Discovery of Substituted 1H-Pyrazolo[3,4-b]pyridine Derivatives as Potent and Selective FGFR Kinase Inhibitors

Ultrapotent influenza hemagglutinin fusion inhibitors developed through SuFEx-enabled high-throughput medicinal chemistry

Seasonal and pandemic-associated influenza strains cause highly contagious viral respiratory infections that can lead to severe illness and excess mortality. Here, we report on the optimization of our small-molecule inhibitor F0045(S) targeting the influenza hemagglutinin (HA) stem with our Sulfur-Fluoride Exchange (SuFEx) click chemistry-based high-throughput medicinal chemistry (HTMC) strategy. A combination of SuFEx- and amide-based lead molecule diversification and structure-guided design led to identification and validation of ultrapotent influenza fusion inhibitors with subnanomolar EC50 cellular antiviral activity against several influenza A group 1 strains. X-ray structures of six of these compounds with HA indicate that the appended moieties occupy additional pockets on the HA surface and increase the binding interaction, where the accumulation of several polar interactions also contributes to the improved affinity. The compounds here represent the most potent HA small-molecule inhibitors to date. Our divergent HTMC platform is therefore a powerful, rapid, and cost-effective approach to develop bioactive chemical probes and drug-like candidates against viral targets.

Pyrazolopyridine-based kinase inhibitors for anti-cancer targeted therapy

The need for effective cancer treatments continues to be a challenge for the biomedical research community. In this case, the advent of targeted therapy has significantly improved therapeutic outcomes. Drug discovery and development efforts targeting kinases have resulted in the approval of several small-molecule anti-cancer drugs based on ATP-mimicking heterocyclic cores. Pyrazolopyridines are a group of privileged heterocyclic cores in kinase drug discovery, which are present in several inhibitors that have been developed against various cancers. Notably, selpercatinib, glumetinib, camonsertib and olverembatinib have either received approval or are in late-phase clinical studies. This review presents the success stories employing pyrazolopyridine scaffolds as hinge-binding cores to address various challenges in kinase-targeted drug discovery research.

Discovery of indoleninyl-pyrazolo[3,4-b]pyridines as potent chemotherapeutic agents against colorectal cancer cells

A new series of indolenines decorated with pyrazolo[3,4-b]pyridines were designed and synthesized in up to 96% yield from the acid-catalyzed cyclocondensation of 1,3-dialdehydes with 3-aminopyrazoles. X-ray crystallography on a representative derivative, 5n, revealed two close to planar conformations whereby the N-atom of the pyridyl residue was syn or anti to the pyrrole-N atom in the two independent molecules of the asymmetric unit. The computational and DNA binding data suggest that 5n is a strong DNA intercalator with the results in agreement with its potent cytotoxicity against two colorectal cancer cell lines (HCT 116 and HT-29). In contrast to doxorubicin, compounds 5k-o have higher druggability (compliance to more criteria stated in Lipinski's rule of five and Veber's rule), higher bioavailability, and better medicinal chemistry properties, indicative of their potential application as chemotherapeutical agents.

New pyrazolopyridine and pyrazolothiazole-based compounds as anti-proliferative agents targeting c-Met kinase inhibition: design, synthesis, biological evaluation, and computational studies

c-Met tyrosine kinase plays a key role in the oncogenic process. Inhibition of the c-Met has emerged as an attractive target for human cancer treatment. This work deals with the design and synthesis of a new set of derivatives bearing pyrazolo[3,4-b]pyridine, pyrazolo[3,4-b]thieno[3,2-e]pyridine, and pyrazolo[3,4-d]thiazole-5-thione scaffolds, 5a,b, 8a-f, and 10a,b, respectively, utilizing 3-methyl-1-tosyl-1H-pyrazol-5(4H)-one (1) as a key starting material. All the new compounds were evaluated as antiproliferative agents against HepG-2, MCF-7, and HCT-116 human cancer cell lines utilizing 5-fluorouracil and erlotinib as two standard drugs. Compounds 5a,b and 10a,b represented the most promising cytotoxic activity of IC₅₀ values ranging from 3.42 ± 1.31 to 17.16 ± 0.37 μM. Both 5a and 5b showed the most cytotoxicity and selectivity toward HepG-2, with IC₅₀ values of 3.42 ± 1.31 μM and 3.56 ± 1.5 μM, respectively. The enzyme assay demonstrated that 5a and 5b had inhibition potency on c-Met with IC₅₀ values in nanomolar range of 4.27 ± 0.31 and 7.95 ± 0.17 nM, respectively in comparison with the reference drug cabozantinib (IC₅₀; 5.38 ± 0.35 nM). The impact of 5a on the cell cycle and apoptosis induction potential in HepG-2 and on the apoptotic parameters; Bax, Bcl-2, p53, and caspase-3 was also investigated. Finally, the molecular docking simulation of the most promising derivatives 5a and 5b was screened against c-Met to investigate the binding patterns of both compounds in the active site of the c-Met enzyme. In silico ADME studies were also performed for 5a and 5b to predict their physicochemical and pharmacokinetic characteristics.

"Magic Chloro": Profound Effects of the Chlorine Atom in Drug Discovery

Chlorine is one of the most common atoms present in small-molecule drugs beyond carbon, hydrogen, nitrogen, and oxygen. There are currently more than 250 FDA-approved chlorine-containing drugs, yet the beneficial effect of the chloro substituent has not yet been reviewed. The seemingly simple substitution of a hydrogen atom (R = H) with a chlorine atom (R = Cl) can result in remarkable improvements in potency of up to 100,000-fold and can lead to profound effects on pharmacokinetic parameters including clearance, half-life, and drug exposure in vivo. Following the literature terminology of the "magic methyl effect" in drugs, the term "magic chloro effect" has been coined herein. Although reports of 500-fold or 1000-fold potency improvements are often serendipitous discoveries that can be considered "magical" rather than planned, hypotheses made to explain the magic chloro effect can lead to lessons that accelerate the cycle of drug discovery.

Signaling Pathway and Small-Molecule Drug Discovery of FGFR: A Comprehensive Review

Targeted therapy is a groundbreaking innovation for cancer treatment. Among the receptor tyrosine kinases, the fibroblast growth factor receptors (FGFRs) garnered substantial attention as promising therapeutic targets due to their fundamental biological functions and frequently observed abnormality in tumors. In the past 2 decades, several generations of FGFR kinase inhibitors have been developed. This review starts by introducing the biological basis of FGF/FGFR signaling. It then gives a detailed description of different types of small-molecule FGFR inhibitors according to modes of action, followed by a systematic overview of small-molecule-based therapies of different modalities. It ends with our perspectives for the development of novel FGFR inhibitors.

From Fragment to Lead: De Novo Design and Development toward a Selective FGFR2 Inhibitor

Fibroblast growth factor receptors (FGFRs) are implicated in a range of cancers with several pan-kinase and selective-FGFR inhibitors currently being evaluated in clinical trials. Pan-FGFR inhibitors often cause toxic side effects and few examples of subtype-selective inhibitors exist. Herein, we describe a structure-guided approach toward the development of a selective FGFR2 inhibitor. De novo design was carried out on an existing fragment series to yield compounds predicted to improve potency against the FGFRs. Subsequent iterative rounds of synthesis and biological evaluation led to an inhibitor with nanomolar potency that exhibited moderate selectivity for FGFR2 over FGFR1/3. Subtle changes to the lead inhibitor resulted in a complete loss of selectivity for FGFR2. X-ray crystallographic studies revealed inhibitor-specific morphological differences in the P-loop which were posited to be fundamental to the selectivity of these compounds. Additional docking studies have predicted an FGFR2-selective H-bond which could be utilized to design more selective FGFR2 inhibitors.

One-pot three-component synthesis of novel pyrazolo[3,4-b]pyridines as potent antileukemic agents

In the current study, we report on the development of novel series of pyrazolo[3,4-b]pyridine derivatives (8a-u, 11a-n, and 14a,b) as potential anticancer agents. The prepared pyrazolo[3,4-b]pyridines have been screened for their antitumor activity in vitro at NCI-DTP. Thereafter, compound 8a was qualified by NCI for full panel five-dose assay to assess its GI₅₀, TGI and LC₅₀ values. Compound 8a showed broad-spectrum anti-proliferative activities over the whole NCI panel, with outstanding growth inhibition full panel GI₅₀ (MG-MID) value equals 2.16 μM and subpanel GI₅₀ (MG-MID) range: 1.92-2.86 μM. Furthermore, pyrazolo[3,4-b]pyridines 8a, 8e-h, 8o, 8u, 11a, 11e, 11h, 11l and 14a-b were assayed for their antiproliferative effect against a panel of leukemia cell lines (K562, MV4-11, CEM, RS4;11, ML-2 and KOPN-8) where they possessed moderate to excellent anti-leukemic activity. Moreover, pyrazolo[3,4-b]pyridines 8o, 8u, 14a and 14b were further explored for their effect on cell cycle on RS4;11 cells, in which they dose-dependently increased populations of cells in G2/M phases. Finally we analyzed the changes of selected proteins (HOXA9, MEIS1, PARP, BcL-2 and McL-1) related to cell death and viability in RS4;11 cells via Western blotting. Collectively, the obtained results suggested pyrazolo[3,4-b]pyridines 8o, 8u, 14a and 14b as promising lead molecules for further optimization to develop more potent and efficient anticancer candidates.

Modular Synthesis and Antiproliferative Activity of New Dihydro-1H-pyrazolo[1,3-b]pyridine Embelin Derivatives

A set of new dihydro-1H-pyrazolo[1,3-b]pyridine and pyrazolo[1,3-b]pyridine embelin derivatives was synthesized through a multicomponent reaction from natural embelin, 3-substituted-5-aminopyrazoles and aldehydes. The synthesized compounds were evaluated against three hematologic tumor cell lines, HEL (acute erythroid leukemia), K-562 (chronic myeloid leukemia) and HL-60 (acute myeloid leukemia), and five breast cancer cell lines (SKBR3, MCF-7, MDA-MB-231, BT-549, HS-578T). The primate non-malignant kidney Vero cell line was used as the control of cytotoxicity. From the obtained results, some structure–activity relationships were outlined. Furthermore, in silico prediction of physicochemical properties and ADME parameters were determined for the derivatives with the best antiproliferative values.

Recent Advances in the Development of Pyrazolopyridines as Anticancer Agents

Cancer, especially malignant tumor, is a serious threat to people's life and health. It is recognized as an enormous challenge in the 21st century. Continuous efforts are needed to overcome this problem. Pyrazolopyridine nucleus, similar in structure to purine, shows a variety of biological activities, which is mainly attributed to the antagonistic nature towards the natural purines in many biological processes. This has aroused enormous attention for many researchers. At present, a large number of new chemical entities containing pyrazolopyridine nucleus have been found as anticancer agents. In this review we summarize novel pyrazolopyridine-containing derivatives with biological activities. Furthermore, we outline the relationships between the structures of variously modified pyrazolopyridines and their anticancer activity.

Synthesis and biological evaluation of indazole derivatives as anti-cancer agents

Several FDA approved small molecule anti-cancer drugs contain indazole scaffolds. Here, we report the design, synthesis and biological evaluation of a series of indazole derivatives. In vitro antiproliferative activity screening showed that compound 2f had potent growth inhibitory activity against several cancer cell lines (IC₅₀ = 0.23–1.15 μM). Treatment of the breast cancer cell line 4T1 with 2f inhibited cell proliferation and colony formation. 2f dose-dependently promoted the apoptosis of 4T1 cells, which was connected with the upregulation of cleaved caspase-3 and Bax, and downregulation of Bcl-2. 2f also decreased the mitochondrial membrane potential and increased the levels of reactive oxygen species (ROS) in 4T1 cells. Additionally, treatment with 2f disrupted 4T1 cells migration and invasion, and the reduction of matrix metalloproteinase metalloproteinase-9 (MMP9) and increase of tissue inhibitor matrix metalloproteinase 2 (TIMP2) were also observed. Moreover, 2f could suppress the growth of the 4T1 tumor model without obvious side effects in vivo. Taken together, these results identified 2f as a potential small molecule anti-cancer agent.

One of the synthesized indazole derivatives, 2f, displayed inhibitory activities against proliferation, migration and invasion of breast cancer cell line 4T1, with the potential of inducing cell apoptosis, and suppressing tumor growth in vivo.

Multicomponent synthesis of styryl linked benzo[h]pyrazolo[3,4-b]quinoline-5,6(10H)-diones by liquid assisted grinding

Herein we report an interesting multicomponent reaction of α,β-unsaturated aldehydes, 2-hydroxy-1,4-naphthoquinone and 5-aminopyrazoles by liquid assisted grinding.

Selective N7 Alkylation of 7-Azaindazoles

A general and mild procedure for alkylation of 7-azaindazoles at the N7 position using alkyl halides in butanone is reported, which requires no additives such as acids or bases. The scope of the reaction regarding substituents on 7-azaindazoles and the alkyl electrophiles is presented.

Design, One Pot Synthesis and Molecular Docking Studies of Substituted-1H-Pyrido[2,1-b] Quinazolines as Apoptosis-Inducing Anticancer Agents

Objective:

The present study focused to build pyridine and quinazoline rings in a single molecule and designed a new fused Pyrido[2,1-b] quinazoline to have a better pharmacological activity.

Material and Methods:

A three component, one-pot synthesis of substituted-1H-Pyrido[2,1-b] quinazoline derivatives has been described by conventional and microwave synthesis using triflic acid as catalyst. These compounds were screened for in vitro cytotoxic activity against the panel of cancer cell lines A549, NCI-H460, HT-29, HCT-15, DU-145, and HFL.

Results:

Among the tested compounds, 11-(1-benzyl-1H-indol-3-y1)-2, 3, 4, 11-tetrahydro-1H-pyrido[2,1-b] quinazoline (4i) showed most potent cytotoxicity against A549 and NCI-H460 lung cancer cell lines with IC₅₀ values 4.57±0.25 and 5.53±0.49 µM, respectively. Moreover, compound 4i was found to be most potent considerable cell growth inhibition with GI₅₀ values of 2.70±0.18 and 3.24±0.40 µM against A549 and NCI-H460 cell lines, respectively. In addition, induction of apoptosis for compound 4i on A549 was investigated by morphological changes, Acridine orange/ethidium bromide (AO/EB) and DAPI staining. Furthermore, a strong anti-clonogenic effect of compound 4i on lung cancer cells was observed. The flow cytometric analysis investigation reveals that compound 4i arrests the A549 cancer cell lines at the G0/G1 phase of the cell cycle. Molecular docking were also performed on 4i, 4j, and erlotinib to predict the binding mode towards the EGFR kinase (PDB code: 1M17) and the compounds have displayed similar interactions and compared with erlotinib.

Conclusion:

Overall, these findings could suggest that the compound 4i would be an ideal lead as an anticancer agent.

The application of nitrogen heterocycles in mitochondrial-targeting fluorescent markers with neutral skeletons

Neutral fluorescent markers containing nitrogen heterocycles as targeting groups were designed and prepared to screen out structural units for targeting mitochondria.

Fibroblast growth factor receptor inhibitors: patent review (2015-2019)

Introduction: fibroblast growth factor receptors (FGFRs) are a family of tyrosine-kinase receptors whose signaling cascade regulates cellular proliferation, differentiation, and survival. Deregulation of the FGFR pathway is recognized as a driving factor in tumor development. On this basis, FGFR is an attractive target for anti-cancer small-molecule therapeutic agents.Areas covered: This review summarizes patent and literature publications spanning from 2015 to 2019 pertaining to small-molecule FGFR kinase inhibitors.Expert opinion: The first generation of non-covalent FGFR inhibitors is characterized by a broad spectrum of activity and a relatively high toxicity profile. The second generation of FGFR inhibitors shows higher selectivity and a more favorable toxicity profile, but the clinical use appears restricted only to small subsets of cancers strongly dependent on FGFR signaling. Nevertheless, erdafitinib has been approved for the treatment of metastatic urothelial carcinoma, becoming the first marketed selective FGFR inhibitor. The insurgence of mutant kinases, resistant to available therapies, has led to the development of irreversible FGFR inhibitors. The adoption of safer and more selective covalent inhibitors might supersede reversible inhibitors in specific therapeutic areas. Alternative strategies, such as FGF trapping by protein or small-molecule therapeutics, deserve attention and further investigations to unravel their potential.

Synthesis and Structure-Activity Relationships of 3,5-Disubstituted-pyrrolo[2,3- b]pyridines as Inhibitors of Adaptor-Associated Kinase 1 with Antiviral Activity

There are currently no approved drugs for the treatment of emerging viral infections, such as dengue and Ebola. Adaptor-associated kinase 1 (AAK1) is a cellular serine-threonine protein kinase that functions as a key regulator of the clathrin-associated host adaptor proteins and regulates the intracellular trafficking of multiple unrelated RNA viruses. Moreover, AAK1 is overexpressed specifically in dengue virus-infected but not bystander cells. Because AAK1 is a promising antiviral drug target, we have embarked on an optimization campaign of a previously identified 7-azaindole analogue, yielding novel pyrrolo[2,3- b]pyridines with high AAK1 affinity. The optimized compounds demonstrate improved activity against dengue virus both in vitro and in human primary dendritic cells and the unrelated Ebola virus. These findings demonstrate that targeting cellular AAK1 may represent a promising broad-spectrum antiviral strategy.

Synthesis of Fluorescent 1,7-Dipyridyl-bis-pyrazolo[3,4-b:4',3'-e]pyridines: Design of Reversible Chemosensors for Nanomolar Detection of Cu2

An efficient access toward novel tridentate ligands based on 1,7-dipyridinyl-substituted bis-pyrazolo[3,4-b:4',3'-e]pyridines (BPs) and their usefulness as fluorescent probes for cation detection is reported. The synthesis proceeds by a three-step sequence starting from 2-chloropyridine (1), all reactions were performed using microwave radiation under solvent-free conditions, and an overall yield of up to 63% was obtained. Photophysical properties of three representative 1,7-dipyridinyl-BPs (PBPs, 6a-6c) substituted at position 4 with different donor (D) or acceptor (A) groups were investigated. Compounds exhibited large Stokes shift in different solvents and strong blue light emission in both solution and solid state, and quantum yields were as high as 88% for some of them; thus, a twisted intramolecular charge transfer (TICT) fluorescence mechanism characteristic of the 1,4,7-triaryl-BPs was confirmed. The 4-phenyl-substituted probe (Ph-PBP, 6b) was used successfully in the detection of some metals (Cu2+, Co2+, Ni2+, and Hg2+) by fluorescence quenching phenomena, which could be reversed in the presence of ethylenediamine. This probe showed a greater sensitivity toward Cu2+ in concentrations as low as 26 nM, and in the process of "on-off-on" for this fluorescent molecular switch, only 1 equiv of the analyte was used.

Na2S-promoted reduction of azides in water: synthesis of pyrazolopyridines in one pot and evaluation of antimicrobial activity

Reduction of various azides using Na2S has been accomplished in water, and, in situ, the resulting amines on reaction with various ketones lead to pyrazolo[3,4-b]pyridines in one pot. Thus, a number of new trifluoromethyl-substituted pyrazolo[3,4-b]pyridine compounds have been prepared and screened for antimicrobial activity against different Gram-positive and Gram-negative strains. A good number of compounds, 4a, 4b, 4d, 4f, 4i, 4k, 4l, 4m, 4r and 4s, were found to possess promising activity. Notably, Na2S on hydrolysis in water generates H2S and NaOH, which facilitate the reduction of azides followed by intramolecular cyclization leading to the title compounds. To the best of our knowledge, this is the first report of the synthesis of the title compounds in aqueous medium in a one-pot reaction.

The irony of chirality – unveiling the distinct mechanistic binding and activities of 1-(3-(4-amino-5-(7-methoxy-5-methylbenzo[b]thiophen-2-yl)-7H-pyrrolo[2,3-d]pyrimidin-7-yl)pyrrolidin-1-yl)prop-2-en-1-one enantiomers as irreversible covalent FGFR4 inhibitors

Theoretical investigation of the effect of chirality on inhibitors is providing essential insights for drug design.

Recent Advances in the Development of Indazole-based Anticancer Agents

Cancer is one of the leading causes of human mortality globally; therefore, intensive efforts have been made to seek new active drugs with improved anticancer efficacy. Indazole-containing derivatives are endowed with a broad range of biological properties, including anti-inflammatory, antimicrobial, anti-HIV, antihypertensive, and anticancer activities. In recent years, the development of anticancer drugs has given rise to a wide range of indazole derivatives, some of which exhibit outstanding activity against various tumor types. The aim of this review is to outline recent developments concerning the anticancer activity of indazole derivatives, as well as to summarize the design strategies and structure-activity relationships of these compounds.

Discovery of Potent Irreversible Pan-Fibroblast Growth Factor Receptor (FGFR) Inhibitors

Fibroblast growth factor receptors (FGFR1-4) are promising therapeutic targets in many cancers. With the resurgence of interest in irreversible inhibitors, efforts have been directed to the discovery of irreversible FGFR inhibitors. Currently, several selective irreversible inhibitors are being evaluated in clinical trials that could covalently target a conserved cysteine in the P-loop of FGFR. In this article, we used a structure-guided approach that is rationalized by a computer-aided simulation to discover the novel and irreversible pan-FGFR inhibitor, 9g, which provided superior FGFR in vitro activities and decent selectivity over VEGFR2 (vascular endothelia growth factor receptor 2). In in vivo studies, 9g displayed clear antitumor activities in NCI-H1581 and SNU-16 xenograft mice models. Additionally, the diluting method confirmed the irreversible binding of 9g to FGFR.

Synthesis of 3,6-diaryl-1H-pyrazolo[3,4-b]pyridines via one-pot sequential Suzuki–Miyaura coupling

A practical synthesis of diarylpyrazolo[3,4-b]pyridine derivatives by a combination of chemoselective Suzuki–Miyaura cross-coupling reactions was developed. The sequential arylation strategy can be performed in a one-pot manner without much loss of efficiency when compared to the corresponding stepwise synthesis. These conditions are applicable to the coupling of a wide variety of aryl and heteroaryl-boronic acids with pyrazolo[3,4-b]pyridines with high selectivity of the C3 over the C6 position, thus enabling the rapid construction of a diverse array of medicinally important diarylpyrazolo[3,4-b]pyridines.

An efficient method to produce diarylpyrazolo[3,4-b]pyridines derivatives via combination of chemoselective Suzuki–Miyaura cross-coupling reactions has been developed.

One-Step Synthesis of Fully Functionalized Pyrazolo[3,4-b]pyridines via Isobenzofuranone Ring Opening

A novel series of fully substituted pyrazolo[3,4-b]pyridines 4 has been prepared in a regioselective manner by the microwave-assisted reaction between N-substituted 5-aminopyrazoles 1 and 3-(3-oxo-2-benzofuran-1(3H)-ylidene)pentane-2,4-dione (2). This is the second reported example of a cyclocondensation reaction using substrate 2 as a 1,3-bis-electrophilic reagent. Remarkably, this synthesis offers functionalized products with acetyl and carboxyl groups in one step, in good yields, and with short reaction times. Additionally, the cyclization intermediate 3 was isolated, allowing us to postulate a mechanism for this reaction, which is initiated via isobenzofuranone ring opening of 2 in a Michael-type reaction. The structures of the products and regioselectivity of the reactions were determined on the basis of NMR measurements and X-ray diffraction. For this new reaction using substrate 2, the optimal reaction conditions and its scope were investigated.

Assembly of Diversely Substituted Quinolines via Aerobic Oxidative Aromatization from Simple Alcohols and Anilines

An aerobic oxidative aromatization of simple aliphatic alcohols and anilines under the Pd(OAc)₂/2,4,6-Collidine/Brønsted acid catalytic system has been established, providing a direct approach for the preparation of diverse substituted quinoline derivatives in high yields with wide functional group tolerance. Practically, the protocol can be easily scaled up to gram-scale and was utilized in the concise formal synthesis of a promising herbicide candidate.

Design, synthesis, and biological evaluation of imidazo[1,2-b]pyridazine derivatives as mTOR inhibitors

ATP-competitive mTOR inhibitors have been studied as potential antitumor agents. Based on the structure-activity relationship of known mTOR inhibitors, a series of novel imidazo[1,2-b]pyridazine derivatives were synthesized and characterized. The anti-proliferative activities of these compounds were evaluated by SRB assay against six human cancer cell lines. Imidazo[1,2-b]pyridazine diaryl urea derivatives A15-A24 exhibited significant anti-proliferative activity especially against non-small cell lung cancer A549 and H460 with IC₅₀ values ranging from 0.02 μM to 20.7 μM. Among them, compounds A17 and A18 showed mTOR inhibitory activity with IC₅₀ of 0.067 μM and 0.062 μM, respectively. A more detailed analysis of compounds A17 and A18 showed that they induced G1-phase cell cycle arrest and suppressed the phosphorylation of AKT and S6 at cellular level. Moreover, obvious anticancer effect of A17 in vivo was observed in established nude mice A549 xenograft model.

The Necessary Nitrogen Atom: A Versatile High-Impact Design Element for Multiparameter Optimization

There is a continued desire in biomedical research to reduce the number and duration of design cycles required to optimize lead compounds into high-quality chemical probes or safe and efficacious drug candidates. The insightful application of impactful molecular design elements is one approach toward achieving this goal. The replacement of a CH group with a N atom in aromatic and heteroaromatic ring systems can have many important effects on molecular and physicochemical properties and intra- and intermolecular interactions that can translate to improved pharmacological profiles. In this Perspective, the "necessary nitrogen atom" is shown to be a versatile high-impact design element for multiparameter optimization, wherein ≥10-, 100-, or 1000-fold improvement in a variety of key pharmacological parameters can be realized.

Design, Synthesis and Biological Evaluation of 6-(2,6-Dichloro-3,5-dimethoxyphenyl)-4-substituted-1H-indazoles as Potent Fibroblast Growth Factor Receptor Inhibitors

Tyrosine kinase fibroblast growth factor receptor (FGFR), which is aberrant in various cancer types, is a promising target for cancer therapy. Here we reported the design, synthesis, and biological evaluation of a new series of 6-(2,6-dichloro-3,5-dimethoxyphenyl)-4-substituted-1H-indazole derivatives as potent FGFR inhibitors. The compound 6-(2,6-dichloro-3,5-dimethoxyphenyl)-N-phenyl-1H-indazole-4-carboxamide (10a) was identified as a potent FGFR1 inhibitor, with good enzymatic inhibition. Further structure-based optimization revealed that 6-(2,6-dichloro-3,5-dimethoxyphenyl)-N-(3-(4-methylpiperazin-1-yl)phenyl)-1H-indazole-4-carboxamide (13a) is the most potent FGFR1 inhibitor in this series, with an enzyme inhibitory activity IC₅₀ value of about 30.2 nM.

Magnetically separable graphene oxide anchored sulfonic acid: a novel, highly efficient and recyclable catalyst for one-pot synthesis of 3,6-di(pyridin-3-yl)-1H-pyrazolo[3,4-b]pyridine-5-carbonitriles in deep eutectic solvent under microwave irradiation

A magnetic separable sulfonic acid catalyst was prepared and applied for the synthesis of 3,6-di(pyridin-3-yl)-1H-pyrazolo[3,4-b]pyridine-5-carbonitriles via three-component reaction of 1-phenyl-3-(pyridin-3-yl)-1H-pyrazol-5-amine, β-ketonitrile and aldehydes in DES.