Design, synthesis, and biological evaluation of 4-((6,7-dimethoxyquinoline-4-yl)oxy)aniline derivatives as FLT3 inhibitors for the treatment of acute myeloid leukemia

Discovery of novel enasidenib analogues targeting inhibition of mutant isocitrate dehydrogenase 2 as antileukaemic agents

Mutant isocitrate dehydrogenase (IDH) 2 "IDH2m" acquires a neo-enzymatic activity reducing α-ketoglutarate to an oncometabolite, D-2-hydroxyglutarate (2-HG). Three s-triazine series were designed and synthesised using enasidenib as a lead compound. In vitro anticancer screening via National Cancer Institute "NCI" revealed that analogues 6a, 6c, 6d, 7g, and 7l were most potent, with mean growth inhibition percentage "GI%" = 66.07, 66.00, 53.70, 35.10, and 81.15, respectively, followed by five-dose screening. Compounds 6c, 6e, and 7c were established as the best IDH2^R140Q inhibitors compared to enasidenib, reporting IC₅₀ = 101.70, 67.01, 88.93, and 75.51 nM, respectively. More importantly, 6c, 6e, and 7c displayed poor activity against the wild-type IDH2, IC₅₀ = 2928, 2295, and 3128 nM, respectively, which implementing high selectivity and accordingly safety. Furthermore, 6c was screened for cell cycle arrest, apoptosis induction, and western blot analysis. Finally, computational tools were applied to predict physicochemical properties and binding poses in IDH2^R140Q allosteric site.

Natural Sesquiterpene Lactone as Source of Discovery of Novel Fungicidal Candidates: Structural Modification and Antifungal Activity Evaluation of Xanthatin Derived from Xanthium strumarium L

As part of our ongoing efforts to discover novel agricultural fungicidal candidates from natural sesquiterpene lactones, in the present work, sixty-three xanthatin-based derivatives containing a arylpyrazole, arylimine, thio-acylamino, oxime, oxime ether, or oxime ester moiety were synthesized. Their structures were well characterized by ¹H and ¹³C nuclear magnetic resonance and high-resolution mass spectrometry, while the absolute configurations of compounds 5' and 6a were further determined by single-crystal X-ray diffraction. Meanwhile, the antifungal activities of the prepared compounds against several phytopathogenic fungi were investigated using the spore germination method and the mycelium growth rate method in vitro. The bioassay results illustrated that compounds 5, 5', and 15 exhibited excellent inhibitory activity against the tested fungal spores and displayed remarkable inhibitory effects on fungal mycelia. Compounds 5 and 5' exhibited more potent inhibitory activity (IC₅₀ = 1.1 and 24.8 μg/mL, respectively) against the spore of Botrytis cinerea than their precursor xanthatin (IC₅₀ = 37.6 μg/mL), wherein the antifungal activity of compound 5 was 34-fold higher than that of xanthatin and 71-fold higher than that of the positive control, difenoconazole (IC₅₀ = 78.5 μg/mL). Notably, compound 6'a also demonstrated broad-spectrum inhibitory activity against the four tested fungal spores. Meanwhile, compounds 2, 5, 8, and 15 showed prominent inhibitory activity against the mycelia of Cytospora mandshurica with the EC₅₀ values of 2.3, 11.7, 11.1, and 3.0 μg/mL, respectively, whereas the EC₅₀ value of xanthatin was 14.8 μg/mL. Additionally, compounds 5' and 15 exhibited good in vivo therapeutic and protective effects against B. cinerea with values of 55.4 and 62.8%, respectively. The preliminary structure-activity relationship analysis revealed that the introduction of oxime, oxime ether, or oxime ester structural fragment at the C-4 position of xanthatin or the introduction of a chlorine atom at the C-3 position of xanthatin might be significantly beneficial to antifungal activity. In conclusion, the comprehensive investigation indicated that partial xanthatin-based derivatives from this study could be considered for further exploration as potential lead structures toward developing novel fungicidal candidates for crop protection.

Targeting Proliferation Signals and the Cell Cycle Machinery in Acute Leukemias: Novel Molecules on the Horizon

Uncontrolled proliferative signals and cell cycle dysregulation due to genomic or functional alterations are important drivers of the expansion of undifferentiated blast cells in acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) cells. Therefore, they are largely studied as potential therapeutic targets in the field. We here present the most recent advancements in the evaluation of novel compounds targeting cell cycle proteins or oncogenic mechanisms, including those showing an antiproliferative effect in acute leukemia, independently of the identification of a specific target. Several new kinase inhibitors have been synthesized that showed effectiveness in a nanomolar to micromolar concentration range as inhibitors of FLT3 and its mutant forms, a highly attractive therapeutic target due to its driver role in a significant fraction of AML cases. Moreover, we introduce novel molecules functioning as microtubule-depolymerizing or P53-restoring agents, G-quadruplex-stabilizing molecules and CDK2, CHK1, PI3Kδ, STAT5, BRD4 and BRPF1 inhibitors. We here discuss their mechanisms of action, including the downstream intracellular changes induced by in vitro treatment, hematopoietic toxicity, in vivo bio-availability and efficacy in murine xenograft models. The promising activity profile demonstrated by some of these candidates deserves further development towards clinical investigation.

meta-Ureidophenoxy-1,2,3-triazole hybrid as a novel scaffold for promising HepG2 hepatocellular carcinoma inhibitors: Synthesis, biological evaluation and molecular docking studies

Thirty-one meta-ureidophenoxymethyl-1,2,3-triazole derivatives were designed and synthesized via nucleophilic addition, nucleophilic substitution and copper-catalyzed azide-alkyne cycloaddition (CuAAC). The evaluation of their cytotoxicity using MTT assay indicated that almost all derivatives exhibited significantly superior inhibitory activity against hepatocellular carcinoma cell line HepG2 compared to the parental molecule sorafenib (1). Among the series, 5r was the most potent anti-HepG2 agent with IC50 = 1.04 µM, which was almost 5-fold more active than sorafenib (IC50 = 5.06 µM), while the cytotoxic activity against human embryonal lung fibroblast cell line MRC-5 remained comparable to sorafenib. The synthetic derivative 5r, thus, possessed 5.2-time higher selectivity index (SI) than that of sorafenib. Molecular docking studies revealed an efficient interaction of 5r at the same sorafenib's binding region in both B-Raf and VEGFR-2 with lower binding energies than those of sorafenib, consistent with its cytotoxic effect. Furthermore, 5r was proven to induce apoptosis in a dose-dependent manner similar to sorafenib. In addition, the prediction using SwissADME suggested that 5r possessed appropriate drug properties conforming to Veber's studies. These findings revealed that the newly designed meta-ureidophenoxy-1,2,3-triazole hybrid scaffold was a promising structural feature for an efficient inhibition of HepG2. Moreover, derivative 5r emerged as a promising candidate for further development as a targeted anti-cancer agent for hepatocellular carcinoma (HCC).

The Design and Synthesis of a New Series of 1,2,3-Triazole-Cored Structures Tethering Aryl Urea and Their Highly Selective Cytotoxicity toward HepG2

Target cancer drug therapy is an alternative treatment for advanced hepatocellular carcinoma (HCC) patients. However, the treatment using approved targeted drugs has encountered a number of limitations, including the poor pharmacological properties of drugs, therapy efficiency, adverse effects, and drug resistance. As a consequence, the discovery and development of anti-HCC drug structures are therefore still in high demand. Herein, we designed and synthesized a new series of 1,2,3-triazole-cored structures incorporating aryl urea as anti-HepG2 agents. Forty-nine analogs were prepared via nucleophilic addition and copper-catalyzed azide-alkyne cycloaddition (CuAAC) with excellent yields. Significantly, almost all triazole-cored analogs exhibited less cytotoxicity toward normal cells, human embryonal lung fibroblast cell MRC-5, compared to Sorafenib and Doxorubicin. Among them, 2m’ and 2e exhibited the highest selectivity indexes (SI = 14.7 and 12.2), which were ca. 4.4- and 3.7-fold superior to that of Sorafenib (SI = 3.30) and ca. 3.8- and 3.2-fold superior to that of Doxorubicin (SI = 3.83), respectively. Additionally, excellent inhibitory activity against hepatocellular carcinoma HepG2, comparable to Sorafenib, was still maintained. A cell-cycle analysis and apoptosis induction study suggested that 2m’ and 2e likely share a similar mechanism of action to Sorafenib. Furthermore, compounds 2m’ and 2e exhibit appropriate drug-likeness, analyzed by SwissADME. With their excellent anti-HepG2 activity, improved selectivity indexes, and appropriate druggability, the triazole-cored analogs 2m’ and 2e are suggested to be promising candidates for development as targeted cancer agents and drugs used in combination therapy for the treatment of HCC.

Discovery of new carbonic anhydrase IX inhibitors as anticancer agents by toning the hydrophobic and hydrophilic rims of the active site to encounter the dual-tail approach

The hydrophobic and the hydrophilic rims in the active site of human carbonic anhydrase IX (hCA IX) which as well contains a zinc ion as part of the catalytic core, were simultaneously matched to design and synthesize potent and selective inhibitors using a dual-tail approach. Seventeen new compounds, 5a-q, were designed to have the benzenesulfonamide moiety as a zinc binding group. In addition, N-substituted hydrazone and N-phenyl fragments were chosen as the hydrophilic and hydrophobic parts, respectively to achieve favorable interactions with the corresponding halves of the active site. All synthesized compounds successfully suppressed the CA IX, with IC₅₀ values in nanomolar range from 13.3 to 259 nM. Compounds, 5h, 5c, 5m, 5e, and 5k were the top-five compounds efficiently inhibited the tumor-related CA IX isoform in the low nanomolar range (K_I = 13.3, 22.6, 25.8, 26.9 and 27.2 nM, respectively). The target compounds 5a-q developed remarkable selectivity toward the tumor-associated isoforms (hCA IX and XII) over the off-target isoforms (hCA I and II). Furthermore, they were assessed for their anti-proliferative activity, according to US-NCI protocol, against a panel of fifty-nine cancer cell lines. Compounds 5d, 5k and 5o were passed the criteria for activity and scheduled automatically for evaluation at five concentrations with 10-fold dilutions. Compound 5k exhibited significant in vitro anticancer activity with GI₅₀-MID; 8.68 μM compared to compounds 5d and 5o with GI₅₀-MID; 25.76 μM and 34.97 μM respectively. The most selective compounds 5h and 5k were further screened for their in vitro cytotoxic activity against SK-MEL-5, HCC-2998 and RXF 393 cancer cell lines under hypoxic conditions. Furthermore, 5k was screened for cell cycle disturbance, apoptosis induction and intracellular reactive oxygen species (ROS) production in SK-MEL-5 cancer cells. Finally, molecular docking studies were performed to gain insights for the plausible binding interactions and affinities for selected compounds within hCA IX active site.

Design, synthesis and biological evaluation of 7H-pyrrolo[2,3-d]pyrimidine derivatives containing 1,8-naphthyridine-4-one fragment

In this study, a series of pyrrolo [2,3-d]pyrimidine derivatives containing 1,8-naphthyridine-4-one fragment were synthesized and their biological activity were tested. Most of the target compounds displayed moderate to excellent activity against one or more cancer cell lines and low activity against human normal cell LO2 in vitro. The most promising compound 51, of which the IC₅₀ values were 0.66 μM, 0.38 μM and 0.44 μM against cell lines A549, Hela and MCF-7, shown more remarkable activity and better apoptosis effect than the positive control Cabozantinib. The structure-activity relationships (SARs) indicated that double-EWGs (such as R₃ = 2-Cl-4-CF₃) on the terminal phenyl rings was a key factor in improving the biological activity. In addition, the further research on compound 51 mainly included c-Met kinase activity and selectivity, concentration dependence, and molecular docking.

Small-Molecule Fms-like Tyrosine Kinase 3 Inhibitors: An Attractive and Efficient Method for the Treatment of Acute Myeloid Leukemia

Fms-like tyrosine kinase 3 (FLT3) is an important member of the class III receptor tyrosine kinase (RTK) family, which is involved in the proliferation of hematopoietic cells and lymphocytes. In recent years, increasing evidence have demonstrated that the activation and mutation of FLT3 is closely implicated in the occurrence and development of acute myeloid leukemia (AML). The exploration of small-molecule inhibitors targeting FLT3 has aroused wide interest of pharmaceutical chemists and is expected to bring new hope for AML therapy. In this review, we specifically highlighted FLT3 mediated JAK/STAT, RAS/MAPK, and PI3K/AKT/mTOR signaling. The structural properties and biological activities of representative FLT3 inhibitors reported from 2014 to the present were also summarized. In addition, the major challenges in the current advance of novel FLT3 inhibitors were further analyzed, with the aim to guide future drug discovery.