MSN8C: A Promising Candidate for Antitumor Applications as a Novel Catalytic Inhibitor of Topoisomerase II.

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.

Discovery of Quinacrine as a Potent Topo II and Hsp90 Dual-Target Inhibitor, Repurposing for Cancer Therapy.

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.

9-Bromo-2,3-diethylbenzo[de]chromene-7,8-dione (MSN54): A novel non-intercalative topoisomerase II catalytic inhibitor.

Novel mansonone F derivative MSN54 (9-bromo-2,3-diethylbenzo[de]chromene-7,8-dione) exhibited significant cytotoxicity against twelve human tumor cell lines in vitro, with particularly strong potency against HL-60/MX2 cell line resistant to Topo II poisons. MSN54 was found to have IC50 of 0.69 and 1.43 µM against HL-60 and HL-60/MX2 cells, respectively. The resistance index is 10 times lower than that of the positive control VP-16 (etoposide). Various biological assays confirmed that MSN54 acted as a Topo IIα specific non-intercalative catalytic inhibitor. Furthermore, MSN54 exhibited good antitumor efficacy and low toxicity at a dose of 5 mg/kg in A549 tumor xenograft models. Thus, compound MSN54 is a promising candidate for the development of novel antitumor agents.

Design, synthesis and biological evaluation of novel perimidine o-quinone derivatives as non-intercalative topoisomerase II catalytic inhibitors.

For the development of novel anticancer agents, we designed and synthesized a total of 37 perimidine o-quinone derivatives containing the o-quinone group at the A or B ring and different substituents (alkyl groups, aryl groups or heterocycles) at the C ring of the compounds. The structure-activity relationships (SARs) were established based on the cytotoxicity data of compounds from the HL-60, Huh7, Hct116, and Hela cell lines. The cytotoxicity results showed that most compounds exhibited potent cytotoxicity. In particular, compound b-12 showed the best anti-proliferative activity (IC50 ≤ 1 µM) against four cancer cell lines and strong potency against the HL-60/MX2 (0.47 µM) cell line, which is resistant to Topo II poisons. Further studies showed that b-12 exhibited potent Topo IIα inhibitory activity (IC50 = 7.54 µM) compared with Topo I, which acted as a class of non-intercalative Topo IIα catalytic inhibitor by inhibiting the ATP binding site of Topo II. Cell apoptosis and cell cycle assays confirmed that b-12 could induce the apoptosis of Huh7 cells in a dose-dependent manner.

Synthesis and evaluation of 1,2,3,4-tetrahydro-1-acridone analogues as potential dual inhibitors for amyloid-beta and tau aggregation.

Amyloid-ß (Aß) and tau protein are two crucial hallmarks in Alzheimer's disease (AD). Their aggregation forms are thought to be toxic to the neurons in the brain. A series of new 1,2,3,4-tetrahydro-1-acridone analogues were designed, synthesized, and evaluated as potential dual inhibitors for Aß and tau aggregation. In vitro studies showed that compounds 25-30 (20 µM) with N-methylation of the quinolone ring effectively inhibited Aß1-42 aggregation by 84.7%-99.5% and tau aggregation by 71.2%-101.8%. Their structure-activity relationships are discussed. In particular, 30 could permeate the blood-brain barrier, bind to Aß1-42 and tau, inhibit Aß1-42 ß-sheets formation, and prevent tau aggregation in living cells.

Synthesis and characterization of 1H-phenanthro[9,10-d]imidazole derivatives as multifunctional agents for treatment of Alzheimer's disease.

BACKGROUND: Alzheimer's disease (AD) is a progressive neurodegenerative brain disorder that is characterized by dementia, cognitive impairment, and memory loss. Diverse factors are related to the development of AD, such as increased level of ß-amyloid (Aß), acetylcholine, metal ion deregulation, hyperphosphorylated tau protein, and oxidative stress. METHODS: The following methods were used: organic syntheses of 1H-phenanthro[9,10-d]imidazole derivatives, inhibition of self-mediated and metal-induced Aß1-42 aggregation, inhibition studies for acetylcholinesterase and butyrylcholinesterase, anti-oxidation activity studies, CD, MTT assay, transmission electron microscopy, dot plot assay, gel electrophoresis, Western blot, and molecular docking studies. RESULTS: We synthesized and characterized a new type of 1H-phenanthro[9,10-d]imidazole derivatives as multifunctional agents for AD treatment. Our results showed that most of these derivatives exhibited strong Aß aggregation inhibitory activity. Compound 9g had 74% Aß1-42 aggregation inhibitory effect at 10µM concentration with its IC50 value of 6.5µM for self-induced Aß1-42 aggregation. This compound also showed good inhibition of metal-mediated (Cu(2+) and Fe(2+)) and acetylcholinesterase-induced Aß1-42 aggregation, as indicated by using thioflavin T assay, transmission electron microscopy, gel electrophoresis, and Western blot. Besides, compound 9g exhibited cholinesterase inhibitory activity, with its IC50 values of 0.86µM and 0.51µM for acetylcholinesterase and butyrylcholinesterase, respectively. In addition, compound 9g showed good anti-oxidation effect with oxygen radical absorbance capacity (ORAC) value of 2.29. CONCLUSIONS: Compound 9g was found to be a potent multi-target-directed agent for Alzheimer's disease. GENERAL SIGNIFICANCE: Compound 9g could become a lead compound for further development as a multi-target-directed agent for AD treatment.

Discovery of natural alkaloid bouchardatine as a novel inhibitor of adipogenesis/lipogenesis in 3T3-L1 adipocytes.

Bouchardatine (1), a naturally occurring ß-indoloquinazoline alkaloid, was synthesized. For the first time, the lipid-lowering effect and mechanism of 1 was investigated in 3T3-L1 adipocytes. Our study showed that 1 could significantly reduce lipid accumulation without cytotoxicity and mainly inhibited early differentiation of adipocyte through proliferation inhibition and cell cycle arrested in dose-dependent manner. Furthermore, the inhibition of early differentiation was reflected by down-regulation of key regulators of adipogenesis/lipogenesis, including CCAAT enhancer binding proteins (C/EBPß, C/EBPδ, C/EBPα), peroxisome proliferator-activated receptors γ (PPARγ) and sterol-regulatory element binding protein-1c (SREBP-1c), in both of mRNA and protein levels. Subsequently decreasing the protein levels of acetyl CoA carboxylase (ACC), fatty acid synthase (FAS), and stearyl coenzyme A desaturated enzyme 1 (SCD-1), the rate-limited metabolic enzymes of fatty acid synthesis, were also observed. Further studies revealed that 1 persistently activated adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) during differentiation, suggesting that the AMPK may be an upstream mechanism for the effect of 1 on adipogenesis and lipogenesis. Our data suggest that 1 can be a candidate for the development of new therapeutic drugs against obesity and related metabolic disorders.

Synthesis and biological evaluation of benzo[a]phenazine derivatives as a dual inhibitor of topoisomerase I and II.

Topoisomerases (Topo I and Topo II) are very important players in DNA replication, repair, and transcription, and are a promising class of antitumor target. In present study, a series of benzo[a]phenazine derivatives with alkylamino side chains at C-5 were designed, synthesized, and their biological activities were evaluated. Most of derivatives showed good antiproliferative activity with a range of IC50 values of 1-10 µM on the four cancer cell lines HeLa, A549, MCF-7, and HL-60. Topoisomerase-mediated DNA relaxation assay results showed that derivatives could effectively inhibit the activity of both Topo I and Topo II, and the structure-activity relationship studies indicated the importance of introducing an alkylamino side chain. Further mechanism studies revealed that the compounds could stabilize the Topo I-DNA cleavage complexes and inhibit the ATPase activity of hTopo II, indicating that they are a rare class of dual topoisomerase inhibitors by acting as Topo I poisons and Topo II catalytic inhibitors. Moreover, flow cytometric analysis and caspase-3/7 activation assay showed that this class of compounds could induce apoptosis of HL-60 cells.

2-(2-indolyl-)-4(3H)-quinazolines derivates as new inhibitors of AChE: design, synthesis, biological evaluation and molecular modelling.

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(3H)-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.

Design and Synthesis of Bouchardatine Derivatives as a Novel AMP-Activated Protein Kinase Activator for the Treatment of Colorectal Cancer.

Metabolic reprogramming is a crucial hallmark of tumorigenesis. Modulating the reprogrammed energy metabolism is an attractive anticancer therapeutic strategy. We previously found a natural product, bouchardatine, modulated aerobic metabolism and inhibited proliferation in the colorectal cancer cell (CRC). Herein, we designed and synthesized a new series of bouchardatine derivatives to discover more potential modulators. We applied the dual-parametric high-content screening (HCS) to evaluate their AMP-activated protein kinase (AMPK) modulation and CRC proliferation inhibition effect simultaneously. And we found their antiproliferation activities were highly correlated to AMPK activation. Among them, 18a was identified with nanomole-level antiproliferation activities against several CRCs. Interestingly, the evaluation found that 18a selectively upregulated oxidative phosphorylation (OXPHOS) and inhibited proliferation by modulating energy metabolism. Additionally, this compound effectively inhibited the RKO xenograft growth along with AMPK activation. In conclusion, our study identified 18a as a promising candidate for CRC treatment and suggested a novel anti-CRC strategy by AMPK activating and OXPHOS upregulating.

Design, Synthesis, and Evaluation of New Sugar-Substituted Imidazole Derivatives as Selective c-MYC Transcription Repressors Targeting the Promoter G-Quadruplex.

c-MYC is a key driver of tumorigenesis. Repressing the transcription of c-MYC by stabilizing the G-quadruplex (G4) structure with small molecules is a potential strategy for cancer therapy. Herein, we designed and synthesized 49 new derivatives by introducing carbohydrates to our previously developed c-MYC G4 ligand 1. Among these compounds, 19a coupled with a d-glucose 1,2-orthoester displayed better c-MYC G4 binding, stabilization, and protein binding disruption abilities than 1. Our further evaluation indicated that 19a blocked c-MYC transcription by targeting the promoter G4, leading to c-MYC-dependent cancer cell death in triple-negative breast cancer cell MDA-MB-231. Also, 19a significantly inhibited tumor growth in the MDA-MB-231 mouse xenograft model accompanied by c-MYC downregulation. Notably, the safety of 19a was dramatically improved compared to 1. Our findings indicated that 19a could become a promising anticancer candidate, which suggested that introducing carbohydrates to improve the G4-targeting and antitumor activity is a feasible option.

A novel HSF1 activator ameliorates non-alcoholic steatohepatitis by stimulating mitochondrial adaptive oxidation.

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.

Discovery of a Novel G-Quadruplex and Histone Deacetylase (HDAC) Dual-Targeting Agent for the Treatment of Triple-Negative Breast Cancer.

The development of triple-negative breast cancer (TNBC) is highly associated with G-quadruplex (G4); thus, targeting G4 is a potential strategy for TNBC therapy. Because concomitant histone deacetylases (HDAC) inhibition could amplify the impact of G4-targeting compounds, we designed and synthesized two novel series of G4/HDAC dual-targeting compounds by connecting the zinc-binding pharmacophore of HDAC inhibitors to the G4-targeting isaindigotone scaffold (1). Among the new compounds, a6 with the potent HDAC inhibitory and G4 stabilizing activity could induce more DNA G4 formation than SAHA and 1 in TNBC cells. Remarkably, a6 caused more G4-related DNA damage and G4-related differentially expressed genes, consistent with its effect on disrupting the cell cycle, invasion, and glycolysis. Furthermore, a6 significantly suppresses the proliferation of various TNBC cells and the MDA-MB-231 xenograft model without evident toxicity. Our study suggests a novel strategy for TNBC therapeutics through dual-targeting HDAC and G4.

Pharmacophore-based discovery of triaryl-substituted imidazole as new telomeric G-quadruplex ligand.

Discovery of potent and selective ligands for telomeric G-quadruplex DNA is a challenging work. Through a combination approach of pharmacophore model construction, model validation, database virtual screening, chemical synthesis and interaction evaluation, we discovered and confirmed triaryl-substituted imidazole TSIZ01 to be a new telomeric G-quadruplex ligand with potent binding and stabilizing activity to G-quadruplex DNA, as well as a 8.7-fold selectivity towards telomeric G-quadruplex DNA over duplex DNA.

Disubstituted 2-phenyl-benzopyranopyrimidine derivatives as a new type of highly selective ligands for telomeric G-quadruplex DNA.

A series of 2-phenyl-benzopyranopyrimidine (PBPP) derivatives with alkylamino side chains were synthesized and found to be a new type of highly selective ligand to bind with telomeric G-quadruplex DNA, and their biological properties were reported for the first time. Their interactions with telomeric G-quadruplex DNA were studied with FRET melting, surface plasmon resonance, CD spectroscopy, and molecular modeling. Our results showed that the disubstituted PBPP derivatives could strongly bind to and effectively stabilize the telomeric G-quadruplex structure, and had significant selectivity for G-quadruplex over duplex DNA. In comparison, the mono substituted derivatives had much less effect on the G-quadruplex, suggesting that the disubstitution of PBPP is essential for its interaction with the G-quadruplex. Furthermore, telomerase inhibition of the PBPP derivatives and their cellular effects were studied, and compound 11b was found to be the most promising compound as a telomerase inhibitor and telomeric G-quadruplex binding ligand for further development for cancer treatment.

Design, synthesis and evaluation of novel tacrine-multialkoxybenzene hybrids as dual inhibitors for cholinesterases and amyloid beta aggregation.

A new series of tacrine-multialkoxybenzene hybrids (9a-9n) were designed, synthesized and evaluated as dual inhibitors of cholinesterases (ChEs) and self-induced ß-amyloid (Aß) aggregation. All the synthesized compounds had high acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitory activity with IC50 values at the nanomolar range, which were much better than tacrine alone. A Lineweaver-Burk plot and molecular modeling study showed that these hybrids targeted both the catalytic active site (CAS) and the peripheral anionic site (PAS) of AChE. Besides, compounds 9a-9f with methylenedioxybenzene moiety showed higher self-induced Aß aggregation inhibitory activity than a reference compound, curcumin. These compounds could be selected as multi-potent agents for further investigation to treat AD.

Effective detection and separation method for G-quadruplex DNA based on its specific precipitation with Mg(2+).

G-quadruplex is a type of DNA secondary structure formed by specific guanine-rich sequences. Because of their enrichment in functional genomic regions and their biological significance, G-quadruplexes are recognized as significant drug targets for cancer and other diseases. Here, we tested the precipitation efficiency of Mg(2+) for various DNA oligomers, including single-stranded, double-stranded, triplex, hairpin, i-motif, and some reported G-quadruplex DNA. It was found that Mg(2+) could specifically recognize and precipitate G-quadruplex DNA with a particularly high efficiency of close to 100% for G-quadruplex structures with parallel conformation, which provided an inexpensive and convenient method for detecting and separating G-quadruplex DNA from other DNA structures as well as identifying parallel G-quadruplex from other conformational G-quadruplexes. Further experiments with both CD and gel electrophoresis validated the effectiveness of this approach. The structure of the precipitate was characterized using transmission electron microscopy (TEM), and the observed linear precipitate suggested that a polymerization of G-quadruplex DNA was formed through π-π stacking of end to end by the unique large aromatic surface of G-quadruplex.

Design, Synthesis, and Evaluation of New Quinazolinone Derivatives that Inhibit Bloom Syndrome Protein (BLM) Helicase, Trigger DNA Damage at the Telomere Region, and Synergize with PARP Inhibitors.

DNA damage response (DDR) pathways are crucial for the survival of cancer cells and are attractive targets for cancer therapy. Bloom syndrome protein (BLM) is a DNA helicase that performs important roles in DDR pathways. Our previous study discovered an effective new BLM inhibitor with a quinazolinone scaffold by a screening assay. Herein, to better understand the structure-activity relationship (SAR) and biological roles of the BLM inhibitor, a series of new derivatives were designed, synthesized, and evaluated based on this scaffold. Among them, compound 9h exhibited nanomolar inhibitory activity and binding affinity for BLM. 9h could effectively disrupt BLM recruitment to DNA in cells. Furthermore, 9h inhibited the proliferation of the colorectal cell line HCT116 by significantly triggering DNA damage in the telomere region and inducing apoptosis, especially in combination with a poly (ADP-ribose) polymerase (PARP) inhibitor. This result suggested a synthetic lethal effect between the BLM and PARP inhibitors in DDR pathways.

Discovery of a promising agent IQZ23 for the treatment of obesity and related metabolic disorders.

Discovery of novel anti-obesity agents is a challenging and promising research area. Based on our previous works, we synthesized 40 novel ß-indoloquinazoline analogues by altering the skeleton and introducing preferential side chains, evaluated their lipid-lowering activity and summarized the structure-activity relationships. In combination with an evaluation of the lipid-lowering efficacies, AMP-dependent activated protein kinase (AMPK) activating ability and liver microsomal stability, compound 23 (named as IQZ23) was selected for further studies. IQZ23 exerted a high efficacy in decreasing the triglyceride level (EC50 = 0.033 µM) in 3T3-L1 adipocytes. Mechanistic studies revealed the lipid-lowering activity of IQZ23 was dependent on the AMPK pathway by modulating ATP synthase activity. This activation was accompanied by mitochondrial biogenesis and oxidation capacity increased, and insulin sensitivity enhanced in pertinent cell models by various interventions. Correspondingly, IQZ23 (20 mg/kg, i.p.) treatment significantly reversed high fat and cholesterol diet (HFC)- induced body weight increases and accompanying clinical symptoms of obesity in mice but without indicative toxicity. These results indicate that IQZ23 could be a useful candidate for the treatment of obesity and related metabolic disorders.

Synthesis and evaluation of 9-O-substituted berberine derivatives containing aza-aromatic terminal group as highly selective telomeric G-quadruplex stabilizing ligands.

A series of new 9-O-substituted berberine derivatives (4a-j) as telomeric quadruplex ligands was synthesized and evaluated. The results from biophysical and biochemical assay indicated that introducing of positive charged aza-aromatic terminal group into the side chain of 9-position of berberine significantly improved the binding ability with G-quadruplex, and exhibited the inhibitory effect on the hybridization and on telomerase activity. These derivatives showed excellent selectivity for telomeric G-quadruplex DNA over duplex.