Design and synthesis of benzylidenecyclohexenones as TrxR inhibitors displaying high anticancer activity and inducing ROS, apoptosis, and autophagy

Benzimidazole-based structure optimization to discover novel anti-gastric cancer agents targeting ROS/MAPK pathway

Given the malignancy of gastric cancer, developing highly effective and low-toxic targeted drugs is essential to prolong patient survival and improve patient outcomes. In this study, we conducted structural optimizations based on the benzimidazole scaffold. Notably, compound 8 f presented the most potent antiproliferative activity in MGC803 cells and induced cell cycle arrest at the G0/G1 phase. Further mechanistic studies demonstrated that compound 8 f caused the apoptosis of MGC803 cells by elevating intracellular reactive oxygen species (ROS) levels and activating the mitogen-activated protein kinase (MAPK) signaling pathway, accompanied by corresponding markers change. In vivo investigations additionally validated the inhibitory effect of compound 8 f on tumor growth in xenograft models bearing MGC803 cells without obvious toxicity. Our studies suggest that compound 8 f holds promise as a potential and safe lead compound for developing anti-gastric cancer agents.

Piperlongumine and its derivatives against cancer: A recent update and future prospective

Piperlongumine, or piplartine (PL), is a bioactive alkaloid isolated from Piper longum L. and a potent phytoconstituent in Indian Ayurveda and traditional Chinese medicine with a lot of therapeutic benefits. Apart from all of its biological activities, it demonstrates multimodal anticancer activity by targeting various cancer-associated pathways and being less toxic to normal cells. According to their structure-activity relationship (SAR), the trimethylphenyl ring (cinnamoyl core) and 5,6-dihydropyridin-2-(1H)-one (piperdine core) are responsible for the potent anticancer activity. However, it has poor intrinsic properties (low aqueous solubility, poor bioavailability, etc.). As a result, pharmaceutical researchers have been trying to optimise or modify the structure of PL to improve the drug-likeness profiles. The present review selected 26 eligible research articles on PL derivatives published between 2012 and 2023, followed by the preferred reporting items for systematic reviews and meta-analyses (PRISMA) format. We have thoroughly summarised the anticancer potency, mode of action, SAR and drug chemistry of the proposed PL-derivatives against different cancer cells. Overall, SAR analyses with respect to anticancer potency and drug-ability revealed that substitution of methoxy to hydroxyl, attachment of ligustrazine and 4-hydroxycoumarin heterocyclic rings in place of phenyl rings, and attachment of heterocyclic rings like indole at the C7-C8 olefin position in native PL can help to improve anticancer activity, aqueous solubility, cell permeability, and bioavailability, making them potential leads. Hopefully, the large-scale collection and critical drug-chemistry analyses will be helpful to pharmaceutical and academic researchers in developing potential, less-toxic and cost-effective PL-derivatives that can be used against different cancers.

Synthesis and antitumor activity evaluation of coumarin Mannich base derivatives

Twenty-one new coumarin Mannich base derivatives (11a-u) were synthesized, which exhibited antiproliferation activities in HepG2 (liver cancer), A549 (lung cancer), MCF-7 (breast cancer), and HT-29 (colon cancer). Most of the target compounds showed the most potent activity against HepG2 cells compared with other cancer cells, compound 11g showed the strongest antiproliferative activity (2.10 μM) against HepG2, even superior to the positive control drug 5-FU(5.49 μM). The nitric oxide (NO) release of all compounds in HepG2 cells was determined, of which compound 11g showed high levels of NO release (10.8 μM). Notably, the solubility of compound 11g increased 13-fold compared with the lead 8. The preliminary cytotoxicity studies suggest that 11g had little effect on LO2 cells(normal liver cells, >50 μM). The effect of compound 11g on the apoptosis of HepG2 cells was also studied, and the results showed that the induction effect of compound 11g on apoptosis is a concentration-dependent manner. Our results indicate that compound 11g might be a promising lead for further studies.

Formation of 5-Aminomethyl-2,3-dihydropyridine-4(1H)-ones from 4-Amino-tetrahydropyridinylidene Salts

Various 4-aminotetrahydropyridinylidene salts were treated with aldehydes in an alkaline medium. Their conversion to 5-substituted β-hydroxyketones in a one-step reaction succeeded only with an aliphatic aldehyde. Instead, aromatic aldehydes gave 5-substituted β-aminoketones or a single δ-diketone. The new compounds were characterized using spectroscopic methods and a single crystal structure analysis. Some of them showed anticancer and antibacterial properties.

The Antitumor Activity of Piplartine: A Review

Cancer is a worldwide health problem with high mortality in children and adults, making searching for novel bioactive compounds with potential use in cancer treatment essential. Piplartine, also known as piperlongumine, is an alkamide isolated from Piper longum Linn, with relevant therapeutic potential. Therefore, this review covered research on the antitumor activity of piplartine, and the studies reported herein confirm the antitumor properties of piplartine and highlight its possible application as an anticancer agent against various types of tumors. The evidence found serves as a reference for advancing mechanistic research on this metabolite and preparing synthetic derivatives or analogs with better antitumor activity in order to develop new drug candidates.

Platinum(II) 5-substituted-8-hydroxyquinoline coordination compounds induces mitophagy-mediated apoptosis in A549/DDP cancer cells

For the first time, two new mononuclear platinum(II) coordination compounds, [Pt(L1)(DMSO)Cl] (PtL1) and [Pt(L2)(DMSO)Cl] (PtL2) with the 5-(ethoxymethyl)-8-hydroxyquinoline hydrochloride (H-L1) and 5-bromo-8-hydroxyquinoline (H-L2) have been synthesized and characterized. The cytotoxic activity of PtL1 and PtL2 were screened in both healthy HL-7702 cell line and cancer cell lines, human lung adenocarcinoma A549 cancer cells and cisplatin-resistant lung adenocarcinoma A549/DDP cancer cells (A549R), and were compared to that of the H-L1, H-L2, H-L3 ligands and 8-hydroxyquinoline (H-L3) platinum(II) complex [Pt(L3)(DMSO)Cl] (PtL3). MTT results showed that PtL1 bearing one deprotonated L1 ligand against A549R was more potent by 8.8-48.6 fold than that of PtL2 and PtL3 complexes but was more selective toward healthy HL-7702 cells. In addition, PtL1 and PtL3 overcomes tumour drug resistance by significantly inducing mitophagy and causing the change of the related proteins expression, which leads to cell apoptosis. Moreover, the inhibitory effect of PtL1 on A549 xenograft tumour was 68.2%, which was much higher than that of cisplatin (cisPt, ca. 50.0%), without significantly changing nude mice weight in comparison with the untreated group. This study helps to explore the potential of the platinum(II) 5-substituted-8-hydroxyquinoline coordination compounds for the new Pt-resistant cancer therapy.

Design, Synthesis and Antitumor Activity of Novel Selenium-Containing Tepotinib Derivatives as Dual Inhibitors of c-Met and TrxR

Cellular mesenchymal-epithelial transition factor (c-Met), an oncogenic transmembrane receptor tyrosine kinase (RTK), plays an essential role in cell proliferation during embryo development and liver regeneration. Thioredoxin reductase (TrxR) is overexpressed and constitutively active in most tumors closely related to cancer recurrence. Multi-target-directed ligands (MTDLs) strategy provides a logical approach to drug combinations and would adequately address the pathological complexity of cancer. In this work, we designed and synthesized a series of selenium-containing tepotinib derivatives by means of selenium-based bioisosteric modifications and evaluated their antiproliferative activity. Most of these selenium-containing hybrids exhibited potent dual inhibitory activity toward c-Met and TrxR. Among them, compound 8b was the most active, with an IC₅₀ value of 10 nM against MHCC97H cells. Studies on the mechanism of action revealed that compound 8b triggered cell cycle arrest at the G₁ phase and caused ROS accumulations by targeting TrxR, and these effects eventually led to cell apoptosis. These findings strongly suggest that compound 8b serves as a dual inhibitor of c-Met and TrxR, warranting further exploitation for cancer therapy.

Lead/Drug Discovery from Natural Resources

Natural products and their derivatives have been shown to be effective drug candidates against various diseases for many years. Over a long period of time, nature has produced an abundant and prosperous source pool for novel therapeutic agents with distinctive structures. Major natural-product-based drugs approved for clinical use include anti-infectives and anticancer agents. This paper will review some natural-product-related potent anticancer, anti-HIV, antibacterial and antimalarial drugs or lead compounds mainly discovered from 2016 to 2022. Structurally typical marine bioactive products are also included. Molecular modeling, machine learning, bioinformatics and other computer-assisted techniques that are very important in narrowing down bioactive core structural scaffolds and helping to design new structures to fight against key disease-associated molecular targets based on available natural products are considered and briefly reviewed.

Structures and electron affinity energies of polycyclic quinones

In this study, quinoid structures, semiquinone radical structures, and electron affinity energies (EAEs) of many polycyclic quinones containing heteroatoms (O, B, and F) or heterocycles (pyrrole, imidazole, and pyrazine) were calculated. Quinones with unstable quinoid structures and stable semiquinone radical structures had high EAEs. The main factors of quinoid structural instability were spatial repulsion and antiaromaticity, and the stability factors of the semiquinone radical structure comprised inductive effects, hydrogen bonds, electrostatic interactions, and orbital interactions. Compound 11 had both the antiaromaticity of the quinoid structure and the orbital interactions of the semiquinone radical structure, thus having the highest EAE. The crystal structure of compound 8 was obtained, and it confirmed the reliability of the calculated results of this work.

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The relationship between electron affinity energy and many factors is revealed.

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The close relationship between the electronic structure and the spatial structure is revealed.

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Various interactions such as orbital, electrostatic, and spatial repulsion are exhibited.

Discovery of thirteen cobalt(II) and copper(II) salicylaldehyde Schiff base complexes that induce apoptosis and autophagy in human lung adenocarcinoma A549/DDP cells and that can overcome cisplatin resistance in vitro and in vivo

In this study, 13 transition metal complexes, namely, [Cu(L¹H)(H₂O)₂]·(H₂O)·NO₃ (1), [Cu(LⁿH₂)₂]·(NO₃)·(H₂O)₂ (2, n = 2; 3, n = 3; 4, n = 4; 5, n = 5), [Co(LⁿH)₂]₂·(H₂O)_0.5 (6, n = 2; 7, n = 3; 8, n = 4; 9, n = 5), [Cu(L⁶H)_0.5(L¹⁰H)_0.5(phen)]·(CH₃OH)_0.25 (10), [Cu(L¹¹H) (phen)]₄·(H₂O)₉ (11), [Cu(L⁸H)_0.27(L¹²H)_0.73(phen)]₄·(H₂O)_5.5(CH₃OH) (12), and [Cu(L⁹H) (phen)]₃·(H₂O)₇·(CH₃OH) (13), were synthesized using Schiff base ligands and characterized by elemental analysis (EA), infrared spectroscopy (IR), and single-crystal X-ray diffraction (SC-XRD). Compared with complexes 1-9, complexes 10-13 displayed stronger cytotoxic activities against the tested A549/DDP cancer cells (IC₅₀ = 0.97-3.31 μM), with differences greater than one order of magnitude. Moreover, complexes 11 and 13 could induce apoptosis and autophagy in A549/DDP cells via the mitochondrial dysfunction pathway that affects the regulation of autophagy- and mitochondrial-related proteins. Importantly, the results indicate that the two novel salicylaldehyde Schiff base analogs, 11 and 13, exhibited pronounced and selective activity against A549/DDP xenografts in vivo.

A Derivative of Piperlongumine and Ligustrazine as a Potential Thioredoxin Reductase Inhibitor in Drug-Resistant Hepatocellular Carcinoma

The natural products piperlongumine (1) and ligustrazine (2) have been reported to exert antiproliferative effects against various types of cancer cells by up-regulating the level of reactive oxidative species (ROS). However, the moderate activities of 1 and 2 limit their application. To improve their potential antitumor activity, novel piperlongumine/ligustrazine derivatives were designed and prepared, and their potential pharmacological effects were determined in vitro and in vivo. Among the derivatives obtained, 11 exerted more prominent inhibitory activities against proliferation of drug-sensitive/-resistant cancer cells with lower IC50 values than 1. Particularly, the IC50 value of 11 against drug-resistant Bel-7402/5-FU cells was 0.9 μM, which was about 9-fold better than that of 1 (IC50 value of 8.4 μM). Mechanistic studies showed that 11 demonstrated thioredoxin reductase (TrxR) inhibitory activity, increase of ROS levels, decrease of mitochondrial transmembrane potential levels, and occurrence of DNA damage and autophagy, in a dose-dependent manner, via regulation of DNA damage protein H2AX and autophagy-associated proteins LC3, beclin-1, and p62 in drug-resistant Bel-7402/5-FU cells. Finally, compound 11 at 5 mg/kg displayed potent antitumor activity in vivo with tumor suppression of 76% (w/w). Taken together, compound 11 may represent a promising candidate drug for the chemotherapy of drug-resistant hepatocellular carcinoma and warrant more intensive study.

Overview of piperlongumine analogues and their therapeutic potential

Natural products have long been an important source for discovery of new drugs to treat human diseases. Piperlongumine (PL) is an amide alkaloid isolated from Piper longum L. (long piper) and other piper plants and has received widespread attention because of its diverse biological activities. A large number of PL derivatives have been designed, synthesized and assessed in many pharmacological functions, including antiplatelet aggregation, neuroprotective activities, anti-diabetic activities, anti-inflammatory activities, anti-senolytic activities, immune activities, and antitumor activities. Among them, the anti-tumor effects and application of PL and its derivatives are most extensively studied. We herein summarize the development of PL derivatives, the structure and activity relationships (SARs), and their therapeutic potential on the treatments of various diseases, especially against cancer. We also discussed the challenges and future directions associated with PL and its derivatives in these indications.

New 3-(1H-benzo[d]imidazol-2-yl)quinolin-2(1H)-one-based triazole derivatives: Design, synthesis, and biological evaluation as antiproliferative and apoptosis-inducing agents

A series of 1,2,3-triazole derivatives based on the quinoline-benzimidazole hybrid scaffold was designed, synthesized, and screened against a panel of NCI-60 humanoid cancer cell lines for in vitro cytotoxicity evaluation, which revealed that compound Q6 was the most potent cytotoxic agent with excellent GI₅₀ , TGI, and LC₅₀ values on multiple cancer cell lines. Q6 was tested further on the BT-474 breast cancer line to evaluate the mechanism of action. Preliminary screening studies based on the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay revealed that compound Q6 had an excellent antiproliferative effect against human breast cancer cells, BT-474, with IC₅₀ values of 0.59 ± 0.01 μM. The detailed study based on the acridine orange/ethidium bromide staining (AO/EB) and the 4',6-diamidino-2-phenylindole (DAPI) assay suggested that the antiproliferative activity shown was due to the induction of apoptosis on exposure to Q6. Further, DCFDA staining showed the generation of reactive oxygen species, altering the mitochondrial potential and leading to the initiation of apoptosis. This was further supported by JC-1 staining, indicating that this scaffold can contribute to the development of more potent derivatives.

A novel selective mitochondrial-targeted curcumin analog with remarkable cytotoxicity in glioma cells

Naturally occurring polyphenol curcumin (4) or demethoxycurcumin (5) and their synthetic derivatives display promising anticancer activities. However, their further development is limited by low bioavailability and poor selectivity. Thus, a mitochondria-targeted compound 14 (DMC-TPP) was prepared in the present study by conjugating a triphenylphosphine moiety to the phenolic hydroxyl group of demethoxycurcumin to enhance its bioavailability and treatment efficacy. The in vitro biological experiments of DMC-TPP showed that it not only displayed higher cytotoxicity as compared with its parent compound 5, but also exhibited superior mitochondria accumulation ability. Glioma cells were more sensitive to DMC-TPP, which inhibited the proliferation of U251 cells with an IC₅₀ of 0.42 μM. The mechanism studies showed that DMC-TPP triggers mitochondria-dependent apoptosis, caused by caspase activation, production of reactive oxygen species (ROS) and decrease of mitochondrial membrane potential (MMP). In addition, DMC-TPP efficiently inhibited cellular thioredoxin reductase, which contributed to its cytotoxicity. Significantly, DMC-TPP delayed tumor progression in a mouse xenograft model of human glioma cancer. Taken together, the potent in vitro and in vivo antitumor activity of DMC-TPP warrant further comprehensive evaluation as a novel anti-glioma agent.

Design and synthesis of novel substituted benzyl pyrrolopyrimidine derivatives as selective BTK inhibitors for treating mantle cell lymphoma

Ibrutinib, a potent irreversible Bruton's tyrosine kinase (BTK) inhibitor, was approved by the FDA for treating mantle cell lymphoma (MCL). Although ibrutinib exhibited excellent antitumor activity, it was associated with certain adverse reactions, with off-target effects against EGFR, Itk and Src family kinases. Our studies yielded a novel series of substituted benzyl pyrrolopyrimidine derivatives capable of potent inhibition of BTK. Compared with ibrutinib, compound 15c exhibited potent BTK inhibitory activity and enhanced antiproliferative activity, a 12-24-fold increase, against MCL cell lines, with IC₅₀ values lower than 1 μM. Low micromolar doses of 15c inhibited the BCR signaling pathway and strongly induced the apoptosis of Z138 cells. Ibrutinib and 15c induced autophagy in a dose-dependent manner in Z138 cells. Moreover, compound 15c induced the production of reactive oxygen species (ROS), which may be a reason for its potent antiproliferative activity. Importantly, compound 15c showed greater BTK selectivity than ibrutinib, indicating a potentially safer treatment of MCL.

Thioredoxin reductase inhibitors: updated patent review (2017-present)

Introduction: Thioredoxin reductase (TrxR) is a selenocysteine-containing enzyme which is responsible - as a part of the thioredoxin system - for maintaining redox homeostasis in cells. It is upregulated in cancerous state as a defense against oxidative stress. TrxR has been mostly considered an anticancer drug target although it has applications in other therapeutic areas such as neurodegeneration, inflammation, microbial infections, and neonatal hyperoxic lung injury.Areas covered: The present review covers the patent literature that appeared in the period 2017-2020, i.e. since the publication of the previous expert opinion patent review on TrxR inhibitors. The recent additions to the following traditional classes of inhibitors are discussed: metal complexes, Michael acceptors as well as arsenic and selenium compounds. At the same time, a novel group of nitro (hetero)aromatic compounds have emerged which likely acts via covalent inhibition mechanism. Several miscellaneous chemotypes are grouped under Miscellaneous subsection.Expert opinion: While specificity over glutathione reductase is achieved easily, TrxR is still moving toward the later stages of development at a very slow rate. Michael acceptors, particularly based on TRXR substrate-mimicking scaffolds, are gaining impetus and so are dual and hybrid compounds. The development prospects of the emerging nitro (hetero)aromatic chemotypes remain uncertain.

High anticancer activity and apoptosis- and autophagy-inducing properties of novel lanthanide(III) complexes bearing 8-hydroxyquinoline-N-oxide and 1,10-phenanthroline

In the quest for rare earth metal complexes with enhanced cancer chemotherapeutic properties, the discovery of seven lanthanide(iii) complexes bearing 8-hydroxyquinoline-N-oxide (NQ) and 1,10-phenanthroline (phen) ligands, i.e., [SmIII(NQ)(phen)(H2O)Cl2] (Ln1), [EuII(NQ)(phen)(H2O)Cl2] (Ln2), [GdIII(NQ)(phen)(H2O)Cl2] (Ln3), [DyIII(NQ)(phen)(H2O)Cl2] (Ln4), [HoIII(NQ)(phen)(H2O)Cl2] (Ln5), [ErIII(NQ)(phen)(H2O)Cl2] (Ln6), and [YbIII(NQ)(phen)(H2O)Cl2] (Ln7), as potential anticancer drugs is described. Complexes Ln1-Ln7 exhibit high antiproliferative activity against cisplatin-resistant A549/DDP cells (IC50 = 0.025-0.097 μM) and low toxicity to normal HL-7702 cells. Moreover, complex Ln1, and to a lesser extent Ln7, can upregulate the expression of LC3 and Beclin1 and downregulate p62 to induce apoptosis in cisplatin-resistant A549/DDP cell lines, which is related to the cell autophagy-inducing properties of Ln1 and Ln7. Furthermore, in vivo assays suggest that Ln1 significantly inhibits A549/DDP xenograft tumor growth (56.5%). These results indicate that lanthanide(iii) complex Ln1 is a promising candidate as an anticancer drug against cisplatin-resistant A549/DDP cells.

Iron Metabolism and Ferroptosis in Epilepsy

Epilepsy is a disease characterized by recurrent, episodic, and transient central nervous system (CNS) dysfunction resulting from an excessive synchronous discharge of brain neurons. It is characterized by diverse etiology, complex pathogenesis, and difficult treatment. In addition, most epileptic patients exhibit social cognitive impairment and psychological impairment. Iron is an essential trace element for human growth and development and is also involved in a variety of redox reactions in organisms. However, abnormal iron metabolism is associated with several neurological disorders, including hemorrhagic post-stroke epilepsy and post-traumatic epilepsy (PTE). Moreover, ferroptosis is also considered a new form of regulation of cell death, which is attributed to severe lipid peroxidation caused by the production of reactive oxygen species (ROS) and iron overload found in various neurological diseases, including epilepsy. Therefore, this review summarizes the study on iron metabolism and ferroptosis in epilepsy, in order to elucidate the correlation between iron and epilepsy. It also provides a novel method for the treatment, prevention, and research of epilepsy, to control epileptic seizures and reduce nerve injury after the epileptic seizure.