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In view of the serious adverse reactions and clinical toxicity of first line therapy 5-fluorouracil and lack of small molecule therapeutics in colorectal cancer chemotherapy, a series of natural scaffold-based 3-arylindanone derivatives (9a-q) were designed, synthesized and evaluated as tubulin polymerization inhibitors targeting the colchicine site. The most potent colchicine binding site inhibitor (CBSI), ( R )-9k , exhibited 14-38 times more dominant anti-proliferative activity against three colon cancer cell lines than 5-fluorouracil. Particularly, ( R )-9k showed higher selectivity against human normal cells compared with 5-fluorouracil and colchicine, and displayed negligible cardiotoxicity through hERG assessment. Furthermore, the binding of ( R )-9k to the colchicine site was strongly supported by EBI competition assay and ( R )-9k inhibited more tubulin polymerization than colchicine. Besides, the mechanism of action and binding modes of ( R )-9k were verified by molecular dynamics simulations and docking. Therefore, ( R )-9k could be regarded as a promising CBSI for colorectal cancer therapy., Competing Interests: The authors declare no conflicts of interest with the contents of the paper., (This journal is © The Royal Society of Chemistry.)

Hederagenin is a pentacyclic triterpenoid isolated from plants and widely distributed in a variety of medicinal plants. By integrating and analyzing external related literature reports, the latest research progress on the pharmacological effects and structural modification of hederagenin was reviewed. Hederagenin has a wide range of pharmacological activities, including antitumor, anti-inflammatory, antidepressant, anti-neurodegenerative, antihyperlipidemic, antidiabetic, anti-leishmaniasis, and antiviral activities. Among them, it shows high potential in the field of anti-tumor treatment. This paper also reviews the structural modifications of hederagenin, including carboxyl group modifications and two hydroxyl group modifications. Future research on hederagenin will focus on prolonging its half-life, improving its bioavailability and structural modification to enhance its pharmacological activity, accelerating the preclinical research stage of hederagenin for it to enter the clinical research stage as soon as possible., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (This journal is © The Royal Society of Chemistry.)

CK2 is a ubiquitous protein kinase with an anti-apoptotic role and is found to be overexpressed in multiple cancer types. To this end, the inhibition of CK2 is of great interest with regard to the development of novel anti-cancer therapeutics. ATP-site inhibition of CK2 is possible; however, this typically results in poor selectivity due to the highly conserved nature of the catalytic site amongst kinases. An alternative methodology for the modulation of CK2 activity is through allosteric inhibition. The recently identified αD site represents a promising binding site for allosteric inhibition of CK2α. The work presented herein describes the development of a series of CK2α allosteric inhibitors through iterative cycles of X-ray crystallography and enzymatic assays, in addition to both fragment growing and fragment merging design strategies. The lead fragment developed, fragment 8, exhibits a high ligand efficiency, displays no drop off in activity between enzymatic and cellular assays, and successfully engages CK2α in cells. Furthermore, X-ray crystallographic analysis provided indications towards a novel mechanism of allosteric inhibition through αD site binding. Fragments described in this paper therefore represent promising starting points for the development of highly selective allosteric CK2 inhibitors., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Pyrazole is a five-membered heterocycle bearing two adjacent nitrogen atoms. Both pharmaceutical agents and natural products with pyrazole as a nucleus have exhibited a broad spectrum of biological activities. In the last few decades, more than 40 pyrazole-containing drugs have been approved by the FDA for the treatment of a broad range of clinical conditions including celecoxib (anti-inflammatory), CDPPB (antipsychotic), difenamizole (analgesic), etc. Owing to the unique physicochemical properties of the pyrazole core, pyrazole-containing drugs may exert better pharmacokinetics and pharmacological effects compared with drugs containing similar heterocyclic rings. The purpose of this paper is to provide an overview of all the existing drugs bearing a pyrazole nucleus that have been approved or in clinical trials, involving their pharmacological activities and SAR studies., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Bile acids (BAs) containing both hydrophilic hydroxyl and carboxyl groups and hydrophobic methyl and steroid nuclei can promote the absorption of fat and other substances in the intestine, and they are synthesized by cholesterol in the liver and then returned to the liver through enteric liver circulation. Because there are many BA receptors on the cell membrane of colon tissues, BAs can improve the specific delivery and transport of medicines to colon tissues. Moreover, BAs have a certain anticancer and inflammation activity by themselves. Based on this theory, a series of BA derivatives against colon cancer including cholic acid (CA), chenodeoxycholic acid (CDCA), ursodeoxycholic acid (UDCA) and lithocholic acid (LCA) were designed and synthesized, and their antitumor activity was evaluated. For in vitro anti-tumor tests, all the compounds displayed cell proliferative inhibition to nine human malignant tumor cell lines to some degree, and in particular they showed stronger inhibition to the colon cancer cells than the other cell lines. Among them, four compounds (4, 5, 6, and 7) showed stronger activity than the other compounds as well as the positive control 5-FU against HCT116 cells, and their IC 50 was between 21.32 μmol L -1 and 28.90 μmol L -1 ; cell clone formation and migration tests showed that they not only effectively inhibited the formation of HCT116 cell colonies, but also inhibited the HCT116 cell migration and invasion; moreover, they induced apoptosis, arrested the mitotic process at the G2/M phase of the cell cycle, reduced the mitochondrial membrane potential, increased the intracellular ROS levels, and reduced the expression of Bcl-2 and p-STAT3 in HCT 116 cells. In addition, they also displayed intermediate anti-inflammatory activity by inhibiting inflammatory mediators NO and downregulating TNF-α expression, which also is one of the causes of colon cancer. This suggests that they deserve to be further investigated as candidates for colon cancer treatment drugs., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (This journal is © The Royal Society of Chemistry.)

Aberrant activation of the PI3K/AKT pathway is considered in many malignant tumors and plays a crucial role in mediating malignancy progression, metastasis, and chemoresistance. Consequently, development of PI3K/AKT pathway targeted drugs is currently an attractive research field for tumor treatment. In this study, twenty-six flavonoid-based amide derivatives were synthesized and evaluated for their antiproliferation effects against seven cancer cell lines, including MDA-MB-231, MCF-7, HCC1937, A549, HepG2, GTL-16 and HeLa. Among them, compound 7t possessed the best specific cytotoxicity against triple negative breast cancer MDA-MB-231 cells with an IC 50 value of 1.76 ± 0.91 μM and also presented inhibitory ability on clonal-formation, migration and invasion of MDA-MB-231 cells. Further cell-based mechanistic studies demonstrated that compound 7t caused cell cycle arrest of MDA-MB-231 cells at the G 0 /G 1 phase and induced apoptosis. Meanwhile, the western blot assay revealed that compound 7t could down-regulate the expression of p-PI3K, p-AKT, and Bcl-2 and up-regulate the production of PTEN, Bax, and caspase-3. Molecular docking also showed a possible binding mode of 7t with PI3Kα. Together, compound 7t was eligible as a potential TNBC therapeutic candidate for further development., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (This journal is © The Royal Society of Chemistry.)

Commonly overexpressed in many cancers and associated with tumor growth, metastasis, drug resistance, and poor overall survival, Axl has emerged as a promising target for cancer therapy. However, the availability of new chemical forms for Axl inhibition is limited. Herein, we present the development and characterization of novel Axl inhibitors, including the design, synthesis, and structure-activity relationships (SARs) of a series of diphenylpyrimidine-diamine derivatives. Most of these compounds exhibited remarkable activity against the Axl kinase. In particular, the promising compound m16 showed the highest enzymatic inhibitory potency (IC 50 = 5 nM) and blocked multiple tumor cells' proliferation potencies (the CC 50 of 4 out of 42 cancer cell lines <100 nM). Furthermore, compound m16 also possessed preferable pharmacokinetic profiles and liver microsome stability. All these favorable results make m16 a good leading therapeutic candidate for further development., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (This journal is © The Royal Society of Chemistry.)

The 4-Aminopyrazolopyrimidine scaffold has been an interesting pharmacophore since the disclosure of the intimate connection between small-molecule inhibitors and the treatment of diseases. Modification of the 4-aminopyrazolopyrimidine scaffold according to different targets, especially tyrosine kinase and serine/threonine kinase, has resulted in a variety of small-molecule inhibitors. Kinase inhibitors with 4-aminopyrazolopyrimidine derivatives as scaffolds have been widely applied in the treatment of diseases. In this article, we summarized the reports on 4-aminopyrazolopyrimidine as well as its deformation and the application of its derivatives in designing small-molecule inhibitors and the treatment of diseases., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (This journal is © The Royal Society of Chemistry.)

Mitogen-activated protein kinases (MAPKs) govern various cellular programs and crucial intermediate pathways in signaling. Microtubule affinity-regulating kinase 4 (MARK4) is a part of the kinase family recognized for actively phosphorylating neural microtubule-associated proteins (MAPs) like MAP2, MAP4 and most importantly, tau. The Ser/Thr kinase MARK4 overexpression is associated with various life-threatening conditions such as neurodegenerative disorders, diabetic neuropathy, and cancer. Functionally, MARK4 is correlated with many important signaling cascades and transcription factors contributing to neurodegeneration and cancer onset and progression. Serotonin is a key molecule associated with regulating mood, stress, and various behavioral aspects. Low serotonin levels promote the progression of neurological and psychotic disorders, which is also a consequence of tau accumulation. MARK4 being a major contributor to phosphorylating tau, leading to its accumulation, and contributing to tauopathy, is targeted for inhibition by serotonin. The study deals with the inhibition of MARK4 by serotonin using combined computational and experimental studies. The results presented in this paper provide strong evidence for the direct physical binding of serotonin to recombinant MARK4 and subsequent inhibition of its kinase activity. In addition, we have performed molecular docking, followed by 100 ns MD simulations of MARK4 in the presence of serotonin, to estimate the stability of the protein-ligand complex. Since MARK4 is a potential drug target and can be exploited for drug design and discovery for cancer and neurodegenerative disorders, the results presented here are of interest and may be further exploited for Alzheimer's disease (AD) and other neurodegenerative diseases., Competing Interests: The authors declare no conflict of interest., (This journal is © The Royal Society of Chemistry.)

Pirfenidone (PFD) was the first approved drug by FDA for the treatment of idiopathic pulmonary fibrosis (IPF). However, the rapid metabolism of 5-methyl of PFD increases the risk of side effects in clinics. Thus, in this paper, a common practice that a stable amide bond linking various groups used to replace 5-methyl of PFD in medicinal chemistry was applied, and total 18 PFD derivatives were synthesized. All compounds were investigated for their antiproliferation activities against NIH3T3 cells and the structure-activity relationships of the target compounds were also discussed. Among them, YZQ17 possessed potent antiproliferation activity compared to PFD and better potency in inhibiting TGF-β-induced migration of NIH3T3 cells at a much lower concentration than that of PFD. In addition, YZQ17 dramatically inhibited the expression levels of fibrotic markers α-SMA, collagen I, and fibronectin. Moreover, further mechanistic studies confirmed that YZQ17 exhibited this considerable anti-fibrosis activity via the TGF-β/Smad2/3 dependent pathway. Finally, the results of human and rat liver microsomes assay in vitro and pharmacokinetic assay in rats confirmed that YZQ17 showed better pharmacokinetics than that of PFD. Collectively, the preliminary study of PFD derivatives modified by the amide group indicated that YZQ17 could be regarded as a lead compound for further investigation and optimization., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Neurodegenerative disorders, i.e. , Alzheimer's or Parkinson's disease, involve progressive degeneration of the central nervous system, resulting in memory loss and cognitive impairment. The intensification of neurodegenerative research in recent years put some molecules into clinical trials, but still there is an urgent need to develop effective therapeutic molecules to combat these diseases. Chromone is a well-identified privileged structure for the design of well-diversified therapeutic molecules of potential pharmacological interest, particularly in the field of neurodegeneration. In this short review, we focused on the recent advancements and developments of chromones for neurodegenerative therapeutics. Different small molecules were reviewed as multi-target-directed ligands (MTDLs) with potential inhibition of AChE, BuChE, MAO-A, MAO-B, Aβ plaque formation and aggregation. Recently developed MTDLs emphasized that the chromone scaffold has the potential to develop new molecules for the treatment of neurodegenerative diseases., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (This journal is © The Royal Society of Chemistry.)

Src homology 2 domain-containing protein tyrosine phosphatase (SHP2) is a non-receptor protein tyrosine phosphatase encoded by the Ptpn11 gene, which regulates cell growth, differentiation and apoptosis via modulating various signaling pathways, such as the RAS/ERK signaling pathway, and participates in the PD-1/PD-L1 pathway governing immune surveillance. It has been recognized as a breakthrough antitumor therapeutic target. Besides, numerous studies have shown that SHP2 plays an important role in the regulation of inflammatory diseases. However, inhibitors targeting the active site of SHP2 lack drug-likeness due to their low selectivity and poor bioavailability, thus none has advanced to clinical development. Recently, allosteric inhibitors that stabilize the inactive conformation of SHP2 have achieved breakthrough progress, providing the clinical proof for the druggability of SHP2 as an antitumor drug target. This paper reviews the recently reported design and discovery of SHP2 small molecule inhibitors, focused on the structure-activity relationship (SAR) analysis of several representative SHP2 inhibitors, outlining the evolution and therapeutic potential of the small molecule inhibitors targeting SHP2., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

PF74 (1) is a potent and well-characterized prototypical small molecule targeting human immunodeficiency virus type 1 (HIV-1) capsid protein (CA), but not a viable antiviral lead due to the lack of metabolic stability. We report herein our molecular hybridization-based medicinal chemistry efforts toward potent and metabolically stable PF74-like small molecules. The design of the new sub-chemotype 4 rationally combines binding features of two recently reported PF74-like compounds 2 and 3. The subsequent confirmation and structure-activity relationship (SAR) of hit 4a entailed the chemical synthesis of 37 novel analogs, most of which showed modest but meaningful thermal shift, and low μM antiviral activity. The most potent analogs (4a, 4d, 4o, and 4r) all exhibited noticeably improved metabolic stability over PF74. Molecular modeling suggests that these new analogs bind to the PF74 binding site. Overall, our work demonstrated that the molecular hybridization approach is suitable for designing compounds with balanced potency and metabolic stability., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (This journal is © The Royal Society of Chemistry.)

The nitrile group is an important functional group widely found in both pharmaceutical agents and natural products. More than 30 nitrile-containing pharmaceuticals have been approved by the FDA for the management of a broad range of clinical conditions in the last few decades. Incorporation of a nitrile group into lead compounds has gradually become a promising strategy in rational drug design as it can bring additional benefits including enhanced binding affinity to the target, improved pharmacokinetic profile of parent drugs, and reduced drug resistance. This paper reviews the existing drugs with a nitrile moiety that have been approved or in clinical trials, involving their targets, molecular mechanism of pharmacology and SAR studies, and classifies them into different categories based on their clinical usages., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

This paper describes the design and synthesis of Strathclyde minor groove binders (S-MGBs) that have been truncated by the removal of a pyrrole ring in order to mimic the structure of the natural product, disgocidine. S-MGBs have been found to be active against many different organisms, however, selective antiparasitic activity is required. A panel of seven truncated S-MGBs was prepared and the activities examined against a number of clinically relevant organisms including several bacteria and parasites. The effect of the truncation strategy on S-MGB aggregation in aqueous environment was also investigated using 1H inspection and DOSY experiments. A lead compound, a truncated S-MGB, which possesses significant activity only against trypanosomes and Leishmania has been identified for further study and was also found to be less affected by aggregation compared to its full-length analogue., Competing Interests: There is no conflict of interest to declare., (This journal is © The Royal Society of Chemistry.)

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease with a typical survival time between three to five years. Two drugs, pirfenidone and nintedanib have been approved for the treatment of IPF, but they have limited efficacy. Thus, the development of new drugs to treat IPF is an urgent medical need. In this paper we report the discovery of a series of orally active pyrimidin-4(3 H )-one analogs which exhibit potent activity in in vitro assays. Among them, HEC-866 showed promising efficacy in rat IPF models. Since HEC-866 also had good oral bioavailability, a long half-life and favorable long-term safety profiles, it was selected for further clinical evaluation., Competing Interests: There is no conflict of interest to declare., (This journal is © The Royal Society of Chemistry.)

As part of our efforts to develop sustainable drugs for Alzheimer's disease (AD), we have been focusing on the inexpensive and largely available cashew nut shell liquid (CNSL) as a starting material for the identification of new acetylcholinesterase (AChE) inhibitors. Herein, we decided to investigate whether cardanol, a phenolic CNSL component, could serve as a scaffold for improved compounds with concomitant anti-amyloid and antioxidant activities. Ten new derivatives, carrying the intact phenolic function and an aminomethyl functionality, were synthesized and first tested for their inhibitory potencies towards AChE and butyrylcholinesterase (BChE). 5 and 11 were found to inhibit human BChE at a single-digit micromolar concentration. Transmission electron microscopy revealed the potential of five derivatives to modulate Aβ aggregation, including 5 and 11 . In HORAC assays, 5 and 11 performed similarly to standard antioxidant ferulic acid as hydroxyl scavenging agents. Furthermore, in in vitro studies in neuronal cell cultures, 5 and 11 were found to effectively inhibit reactive oxygen species production at a 10 μM concentration. They also showed a favorable initial ADME/Tox profile. Overall, these results suggest that CNSL is a promising raw material for the development of potential disease-modifying treatments for AD., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (This journal is © The Royal Society of Chemistry.)

Visceral leishmaniasis (VL) affects millions of people across the world, largely in developing nations. It is fatal if left untreated and the current treatments are inadequate. As such, there is an urgent need for new, improved medicines. In this paper, we describe the identification of a 6-amino- N -(piperidin-4-yl)-1 H -pyrazolo[3,4- d ]pyrimidine scaffold and its optimization to give compounds which showed efficacy when orally dosed in a mouse model of VL., (This journal is © The Royal Society of Chemistry 2020.)

One of the key motifs of type I kinase inhibitors is their interactions with the hinge region of ATP binding sites. These interactions contribute significantly to the potency of the inhibitors; however, only a tiny fraction of the available chemical space has been explored with kinase inhibitors reported in the last twenty years. This paper describes a workflow utilizing docking with rDock and dynamic undocking (DUck) for the virtual screening of fragment libraries in order to identify fragments that bind to the kinase hinge region. We have identified 8-amino-2 H -isoquinolin-1-one ( MR1 ), a novel and potent hinge binding fragment, which was experimentally tested on a diverse set of kinases, and is hereby suggested for future fragment growing or merging efforts against various kinases, particularly MELK. Direct binding of MR1 to MELK was confirmed by STD-NMR, and its binding to the ATP-pocket was confirmed by a new competitive binding assay based on microscale thermophoresis., (This journal is © The Royal Society of Chemistry 2020.)