Synthesis and SAR studies of novel 6,7,8-substituted 4-substituted benzyloxyquinolin-2(1H)-one derivatives for anticancer activity

In Vitro and In Silico Biological Studies of 4-Phenyl-2-quinolone (4-PQ) Derivatives as Anticancer Agents

Our previous study found that 2-phenyl-4-quinolone (2-PQ) derivatives are antimitotic agents, and we adopted the drug design concept of scaffold hopping to replace the 2-aromatic ring of 2-PQs with a 4-aromatic ring, representing 4-phenyl-2-quinolones (4-PQs). The 4-PQ compounds, whose structural backbones also mimic analogs of podophyllotoxin (PPT), maybe a new class of anticancer drugs with simplified PPT structures. In addition, 4-PQs are a new generation of anticancer lead compounds as apoptosis stimulators. On the other hand, previous studies showed that 4-arylcoumarin derivatives with 5-, 6-, and 7-methoxy substitutions displayed remarkable anticancer activities. Therefore, we further synthesized a series of 5-, 6-, and 7-methoxy-substituted 4-PQ derivatives (19-32) by Knorr quinoline cyclization, and examined their anticancer effectiveness. Among these 4-PQs, compound 22 demonstrated excellent antiproliferative activities against the COLO205 cell line (50% inhibitory concentration (IC₅₀) = 0.32 μM) and H460 cell line (IC₅₀ = 0.89 μM). Furthermore, we utilized molecular docking studies to explain the possible anticancer mechanisms of these 4-PQs by the docking mode in the colchicine-binding pocket of the tubulin receptor. Consequently, we selected the candidate compounds 19, 20, 21, 22, 25, 27, and 28 to predict their absorption, distribution, metabolism, excretion, and toxicity (ADMET) profiles. Pharmacokinetics (PKs) indicated that these 4-PQs displayed good drug-likeness and bioavailability, and had no cardiotoxic side effects or carcinogenicity, but we detected risks of drug-drug interactions and AMES toxicity (mutagenic). However, structural modifications of these 4-PQs could improve their PK properties and reduce their side effects, and their promising anticancer activities attracted our attention for further studies.

The power of heteronemin in cancers

Heteronemin (Haimian jing) is a sesterterpenoid-type natural marine product that is isolated from sponges and has anticancer properties. It inhibits cancer cell proliferation via different mechanisms, such as reactive oxygen species (ROS) production, cell cycle arrest, apoptosis as well as proliferative gene changes in various types of cancers. Recently, the novel structure and bioactivity evaluation of heteronemin has received extensive attention. Hormones control physiological activities regularly, however, they may also affect several abnormalities such as cancer. L-Thyroxine (T₄), steroid hormones, and epidermal growth factor (EGF) up-regulate the accumulation of checkpoint programmed death-ligand 1 (PD-L1) and promote inflammation in cancer cells. Heteronemin suppresses PD-L1 expression and reduces the PD-L1-induced proliferative effect. In the current review, we evaluated research and evidence regarding the antitumor effects of heteronemin and the antagonizing effects of non-peptide hormones and growth factors on heteronemin-induced anti-cancer properties and utilized computational molecular modeling to explain how these ligands interacted with the integrin αvβ3 receptors. On the other hand, thyroid hormone deaminated analogue, tetraiodothyroacetic acid (tetrac), modulates signal pathways and inhibits cancer growth and metastasis. The combination of heteronemin and tetrac derivatives has been demonstrated to compensate for anti-proliferation in cancer cells under different circumstances. Overall, this review outlines the potential of heteronemin in managing different types of cancers that may lead to its clinical development as an anticancer agent.

Synthesis, Characterization and In Vitro Evaluation of Novel 5-Ene-thiazolo[3,2-b][1,2,4]triazole-6(5H)-ones as Possible Anticancer Agents

The present paper is devoted to the search for drug-like molecules with anticancer properties using the thiazolo[3,2-b][1,2,4]triazole-6-one scaffold. A series of 24 novel thiazolo-[3,2-b][1,2,4]triazole-6-ones with 5-aryl(heteryl)idene- and 5-aminomethylidene-moieties has been synthesized employing three-component and three-stage synthetic protocols. A mixture of Z/E-isomers was obtained in solution for the synthesized 5-aminomethylidene-thiazolo[3,2-b]-[1,2,4]triazole-6-ones. The compounds have been studied for their antitumor activity in the NCI 60 lines screen. Some compounds present excellent anticancer properties at 10 μM. Derivatives 2h and 2i were the most active against cancer cell lines without causing toxicity to normal somatic (HEK293) cells. A preliminary SAR study had been performed for the synthesized compounds.

Greening Solid-Phase Organic Synthesis: Environmentally Conscious Synthesis of Pharmaceutically Relevant Privileged Structures 5,6-Dihydropyridin-2(1H)-ones and Quinolin-2(1H)-ones

Solid-phase organic synthesis (SPOS) is a very efficient methodology for the synthesis of diverse organic molecules, particularly exploited in drug discovery. Here, we present the transformation of the traditional SPOS to an eco-friendlier methodology on examples of pharmacologically relevant privileged structures 5,6-dihydropyridin-2(1H)-ones and quinolin-2(1H)-ones. The green approach is primarily based on the utilization of environmentally friendly solvent 2-MeTHF in all steps of the synthesis. Target heterocycles were synthesized by extending our previously published synthesis of five-membered tetramic acid analogues to six-membered cycles. The crucial step of the synthesis is cyclization via nonclassical Wittig olefination of resin-bound esters. Traditional and green protocols provided comparable results with respect to purity and yield of products, thus opening the way for greener access to a variety of diverse heterocycles.

Hybrid Compounds & Oxidative Stress Induced Apoptosis in Cancer Therapy

Elevated Reactive Oxygen Species (ROS) generated by the conventional cancer therapies and the endogenous production of ROS have been observed in various types of cancers. In contrast to the harmful effects of oxidative stress in different pathologies other than cancer, ROS can speed anti-tumorigenic signaling and cause apoptosis of tumor cells via oxidative stress as demonstrated in several studies. The primary actions of antioxidants in cells are to provide a redox balance between reduction-oxidation reactions. Antioxidants in tumor cells can scavenge excess ROS, causing resistance to ROS induced apoptosis. Various chemotherapeutic drugs, in their clinical use, have evoked drug resistance and serious side effects. Consequently, drugs having single-targets are not able to provide an effective cancer therapy. Recently, developed hybrid anticancer drugs promise great therapeutic advantages due to their capacity to overcome the limitations encountered with conventional chemotherapeutic agents. Hybrid compounds have advantages in comparison to the single cancer drugs which have usually low solubility, adverse side effects, and drug resistance. This review addresses two important treatments strategies in cancer therapy: oxidative stress induced apoptosis and hybrid anticancer drugs.

Novel quinoline derivatives carrying nitrones/oximes nitric oxide donors: Design, synthesis, antiproliferative and caspase-3 activation activities

Novel quinoline derivatives carrying nitrones and oxime as nitric oxide donors were prepared and characterized using different spectroscopic techniques. Nitrones can release nitric oxide in larger amounts compared to corresponding oximes. Antiproliferative screening results showed that the 2-benzylthioquinoline nitrones 6e and 6f and the 2-methylthio analogues 6g and 6h exhibited promising antiproliferative activity especially against leukemia and colon cancer cell lines. Compounds 6c, 6e, and 6f exhibited higher potency as anticancer agents compared to doxorubicin, with IC₅₀ ranging from 0.45 to 0.91 μM. A remarkable overexpression of caspase-3 protein levels was observed in cells treated with the tested compounds. Compound 6e exhibited more pre-G1 apoptosis and cell cycle arrest at the G2/M phase than in other phases. These results revealed that the tested compounds can cause programmed cell death through overexpression of caspase 3, which may be attributed to the release of nitric oxide.

Discovery of Hybrid Purine-quinoline Molecules and Their Cytotoxic Evaluation

Background:

Apart from the “hit drugs”, there are many others being studied for their potent activity against several hostilities. To date, anticancer research has been exploited on the inherent versatility and active core skeleton of the compounds. Literature suggests that nitrogen rich molecules are most active and found in their potent cancer activity. Purine-based compounds such as olomoucine and roscovitine, which contain other heterobicyclic ring systems, are useful for the cell proliferation inhibitors in the treatment of many types of cancer.

Methods:

We put forward the novel purine based compounds, aryl amino-quinoline-purine by a two-step procedure. In the first step, nitrogen rich molecule was synthesized by the coupling of 2,6- dichloropurine with 3-aminoquinoline in an acidic reaction conditions at the C-6 position of purine. Aryl amines were introduced at the C-2 position by acid catalyst and using polar solvent at comparatively higher reaction conditions to furnish the desired products.

Results:

Stereochemical aspect was introduced for the identification of attachment of 3- aminoquinoline at the C-2/ C-6 position of purine and it was concluded by the spectral analysis (HMBC spectrum). The spectral data revealed that the first chloro-amine coupling was directed at the C-6 position rather than C-2 and the second chloro-amine coupling by various aryl amines were directed at the C-2 position. The applications of synthesized compounds were identified by their cytotoxic study against NCI-60 cell-lines. Out of nine selected molecules by NCI, 5a has shown promising response in a single dose study and GI50 value, 7.57 µM indicated that it has 7.57% lethality over HOP-92 cell-line (non-small cell lung cancer panel).

Conclusion:

Two straightforward novelties were introduced, first stereochemical identification for chloro-amine coupling in purine either at the C-2 or C-6 position on the basis of HMBC spectrum. And a second type of uniqueness was to identify better anti-cancer agents out of synthesized scaffolds. Overall study shows that compound 5a is a novel therapeutic agent after modification for the treatment of non-small cell lung and it satisfied determined threshold growth inhibition criteria at a single dose level.

Use of Nanocrystalline ZnO as an Efficient and Reusable Catalyst for a One-Pot, Three-Component Synthesis of 6-Chloro- and 5,7-Dichloro-4-Hydroxy-3-[Aryl (Piperidin-1-yl)Methyl]Quinolin-2(1H)-Ones in Water

A one-pot, green, efficient and facile procedure was applied for the preparation of a series of 4-hydroxy-3-[aryl(piperidin-1-yl)methyl] quinolin-2(1 H)-ones via the reaction of 6-chloro-4- hydroxyquinoline-2(1 H)-one 1 and/or 5,7-dichloro-4-hydroxyquinoline-2(1 H)-one 2, piperidine and aromatic aldehydes in water in the presence of nanocrystalline ZnO under reflux conditions. The desired products were obtained in satisfactory yields. The nanocrystalline ZnO can be separated and reused at least up to three times with almost the same catalytic activity.

Photoreductive Removal of O-Benzyl Groups from Oxyarene N-Heterocycles Assisted by O-Pyridine-pyridone Tautomerism

Facile photoreductive protocols have been developed to remove benzyl O-protective groups from oxyarene N-heterocycles at positions capable for 2-/4-O-pyridine-2-/4-pyridone tautomerism. Blue light irradiation, a [Ru] or [Ir] photocatalyst, and ascorbic acid in a water-acetonitrile solution debenzylates a variety of aryl N-heterocycles cleanly and selectively. Ascorbic acid has two functions in the reaction. On the one hand, it protonates the N-heterocycles that reduces their reduction potentials notably and on the other hand it acts as a sacrificial reductant. Reduction potentials and free energy barriers calculated at the CPCM-B3LYP/6-31+G** level can predict the reactivities of the studied substrates.

Synthesis and biological evaluation of novel 3,9-substituted β-carboline derivatives as anticancer agents

In our previous studies on 1-benzyl-3-(5-hydroxymethyl-2-furyl)indazole (YC-1) analogs, we synthesised numerous substituted carbazole and α-carboline derivatives, which exhibited anticancer activity. In this study, we designed and synthesised a series of 3,9-substituted β-carbolines, by replacing the tricyclic rings of carbazole and α-carboline derivatives with isosteric β-carboline, and evaluated anticancer activity. We observed that 9-(2-methoxybenzyl)-β-carboline-3-carboxylic acid (11a) inhibited the growth of HL-60 cells by inducing apoptosis, with a half maximal inhibitory concentration of 4.0 μM. Our findings indicate that β-carboline derivatives can be used as lead compounds for developing novel antitumor agents.