A coumarin derivative (RKS262) inhibits cell-cycle progression, causes pro-apoptotic signaling and cytotoxicity in ovarian cancer cells

A comprehensive review on the potential of coumarin and related derivatives as multi-target therapeutic agents in the management of gynecological cancers

Current treatments for gynecological cancers include surgery, radiotherapy, and chemotherapy. However, these treatments often have significant side effects. Phytochemicals, natural compounds derived from plants, offer promising anticancer properties. Coumarins, a class of benzopyrone compounds found in various plants like tonka beans, exhibit notable antitumor effects. These compounds induce cell apoptosis, target PI3K/Akt/mTOR signaling pathways, inhibit carbonic anhydrase, and disrupt microtubules. Additionally, they inhibit tumor multidrug resistance and angiogenesis and regulate reactive oxygen species. Specific coumarin derivatives, such as auraptene, praeruptorin, osthole, and scopoletin, show anti-invasive, anti-migratory, and antiproliferative activities by arresting the cell cycle and inducing apoptosis. They also inhibit metalloproteinases-2 and -9, reducing tumor cell migration, invasion, and metastasis. These compounds can sensitize tumor cells to radiotherapy and chemotherapy. Synthetic coumarin derivatives also demonstrate potent antitumor and anticancer activities with minimal side effects. Given their diverse mechanisms of action and minimal side effects, coumarin-class phytochemicals hold significant potential as therapeutic agents in gynecological cancers, potentially improving treatment outcomes and reducing side effects. This review will aid in the synthesis and development of novel coumarin-based drugs for these cancers.

Design and synthesis of novel coumarin-benzimidazole hybrids as human galectin-1 inhibitors

Aim: To develop novel non-carbohydrate inhibitors of human galectin-1 (GAL-1), we have designed a series of coumarin-benzimidazole hybrids. Methods: We synthesized and characterized the coumarin-benzimidazole hybrids and further evaluated them using an in vitro GAL-1 enzyme-linked immunosorbent assay and in silico methods. Results: Among all, the compounds 6p and 6q were found to be potent, with GAL-1 inhibition of 37.61 and 36.92%, respectively, at 10 μM in GAL-1-expressed cell culture supernatant of MCF-7 cells. These two compounds are feasible for fluorine-18 radiolabeling to develop GAL-1 selective PET radiotracers. Computational studies revealed strong binding interactions of GAL-1 with these novel coumarin-benzimidazole hybrids. Conclusion: Coumarin-benzimidazole hybrids can serve as potential leads to develop selective non-carbohydrate GAL-1 inhibitors for cancer therapy.

Phenolic Acids-Mediated Regulation of Molecular Targets in Ovarian Cancer: Current Understanding and Future Perspectives

Cancer is a global health concern with a dynamic rise in occurrence and one of the leading causes of mortality worldwide. Among different types of cancer, ovarian cancer (OC) is the seventh most diagnosed malignant tumor, while among the gynecological malignancies, it ranks third after cervical and uterine cancer and sadly bears the highest mortality and worst prognosis. First-line treatments have included a variety of cytotoxic and synthetic chemotherapeutic medicines, but they have not been particularly effective in extending OC patients' lives and are associated with side effects, recurrence risk, and drug resistance. Hence, a shift from synthetic to phytochemical-based agents is gaining popularity, and researchers are looking into alternative, cost-effective, and safer chemotherapeutic strategies. Lately, studies on the effectiveness of phenolic acids in ovarian cancer have sparked the scientific community's interest because of their high bioavailability, safety profile, lesser side effects, and cost-effectiveness. Yet this is a road less explored and critically analyzed and lacks the credibility of the novel findings. Phenolic acids are a significant class of phytochemicals usually considered in the nonflavonoid category. The current review focused on the anticancer potential of phenolic acids with a special emphasis on chemoprevention and treatment of OC. We tried to summarize results from experimental, epidemiological, and clinical studies unraveling the benefits of various phenolic acids (hydroxybenzoic acid and hydroxycinnamic acid) in chemoprevention and as anticancer agents of clinical significance.

Novel inhibitors of eukaryotic elongation factor 2 kinase: In silico, synthesis and in vitro studies

Eukaryotic elongation factor 2 kinase (eEF2K) is an unusual alpha kinase whose expression is highly upregulated in various cancers and contributes to tumor growth, metastasis, and progression. More importantly, eEF2K expression is associated with poor clinical outcome and shorter patient survival in breast, lung and ovarian cancers. Therefore, eEF2K is an emerging molecular target for development of novel targeted therapeutics and precision medicine in solid cancers. Currently, there are not any available potent and specific eEF2K inhibitors for clinical translation. In this study, we designed and synthesized a series of novel compounds with coumarin scaffold with various substitutions and investigated their effects in inhibiting eEF2K activity using in silico approaches and in vitro studies in breast cancer cells. We utilized an amide substitution at position 3 on the coumarin ring with their pharmacologically active groups containing pyrrolidine, piperidine, morpholine and piperazine groups with (CH₂)₂ bridged for aliphatic amides. Due to their ability to form covalent binding to the target enzyme, we also investigated the effects of boron containing groups on functionalized coumarin ring (3 compounds) and designed novel aliphatic and aromatic derivatives of coumarin scaffolds (10 compounds) and phenyl ring with boron groups (4 compounds). The Glide/SP module of the Maestro molecular modeling package was used to perform in silico analysis and molecular docking studies. According to our combined results, structure activity relationship (SAR) was performed in detail. Among the newly designed, synthesized, and tested compounds, our in vitro findings revealed that several compounds displayed a highly effective eEF2K inhibition at submicromolar concentrations in in vitro breast cancer cells. In conclusion, we identified novel compounds that can be used as eEF2K inhibitors and that they should be further evaluated by in vivo preclinical tumor models studies for antitumor efficacy and clinical translation.

Coumarin-carbazole based functionalized pyrazolines: synthesis, characterization, anticancer investigation and molecular docking

A series of novel pyrazoline scaffolds from coumarin-carbazole chalcones were synthesized. We explored various acetyl, amide, and phenyl substituents at the N-1 position of the pyrazoline core. The synthesized compounds were characterized by FTIR, 1H-NMR, 13C-NMR, DEPT, and mass spectroscopic techniques. The in vitro cytotoxicity study of all the synthesized compounds was evaluated against HeLa, NCI-H520 and NRK-52E cell lines. Compounds 4a and 7b became the most active compounds and exhibited their potential to arrest the cell cycle progression and induce apoptosis in both the cell lines. In addition, molecular docking studies revealed a higher binding affinity of both the molecules with CDK2 protein. Based on the obtained results, a comprehensive analysis is warranted to establish the role of compounds 4a and 7b as promising cancer therapeutic agents.

Cytotoxic and apoptosis-inducing effects of novel 8-amido isocoumarin derivatives against breast cancer cells

Isocoumarin is a lactone, a type of natural organic compound that is used as synthetic intermediates of several natural products and pharmaceutical compounds explored for their potential therapeutic applications like antifungal, antimicrobial, anti-inflammatory, and anticancer activities. In our previous work, we were the first group to report the use of amide C-N bond of isatins as the oxidizing directing group for the synthesis of 8-amido isocoumarin derivatives. Whereas in our present work, we have screened the cytotoxic effects of novel 8-amido isocoumarin derivatives (S1-S10) in human breast cancer MCF-7 and MDA-MB-231 cells. Our novel results revealed that N-(3-(4-methoxyphenyl)-1-oxo-4-(4-propylphenyl)-1H-isochromen-8yl)acetamide (S1) and N-(4-(3,5-difluorophenyl)-1-oxo-3-(p-tolyl)-1H-isochromen-8-yl) acetamide (S2) are the two potent compounds among the rest synthesized isocoumarin derivatives that are cytotoxic against MCF-7 and MDA-MB-231 cells, whereas less toxic to the non-tumorigenic IOSE-364 cells. Flow cytometry studies have confirmed the induction of apoptotic effects of compounds by Annexin V/PI double staining. We also observed the cytotoxic effects of S1 and S2, as evaluated by DAPI-PI immunostaining and H&E staining. The morphological alterations consistent with apoptotic blebs were observed in both cancer cells treated with compounds assessed by scanning electron microscopy. Overall, this present study strongly demonstrates that 8-amido isocoumarin derivatives have potent cytotoxic and apoptotic effects in breast cancer cells.

Design, synthesis and in vivo evaluation of 3-arylcoumarin derivatives of rhenium(I) tricarbonyl complexes as potent antibacterial agents against methicillin-resistant Staphylococcus aureus (MRSA)

We have prepared a series of ten 3-arylcoumarin molecules, their respective fac-[Re(CO)₃(bpy)L]⁺ and fac-[Re(CO)₃(L⁀L)Br] complexes and tested all compounds for their antimicrobial efficacy. Whereas the 3-arylcoumarin ligands are virtually inactive against the human-associated pathogens with minimum inhibitory concentrations (MICs) > 150 μM, when coordinated to the fac-[Re(CO)₃]⁺ core, most of the resulting complexes showed remarkable antibacterial potency. Several rhenium complexes exhibit activity in nanomolar concentrations against Gram-positive pathogens such as Staphylococcus aureus strains, including methicillin-resistant S. aureus (MRSA) and Enterococcus faecium. The molecules do not affect bacterial cell membrane potential, but some of the most potent complexes strongly interact with DNA, indicating it as a possible target for their mode of action. In vivo studies in the zebrafish model showed that the complexes with anti-staphylococcal/MRSA activity were non-toxic to the organism even at much higher doses of the corresponding MICs. In the zebrafish-MRSA infection model, the complexes increased the survival rate of infected fish up to 100% and markedly reduced bacterial burden. Moreover, all rescued fish developed normally following the treatments with the metallic compounds.

Discovery of coumarin derivatives as potent and selective cyclin-dependent kinase 9 (CDK9) inhibitors with high antitumour activity

Specific inhibition of CDK9 is considered a promising strategy for developing effective anticancer therapeutics. However, most of the reported CDK9 inhibitors are still at an early stage of development and lack selectivity against other CDKs. Herein, we discovered coumarin derivative 30i as a potent CDK9 inhibitor with high selectivity (8300-fold over CDK7). Binding mode analysis illustrated that the substituent coumarin moiety is a critical group for CDK9 selectivity by occupying a flexible hinge/αD region, which is sterically hindered in other CDKs. Compound 30i showed excellent cellular antiproliferative activity, moderate pharmacokinetic property and low hERG inhibition. Moreover, 30i significantly induced tumour growth inhibition in a dose-dependent manner without causing an obvious loss of body weight in an MV4-11 xenograft mice model. Altogether, these results suggest that 30i may serve as a potential acute myeloid leukaemia (AML) therapeutics by selectively targeting CDK9.

A QSAR Study on the 4-Substituted Coumarins as Potent Tubulin Polymerization Inhibitors

Purpose: Despite the discovery and synthesis of several anticancer drugs, cancer is still a major life threatening incident for human beings after cardiovascular diseases. Toxicity, severe side effects, and drug resistance are serious problems of available commercial anticancer drugs. Coumarins are synthetic and natural heterocycles that show promising antiproliferative activities against various tumors. The aim of this research is to computationally study the coumarin derivatives in order to develop reliable quantitative structure-activity relationship (QSAR) models for predicting their anticancer activities.

Methods: A data set of thirty one coumarin analogs with significant antiproliferative activities toward HepG2 cells were selected from the literature. The molecular descriptors for these compounds were calculated using Dragon, HyperChem, and ACD/Labs programs. Genetic algorithm (GA) accompanied by multiple linear regression (MLR) for simultaneous feature selection and model development was employed for generating the QSAR models.

Results: Based on the obtained results, the developed linear QSAR models with three and four descriptors showed good predictive power with r2 values of 0.670 and 0.692, respectively. Moreover, the calculated validation parameters for the models confirmed the reliability of the QSAR models.

Conclusion: The findings of the current study could be useful for the design and synthesis of novel anticancer drugs based on coumarin structure.

Fouling properties of reverse osmosis membranes along the feed channel in an industrial-scale system for wastewater reclamation

Membrane fouling is an inevitable disadvantage of the reverse osmosis (RO) process for wastewater reclamation. In order to clarify the development process of membrane fouling, all the fouled membranes along a feed channel of a two-stage industrial-scale RO system for wastewater reclamation (six elements in each stage) were autopsied and analyzed. The water flux and salt rejection efficiency of the fouled membranes at the head and tail were the lowest among 12 elements, thereby indicating more severe fouling on these membranes. In this RO system, most of the organic compounds deposited on the head elements of each stage were mainly composed of proteins, polysaccharides, and fulvic acid. The ATP concentrations of the foulants on the first and twelfth elements were much higher than those of the other elements, suggesting severe biofouling. Although microbes can cause organic fouling owing to extracellular polymeric substances production, no clear correlation was found between organic fouling and biofouling in this study. For example, the ATP concentrations on the second element and seventh element were similar (1.16 ng/cm² and 1.26 ng/cm², respectively), thereby suggesting a similar extent of biofouling, but organic fouling of the second element was relatively slight (DOC: 24.8 mg/m²) compared with that of the seventh element (DOC: 46.2 mg/m²). The seventh element (ATP: 1.26 ng/cm²) was more severely biofouled than the eighth element (ATP: 0.15 ng/cm²), but they suffered from the same level of organic fouling (DOC: 46.2 mg/m² and 47.1 mg/m², respectively). Approximately 70% of metallic elements, predominantly Fe, were deposited on the first element. Although the concentration of Fe in the feed water was much lower than those of Ca and Mg, the concentration of Fe on the first three elements was significantly higher than that of any other element, suggesting that Fe was more easily deposited on the RO membranes.

Design, Synthesis, and Molecular Modeling Studies of Novel Coumarin Carboxamide Derivatives as eEF-2K Inhibitors

Eukaryotic elongation factor-2 kinase (eEF-2K) is an unusual alpha kinase commonly upregulated in various human cancers, including breast, pancreatic, lung, and brain tumors. We have demonstrated that eEF-2K is relevant to poor prognosis and shorter patient survival in breast and lung cancers and validated it as a molecular target using genetic methods in related in vivo tumor models. Although several eEF-2K inhibitors have been published, none of them have shown to be potent and specific enough for translation into clinical trials. Therefore, development of highly effective novel inhibitors targeting eEF-2K is needed for clinical applications. However, currently, the crystal structure of eEF-2K is not known, limiting the efforts for designing novel inhibitor compounds. Therefore, using homology modeling of eEF-2K, we designed and synthesized novel coumarin-3-carboxamides including compounds A1, A2, and B1-B4 and evaluated their activity by performing in silico analysis and in vitro biological assays in breast cancer cells. The Molecular Mechanics/Generalized Born Surface Area (MM/GBSA) area results showed that A1 and A2 have interaction energies with eEF-2K better than those of B1-B4 compounds. Our in vitro results indicated that compounds A1 and A2 were highly effective in inhibiting eEF-2K at 1.0 and 2.5 μM concentrations compared to compounds B1-B4, supporting the in silico findings. In conclusion, the results of this study suggest that our homology modeling along with in silico analysis may be effectively used to design inhibitors for eEF-2K. Our newly synthesized compounds A1 and A2 may be used as novel eEF-2K inhibitors with potential therapeutic applications.

Antitumor Features of Vegetal Protein-Based Nanotherapeutics

The introduction of nanotechnology into pharmaceutical application revolutionized the administration of antitumor drugs through the modulation of their accumulation in specific organs/body compartments, a decrease in their side-effects and their controlled release from innovative systems. The use of plant-derived proteins as innovative, safe and renewable raw materials to be used for the development of polymeric nanoparticles unlocked a new scenario in the drug delivery field. In particular, the reduced size of the colloidal systems combined with the peculiar properties of non-immunogenic polymers favored the characterization and evaluation of the pharmacological activity of the novel nanoformulations. The aim of this review is to describe the physico-chemical properties of nanoparticles composed of vegetal proteins used to retain and deliver anticancer drugs, together with the most important preparation methods and the pharmacological features of these potential nanomedicines.

Synthesis and Characterization of 3-(1-((3,4-Dihydroxyphenethyl)amino)ethylidene)-chroman-2,4-dione as a Potential Antitumor Agent

The newly synthesized coumarin derivative with dopamine, 3-(1-((3,4-dihydroxyphenethyl)amino)ethylidene)-chroman-2,4-dione, was completely structurally characterized by X-ray crystallography. It was shown that several types of hydrogen bonds are present, which additionally stabilize the structure. The compound was tested in vitro against different cell lines, healthy human keratinocyte HaCaT, cervical squamous cell carcinoma SiHa, breast carcinoma MCF7, and hepatocellular carcinoma HepG2. Compared to control, the new derivate showed a stronger effect on both healthy and carcinoma cell lines, with the most prominent effect on the breast carcinoma MCF7 cell line. The molecular docking study, obtained for ten different conformations of the new compound, showed its inhibitory nature against CDK_S protein. Lower inhibition constant, relative to one of 4-OH-coumarine, proved stronger and more numerous interactions with CDK_S protein. These interactions were carefully examined for both parent molecule and derivative and explained from a structural point of view.

Synthesis and Biological Evaluation of Novel Triazoles Linked 7-hydroxycoumarin as Potent Cytotoxic Agents

Background:

BacCancer is regarded as second leading cause of death worldwide. Therefore, there is a high demand for the discovery, development and improvement of novel anti-cancer agents which could efficiently prevent proliferative pathways and clonal expansion of cells.

Objective:

In view of this, a new series of bioactive scaffolds viz triazoles linked 7-hydroxycoumarin (1) were synthesized using click chemistry approach.

Method:

All the synthesized compounds were screened for cytotoxicity against a panel of seven different human cancer cell lines viz. Colon (Colo-205 and HCT-116), breast (MCF-7), lung (NCI-H322 and A549), prostate (PC-3) and skin (A-431) using 3-(4,5-Dimethylthiazol-yl)-diphenyl tetrazoliumbromide (MTT) assay.

Results:

Among all tested analogs, compound 5, displayed better cytotoxic activity as compared to the parent 7- hydroxycoumarin (1) with IC50 of 5.1, 22.7, 14.3 and 10.2 µM against breast (MCF-7), lung (NCI- H322), prostate (PC-3) and skin (A-431) cancer cell lines, respectively; the compound 5 was 8-fold more sensitive against MCF-7 than the parent 7-hydroxycoumarin. Moreover, Compound 5 induced both cytotoxic as well as cytostatic effects via induction of apoptosis and G1 phase arrest, respectively in breast cancer cells (MCF-7). The apoptotic cell population enhanced to 18.8% at 8 µM of 5 from 9.8% in case of negative control, while G1 phase arrest increased to 54.4% at 8 µM compared to negative control of 48.1%. Moreover, Compound 5 also exhibited a remarkable decrease in mitochondrial membrane potential (ΛΨm) leading to apoptosis of cancer cells used.

Conclusion:

The structure-activity relationship study revealed that the derivatives bearing electron-withdrawing substituents were more effective. The present study resulted in identification of the compounds demonstrating broad spectrum cytotoxic activity.

In silico and in vitro analysis of coumarin derivative induced anticancer effects by undergoing intrinsic pathway mediated apoptosis in human stomach cancer

BACKGROUND

Coumarin plays a vital role in drug discovery process due to its diverse biologically active components. Recently, coumarin derivatives are paying attention to treat various diseases including cancer. The effect of coumarin derivatives on gastric cancer is not well established although gastric cancer being the fourth leading cancer. Therefore, we attempt to study the effect of styrene substituted biscoumarin (SSBC) to induce apoptosis and inhibit cancer proliferation using in silico and in vitro approaches.

METHODS

We performed 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay to identify the anti-proliferative activity of SSBC in stomach cancer cell lines (AGS) and toxicity of the compared was also assessed using lung normal cell lines (L-132 and MRC-5). A docking study was carried out between anti-apoptotic protein (BCL2) and SSBC compound. Furthermore, we analyzed the drug likeliness by screening pharmacological properties (ADME) and biological activity of SSBC by performing spectrum prediction analysis (PASS). The apoptotic effect of SSBC in AGS cell lines were detected using flow cytometry (FACS), Hoechst staining and DAPI/PI staining. Later, the regulation of apoptotic pathway by SSBC was also confirmed by qRT-PCR and western blotting analysis.

RESULTS

The inhibition concentration (IC₅₀) of SSBC was assayed against AGS and lung normal cell lines (L-132 and MRC-5). The IC₅₀ value of SSBC toward AGS, L-132 and MRC-5 was 4.56, 268 and 285 μg/ml, respectively. In silico analysis predicted SSBC could bind to the active site of BH3 domain of anti-apoptotic protein and thus resulted in apoptotic mediated cell death. ADME prediction of SSBC exhibit strong binding capacity of 99.08% and showed absorption rate about 95.57% in the intestine. In addition, biological activity of SSBC was also predicted using PASS program and we found SSBC exhibit high activity for various cancer related protein expression including apoptosis pathway proteins such as caspase 3 stimulant, apoptosis agonist. Furthermore, apoptosis of AGS was also assessed using Hoechst staining, DAPI/PI analysis, flow-cytometric analysis, qRT-PCR and western blot analysis.

CONCLUSION

Our study denotes that SSBC could be very effective against AGS by inducing apoptosis through intrinsic pathway and recommended for in vivo and human trials.

Designing novel inhibitors against falcipain-2 of Plasmodium falciparum

Coumarin containing pyrazoline derivatives have been synthesized and tested as inhibitors of in vitro development of a chloroquine-sensitive (MRC-02) and chloroquine-resistant (RKL-2) strain of Plasmodium falciparum and in vivo Plasmodium berghei malaria. Docking study was also done on cysteine protease falcipain-2 which showed that the binding pose of C-14 molecule and epoxysuccinate, inhibitor of falcipain-2, binds in the similar pattern. The most active antimalarial compound was 3-(1-benzoyl-5-(4-flurophenyl)-4,5-dihydro-1H-pyrazol-3yl)-7-(diethyamino)-2H-chromen-2-one C-14, with an IC₅₀ of 4.21 µg/ml provided complete protection to the infected mice at 24 mg/kg X 4 days respectively.

Effects of isoimperatorin on proliferation and apoptosis of human gastric carcinoma cells

Resistance to apoptosis is an characteristic of cancer cells that serves a critical function in tumor development and represents a target for antitumor therapy. Isoimperatorin (ISOIM), a coumarin compound, exhibits antitumor functions in multiple types of tumor cells. However, its antitumor effects and molecular mechanisms with respect to gastric cancer have not been elucidated. The present study assessed the anti-proliferative and apoptotic effects of ISOIM on human BGC-823 gastric cancer cells and elucidated its underlying molecular mechanisms. Cell proliferation was evaluated using MTT assays. Analysis of cell morphology was performed by hematoxylin and eosin, Hoechst 33258 and acridine orange/ethidium bromide staining. In addition, cell cycle and apoptosis was evaluated using flow cytometry analysis; expression of apoptosis-associated proteins was studied by western blotting. The results of the present study revealed that ISOIM significantly inhibited cell proliferation by arresting the cell cycle at the G₂/M phase and induced apoptosis by increasing Bcl-2-associated X (Bax) expression with a concomitant decrease in Bcl-2 expression, resulting in a decreased Bcl-2/Bax ratio compared with the control. In addition, ISOIM treatment also resulted in cytochrome c translocating from the mitochondria to the cytosol. Furthermore, caspase-3 was significantly activated in response to treatment with ISOIM, suggesting that apoptosis in BGC-823 cells is induced in the mitochondrial pathway. Taken together, the results of the present study indicate that ISOIM may significantly induce apoptosis in BGC-823 cells and that the pro-apoptotic mechanisms of ISOIM could be associated with the mitochondrial pathway.

Mono and dihydroxy coumarin derivatives: Copper chelation and reduction ability

Due to the limited array of the currently available copper chelators, research of such compounds continues to be of clinical interest. Notably, o-dihydroxycoumarins have been previously shown to be potent iron chelators under neutral conditions. Within this study, the interaction of a series of natural coumarins and their synthetic analogs with copper has been evaluated in order to obtain structure-activity relationships under different pathophysiological pH conditions. Both competitive and non-competitive methods have been employed. Analysis of cupric ion reduction has also been performed. Under mildly competitive conditions, cupric chelation was observed for o-dihydroxycoumarins, and partially for o-diacetoxycoumarin. Non-competitive studies showed that cuprous ions are not chelated at all and that the stoichiometries of the most active 6,7- and 7,8-dihydroxycoumarins to cupric ions ranged from 1:1 to 2:1 depending on pH and concentration. Interestingly, under highly competitive conditions, coumarins were not capable of chelating cupric ions, either. Reduction experiments have shown that 13 out of the 15 coumarins included in this study reduced cupric ions. However, significant differences depending on their structures were apparent in their potencies. O-dihydroxycoumarins were the most potent ones again.

CONCLUSION

O-dihydroxycoumarins are moderately active cupric ion chelators with potent copper reducing properties.

Recent advances on CDK inhibitors: An insight by means of in silico methods

The cyclin dependent kinases (CDKs) are a small family of serine/threonine protein kinases that can act as a potential therapeutic target in several proliferative diseases, including cancer. This short review is a survey on the more recent research progresses in the field achieved by using in silico methods. All the "armamentarium" available to the medicinal chemists (docking protocols and molecular dynamics, fragment-based, de novo design, virtual screening, and QSAR) has been employed to the discovery of new, potent, and selective inhibitors of cyclin dependent kinases. The results cited herein can be useful to understand the nature of the inhibitor-target interactions, and furnish an insight on the structural/molecular requirements necessary to achieve the required selectivity against cyclin dependent kinases over other types of kinases.

Synthesis and Characterization of Some New Coumarins with in Vitro Antitumor and Antioxidant Activity and High Protective Effects against DNA Damage

Coumarins are naturally occurring oxygen heterocyclic compounds having multifarious medicinal properties, hence used as lead compounds for designing new potent analogs. The chromene butenoic acid 3 and the benzochromene butenoic acid 4 which are derived from the reaction of glyoxalic acid with 3-acetylcoumarin and 3-acetylbenzocoumarin, respectively, were reacted with different nitrogen and carbon nucleophiles to give new heterocyclic compounds. The structures of the prepared compounds were elucidated by IR, ¹H-NMR, and mass spectroscopy. Some of the newly prepared compounds were tested in vitro against a panel of four human tumor cell lines namely; hepatocellular carcinoma (liver) HepG2, colon cancer HCT-116, human prostate cancer PC3, and mammary gland breast MCF-7. Also they were tested as antioxidants. Almost all of the tested compounds showed satisfactory activity.

Nifurtimox reduces N-Myc expression and aerobic glycolysis in neuroblastoma

Neuroblastoma is one of the most common solid tumors in childhood and usually accompanied with poor prognosis and rapid tumor progression when diagnosed with amplification of the proto-oncogene N-Myc. The amplification of N-Myc has major influence on the maintenance of aerobic glycolysis, also known as the Warburg effect. This specific switch in the conversion of pyruvate to lactate instead of the conversion of pyruvate to acetyl-coenzyme A even in the presence of oxygen has important benefits for the tumor, e.g. increased production of enzymes and enzyme substrates that are involved in tumor progression, angiogenesis and inhibition of apoptosis. The antiprotozoal drug nifurtimox, which is generally used for the treatment of infections with the parasitic protozoan Trypanosoma cruzi, has been reported to have cytotoxic properties in the therapy of neuroblastoma. However, its action of mechanism has not been described in detail yet. The presented in vitro study on the neuroblastoma cell lines LA-N-1, IMR-32, LS and SK-N-SH shows an increased production of oxidative stress, a reduced lactate dehydrogenase enzyme activity and reduced lactate production after nifurtimox treatment. Furthermore, nifurtimox leads to reduced mRNA and protein levels of the proto-oncogene protein N-Myc. Thus, the current work gives new insights into the effect of nifurtimox on tumor metabolism revealing a shifted glucose metabolism from production of lactate to oxidative phosphorylation and a reduced expression of the major molecular prognostic factor in neuroblastoma N-Myc, presenting nifurtimox as a possible adjuvant therapeutic agent against (high risk) neuroblastoma.

Structure-activity relationship studies of 4-methylcoumarin derivatives as anticancer agents

CONTEXT

Cancer is a leading cause of death worldwide and novel chemotherapeutic agents with better efficacy and safety profiles are much needed. Coumarins are natural polyphenolic compounds with important pharmacological activities, which are present in many dietary plants and herbal remedies.

OBJECTIVES

The objective of this study is to investigate natural and synthetic coumarin derivatives with considerable anticancer capacity against three human cancer cell lines.

MATERIALS AND METHODS

We synthesized 27 coumarin derivatives (mostly having 4-methyl moiety) and examined their cytotoxic effect on three human cancer cell lines, K562 (chronic myelogenous leukemia), LS180 (colon adenocarcinoma), and MCF-7 (breast adenocarcinoma) by MTT reduction assay. Screened compounds included 7-hydroxy-4-methylcoumarins (7-HMCs), 7-acetoxy-4-methylcoumarins (7-AMCs), and different dihydroxy-4-methylcoumarin (DHMC) and diacetoxy-4-methylcoumarin (DAMC) derivatives. Some compounds with methoxy, amine, and bromine substitutions were also examined.

RESULTS

7,8-DHMCs bearing alkyl groups at C3 position were the most effective subgroup, and of which, the most potent is compound 11, with an n-decyl chain at C3, which had IC50 values of 42.4, 25.2, and 25.1 µM against K562, LS180, and MCF-7 cells, respectively. The second most active subgroup was 7,8-DAMCs containing ethoxycarbonylmethyl and ethoxycarbonylethyl moieties at C3 position. Compound 27 (6-bromo-4-bromomethyl-7-hydroxycoumarin), the only derivative containing bromine also showed reasonable cytotoxic activities (IC50 range: 32.7-45.8 µM).

DISCUSSION AND CONCLUSION

This structure-activity relationship (SAR) study of 4-methylcoumarins shows that further investigation of these derivatives may lead to the discovery of novel anticancer agents.

3-cinnamoyl-4-hydroxy-6-methyl-2H-pyran-2-one (CHP) inhibits human ovarian cell proliferation by inducing apoptosis

Coumarins induce apoptosis by activating mitochondrial pathway and caspase-3-dependent apoptotic pathway. In the present study, we first time investigated the effect of 3-cinnamoyl-4-hydroxy-6-methyl-2H-pyran-2-one (CHP) on induction of apoptosis in human ovarian carcinoma cells. The data from MTT assay revealed a significant inhibitory effect on cell viability at 30 (87%) and 50 μM (74%) concentration of CHP in OVCAR-3 and OVCAR-420 cells, respectively after 72 h. Apoptosis analysis using annexin V/PI double staining followed by flow cytometry showed 59 and 52% binding to annexin V-FITC in OVCAR-3 and OVCAR-420 cells respectively. propidium iodide (PI) staining and flow cytometry examination indicated a significant increase in percentage of cells in G2/M phase after treatment with CHP compared to DMSO control group. Reactive oxygen species (ROS) assay kit showed increase in levels of ROS. We used rhodamine-123 (Rh-123) staining and flow cytometry assay to determine changes in mitochondrial membrane potential (ΛΨm). The results revealed that CHP significantly decreased MMP to 85.65 ± 1.2443% & 49.78 ± 1.6554% at 10 and 30 μM respectively in OVCAR-3 compared to 95.97 ± 2.1243% in control group. Western blot analysis clearly indicated a significant increase in the expression of Caspase-3, Bax, and release of Cytochrome c and decrease in Bcl-2, CDK1 and Cyclin B1 expression on treatment with CHP. Therefore, CHP may become a potential candidate for the treatment of human ovarian cancers.

Low-energy collision-induced dissociation tandem mass spectrometry of 7-acetonyloxycoumarins

RATIONALE

Coumarins are naturally occurring, oxygen-containing heterocycles with considerable pharmaceutical potential. For structural elucidation of natural or synthetic coumarins, tandem mass spectrometry (MS(n)) represents an essential tool. In this study, fragmentation characteristics of twenty-two 7-acetonyloxycoumarins, having promising anti-inflammatory properties, were investigated with low-energy collision-induced dissociation (CID).

METHODS

Accurate mass measurements were performed on a 12-T Fourier transform ion cyclotron resonance (FT-ICR) instrument. Most CID-MS(n) measurements were performed on a quadrupole ion trap (QIT) instrument, except some additional CID-MS(2) measurements performed on the FT-ICR instrument for further confirmation of some fragment ions. Positive-ion electrospray ionization (ESI) was employed throughout. Density functional theory (DFT) calculations (B3LYP) were carried out to analyze putative ion structures/fragmentation channels.

RESULTS

The most favourable dissociation channel for [M + H](+) ions of 7-acetonyloxycoumarins was the elimination of a C3H5O(●) radical (57 Da) from the 7-acetonyloxy group via homolytic bond cleavage. The resulting phenolic radical ion was the primary fragment ion for the most compounds studied. Losses of even-electron neutrals, C3H4O and C3H6O (56 and 58 Da), were also observed. These primary eliminations were accompanied with other characteristic neutral losses from the coumarin skeleton, including H2O, CO, CO2, and C2H2O (ketene). In addition, propene (C3H6) loss was also observed for 4-propyl or 3-ethyl-4-methyl-substituted compounds.

CONCLUSIONS

The studied coumarins showed interesting characteristics in low-energy CID due to the presence of a 7-acetonyloxy group, leading to both even- and odd-electron product ions. The main dissociation channels observed for each compound were highly dependent on the substituents in the benzopyranone ring. The present results will advance our knowledge on the dissociation characteristics of both synthetic and natural coumarins.

The toxicity of nitrofuran compounds on melanoma and neuroblastoma cells is enhanced by Olaparib and ameliorated by melanin pigment

Nitrofurans are commonly used for the treatment of trypanosomal diseases including Chagas disease. More recently, following the fortuitous discovery that nifurtimox was clinically active against neuroblastoma, nitrofuran compounds are being investigated for activity against cancer. Herein, we show that nitrofuran compounds are similarly potent to human malignant melanoma and neuroblastoma cells. Furthermore, a recently discovered nitrofuran compound, NFN1, was 50- to 175-fold more potent than nifurtimox against human melanoma and neuroblastoma cell lines. As nitrofuran compounds are known to act as pro-drugs, producing DNA-damaging reactive intermediates upon activation, we investigated the DNA repair pathways involved. We show that, contrary to research in Escherichia coli, the Nucleotide Excision Repair pathway is not required to repair nitrofuran-induced DNA damage in mammalian cells. Instead, we show that inhibiting repair of single-strand DNA breaks with the poly(ADP-ribose) polymerase (PARP) inhibitor, Olaparib, enhances nitrofuran toxicity in melanoma and neuroblastoma cells. We propose that this is due to mammalian cells utilising Type 2 nitroreductases for nitrofuran activation producing Reactive Oxygen Species which cause DNA damage that is repaired by the Single Strand Break Repair and/or Base Excision Repair pathways, whereas in bacteria and trypanosomes, Type 1 nitroreductases are also utilised resulting in different DNA lesions. In addition we show that, consistent with Reactive Oxygen Species being formed upon nitrofuran activation and the ability of melanin to absorb Reactive Oxygen Species, production of melanin in melanoma cells offers some protection from NFN1- and hydrogen peroxide-induced toxicity. Our data suggest that combinations of Olaparib and nitrofuran compounds may be advantageous for the treatment of melanoma and neuroblastoma, but that the protection offered to melanoma cells by their melanin pigment must be taken into account.

7,8-Dihydroxycoumarin inhibits A549 human lung adenocarcinoma cell proliferation by inducing apoptosis via suppression of Akt/NF-κB signaling

The Akt/NF-κB pathways are involved in numerous anti-apoptotic and drug-resistance events that occur in non-small cell lung cancer (NSCLC). In the present study, the role of 7,8-dihydroxycoumarin in the regulation of the anti-apoptotic Akt and NF-κBp65 signaling pathways was explored. A549 human lung adenocarcinoma cells were exposed to 7,8-dihydroxycoumarin with a final concentration of 25, 50 and 100 μmol/l for 48 h. Quantitative polymerase chain reaction (PCR) and western blotting were performed to detect mRNA and protein expression, respectively. The MTT assay was performed to detect cell proliferation. The results demonstrated that anti-apoptotic phospho-Akt1 (pAkt1), phospho-IκBα (pIκBα), NF-κBp65 and Bcl-2 were inhibited and pro-apoptotic caspase-3 was upregulated in a concentration-dependent manner. At a concentration of 100 μmol/l, the anti-apoptotic NF-κBp65 and Bcl-2 mRNA expression levels decreased 0.12 (5.82/48.5, treated/control)-fold and 0.17 (6.7/39.4, treated/control)-fold, respectively. The pro-apoptotic caspase-3 mRNA was upregulated 4.43 (39.4/8.9, treated/control)-fold. The anti-apoptotic pAkt1, pIκBα, NF-κBp65 and Bcl-2 proteins were downregulated, with blot grayscale values of 7.3 (vs. 52.4 control), 4.3 (vs. 42.2 control), 5.08 (vs. 44.5 control) and 5.92 (vs. 38.5 control), respectively. The proapoptotic caspase-3 was upregulated to a blot grayscale value of 27.8 (vs. 5.8 control). The proliferative activity of A549 cells was reduced significantly compared with that of the control cells (83.7, 27.2 and 9.5 vs. 100%, respectively; P<0.05 for each). 7,8-Dihydroxycoumarin plays an important role in the induction of apoptosis via suppression of Akt/NF-κB signaling in A549 human lung adenocarcinoma cells in a concentration-dependent manner. 7,8-Dihydroxycoumarin may be a candidate naturally-occurring drug for the treatment and prevention of lung adenocarcinoma.

Synthesis and antibacterial activities of novel 4-hydroxy-7-hydroxy- and 3-carboxycoumarin derivatives

Coumarin derivatives are used as fluorescent dyes and medicines. They also have some notable physiological effects, including the acute hepatoxicity and carcinogenicity of certain aflatoxins, the anticoagulant action of dicoumarol, and the antibiotic activity of novobicin and coumerymycin A1. Because the number of drug resistant strains is increasing at present, the synthesis of new antibacterial compounds is one of the critical methods for treating infectious diseases. Therefore, a series of coumarin-substituted derivatives, namely 4-hydroxy- and 7-hydroxycoumarins, and 3-carboxycoumarins were synthesized. 4-Hydroxycoumarin derivatives 4a–c underwent rearrangement reactions. Both 4- and 7-hydroxycoumarins were treated with activated aziridines which produced series of ring-opened products 7, 8, 10, and 11. 3-Carboxy-coumarin amide dimer derivatives 14–21 were prepared by reacting aliphatic alkylamines and alkyldiamines with PyBOP and DIEA. In this study, we use a new technique called modified micro-plate antibiotic susceptibility test method (MMAST), which is more convenient, more efficient, and more accurate than previous methods and only a small amount of the sample is required for the test. Some of the compounds were produced by reactions with acid anhydrides and demonstrated the ability to inhibit Gram-positive microorganisms. The dimer derivatives displayed lower antibacterial activities.

Alterations in nuclear pore architecture allow cancer cell entry into or exit from drug-resistant dormancy

Phenotypic diversity arises in tumors just as it does in developing organisms, and tumor recurrence frequently manifests from the selective survival of divergent drug-resistant cells. Although the expanding tumor cell population may be successfully targeted, drug-resistant cells may persist and sustain the tumor or enter dormancy before igniting a future relapse. Herein, we show that partial knockdown of nucleoporin p62 (NUP62) by small-interfering RNA confers cisplatin resistance to cultured high-grade ovarian carcinoma cells. Treatment with NUP62 small-interfering RNA and cisplatin leaves resistant cells in a state of dormancy; some dormant cells can be induced to proliferate by transient induction of NUP62 expression from an ectopic expression construct. In addition to suggesting functional links between nuclear pore complex architecture and cancer cell survival, the culture system provides a novel experimental window into the dynamics of tumor cell drug resistance and dormancy.