. Serum or adipose L‐aspartate levels were found to be negatively correlated with the severity of obesity in both humans and mice. Administration of L‐aspartate to HFC diet mice led to a significant reduction in body weight, with decreases of 14.5% in HFC diet mice and 8.5% in HFC diet‐induced obese mice, respectively. In addition, the treatment improved related metabolic syndrome (Figure 2 and Figure S3). These therapeutics were associated with enhancements in whole‐body energy expenditure and suppression of adipocyte adipogenesis along with activation of Adenosine 5′‐monophosphate‐activated protein kinase (AMPK) signalling pathway. Conclusion: L‐aspartate may serve as a novel endogenous inducer of energy expenditure and suppressor of adipogenesis and lipogenesis along with activation of AMPK, thereby offering a promising therapeutic strategy for obesity prevention and treatment. [ABSTRACT FROM AUTHOR]

Both the pyrroloindoline core and N–CF3 moiety hold significant importance in medicinal chemistry. However, to date, no instances of constructing N–CF3-containing pyrroloindolines have been reported. Herein, we present a robust and operationally simple approach to assembling such intriguing skeletons from tryptamine-derived isocyanides through a cascade sequence, which includes an oxidative trifluorination and a subsequent halogenative cyclization. Key to the success lies in the development of a facile conversion of isocyanides to N–CF3 moiety with commercially available reagents N-halosuccinimide and Et3N·HF. The protocol features mild reaction conditions, broad functional group tolerance, good to excellent yields, and high diastereoselectivities. In addition, we demonstrate that the halide substituent within the products serves as a versatile functional handle for accessing diverse C3-quaternary-substituted N–CF3-pyrroloindolines. Both the pyrroloindoline core and N–CF3 moiety hold significant importance in medicinal chemistry. Herein, the authors present a simple approach to assembling such intriguing skeletons from tryptamine-derived isocyanides through a cascade sequence, which includes an oxidative trifluorination and a subsequent halogenative cyclization. [ABSTRACT FROM AUTHOR]

Both the pyrroloindoline core and N–CF3 moiety hold significant importance in medicinal chemistry. However, to date, no instances of constructing N–CF3-containing pyrroloindolines have been reported. Herein, we present a robust and operationally simple approach to assembling such intriguing skeletons from tryptamine-derived isocyanides through a cascade sequence, which includes an oxidative trifluorination and a subsequent halogenative cyclization. Key to the success lies in the development of a facile conversion of isocyanides to N–CF3 moiety with commercially available reagents N-halosuccinimide and Et3N·HF. The protocol features mild reaction conditions, broad functional group tolerance, good to excellent yields, and high diastereoselectivities. In addition, we demonstrate that the halide substituent within the products serves as a versatile functional handle for accessing diverse C3-quaternary-substituted N–CF3-pyrroloindolines.Both the pyrroloindoline core and N–CF3 moiety hold significant importance in medicinal chemistry. Herein, the authors present a simple approach to assembling such intriguing skeletons from tryptamine-derived isocyanides through a cascade sequence, which includes an oxidative trifluorination and a subsequent halogenative cyclization. [ABSTRACT FROM AUTHOR]

Electrophilic addition reaction to alkynes is of fundamental importance in organic chemistry, yet the regiocontrol when reacting with unsymmetrical 1,2‐dialkyl substituted alkynes is often problematic. Herein, it is demonstrated that the rarely recognized β‐boron effect can confer a high level of site‐selectivity in several alkyne electrophilic addition reactions. A broad range of highly functionalized and complex organoborons are thus formed under simple reaction conditions starting from propargylic MIDA (N‐methyliminodiacetic acid) boronates. These products are demonstrated to be valuable building blocks in organic synthesis. In addition to the regiocontrol, this study also observes a drastic rate enhancement upon B(MIDA) substitution. Theoretical calculation reveals that the highest occupied molecular obital (HOMO) energy level of propargylic B(MIDA) is significantly raised by 0.3 eV, and the preferential electrophilic addition to the γ position is due to its higher HOMO orbital coefficient and more negative natural bond orbital (NBO) charge compared to the β position. This study demonstrates the potential of utilizing the β‐boron effect in stereoelectronic control of chemical transformations, which can inspire further research in this area. [ABSTRACT FROM AUTHOR]

Organofluorine compounds have been widely used in pharmaceutical, agrochemical, and material sciences. Reported herein are divergent fluorination reactions of vinylcyclopropanes with different electrophiles, which allow the facile synthesis of homoallylic monofluorides and vicinal‐difluorides through ring‐opening 1,5‐hydrofluorination and ring‐retaining 1,2‐difluorination, respectively. Both protocols feature mild conditions, simple operations, good functional group tolerance, and generally good yields. The practicality of these reactions is demonstrated by their scalability, as well as the successful conversion of the formed homoallylic monofluorides into other complex fluorinated molecules. [ABSTRACT FROM AUTHOR]

MSN8C, an analog of mansonone E, has been identified as a novel catalytic inhibitor of human DNA topoisomerase II that induces tumor regression and differs from VP-16(etoposide). Treatment with MSN8C showed significant antiproliferative activity against eleven human tumor cell lines in vitro. It was particularly effective against the HL-60/MX2 cell line, which is resistant to Topo II poisons. The resistance factor (RF) of MSN8C for Topo II in HL-60/MX2 versus HL-60 was 1.7, much lower than that of traditional Topo II poisons. Furthermore, in light of its potent antitumor efficacy and low toxicity, as demonstrated in the A549 tumor xenograft model, MSN8C has been identified as a promising candidate for antitumor applications. [ABSTRACT FROM AUTHOR]

Helicases are crucial enzymes in DNA and RNA metabolism and function by unwinding particular nucleic acid structures. However, most convenient and high-throughput helicase assays are limited to the typical duplex DNA. Herein, we developed an immunosorbent assay to monitor the Werner syndrome (WRN) helicase unwinding a wide range of DNA structures, such as a replication fork, a bubble, Holliday junction, G-quadruplex and hairpin. This assay could sensitively detect the unwinding of DNA structures with detection limits around 0.1 nM, and accurately monitor the substrate-specificity of WRN with a comparatively less time-consuming and high throughput process. Remarkably, we have established that this new assay was compatible in evaluating helicase inhibitors and revealed that the inhibitory effect was substrate-dependent, suggesting that diverse substrate structures other than duplex structures should be considered in discovering new inhibitors. Our study provided a foundational example for using this new assay as a powerful tool to study helicase functions and discover potent inhibitors. [ABSTRACT FROM AUTHOR]

Mitochondria have a crucial role in regulating energy metabolism and their dysfunction has been linked to tumorigenesis. Cancer diagnosis and intervention have a great interest in the development of new agents that target biomolecules within mitochondria. However, monitoring and modulating mitochondria RNA (mtRNA), an essential component in mitochondria, in cells is challenging due to limited functional research and the absence of targeting agents. In this study, we designed and synthesized a fluorescent quinolinium derivative, QUCO-1, which actively lit up with mtRNA in both normal and cancer cells in vitro. Additionally, we evaluated the function of QUCO-1 as an mtRNA ligand and found that it effectively induced severe mitochondrial dysfunction and OXPHOS inhibition in RKO colorectal cancer cells. Treatment with QUCO-1 resulted in apoptosis, cell cycle blockage at the G2/M phase, and the effective inhibition of cell proliferation. Our findings suggest that QUCO-1 has great potential as a promising probe and therapeutic agent for mtRNA, with the potential for treating colorectal cancer. [ABSTRACT FROM AUTHOR]

RNA imaging is of great importance for understanding its complex spatiotemporal dynamics and cellular functions. Considerable effort has been devoted to the development of small-molecule fluorescent probes for RNA imaging. However, most of the reported studies have mainly focused on improving the photostability, permeability, long emission wavelength, and compatibility with live-cell imaging of RNA probes. Less attention has been paid to the selectivity and detection limit of this class of probes. Highly selective and sensitive RNA probes are still rarely available. In this study, a new set of styryl probes were designed and synthesized, with the aim of upgrading the detection limit and maintaining the selectivity of a lead probe QUID−1 for RNA. Among these newly synthesized compounds, QUID−2 was the most promising candidate. The limit of detection (LOD) value of QUID−2 for the RNA was up to 1.8 ng/mL in solution. This property was significantly improved in comparison with that of QUID−1. Further spectroscopy and cell imaging studies demonstrated the advantages of QUID−2 over a commercially available RNA staining probe, SYTO RNASelect, for highly selective and sensitive RNA imaging. In addition, QUID−2 exhibited excellent photostability and low cytotoxicity. Using QUID−2, the global dynamics of RNA were revealed in live cells. More importantly, QUID−2 was found to be potentially applicable for detecting RNA granules in live cells. Collectively, our work provides an ideal probe for RNA imaging. We anticipate that this powerful tool may create new opportunities to investigate the underlying roles of RNA and RNA granules in live cells. [ABSTRACT FROM AUTHOR]

Topo II and Hsp90 are promising targets. In this study, we first verified the structural similarities between Topo IIα ATPase and Hsp90α N−ATPase. Subsequently, 720 compounds from the Food and Drug Administration (FDA) drug library and kinase library were screened using the malachite green phosphate combination with the Topo II-mediated DNA relaxation and MTT assays. Subsequently, the antimalarial drug quinacrine was found to be a potential dual−target inhibitor of Topo II and Hsp90. Mechanistic studies showed that quinacrine could specifically bind to the Topo IIα ATPase domain and inhibit the activity of Topo IIα ATPase without impacting DNA cleavage. Furthermore, our study revealed that quinacrine could bind Hsp90 N−ATPase and inhibit Hsp90 activity. Significantly, quinacrine has broad antiproliferation activity and remains sensitive to the multidrug−resistant cell line MCF−7/ADR and the atypical drug−resistant tumor cell line HL−60/MX2. Our study identified quinacrine as a potential dual−target inhibitor of Topo II and Hsp90, depending on the ATP−binding domain, positioning it as a hit compound for further structural modification. [ABSTRACT FROM AUTHOR]

Background and Purpose: Non‐alcoholic steatohepatitis (NASH) is the more severe form of metabolic associated fatty liver disease (MAFLD) and no pharmacological treatment as yet been approved. Identification of novel therapeutic targets and their agents is critical to overcome the current inadequacy of drug treatment for NASH. Experimental Approach The correlation between heat shock factor 1 (HSF1) levels and the development of NASH and the target genes of HSF1 in hepatocyte were investigated by chromatin‐immunoprecipitation sequencing. The effects and mechanisms of SYSU‐3d in alleviating NASH were examined in relevant cell models and mouse models (the Ob/Ob mice, high‐fat and high‐cholesterol diet and the methionine‐choline deficient diet‐fed mice). The actions of SYSU‐3d in vivo were evaluated. Key Results: HSF1 is progressively reduced with mitochondrial dysfunction in NASH pathogenesis and activation of this transcription factor by its newly identified activator SYSU‐3d effectively inhibited all manifestations of NASH in mice. When activated, the phosphorylated HSF1 (Ser326) translocated to nucleus and bound to the promoter of PPARγ coactivator‐1α (PGC‐1α) to induce mitochondrial biogenesis. Thus, increasing mitochondrial adaptive oxidation and inhibiting oxidative stress. The deletion of HSF1 and PGC‐1α or recovery of HSF1 in HSF1‐deficiency cells showed the HSF1/PGC‐1α pathway was mainly responsible for the anti‐NASH effects of SYSU‐3d independent of AMP‐activated protein kinase (AMPK). Conclusion and Implications: Activation of HSF1 is a practical therapeutic approach for NASH treatment via the HSF1/PGC‐1α/mitochondrial pathway and SYSU‐3d can be considered as a potential candidate for the treatment of NASH. [ABSTRACT FROM AUTHOR]

I-motifs play key regulatory roles in biological processes, holding great potential as attractive therapeutic targets. In the present study, we developed a novel fluorescent probe G59 with strong and selective binding to the c-myc gene promoter i-motif. G59 had an i-motif-binding carbazole moiety conjugated with naphthalimide fluorescent groups. G59 could differentiate the c-myc i-motif from other DNA structures through selective activation of its fluorescence, with its apparent visualization in solution. The smart probe G59 showed excellent sensitivity, with a low fluorescent detection limit of 154 nM and effective stabilization to the c-myc i-motif. G59 could serve as a rapid and sensitive probe for label-free screening of selective c-myc i-motif binding ligands under neutral crowding conditions. To the best of our knowledge, G59 is the first fluorescent probe with high sensitivity for recognizing the i-motif structure and screening for selective binding ligands. [ABSTRACT FROM AUTHOR]

Telomere is a specialized DNA–protein complex that plays an important role in maintaining chromosomal integrity. Shelterin is a protein complex formed by six different proteins, with telomeric repeat factors 1 (TRF1) and 2 (TRF2) binding to double-strand telomeric DNA. Telomeric DNA consists of complementary G-rich and C-rich repeats, which could form G-quadruplex and intercalated motif (i-motif), respectively, during cell cycle. Its G-rich transcription product, telomeric repeat-containing RNA (TERRA), is essential for telomere stability and heterochromatin formation. After extensive screening, we found that acridine derivative 2c and acridine dimer DI26 could selectively interact with TRF1 and telomeric i-motif, respectively. Compound 2c blocked the binding of TRF1 with telomeric duplex DNA, resulting in up-regulation of TERRA. Accumulated TERRA could bind with TRF1 at its allosteric site and further destabilize its binding with telomeric DNA. In contrast, DI26 could destabilize telomeric i-motif, resulting in down-regulation of TERRA. Both compounds exhibited anti-tumour activity for A549 cells, but induced different DNA damage pathways. Compound 2c significantly suppressed tumour growth in A549 xenograft mouse model. The function of telomeric i-motif structure was first studied with a selective binding ligand, which could play an important role in regulating TERRA transcription. Our results showed that appropriate level of TERRA transcript could be important for stability of telomere, and acridine derivatives could be further developed as anti-cancer agents targeting telomere. This research increased understanding for biological roles of telomeric i-motif, TRF1 and TERRA, as potential anti-cancer drug targets. [ABSTRACT FROM AUTHOR]

Background and Purpose: Non-alcoholic hepatic fatty liver disease (NAFLD) is a manifestation of the metabolic syndrome in the liver and non-alcoholic steatohepatitis (NASH) represents its advanced stage. R17 derived from bouchardatine, shows benefits in the metabolic syndrome, but has not been tested in the liver. The present study examined the pharmacological effects of R17 in a model of NAFLD/NASH and its mode of action.Experimental Approach: The effects of R17 were examined in mice fed a high-fat (HF) diet to induce the pathological characteristics of NAFLD/NASH and in cultures of HuH7 cells. We used histological and immunohistochemical techniques along with western blotting and siRNA. Generation of ROS and apoptosis were measured.Key Results: Administration of R17 (20 mg·kg-1 , i.p. every other day) for 5 weeks reversed HF-induced hepatic triglyceride content, inflammation (inflammatory cytokines and macrophage numbers), injury (hepatocyte ballooning and apoptosis, plasma levels of alanine aminotransferase and aspartate aminotransferase), and fibrogenesis (collagen deposition and mRNA expression of fibrosis markers). In cultured cells, R17 reduced cell steatosis from both lipogenesis and fatty acid influx. The attenuated inflammation and cell injury were associated with inhibition of both endoplasmic reticulum (ER) stress and oxidative stress. Notably, R17 activated the liver kinase B1-AMP-activated protein kinase (AMPK) pathway by inhibiting activity of ATP synthase, rather than direct stimulation of AMPK.Conclusion and Implications: R17 has therapeutic potential for NAFLD/NASH. Its mode of action involves the elimination of ER and oxidative stresses, possibly via activating the LKB1-AMPK axis by inhibiting the activity of ATP synthase. [ABSTRACT FROM AUTHOR]

α‐Haloboronates are useful organic synthons that can be converted to a diverse array of α‐substituted alkyl borons. Methods to α‐haloboronates are limiting and often suffer from harsh reaction conditions. Reported herein is a photochemical radical C‐H halogenation of benzyl N‐methyliminodiacetyl (MIDA) boronates. Fluorination, chlorination, and bromination reactions were effective by using this protocol. Upon reaction with different nucleophiles, the C−Br bond in the brominated product could be readily transformed to a series of C−C, C−O, C−N, C−S, C−P, and C−I bonds, some of which are difficult to forge with α‐halo sp2‐B boronate esters. An activation effect of B(MIDA) moiety was found. [ABSTRACT FROM AUTHOR]

α‐Haloboronates are useful organic synthons that can be converted to a diverse array of α‐substituted alkyl borons. Methods to α‐haloboronates are limiting and often suffer from harsh reaction conditions. Reported herein is a photochemical radical C‐H halogenation of benzyl N‐methyliminodiacetyl (MIDA) boronates. Fluorination, chlorination, and bromination reactions were effective by using this protocol. Upon reaction with different nucleophiles, the C−Br bond in the brominated product could be readily transformed to a series of C−C, C−O, C−N, C−S, C−P, and C−I bonds, some of which are difficult to forge with α‐halo sp2‐B boronate esters. An activation effect of B(MIDA) moiety was found. [ABSTRACT FROM AUTHOR]

Background and Purpose: Promoting energy metabolism is known to provide therapeutic effects for obesity and associated metabolic disorders. The present study evaluated the therapeutic effects of the newly identified bouchardatine (Bou) on obesity-associated metabolic disorders and the molecular mechanisms of these effects.Experimental Approach: The molecular mode of action of Bou for its effects on lipid metabolism was first examined in 3T3-L1 adipocytes and HepG2 cells. This was followed by an evaluation of its metabolic effects in mice fed a high-fat diet for 16 weeks with Bou being administered in the last 5 weeks. Further mechanistic investigations were conducted in pertinent organs of the mice and relevant cell models.Key Results: In 3T3-L1 adipocytes, Bou reduced lipid content and increased sirtuin 1 (SIRT1) activity to facilitate liver kinase B1 (LKB1) activation of AMPK. Chronic administration of Bou (50 mg∙kg-1 every other day) in mice significantly attenuated high-fat diet-induced increases in body weight gain, dyslipidaemia and fatty liver without affecting food intake and no adverse effects were detected. These metabolic effects were associated with activation of the SIRT1-LKB1-AMPK signalling pathway in adipose tissue and liver. Of particular note, UCP1 expression and mitochondrial biogenesis were increased in both white and brown adipose tissues of Bou-treated mice. Incubation with Bou induced similar changes in primary brown adipocytes isolated from mice.Conclusions and Implications: Bou may have therapeutic potential for obesity-related metabolic diseases by increasing the capacity of energy expenditure in adipose tissues and liver through a mechanism involving the SIRT1-LKB1-AMPK axis. [ABSTRACT FROM AUTHOR]

Abstract: Because of the absence of methods for tracking RNA G‐quadruplex dynamics, especially the folding and unfolding of this attractive structure in live cells, understanding of the biological roles of RNA G‐quadruplexes is so far limited. Herein, we report a new red‐emitting fluorescent probe, QUMA‐1, for the selective, continuous, and real‐time visualization of RNA G‐quadruplexes in live cells. The applications of QUMA‐1 in several previously intractable applications, including live‐cell imaging of the dynamic folding, unfolding, and movement of RNA G‐quadruplexes and the visualization of the unwinding of RNA G‐quadruplexes by RNA helicase have been demonstrated. Notably, our real‐time results revealed the complexity of the dynamics of RNA G‐quadruplexes in live cells. We anticipate that the further application of QUMA‐1 in combination with appropriate biological and imaging methods to explore the dynamics of RNA G‐quadruplexes will uncover more information about the biological roles of RNA G‐quadruplexes. [ABSTRACT FROM AUTHOR]

Abstract: Because of the absence of methods for tracking RNA G‐quadruplex dynamics, especially the folding and unfolding of this attractive structure in live cells, understanding of the biological roles of RNA G‐quadruplexes is so far limited. Herein, we report a new red‐emitting fluorescent probe, QUMA‐1, for the selective, continuous, and real‐time visualization of RNA G‐quadruplexes in live cells. The applications of QUMA‐1 in several previously intractable applications, including live‐cell imaging of the dynamic folding, unfolding, and movement of RNA G‐quadruplexes and the visualization of the unwinding of RNA G‐quadruplexes by RNA helicase have been demonstrated. Notably, our real‐time results revealed the complexity of the dynamics of RNA G‐quadruplexes in live cells. We anticipate that the further application of QUMA‐1 in combination with appropriate biological and imaging methods to explore the dynamics of RNA G‐quadruplexes will uncover more information about the biological roles of RNA G‐quadruplexes. [ABSTRACT FROM AUTHOR]

We synthesized a series of acridone derivatives for specific binding ligands of i-motifs. Subsequent evaluations showed that B19 could selectively bind to and stabilize the c-myc promoter i-motif without significant binding to the G-quadruplex and duplex DNA. This caused down-regulation of c-myc transcription and expression, resulting in tumor cell apoptosis. [ABSTRACT FROM AUTHOR]

G-quadruplexes are four-stranded nucleic acid secondary structures that are formed in guanine-rich sequences. G-quadruplexes are widely distributed in functional regions of the human genome and transcriptome, such as human telomeres, oncogene promoter regions, replication initiation sites, and untranslated regions. Many G-quadruplex-forming sequences are found to be associated with cancer, and thus, these non-canonical nucleic acid structures are considered to be attractive molecular targets for cancer therapeutics with novel mechanisms of action. In this mini review, we summarize recent advances made by our lab in the study of G-quadruplex-targeted natural alkaloids and their derivatives toward the development of potential anticancer agents. [ABSTRACT FROM AUTHOR]

Nine types of diversely fused heterocyclic quaternary ammonium salts were constructed through an oxidative CH annulation reaction. Both high-valent pentamethylcyclopentadienylcobalt(III) and pentamethylcyclopentadienyliridium(III) were found to be effective as catalyst for this reaction. Broad substrate scope and good functional group tolerance were observed. [ABSTRACT FROM AUTHOR]

A colorimetric and red-emitting fluorescent dual probe for G-quadruplexes was devised with a conjugated coumarin–benzothiazole scaffold. Its significant and distinct changes in both color and fluorescence enable the label-free and visual detection of G-quadruplex structures. In addition, this probe gives a distinct strong emission response to the nucleoli in fixed cells imaging, which might be attributed to the interaction between the probe and rDNA G-quadruplex based on the chromatin immunoprecipitation assay. All these results suggest its promising application prospects in the G-quadruplex research field. [ABSTRACT FROM AUTHOR]

G-quadruplexes are higher-order nucleic acid structures that have attracted extensive attention because of their biological significance and potential applications in supramolecular chemistry. An ever-increasing interest in G-quadruplexes has promoted the development of selective and sensitive fluorescent probes as research tools for these structures. However, most current studies primarily focus on the improved selectivity of probes for G-quadruplexes. Their detection limits or ways to improve their detection limits are rarely described. In this study, a new set of di-substituted triarylimidazole fluorescent probes were designed and synthesized, with the aim of upgrading the detection limit of a lead triarylimidazole IZCM-1 for G-quadruplexes. Among these compounds, IZCM-7 was the most promising candidate. The limit of detection (LOD) value of IZCM-7 for the G-quadruplex was up to 3 nM in solution and up to 5 ng in a gel matrix. These values were significantly improved in comparison with those of IZCM-1. Further biophysical studies revealed that the fluorescence quantum yield and binding affinity of IZCM-7 for G-quadruplexes were markedly increased, and these two factors might be responsible for the significantly improved detection limit of IZCM-7. In addition, the sensitive and selective fluorescence performance of IZCM-7 for G-quadruplexes remained the same even in the presence of large amounts of non-G-quadruplex competitors, suggesting its promising application prospect. [ABSTRACT FROM AUTHOR]

Cp*Rh(iii)- and Cp*Ir(iii)-catalysed direct C–H arylation with quinone diazides as efficient coupling partners is disclosed. This redox-neutral protocol offers a facile, operationally simple and environmentally benign access to arylated phenols. The reaction represents the first example of Cp*Ir(iii)-catalysed C–H direct arylation reaction. [ABSTRACT FROM AUTHOR]

G-quadruplexes comprise a class of secondary structures that are formed in guanine-rich sequences in eukaryotic genomes and play a crucial role in the regulation of many biological events. G-quadruplexes have become targets for anticancer drugs with high selectivity vs. duplex DNA and low cytotoxicity against normal cells. Natural products and their derivatives display polymorphism, structural complexity, and potent activity. It is, therefore, reasonable to seek ligands targeting G-quadruplexes from natural products. Recently, many successful examples have been reported, showing ligands with excellent anticancer activities. In this review, we summarized the development of research on natural products and derivatives that target G-quadruplex structures in an effort to guide future studies. [ABSTRACT FROM AUTHOR]

We recently reported that synthetic derivatives of rutaecarpine alkaloid exhibited high acetyl cholinesterase (AChE) inhibitory activity and high selectivity for AChE over butyrylcholinesterases (BuChE). To explore novel effective drugs for the treatment of Alzheimer's disease (AD), in this paper, further research results were presented. Starting from a structure-based drug design, a series of novel 2-(2-indolyl-)-4(3 H)-quinazolines derivates were designed and synthesized as the ring-opened analogues of rutaecarpine alkaloid and subjected to pharmacological evaluation as AChE inhibitors. Among them, derivates 3a-c and 3g-h exhibited strong inhibitory activity for AChE and high selectivity for AChE over BuChE. The structure-activity relationships were discussed and their binding conformation and simultaneous interactions mode were further clarified by kinetic characterization and the molecular docking studies. [ABSTRACT FROM AUTHOR]

Context: N'-(7-Fluoro-5- N-methyl-10 H-indolo[3,2- b]quinolin-5-ium)- N,N-dimethylpropane-1,3-diamine iodide (SYUIQ-FM05) is a semi-synthetic derivative of cryptolepine which is from Cryptolepis sanguinolenta (Lindl.) Schlechter (Periplocaeae). This ligand inhibits telomerase activity by stabilizing the G-quadruplex structure and induces growth arrest in cancer cells. Objective: The anticancer activity of SYUIQ-FM05 via inhibiting c-kit transcription was investigated in leukemic cells. Materials and methods: The cytotoxicity of SYUIQ-FM05 in K562 cells was evaluated using a cell viability assay and flow cytometry (FCM) at 0.4, 2.0, 10.0 and 20.0 nM. Under the same concentrations of SYUIQ-FM05 or 100 nM imatinib mesylate (IM), quantitative polymerase chain reaction (Q-PCR) investigated transcription of c-kit and bcl-2, and western blotting analyzed the expression levels of c-Kit, total mitogen-activated protein kinase kinases (MEKs), phospho-MEK (p-MEK), total extracellular regulated protein kinases (ERKs), phospho-ERK (p-ERK), Bcl-2 and Bax. Results: SYUIQ-FM05 inhibited cellular growth with an IC50 of 10.83 ± 0.05 nM in K562 cells. c-Kit transcription was suppressed 2.69-, 4.39-, 7.71- and 10.52-fold at 0.4, 2.0, 10.0 and 20.0 nM SYUIQ-FM05, respectively, which produced proportional loss of total c-Kit protein except IM. Both SYUIQ-FM05 and IM downregulated p-MEK and p-ERK. Furthermore, bcl-2 transcription was suppressed 1.58- and 1.86-fold at 10.0 and 20.0 nM SYUIQ-FM05, respectively, but 0.4 and 2.0 nM SYUIQ-FM05 had no effect. A decrease in Bcl-2 and an increase in Bax appeared in these treated cells. Discussion and conclusion: These findings demonstrate that SYUIQ-FM05 could induce apoptosis in a leukemic cell line through inhibiting c-kit transcription, which supports the anticancer potency of SYUIQ-FM05 in c-Kit-positive leukemic cells. [ABSTRACT FROM AUTHOR]

G-quadruplexes are higher-order DNA and RNA structures formed from guanine-rich sequences. These structures have recently emerged as a new class of potential molecular targets for anticancer drugs. An understanding of the three-dimensional interactions between small molecular ligands and their G-quadruplex targets in solution is crucial for rational drug design and the effective optimization of G-quadruplex ligands. Thus far, rational ligand design has been focused mainly on the G-quartet platform. It should be noted that small molecules can also bind to loop nucleotides, as observed in crystallography studies. Hence, it would be interesting to elucidate the mechanism underlying how ligands in distinct binding modes influence the flexibility of G-quadruplex. In the present study, based on a crystal structure analysis, the models of a tetra-substituted naphthalene diimide ligand bound to a telomeric G-quadruplex with different modes were built and simulated with a molecular dynamics simulation method. Based on a series of computational analyses, the structures, dynamics, and interactions of ligand-quadruplex complexes were studied. Our results suggest that the binding of the ligand to the loop is viable in aqueous solutions but dependent on the particular arrangement of the loop. The binding of the ligand to the loop enhances the flexibility of the G-quadruplex, while the binding of the ligand simultaneously to both the quartet and the loop diminishes its flexibility. These results add to our understanding of the effect of a ligand with different binding modes on G-quadruplex flexibility. Such an understanding will aid in the rational design of more selective and effective G-quadruplex binding ligands. [ABSTRACT FROM AUTHOR]

A novel series of N, N′-bis-methylenedioxybenzyl-alkylenediamines 5a- 5g have been designed, synthesized and evaluated as bivalent anti-Alzheimer's disease ligands. The enzyme inhibition assay results indicated that compounds 5e- 5g inhibit both acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) in the micromolar range (IC50, 2.76-4.24 µM for AChE and 3.02-5.14 µM for BuChE), which was in the same potential as the reference compound rivastigmine (IC50, 5.50 µM for AChE and 1.60 µM for BuChE). It was found that compounds could bind simultaneously to the peripheral and catalytic sites of AChE. β-Amyloid (Aβ) aggregation inhibition assay results showed that compound 5e exhibited highest self-mediated Aβ fibril aggregation inhibition activity (40.3%) with a similar potential as curcumin (41.6%). It was also found that 5e- 5g did not affect neuroblastoma cell viability at the concentration of 50 μM. [ABSTRACT FROM AUTHOR]

New Mansonone analogues of 9‐substitued benzo[ de ]chromene‐7,8‐dione 5b – e and 5‐benzyl‐9‐substitued benzo[ de ]chromene‐7,8‐dione 6a – e were prepared through a modified route. The first step involved a bulky base t ‐butylamine mediated regioselective deacetylation of 2‐substituted‐1,4‐naphth‐diyl diacetate, resulting in obtaining of monoacetate 4‐acetate 2 in high yield. The mechanism of cyclization, debenzylation, and oxidation for the formation of 5a – e and 6a – e were discussed. The cytotoxicity of the prepared compounds 5 and 6 were comparable with naturally occurring Mansonone F. [ABSTRACT FROM AUTHOR]

A new switch-on fluorescent probe containing the natural product cryptolepine analogue benzofuroquinolinium moiety (binding scaffold) and a benzothiazole moiety (signalling unit) shows a remarkable fluorescence enhancement selective for the G-quadruplex nucleic acid structure. Binding studies revealed that the highly selective response of the fluorescent probe arises from end-stack binding to G-quadruplex. [ABSTRACT FROM AUTHOR]

Target-guided synthesis is an approach to drug discovery that allows the target to self-assemble its own binding agents. So far, target-guided synthesis and especially in situ click chemistry have attracted extensive attention and have led to the identification of highly potent inhibitors for proteins. In this study, we expand the application of in situ click chemistry and present a procedure using this approach to identify selective fluorescent probes for a specific topology of G-quadruplex nucleic acids, the parallel G-quadruplexes. On this basis, compound 15 assembled by triarylimidazole scaffold and carboxyl side chain was a positive hit, demonstrating highly potential in the sensitive and selective detection of parallel G-quadruplexes. Such selective fluorescence response can be rationalized in terms of different binding affinities between 15 and G-quadruplexes. Our work accordingly represents a new development towards the application of in situ click chemistry to develop selective fluorescent probes and may also shed light on the search for probes for a specific G-quadruplex topology. [ABSTRACT FROM AUTHOR]