Design, synthesis and biological evaluation of 3-substituted-2-oxindole hybrid derivatives as novel anticancer agents

Quinoline-based thiazolyl-hydrazones target cancer cells through autophagy inhibition

Heterocyclic pharmacophores such as thiazole and quinoline rings have a significant role in medicinal chemistry. They are considered privileged structures since they constitute several Food and Drug Administration (FDA)-approved drugs for cancer treatment. Herein, we report the synthesis, in silico evaluation of the ADMET profiles, and in vitro investigation of the anticancer activity of a series of novel thiazolyl-hydrazones based on the 8-quinoline (1a-c), 2-quinoline (2a-c), and 8-hydroxy-2-quinolyl moiety (3a-c). The panel of several human cancer cell lines and the nontumorigenic human embryonic kidney cell line HEK-293 were used to evaluate the compound-mediated in vitro anticancer activities, leading to [2-(2-(quinolyl-8-ol-2-ylmethylene)hydrazinyl)]-4-(4-methoxyphenyl)-1,3-thiazole (3c) as the most promising compound. The study revealed that 3c blocks the cell-cycle progression of a human colon cancer cell line (HCT-116) in the S phase and induces DNA double-strand breaks. Also, our findings demonstrate that 3c accumulates in lysosomes, ultimately leading to the cell death of the hepatocellular carcinoma cell line (Hep-G2) and HCT-116 cells, by the mechanism of autophagy inhibition.

A one-pot and eco-friendly synthesis of novel β-substituted-α-halomethyl acrylates and the bioactivity of these compounds in an in vitro model of mast cell degranulation induced by pro-inflammatory stimuli

The goal of the present work was to develop novel β-substituted-α-halomethyl acrylates from a methodology in an aqueous phase and to evaluate their bioactivity as potential inhibitors of mast cell activation. Eleven β-substituted-α-halomethyl acrylates were synthesized through a modified Horner-Wadsworth-Emmons reaction. Compound 48/80 and the calcium ionophore A23187 stimulated the release of β-hexosaminidase from mast cells. The effect induced by compound 48/80 was inhibited by compound 5 (320 µM) and compound 9 (160 and 320 µM) without causing cytotoxic effects. The effect induced by A23187 was inhibited by compound 5 (40, 80, 160, and 320 µM) without affecting cell viability. The inhibitory effects exhibited by compounds 5 and 9 were more potent than those of the reference compound sodium cromoglycate at the same concentrations. The biochemical results were consistent with the morphological findings obtained by light and transmission electron microscopy. This study reports, for the first time, that the new synthetic compounds methyl (Z)- 2-bromo-3-(furan-3-yl)acrylate (compound 5) and methyl (E)- 2-bromo-3-(3-bromophenyl)acrylate (compound 9) strongly inhibit mast cell degranulation, without affecting cell viability. The implications of these results are relevant as a basis for developing new anti-inflammatory and mast cell stabilizing drugs.

Computational investigation of the radical-mediated mechanism of formation of difluoro methyl oxindoles: Elucidation of the reaction selectivity and yields

Oxindoles are an important class of heterocyclic alkaloids with demonstrated pharmacological activity at multiple biological targets. Preparation of new analogs through novel synthetic routes is therefore highly attractive. In this work, we report a computational study to investigate the synthesis of ethoxycarbonyldifluoromethylated oxindoles from N-arylmethacrylamides. The reaction tolerates a diverse range of acrylamides, shows yields ranging from approximately 38%-96%. We have applied density functional theory (DFT) to explore the reaction mechanism, kinetics and thermodynamics to gain further understanding. We demonstrate that a radical-based ring closure reaction is energetically more favorable than a heterolytic process, that the rate-determining step is the formation of the arylmethacrylamide radical, and that the product yields and selectivities are consistent with experiment. The results demonstrate that theoretical methods can prove useful to understand how such reaction and could be potentially employed to rapidly explore the reaction scope further.

A Review of the Recent Developments of Molecular Hybrids Targeting Tubulin Polymerization

Microtubules are cylindrical protein polymers formed from αβ-tubulin heterodimers in the cytoplasm of eukaryotic cells. Microtubule disturbance may cause cell cycle arrest in the G2/M phase, and anomalous mitotic spindles will form. Microtubules are an important target for cancer drug action because of their critical role in mitosis. Several microtubule-targeting agents with vast therapeutic advantages have been developed, but they often lead to multidrug resistance and adverse side effects. Thus, single-target therapy has drawbacks in the effective control of tubulin polymerization. Molecular hybridization, based on the amalgamation of two or more pharmacophores of bioactive conjugates to engender a single molecular structure with enhanced pharmacokinetics and biological activity, compared to their parent molecules, has recently become a promising approach in drug development. The practical application of combined active scaffolds targeting tubulin polymerization inhibitors has been corroborated in the past few years. Meanwhile, different designs and syntheses of novel anti-tubulin hybrids have been broadly studied, illustrated, and detailed in the literature. This review describes various molecular hybrids with their reported structural-activity relationships (SARs) where it is possible in an effort to generate efficacious tubulin polymerization inhibitors. The aim is to create a platform on which new active scaffolds can be modeled for improved tubulin polymerization inhibitory potency and hence, the development of new therapeutic agents against cancer.

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.

Following Nature's Footprint: Mimicking the High-Valent Heme-Oxo Mediated Indole Monooxygenation Reaction Landscape of Heme Enzymes

Pathways for direct conversion of indoles to oxindoles have accumulated considerable interest in recent years due to their significance in the clear comprehension of various pathogenic processes in humans and the multipotent therapeutic value of oxindole pharmacophores. Heme enzymes are predominantly responsible for this conversion in biology and are thought to proceed with a compound-I active oxidant. These heme-enzyme-mediated indole monooxygenation pathways are rapidly emerging therapeutic targets; however, a clear mechanistic understanding is still lacking. Additionally, such knowledge holds promise in the rational design of highly specific indole monooxygenation synthetic protocols that are also cost-effective and environmentally benign. We herein report the first examples of synthetic compound-I and activated compound-II species that can effectively monooxygenate a diverse array of indoles with varied electronic and steric properties to exclusively produce the corresponding 2-oxindole products in good to excellent yields. Rigorous kinetic, thermodynamic, and mechanistic interrogations clearly illustrate an initial rate-limiting epoxidation step that takes place between the heme oxidant and indole substrate, and the resulting indole epoxide intermediate undergoes rearrangement driven by a 2,3-hydride shift on indole ring to ultimately produce 2-oxindole. The complete elucidation of the indole monooxygenation mechanism of these synthetic heme models will help reveal crucial insights into analogous biological systems, directly reinforcing drug design attempts targeting those heme enzymes. Moreover, these bioinspired model compounds are promising candidates for the future development of better synthetic protocols for the selective, efficient, and sustainable generation of 2-oxindole motifs, which are already known for a plethora of pharmacological benefits.

Oxindole and its derivatives: A review on recent progress in biological activities

Oxindole has been shown to be a pharmacologically advantageous scaffold having many biological properties that are relevant to medicinal chemistry. The simplicity and widespread occurrence of this scaffold in plant-based alkaloids have further reinforced oxindole's merit in the domain of novel drug discovery. First extracted from Uncaria tomentosa, commonly the known as cat claw's plant which was found abundantly in the Amazon rainforest, molecules with the oxindole moiety have been shown to be common in a wide variety of compounds extracted from plant sources. The role of oxindole as a chemical scaffold for fabricating and designing biological drugs agents can be ascribed to its ability to be modified by a number of chemical groups to generate novel biological functions. This review is aimed at providing a description of the general chemistry based on existing corresponding structure-activity relationships (SARs) and compile all recent developmentary studies on oxindole-derived compounds as a successful pharmaceutical agent. A substantial group of oxindole derivatives are chiefly being tested as anticancer agents, however, a several oxindole derivatives have been shown to possesses antimicrobial, α-glucosidase inhibitory, antiviral, antileishmanial, antitubercular, antioxidative, tyrosinase inhibitory, PAK4 inhibitory, antirheumatoid arthritis and intraocular pressure reducing activities, to name a few. In this review we show the potential value of developing newer oxindole derivatives with an improved range of pharmacological implications as well as identifying drugs possessing oxindole core, that are showing and serving increased efficacy in clinical practice.

Biological Evaluation of Oxindole Derivative as a Novel Anticancer Agent against Human Kidney Carcinoma Cells

Renal cell carcinoma has emerged as one of the leading causes of cancer-related deaths in the USA. Here, we examined the anticancer profile of oxindole derivatives (SH-859) in human renal cancer cells. Targeting 786-O cells by SH-859 inhibited cell growth and affected the protein kinase B/mechanistic target of rapamycin 1 pathway, which in turn downregulated the expression of glycolytic enzymes, including lactate dehydrogenase A and glucose transporter-1, as well as other signaling proteins. Treatment with SH-859 altered glycolysis, mitochondrial function, and levels of adenosine triphosphate and cellular metabolites. Flow cytometry revealed the induction of apoptosis and G0/G1 cell cycle arrest in renal cancer cells following SH-859 treatment. Induction of autophagy was also confirmed after SH-859 treatment by acridine orange and monodansylcadaverine staining, immunocytochemistry, and Western blot analyses. Finally, SH-859 also inhibited the tumor development in a xenograft model. Thus, SH-859 can serve as a potential molecule for the treatment of human renal carcinoma.

Palladium Nanoparticle-Catalyzed Stereoselective Domino Synthesis of 3-Allylidene-2(3H)-oxindoles and 3-Allylidene-2(3H)-benzofuranones

A single-step, stereoselective protocol for the synthesis of unsymmetrically substituted (E)-3-allylideneoxindole and (E)-3-allylidenebenzofuran from readily accessible starting materials using palladium binaphthyl nanoparticles (Pd-BNPs) has been developed. Pd-BNP showing a wide range of functional group tolerance and an immense array of substrate scope have been explored with the successful synthesis of the drug molecule "tubulin polymerization inhibitor" free from trace metal impurities. The model reaction is extended to a gram-scale synthesis, and one of the products is utilized for derivatization. The Pd-BNP has been recycled up to 5 catalytic cycles without any loss in reaction yields and particle size of nanoparticles.

Medicinal chemistry of indole derivatives: Current to future therapeutic prospectives

Indole is a versatile pharmacophore, a privileged scaffold and an outstanding heterocyclic compound with wide ranges of pharmacological activities due to different mechanisms of action. It is an superlative moiety in drug discovery with the sole property of resembling different structures of the protein. Plenty of research has been taking place in recent years to synthesize and explore the various therapeutic prospectives of this moiety. This review summarizes some of the recent effective chemical synthesis (2014-2018) for indole ring. This review also emphasized on the structure-activity relationship (SAR) to reveal the active pharmacophores of various indole analogues accountable for anticancer, anticonvulsant, antimicrobial, antitubercular, antimalarial, antiviral, antidiabetic and other miscellaneous activities which have been investigated in the last five years. The precise features with motives and framework of each research topic is introduced for helping the medicinal chemists to understand the perspective of the context in a better way. This review will definitely offer the platform for researchers to strategically design diverse novel indole derivatives having different promising pharmacological activities with reduced toxicity and side effects.

Facile synthesis of simple 2-oxindole-based compounds with promising antiproliferative activity

AIM

Discovery of novel potent anticancer agents with lower side effects is a challenge to overcome cancer, the second leading cause of death.

METHODOLOGY

2-oxindole-based hydrazides (6a-g) and benzenesulfonyl hydrazides (9a-d) were synthesized by simple condensation reactions of the appropriate hydrazides (2a-g) or (8a-d) with 1-ethyl-2,3-oxindolinedione (4). They were screened for their cytotoxicity against HepG2 (liver), MCF-7 (breast), HCT116 (colon) and A549 (lung) cancer cell lines.

RESULTS

The substituted benzohydrazides (6b-g) revealed higher activity and selectivity toward the tested cell lines than doxorubicin and 9a-d. Compound 6c exhibited the highest activity against MCF-7 cell line with IC₅₀ = 0.0058 μM and it induced apoptosis by caspase-3 activation, Bax upregulation and Bcl-2 downregulation in a dose-dependent manner.

CONCLUSION

This compound can be considered as a potent cytotoxic agent with apoptotic induction property.