N'-Alkylaminosulfonyl Analogues of 6-Fluorobenzylideneindolinones with Desirable Physicochemical Profiles and Potent Growth Inhibitory Activities on Hepatocellular Carcinoma

Discovery and Anticancer Screening of Novel Oxindole-Based Derivative Bearing Pyridyl Group as Potent and Selective Dual FLT3/CDK2 Kinase Inhibitor

Protein kinases regulate cellular activities and make up over 60% of oncoproteins and proto-oncoproteins. Among these kinases, FLT3 is a member of class III receptor tyrosine kinase family which is abundantly expressed in individuals with acute leukemia. Our previous oxindole-based hit has a particular affinity toward FLT3 (IC50 = 2.49 μM) and has demonstrated selectivity towards FLT3 ITD-mutated MV4-11 AML cells, with an IC50 of 4.3 μM. By utilizing the scaffold of the previous hit, sixteen new compounds were synthesized and screened against NCI-60 human cancer cell lines. This leads to the discovery of a potent antiproliferative compound, namely 5l, with an average GI50 value against leukemia and colon cancer subpanels equalling 3.39 and 5.97 µM, respectively. Screening against a specific set of 10 kinases that are associated with carcinogenesis indicates that compound 5l has a potent FLT3 inhibition (IC50 = 36.21 ± 1.07 nM). Remarkably, compound 5l was three times more effective as a CDK2 inhibitor (IC50 = 8.17 ± 0.32 nM) compared to sunitinib (IC50 = 27.90 ± 1.80 nM). Compound 5l was further analyzed by means of docking and molecular dynamics simulation for CDK2 and FLT3 active sites which provided a rational for the observed strong inhibition of kinases. These results suggest a novel structural scaffold candidate that simultaneously inhibits CDK2 and FLT3 and gives encouragement for further development as a potential therapeutic for leukemia and colon cancer.

BF3-Catalyzed Intramolecular Fluorocarbamoylation of Alkynes via Halide Recycling

A BF₃-catalyzed atom-economical fluorocarbamoylation reaction of alkyne-tethered carbamoyl fluorides is reported. The catalyst acts as both a fluoride source and Lewis acid activator, thereby enabling the formal insertion of alkynes into strong C-F bonds through a halide recycling mechanism. The developed method provides access to 3-(fluoromethylene) oxindoles and γ-lactams with excellent stereoselectivity, including fluorinated derivatives of known protein kinase inhibitors. Experimental and computational studies support a stepwise mechanism for the fluorocarbamoylation reaction involving a turnover-limiting cyclization step, followed by internal fluoride transfer from a BF₃-coordinated carbamoyl adduct. For methylene oxindoles, a thermodynamically driven Z-E isomerization is facilitated by a transition state with aromatic character. In contrast, this aromatic stabilization is not relevant for γ-lactams, which results in a higher barrier for isomerization and the exclusive formation of the Z-isomer.

Synthesis and biological activity evaluation of 3-(hetero) arylideneindolin-2-ones as potential c-Src inhibitors

Inhibition of c-Src is considered one of the most studied approaches to cancer treatment, with several heterocyclic compounds approved during the last 15 years as chemotherapeutic agents. Starting from the biological evaluation of an in-house collection of small molecules, indolinone was selected as the most promising scaffold. In this work, several functionalised indolinones were synthesised and their inhibitory potency and cytotoxic activity were assayed. The pharmacological profile of the most active compounds, supported by molecular modelling studies, revealed that the presence of an amino group increased the affinity towards the ATP-binding site of c-Src. At the same time, bulkier derivatizations seemed to improve the interactions within the enzymatic pocket. Overall, these data represent an early stage towards the optimisation of new, easy-to-be functionalised indolinones as potential c-Src inhibitors.

Contribution of Knoevenagel Condensation Products towards Development of Anticancer Agents: An Updated Review

Knoevenagel condensation is an entrenched, prevailing, prominent arsenal following greener principles in the generation of α, β-unsaturated ketones/carboxylic acids by involving carbonyl functionalities and active methylenes. This reaction has proved to be a major driving force in many multicomponent reactions indicating the prolific utility towards the development of biologically fascinating molecules. This eminent reaction was acclimatised on different pharmacophoric aldehydes (benzimidazole, β-carboline, phenanthrene, indole, imidazothiadiazole, pyrazole etc.) and active methylenes (oxindole, barbituric acid, Meldrum's acid, thiazolidinedione etc.) to generate the library of chemical compounds. Their potential was also explicit to understand the significance of functionalities involved, which thereby evoke further developments in drug discovery. Furthermore, most of these reaction products exhibited remarkable anticancer activity in nanomolar to micromolar ranges by targeting different cancer targets like DNA, microtubules, Topo-I/II, and kinases (PIM, PARP, NMP, p300/CBP) etc. This review underscores the efficiency of the Knoevenagel condensation explored in the past six-year to generate molecules of pharmacological interest, predominantly towards cancer. The present review also provides the aspects of structure-activity relationships, mode of action and docking study with possible interaction with the target protein.

Inversion kinetics of some E/Z 3-(benzylidene)-2-oxo-indoline derivatives and their in silico CDK2 docking studies

The structure-based design of some CDK2 inhibitors with a 3-(benzylidene)indolin-2-one scaffold as potential anticancer agents was realized. Target compounds were obtained as E/Z mixtures and were resolved to corresponding E- and Z-diastereomers. In silico studies using MOE 2019.01 software revealed better docking on the targeted enzyme for the Z-diastereomer compared to the E-one. A time-dependent kinetic isomerization study was carried out for the inversion of E/Z diastereomers in DMSO-d6 at room temperature, and were found to obey the first order kinetic reactions. Furthermore, a determination of the kinetic inter-conversion rate order by graphical analysis method and calculation of the rate constant and half-life of this kinetic process were carried out. For the prediction of the stability of the diastereomer(s), a good multiple regression equation was generated between the reaction rates of isomerization and some QM parameters with significant p value.

N-Substituted Pyrido-1,4-Oxazin-3-Ones Induce Apoptosis of Hepatocellular Carcinoma Cells by Targeting NF-κB Signaling Pathway

Hepatocellular carcinoma (HCC) is a fatal disease and ranked fifth in cancer related mortality. Persistent activation of NF-κB is responsible for the oncogenesis, metastasis, tumor evasion, anti-apoptosis, angiogenesis and proliferation in HCC. Therefore, designing of chemically novel, biologically potent small molecules that target NF-κB signaling cascade have gained prominent clinical interest. Herein we synthesized a novel class of 4-(substituted)-2H-pyrido[3,2-b][1,4]oxazin-3(4H)-one by reacting 2H-pyrido[3,2-b][1,4]oxazin-3(4H)-one with various alkyl halides by using combustion derived bismuth oxide. We evaluated the antiproliferative efficacy of newly synthesized compounds against HCC cells and identified 4-(4-nitrobenzyl)-2H-pyrido[3,2-b][1,4]oxazin-3(4H)-one (NPO) as lead anticancer agent. In addition, we investigated the effect of NPO on the DNA binding ability of NF-κB and NF-κB regulated luciferase expression in HCC cells. The results demonstrated that NPO can induce significant growth inhibitory effects in HepG2, HCCLM3 and Huh-7 cells in dose and time-dependent manner. Interestingly, NPO induced significant downregulation in p65 DNA binding ability, p65 phosphorylation and subsequent expression of NF-κB dependent luciferase gene expression in diverse HCC cell lines. Further, in silico docking analysis suggested that NPO can show direct physical interaction with NF-κB. Finally, NPO was found to significantly abrogate tumor growth at a dose of 50 mg/kg in an orthotopic mouse model. Thus, we report the potential anticancer effects of NPO as a novel inhibitor of NF-κB signaling pathway in HCC.