7-Diethylamino-3(2'-benzoxazolyl)-coumarin is a novel microtubule inhibitor with antimitotic activity in multidrug resistant cancer cells

Synthesis of novel imino-coumarin and acrylonitrile 2-benzazole hybrids as potent anticancer agents targeting tubulin

Building on previous research indicating the robust biological effects of coumarins, we focused on exploring imino-coumarin 2-benzazole conjugates. Compounds were tested for antiproliferative activity in vitro, with the most active ones further examined to determine the mechanism of biological action. Five derivatives exhibited significant antiproliferative activity against all tested cancer cells (IC50 ranging from 0.04 to 8.5 μM), falling within the low micromolar/submicromolar range of inhibitory concentrations. Three compounds had remarkable antiproliferative effects against Capan-1 (IC50 0.04-0.05 μM) and DND-41 (IC50 0.06-0.07 μM). Promising compounds were further investigated, confirming their mechanism of action through tubulin polymerization inhibition. Computational docking and molecular dynamics simulations confirmed the high affinity of potent derivatives for the tubulin colchicine site and justified the suitability of the employed skeleton by identifying crucial protein-ligand interactions promoting binding. This insight highlights a strategy for further potency improvements through substituents that can donate hydrogen bonds or bear a positive charge, allowing such ligands to more optimally adapt to the identified anionic binding site environment.

The Benzoxazole Heterocycle: A Comprehensive Review of the Most Recent Medicinal Chemistry Developments of Antiproliferative, Brain-Penetrant, and Anti-inflammatory Agents

The benzoxazole is one of the most widely exploited heterocycles in drug discovery. Natural occurring and synthetic benzoxazoles show a broad range of biological activities. Many benzoxazoles are available for treating several diseases, and, to date, a few are in clinical trials. Moreover, an ever-increasing number of benzoxazole derivatives are under investigation in the early drug discovery phase and as potential hit or lead compounds. This perspective is an attempt to thoroughly review the rational design, the structure-activity relationship, and the biological activity of the most notable benzoxazoles developed during the past 5 years (period 2019-to date) in cancers, neurological disorders, and inflammation. We also briefly overviewed each target and its role in the disease. The huge amount of work examined suggests the great potential of the scaffold and the high interest of the scientific community in novel biologically active compounds containing the benzoxazole core.

PRMT7 Inhibitor SGC8158 Enhances Doxorubicin-Induced DNA Damage and Its Cytotoxicity

Protein arginine methyltransferase 7 (PRMT7) regulates various cellular responses, including gene expression, cell migration, stress responses, and stemness. In this study, we investigated the biological role of PRMT7 in cell cycle progression and DNA damage response (DDR) by inhibiting PRMT7 activity with either SGC8158 treatment or its specific siRNA transfection. Suppression of PRMT7 caused cell cycle arrest at the G₁ phase, resulting from the stabilization and subsequent accumulation of p21 protein. In addition, PRMT7 activity is closely associated with DNA repair pathways, including both homologous recombination and non-homologous end-joining. Interestingly, SGC8158, in combination with doxorubicin, led to a synergistic increase in both DNA damage and cytotoxicity in MCF7 cells. Taken together, our data demonstrate that PRMT7 is a critical modulator of cell growth and DDR, indicating that it is a promising target for cancer treatment.

Benzazole Substituted Iminocoumarins as Potential Antioxidants with Antiproliferative Activity

BACKGROUND

Benzazole and coumarin derivatives are one of the most privileged heterocyclic substructures in the medicinal chemistry with well-known biological features, which include a wide range of versatile biological activities as well as excellent spectroscopic characteristics thus offering their potential application in many research fields.

OBJECTIVE

The prepared iminocoumarins were synthesized to evaluate their antioxidative potential by using ABTS and FRAP assays and in vitro antiproliferative activity.

METHODS

A series of coumarin derivatives containing a 2-benzazole motif were synthesized and evaluated for their antioxidative capacity and antiproliferative activity. Their molecular structure incorporates a push-pull functionality: an electron donor donating group at the 7-position with an electron-withdrawing group, such as benzimidazole, benzothiazole and imidazopyridine fragment at the 3-position.

RESULTS

The iminocoumarins bearing different substituents on 7-position were evaluated for their antiproliferative activity on tree cancer cells with only 4 compounds showing the antiproliferative activity. The most active derivative was N,N-diethylamino substituted benzimidazole derivative 4d and imidazo[4,5-b]pyridine analogue 6b, both also displayed selective activity toward CEM with submicromolar inhibitory concentration (0.059 μM; 0.17 ± 0.09, respectively). The inhibitory effect of 4d and 6b derivatives on the cell-cycle progression of HeLa cells was studied. A flow cytometric analysis of the HeLa cells indicated an appreciable cell-cycle arrest in a dose-dependent manner. Antioxidant properties were studied by ABTS and FRAP assays and obtained results revealed that the most promising antioxidant has proven to be compound 3b while other compounds, in general, showed moderate to very low antioxidative capacity in both assays.

CONCLUSION

Unsubstituted benzimidazole derivatives bearing hydroxyl group on iminocoumarin nuclei exhibited the most prominent antioxidant potential in ABTS assay (3b; 40.5 ± 0.01). The most significant and selective antiproliferative activity was displayed by compounds 4d and 6b (0.059 μM; 0.17 ± 0.09, respectively), which were chosen as lead compounds for further optimization and rational design to obtain more active and selective antiproliferative agents.

A novel synthetic microtubule inhibitor exerts antiproliferative effects in multidrug resistant cancer cells and cancer stem cells

The success of cancer chemotherapy is limited by multidrug resistance (MDR), which is mainly caused by P-glycoprotein (P-gp) overexpression. In the present study, we describe a novel microtubule inhibitor, 5-(N-methylmaleimid-3-yl)-chromone (SPC-160002), that can be used to overcome MDR. A synthetic chromone derivative, SPC-160002, showed a broad spectrum of anti-proliferative effects on various human cancer cells without affecting P-gp expression and its drug efflux function. Treatment with SPC-160002 arrested the cell cycle at the M phase, as evidenced using fluorescence-activated cell sorting analysis, and increased the levels of mitotic marker proteins, including cyclin B, pS10-H3, and chromosomal passenger complex. This mitotic arrest by SPC-160002 was mediated by promoting and stabilizing microtubule polymerization, similar to the mechanism observed in case of taxane-based drugs. Furthermore, SPC-160002 suppressed the growth and sphere-forming activity of cancer stem cells. Our data herein strongly suggest that SPC-160002, a novel microtubule inhibitor, can be used to overcome MDR and can serve as an attractive candidate for anticancer drugs.

Potentials of Musa Species Fruits against Oxidative Stress-Induced and Diet-Linked Chronic Diseases: In Vitro and In Vivo Implications of Micronutritional Factors and Dietary Secondary Metabolite Compounds

Nutritional quality and the well-being of the body system are directly linked aspects of human survival. From the unborn foetus to adulthood, the need for sustainable access to micronutrient-rich foods is pertinent and the global consumption of banana and plantain fruits, in effect, contributes to the alleviation of the scourge of malnutrition. This review is particularly aimed at evaluating the pharmacological dimensions through the biological mechanisms of Musa fruits in the body, which represent correlations with their constituent micronutrient factors and dietary polyphenolic constituents such as minerals, vitamin members, anthocyanins, lutein, α-,β- carotenes, neoxanthins and cryptoxanthins, epi- and gallo catechins, catecholamines, 3-carboxycoumarin, β-sitosterol, monoterpenoids, with series of analytical approaches for the various identified compounds being highlighted therein. Derivative value-products from the compartments (flesh and peel) of Musa fruits are equally highlighted, bringing forth the biomedicinal and nutritional relevance, including the potentials of Musa species in dietary diversification approaches.

Bromocoumarinplatin, targeting simultaneously mitochondria and nuclei with p53 apoptosis pathway to overcome cisplatin resistance

Mitochondria as one of potential anticancer target, alternatively damaging mtDNA other than nDNA is a potential method for platinum-based anticancer drugs to overcome cisplatin resistance. We herein report that bromocoumarinplatin 1, a coumarin-Pt(IV) prodrug, targeted simultaneously mitochondria and nuclei with the contents of Pt in nDNA and mtDNA were 25.75% and 65.91%, respectively, which demonstrated mtDNA apoptosis played a key role in overcoming cisplatin resistance. Moreover, 1 promoted the expression of p53 gene and protein more effectively than cisplatin, leading to the increased anticancer activity of 1 through p53 pathway. The property of preferential accumulation in cancer cells (Snu-368 and Snu-739) compared to the matched normal cells (HL-7702 cells) demonstrated that 1 was potentially safe for clinical therapeutic use. In addition, the higher therapeutic indices of 1 for HCT-116 cells in vivo indicated that bromocoumarinplatin behaved a vital function in the treatment of colon cancer.

A drug discovery platform to identify compounds that inhibit EGFR triple mutants

Receptor tyrosine kinases (RTKs) are transmembrane receptors of great clinical interest due to their role in disease. Historically, therapeutics targeting RTKs have been identified using in vitro kinase assays. Due to frequent development of drug resistance, however, there is a need to identify more diverse compounds that inhibit mutated but not wild-type RTKs. Here, we describe MaMTH-DS (mammalian membrane two-hybrid drug screening), a live-cell platform for high-throughput identification of small molecules targeting functional protein-protein interactions of RTKs. We applied MaMTH-DS to an oncogenic epidermal growth factor receptor (EGFR) mutant resistant to the latest generation of clinically approved tyrosine kinase inhibitors (TKIs). We identified four mutant-specific compounds, including two that would not have been detected by conventional in vitro kinase assays. One of these targets mutant EGFR via a new mechanism of action, distinct from classical TKI inhibition. Our results demonstrate how MaMTH-DS is a powerful complement to traditional drug screening approaches.

Enhanced uptake, high selective and microtubule disrupting activity of carbohydrate fused pyrano-pyranones derived from natural coumarins attributes to its anti-malarial potential

Background

Malaria is one of the deadliest infectious diseases caused by protozoan parasite of Plasmodium spp. Increasing resistance to anti-malarials has become global threat in control of the disease and demands for novel anti-malarial interventions. Naturally-occurring coumarins, which belong to a class of benzo-α-pyrones, found in higher plants and some essential oils, exhibit therapeutic potential against various diseases. However, their limited uptake and non-specificity has restricted their wide spread use as potential drug candidates.

Methods

Two series of carbohydrate fused pyrano[3,2-c]pyranone carbohybrids which were synthesized by combination of 2-C-formyl galactal and 2-C-formyl glucal, with various freshly prepared 4-hydroxycoumarins were screened against Plasmodium falciparum. The anti-malarial activity of these carbohybrids was determined by growth inhibition assay on P. falciparum 3D7 strain using SYBR green based fluorescence assay. Haemolytic activity of carbohybrid 12, which showed maximal anti-malarial activity, was determined by haemocompatibility assay. The uptake of the carbohybrid 12 by parasitized erythrocytes was determined using confocal microscopy. Growth progression assays were performed to determine the stage specific effect of carbohybrid 12 treatment on Pf3D7. In silico studies were conducted to explore the mechanism of action of carbohybrid 12 on parasite microtubule dynamics. These findings were further validated by immunofluorescence assay and drug combination assay.

Results

2-C-formyl galactal fused pyrano[3,2-c]pyranone carbohybrid 12 exhibited maximum growth inhibitory potential against Plasmodium with IC₅₀ value of 5.861 µM and no toxicity on HepG2 cells as well as no haemolysis of erythrocytes. An enhanced uptake of this carbohybrid compound was observed by parasitized erythrocytes as compared to uninfected erythrocytes. Further study revealed that carbohybrid 12 arrests the growth of parasite at trophozoite and schizonts stage during course of progression through asexual blood stages. Mechanistically, it was shown that the carbohybrid 12 binds to α,β-heterodimer of tubulin and affects microtubule dynamics.

Conclusion

These findings show carbohydrate group fusion to 4-hydroxycoumarin precursor resulted in pyrano-pyranones derivatives with better solubility, enhanced uptake and improved selectivity. This data confirms that, carbohydrate fused pyrano[3,2-c]pyranones carbohybrids are effective candidates for anti-malarial interventions against P. falciparum.

Extending the Inhibition Profiles of Coumarin-Based Compounds Against Human Carbonic Anhydrases: Synthesis, Biological, and In Silico Evaluation

Carbonic anhydrases (CAs, EC 4.2.1.1) catalyze the fundamental reaction of CO₂ hydration in all living organisms and are actively involved in the regulation of a plethora of pathological and physiological conditions. A set of new coumarin/ dihydrocoumarin derivatives was here synthesized, characterized, and tested as human CA inhibitors. Their inhibitory activity was evaluated against the cytosolic human isoforms hCA I and II and the transmembrane hCA IX and hCA XII. Two compounds showed potent inhibitory activity against hCA IX, being more active or equipotent with the reference drug acetazolamide. Computational procedures were used to investigate the binding mode of this class of compounds within the active site of hCA IX and XII that are validated as anti-tumor targets.

7,8-Dihydroxy-3-(4-nitrophenyl)coumarin induces cell death via reactive oxygen species-independent S-phase cell arrest

We herein report the synthesis and in vitro cytotoxicity of 3-arylcoumarin derivatives (6a-f and 7a-f) in human liver (HepG2), prostate (LNCap), and pancreatic (BxPC3) cancer cell lines. Among the tested compounds, 7,8-dihydroxy-3-(4-nitrophenyl) coumarin (7b) showed the highest cytotoxicity in the HepG2 cell line. The mechanism of cytotoxic action indicated that compound (7b) arrested HepG2 cells at the S phase of the cell cycle progression, induced loss of mitochondrial membrane potential, and caused reactive oxygen species (ROS)-independent cell death. The cell viability result of pretreated HepG2 cells with antioxidant N-acetylcysteine followed by compound (7b) treatment and the free radical scavenging activities of compound (7b) confirmed the ROS-independent cell death. These results demonstrate that compound (7b) could serve as a valuable template for the development of novel synthetic compounds as potential anticancer agents for hepatocellular carcinoma treatment.

Synthesis and Investigation of the Role of Benzopyran Dihydropyrimidinone Hybrids in Cell Proliferation, Migration and Tumor Growth

BACKGROUND

Cancer is the second leading cause of mortality worldwide after heart diseases, and lung cancer is the topmost cause of all cancer-related deaths in both sexes. Dihydropyrimidinones (DHPMs) are medicinally important class of molecules with diverse pharmacological activities including anticancer activity. The present study focuses on the molecular hybridization of novel Benzopyran with Dihydropyrimidinone and evaluation of the resulting hybrids for cancer cell proliferation, migration and tumor growth.

METHODS

We have synthesized a focused library of dihydropyrimidinone benzopyran hybrids (compounds 1-11) by joining the aromatic as well as pyran portions of the benzopyran core with dihydropyrimidinone. All the synthesized hybrid molecules were evaluated for their cytotoxic activities against a panel of four human cancer cell lines of diverse tissue origin, viz: A549 (lung carcinoma), MCF7 (mammary gland adenocarcinoma), HCT-116 (colorectal carcinoma), and PANC-1 (pancreatic duct carcinoma) with the help of MTT cell viability assay. A structure-activity relationship was made on the basis of IC50 values of different hybrids. Effect on cell proliferation was examined through colony formation assay, reactive oxygen species generation and mitochondrial membrane potential studies. Wound healing assays and cell scattering assays were employed to check the effect on cell migration. Western blotting experiments were performed to find out the molecular mechanism of action and anti-tumor studies were carried out to evaluate the in vivo efficacy of the selected lead molecule.

RESULTS

Two types of novel hybrids were synthesized efficiently from benzopyran aldehydes, ethylacetoacetate and urea under heteropolyacid catalysis. Compound 3 was found to be the most potent hybrid among the synthesized compounds with consistent cytotoxic activities against four human cancer cell lines (IC50 values: 0.139 - 2.32 μM). Compound 3 strongly inhibited proliferation abilities of A549 cells in colony formation assay. Compound 3 exerted oxidative stress-mediated mitochondrial dysfunction, in which mitochondrial reactive oxygen species (ROS) generation as a mechanism of its anti-proliferative effects was analysed. Further, the molecule abrogated migration and cell scattering properties of aggressive PANC-1 cells. Mechanistic studies revealed that compound 3 modulated NF-kB expression and its downstream oncogenic proteins involved in cancer cell proliferation and invasion. Finally, compound 3 confirmed its in vivo anti-tumor efficacy; there observed 41.87% tumor growth inhibition at a dose of 30 mg/kg/body weight against a mouse model of Ehrlich solid tumor.

CONCLUSION

Our study unravels a potential anticancer lead (compound 3) from DHPMs that have opened up new research avenues for the development of promising anticancer therapeutic agents.

Hybrid Molecules Composed of 2,4-Diamino-1,3,5-triazines and 2-Imino-Coumarins and Coumarins. Synthesis and Cytotoxic Properties

A series of 2-imino-2H-chromen-3-yl-1,3,5-triazine compounds 5⁻12, which are namely hybrids of 2,4-diamino-1,3,5-triazines and 2-imino-coumarins, was synthesized by reacting 2-(4,6-diamine-1,3,5-triazin-2-yl)acetonitriles 1⁻4 with 2-hydroxybenzaldehydes. After this, upon heating in aqueous DMF, 2-imino-2H-chromen-3-yl-1,3,5-triazines 10 and 12 were converted into the corresponding 2H-chromen-3-yl-1,3,5-triazines 13 and 14, which are essentially hybrids of 2,4-diamino-1,3,5-triazines and coumarins. The in vitro anticancer activity of the newly prepared compounds was evaluated against five human cancer cell lines: DAN-G, A-427, LCLC-103H, SISO and RT-4. The greatest cytotoxic activity displayed 4-[7-(diethylamino)-2-imino-2H-chromen-3-yl]-6-(4-phenylpiperazin-1-yl)-1,3,5-triazin-2-amine (11, IC₅₀ in the range of 1.51⁻2.60 μM).

A nano-composite of magnetite and hot-water-soluble starch: a cooperation resulting in an amplified catalytic activity on water

A cooperation between magnetite and hot-water-soluble starch led to an efficient catalytic activity of their nano-composite in the pseudo three-component synthesis of bis-coumarins and xanthenes.

5-(Furan-2-yl)-4-(3,4,5-trimethoxyphenyl)-3H-1,2-dithiol-3-one oxime (6f), a new synthetic compound, causes human fibrosarcoma HT-1080 cell apoptosis by disrupting tubulin polymerisation and inducing G2/M arrest

In the current study, we synthesized a series of new compounds targeting tubulin and tested their anti-proliferative activities. Among these new synthetic com-pounds, 5-(furan-2-yl)-4-(3,4,5-trimethoxyphenyl)-3H-1,2-dithiol-3-one oxime (6f) exhibited significant anti-proliferative activity against different human cancer cell lines including human gastric adenocarcinoma SGC-7901, human non-small cell lung cancer A549, and human fibrosarcoma HT-1080. As a result, 6f was selected to further test the sensitivity to different cancer cell lines including human cervical cancer cell line HeLa, human breast cancer cell line MCF-7, non-small cell lung cancer cell line A549, human liver carcinoma cell line HepG-2, human oral squamous cell carcinoma cell lines KB, SGC-7901 and HT-1080. Among these cell lines, HT-1080 and HeLa are the most sensitive. Therefore, HT-1080 was selected to further explore the properties of anti-proliferative activity and the underlying mechanisms. Our data proved that 6f exhibited strong anti-proliferative effects against HT-1080 cells in a time- and dose-dependent manner. We showed that the growth inhibitory effect of 6f in HT-1080 cells was related with microtubule depolymerisation. Molecular docking studies revealed that 6f interacted and bound efficiently with the colchicine-binding site of tubulin. In addition, 6f treatment induced G2/M cell cycle arrest dose-dependently and subsequently induced cell apoptosis. Western blot study indicated that upregulation of cyclin B1 and p-cdc2 was related with G2/M arrest. 6f-induced cell apoptosis was associated with both mitochondrial and death receptor pathway. In conclusion, our data showed that 6f, among the newly synthetic compounds, exhibited highest anti-proliferative activity by disrupting the microtubule polymerisation, causing G2/M arrest and subsequently inducing cell apoptosis in HT-1080 cells. Hence, 6f is a promising microtubule depolymerising agent for the treatment of various cancers especially human fibrosarcoma.

Synthesis, in vitro and in vivo evaluation of new hybrids of millepachine and phenstatin as potent tubulin polymerization inhibitors

In this paper, a series of millepachine derivatives were synthesized and evaluated as tubulin polymerization inhibitors.

Immune-associated proteins with potential in vivo anti-tumor activities are upregulated in lung cancer cells treated with umbelliprenin: A proteomic approach

Umbelliprenin (Umb), a natural coumarin, has demonstrated anti-tumor activities, both in vitro and particularly in vivo, in several types of cancer, including lung cancer. The present study aimed to identify molecular targets of Umb using a high-throughput approach. Lung cancer cell lines, QU-DB (large-cell lung carcinoma) and A549 (adenocarcinoma), were treated with Umb. Differentially-expressed proteins were identified using two-dimensional electrophoresis coupled to mass spectrometry. In the QU-DB cells, differential expression of proteins, including downregulation of the tumorigenic protein heat shock protein 90 kDa and upregulation of the potential anti-tumor proteins Nipsnap1 and glycine-tRNA ligase (GRS), suggested that Umb is a strong anti-tumor compound. In the A549 cells, differential expression of proteins indicated possible contradictory effects of Umbregarding tumorigenesis, which included downregulation of the tumorigenic protein cyclophilin and the tumor suppressor MST, and upregulation of stathmin (tumorigenic) and calreticulin. Calreticulun, in addition to GRS in QU-DB cells, stimulates anti-tumor immune responses in vivo. To the best of our knowledge, the present study is the first to use a high-throughput approach to identify targets of Umb in cancer. These molecular targets suggested that Umb may exhibit stronger in vitro anti-tumor activity against the large-cell carcinoma model than the adenocarcinoma model. Furthermore, it has been reported that Umb exhibits higher cytotoxicity against QU-DB cells than A549 cells in vitro, and significant Umb anti-tumor activity against lung cancer in vivo, which is consistent with previously published literature. In each cell type, immune-associated molecules were upregulated, indicating that this naturally occurring compound exhibits marked anti-tumor activity in vivo. However, further studies that investigate the effect of Umb in different in vitro models of cancer are required.

Umbelliprenin is Potentially Toxic Against the HT29, CT26, MCF-7, 4T1, A172, and GL26 Cell Lines, Potentially Harmful Against Bone Marrow-Derived Stem Cells, and Non-Toxic Against Peripheral Blood Mononuclear Cells

BACKGROUND

Resistance to chemotherapy is a growing concern, thus natural anticancer agents are drawing the attention of many scientists and clinicians. One natural anticancer agent, umbelliprenin, is a coumarin produced by many species of Ferula.

OBJECTIVES

We aimed to examine the inhibitory effect of umbelliprenin on human and mouse bone marrow-derived stem cells (BMDSCs), peripheral blood mononuclear cells (PBMCs), and different cancer cell lines.

MATERIALS AND METHODS

In this in vitro experimental study, the HT29, CT26, MCF-7, 4T1, A172, and GL26 cancer cells and human and mouse BMDSCs and PBMCs were cultured in RPMI-1640 medium supplemented with 10% fetal bovine serum (FBS), incubated at 37°C for 24 hours in a 5% CO2 atmosphere, and then were treated with different concentrations of umbelliprenin dissolved in dimethyl sulfoxide (DMSO) (3, 6, 12, 25, 50, 100, and 200 µg/mL) for 24, 48, and 72 hours at 37°C. Each experiment was performed in triplicate. Finally, the cell survival rate was assessed by MTT assay. The IC50 values were calculated based on the log values using GraphPad Prism version 5 software for windows (La Jolla CA, USA) and were expressed as mean ± SEM.

RESULTS

Umbelliprenin inhibited the cancer cells in a concentration-dependent (P < 0.05) but not time-dependent manner (P > 0.05). The most sensitive and resistant cell lines at the 24-hour incubation time were 4T1 (IC50, 30.9 ± 3.1 µg/mL) and A172 (IC50, 51.9 ± 6.7 µg/mL); at the 48-hour incubation time: 4T1 (IC50, 30.6 ± 2.6 µg/mL) and CT26 (IC50, 53.2 ± 3.6 µg/mL); and at the 72-hour incubation time: HT29 (IC50, 37.1 ± 1.4 µg/mL) and 4T1 (IC50, 62.2 ± 4.8 µg/mL). Both human and mouse BMDSCs showed the highest resistance at the 24-hour incubation time (IC50s, 254.7 ± 21 and 204.4 ± 4.5 µg/mL, respectively) and the highest sensitivity at the 72-hour incubation time (IC50s, 120.4 ± 5 and 159.0 ± 7.3 µg/mL, respectively). The PBMCs of both human and mouse origin revealed very strong resistance to the studied concentrations of umbelliprenin (IC50s ranging from 713.5 ± 499.1 to 6651 ± 3670.7 µg/mL).

CONCLUSIONS

Our findings indicate that umbelliprenin exhibits concentration-dependent inhibitory effects on various cell types; it is potentially toxic against the HT29, CT26, MCF-7, 4T1, A172, and GL26 cell lines, potentially harmful against BMDSCs, and non-toxic against PBMCs. Therefore, if our results are approved in the future, umbelliprenin can be an appropriate candidate for developing treatments against different cancers.

Design, Synthesis, and Evaluation of in Vitro and in Vivo Anticancer Activity of 4-Substituted Coumarins: A Novel Class of Potent Tubulin Polymerization Inhibitors

In this paper, a series of novel 4-substituted coumarin derivatives were synthesized. Among these compounds 34, 39, 40, 43, 62, 65, and 67 exhibited significant antiproliferative activity toward a panel of tumor cell lines at subnanomolar IC50 values. Compound 65 showed potent antiproliferative ability (IC50 values of 7-47 nM) and retained full activity in multidrug resistant cancer cells. Compound 65 caused G2/M phase arrest and interacted with the colchicine-binding site in tubulin, as confirmed by immune-fluorescence staining, microtubule dynamics assays, and competition assays with N,N'-ethylene-bis(iodoacetamide). Compound 65 reduced the cell migration and disrupted capillary-like tube formation in HUVEC cells. Importantly, compound 65 significantly and dose-dependently reduced tumor growth in four xenografts models including paclitaxel sensitive and resistant ovarian tumors (A2780s and A2780/T), adrmicycin sensitive and resistant breast tumors (MCF-7 and MCF-7/ADR), suggesting that compound 65 is a promising novel antimitotic compound for the potential treatment of cancer.

Coumarin-Chalcone Hybrids as Peroxyl Radical Scavengers: Kinetics and Mechanisms

The primary antioxidant activity of coumarin-chalcone hybrids has been investigated using the density functional and the conventional transition state theories. Their peroxyl radical scavenging ability was studied in solvents of different polarity and taking into account different reaction mechanisms. It was found that the activity of the hybrids increases with the polarity of the environment and the number of phenolic sites. In addition, their peroxyl radical scavenging activity is larger than those of the corresponding nonhybrid coumarin and chalcone molecules. This finding is in line with previous experimental evidence. All the investigated molecules were found to react faster than Trolox with (•)OOH, regardless of the polarity of the environment. The role of deprotonation on the overall activity of the studied compounds was assessed. The rate constants and branching ratios for the reactions of all the studied compounds with (•)OOH are reported for the first time.

One-pot transition-metal-free cascade synthesis of thieno[2,3-c]coumarins from chromones

A one-pot transition-metal-free, base-mediated synthesis of a novel series of functionalized thieno[2,3-c]coumarins has been developed through a cascade reaction from chromones.

Selenate specifically sensitizes drug-resistant cancer cells by increasing apoptosis via G2 phase cell cycle arrest without P-GP inhibition

The purpose of this study was to identify conditions that will increase the sensitivity of drug-resistant cancer cells. Selenium derivatives have been shown to present anti-cancer properties in the clinic. Currently, selenate, selenite, selenomethionine (SeMet), methyl-selenocysteine (MSC), and methaneselenic acid (MSA) are the most common selenium derivatives used as drugs in humans. Herein, we tested whether these selenium derivatives can sensitize KBV20C cancer cells, which are highly resistant to anti-cancer drugs such as vincristine. All five drugs could sensitize KBV20C cells to the same extent as they sensitized the sensitive parent KB cells, suggesting that selenium-derived drugs can be used for drug-resistant cancer cells. We also observed that these drugs did not inhibit the P-glycoprotein (P-gp) pumping-out ability, suggesting that the sensitization by selenium-derived drugs does not depend on P-gp activity in resistant KBV20C cells. Interestingly, using a cell viability assay, microscopic observation, and Hoechst staining, we found that selenate highly sensitized drug-resistant KBV20C cells by activating the apoptotic pathway, when compared to sensitive KB cells. Furthermore, we investigated why selenate sensitizes resistant KBV20C cells. Selenate-induced toxicity was associated with an increase in G2-phase cell cycle arrest in KBV20C cells, suggesting that the selenate-induced increase in apoptosis resulted from cell cycle arrest in resistant KBV20C cells. Our findings may contribute to the development of selenate-based therapies for patients resistant to cancer drugs.

In vitro assessment of mutagenic and genotoxic effects of coumarin derivatives 6,7-dihydroxycoumarin and 4-methylesculetin

Coumarins are naturally occurring compounds, widely distributed throughout the plant kingdom (Plantae), and possess important pharmacological properties, including inhibition of oxidative stress. In this context, newly synthesized coumarin compounds are being produced due to their potent antioxidant activities. Therefore, the aim of the present study was to determine the in vitro cytotoxic, mutagenic, and genotoxic effects of 6,7-dihydroxycoumarin (6,7-HC) and 4-methylesculetin (4-ME) using the Salmonella/microsome test and in cultured human lymphocytes the comet assay and micronucleus test. The three coumarin derivatives concentrations evaluated in comet and MN assays were 2, 8, and 32 μg/mL, selected through a preliminary trypan blue-staining assay. In the Ames test, the 5 concentrations tested were 62.5, 125, 250, 500, and 750 μg/plate. Positive (methyl methane-sulfonate, MMS) and negative (dimethyl sulfoxide, DMSO) control groups were also included in the analysis. Our results showed that 4-ME induced greater cytotoxicity at high concentrations than 6,7-HC. In addition, both compounds were not mutagenic in the Ames test and not genotoxic or clastogenic/aneugenic in cultured human lymphocytes.

Thioridazine specifically sensitizes drug-resistant cancer cells through highly increase in apoptosis and P-gp inhibition

This study was designed to identify conditions that induce an increase in the sensitivity of drug-resistant cancer cells compared to sensitive cells. Using cell proliferation assays and microscopic observation, thioridazine (THIO) was found to induce higher sensitization in drug-resistant KBV20C cancer cells compared to sensitive KB parent cells. By studying cleaved PARP, annexin V staining, and Hoechst staining, we found that THIO largely increased apoptosis specifically in KBV20C cells, suggesting that the difference in sensitization between the resistant and sensitive cells can be attributed to the ability of THIO to induce apoptosis. THIO could also inhibit p-glycoprotein (P-gp) activity in the resistant KBV20C cells. These observations suggest that the mechanisms underlying THIO sensitization in resistant KBV20C cells involve both apoptosis and P-gp inhibition. Furthermore, co-treatment with THIO and vinblastine (VIB) induces higher sensitization in KBV20C cells than KB cells. As observed in a single treatment with THIO, the sensitization mechanism induced by the co-treatment also involves both apoptosis and P-gp inhibition. These results suggest that the THIO sensitization mechanism is generally conserved. Our findings may contribute to the development of THIO-based therapies for patients presenting resistance to antimitotic drugs.

Induction of ROS-independent JNK-activation-mediated apoptosis by a novel coumarin-derivative, DMAC, in human colon cancer cells

In this study, we investigated the antitumor activity of a novel coumarin derivative, 5,7-dihydroxy-4-methyl-6-(3-methylbutanoyl)-coumarin (DMAC), on colorectal carcinoma. DMAC treatment resulted in substantial proapoptotic activity against colon cancer HCT116 and LoVo cells. Induction of apoptotic characteristics, including cellular shrinkage, chromatin condensation, and Annexin V detection, was observed following DMAC treatment. Mechanistically, we observed that DMAC elicited induction of proteolytic cascade activation including cleavage of caspase-3 and poly ADP-ribose polymerase (PARP) expression and loss of the antiapoptotic proteins, Mcl-1 and Bcl-XL, accompanied by an increase in expression of the proapoptotic protein, Bak. In addition, suppressing c-Jun N-terminal protein kinase (JNK), but not extracellular-regulated protein kinase (ERK) or p38, substantially diminished DMAC-induced cell death and caspase-3 and PARP cleavage. However, pretreatment with antioxidants, including N-acetyl-l-cysteine (NAC) and diphenylene iodonium (DPI), failed to protect against DMAC-elicited apoptosis. Pretreatment with the JNK inhibitor, SP600125, suppressed DMAC-induced JNK phosphorylation, which was accompanied by a reversal of Bcl-XL expression. Moreover, combining DMAC treatment with the conventional anticancer drugs, 5-FU and CPT-11, considerably enhanced their therapeutic efficacies. Structural-activity relationship analyses further revealed that an alkylation substitution at position 6 of the coumarin ring was critical for inducing apoptosis, and the phenyl group at position 4 might have enhanced its bioactivity. Our data showed that DMAC can be used as part of a promising strategy to enhance therapeutic efficacies, and could be used to develop an approach for structure-based drug design for cancer treatment.

SP600125 overcomes antimitotic drug-resistance in cancer cells by increasing apoptosis with independence of P-gp inhibition

The purpose of this study was to identify conditions that increase the sensitivity of resistant cancer cells to antimitotic drugs. Using MTS assays, microscopic observation, assessment of cleaved PARP, FACS analysis, and Hoechst staining, we found that the c-Jun N-terminal kinase (Jnk) inhibitor SP600125 (SP) sensitized the antimitotic drug-resistant KBV20C cancer cell line. The sensitization mechanism was independent of p-glycoprotein (P-gp) inhibition. Interestingly, SP-induced sensitization was greater in resistant KBV20C cancer cells than in KB parent cells. The mechanism of SP-induced sensitization involved G2 arrest. KBV20C cells treated with SP and antimitotic drugs were more sensitized than cells treated with SP alone. This suggests that SP can restore sensitization for antimitotic drugs in resistant cancer cells. Our findings may contribute to the development of SP-based combination therapies for patients receiving anti-cancer agents that target microtubules.

Umbelliprenin is cytotoxic against QU-DB large cell lung cancer cell line but anti-proliferative against A549 adenocarcinoma cells

Background

Umbelliprenin is a natural compound, belonging to the class of sesquiterpene coumarins. Recently, umbelliprenin has attracted the researchers' attention for its antitumor activities against skin tumors. Its effect on lung cancer is largely unknown. The aim of our study was to investigate the effects of this natural compound, which is expected to have low adverse effects, on lung cancer.

Methods

The QU-DB large cell and A549 adenocarcinoma lung cancer cell lines were treated with umbelliprenin. IC₅₀ values were estimated using methyl thiazolely diphenyl-tetrazolium bromide (MTT) assay, in which a decrease in MTT reduction can occur as a result of cell death or cell proliferation inhibition. To quantify the rate of cell death at IC₅₀ values, flow cytometry using Annexin V-FITC (for apoptotic cells), and propidium iodide (for necrotic cells) dyes were employed.

Results

Data from three independent MTT experiments in triplicate revealed that IC₅₀ values for QU-DB and A549 were 47 ± 5.3 μM and 52 ± 1.97 μM, respectively. Annexin V/PI staining demonstrated that umbelliprenin treatment at IC₅₀ induced 50% cell death in QU-DB cells, but produced no significant death in A549 cells until increasing the umbelliprenin concentration to IC₈₀. The pattern of cell death was predominantly apoptosis in both cell lines. When peripheral blood mononuclear cells were treated with 50 μM and less concentrations of umbelliprenin, no suppressive effect was observed.

Conclusions

We found cytotoxic/anti-proliferative effects of umbelliprenin against two different types of lung cancer cell lines.

Evaluation of the antioxidant capacity of synthesized coumarins

Coumarins are secondary metabolites that are widely distributed within the plant kingdom, some of which have been extensively studied for their antioxidant properties. The antioxidant activity of coumarins assayed in the present study was measured by different methods, namely the 1,1-diphenyl-2-picryl-hydrazyl (DPPH(•)) method, cyclic voltammetry and the antioxidant capacity against peroxyl radicals (ACAP) method. The 7,8-dihydroxy-4-methylcoumarin (LaSOM 78), 5-carboxy-7,8-dihydroxy-4-methylcoumarin (LaSOM 79), and 6,7-dihydroxycoumarin (Esculetin) compounds proved to be the most active, showing the highest capacity to deplete the DPPH radicals, the highest antioxidant capacity against peroxyl radicals, and the lowest values of potential oxidation.

Plasma membrane ion fluxes and NFAT-dependent gene transcription contribute to c-met-induced epithelial scattering

Hepatocyte growth factor (HGF) signaling drives epithelial cells to scatter by breaking cell-cell adhesions and causing them to migrate as solitary cells, a process that parallels epithelial-mesenchymal transition. HGF binds and activates the c-met receptor tyrosine kinase, but downstream signaling required for scattering remains poorly defined. We have applied a chemical biology approach to identify components of HGF signaling that are required for scattering in an in vitro model system. This approach yields a number of small molecules that block HGF-induced scattering, including a calcium channel blocker. We show that HGF stimulation results in sudden and transient increases in ion channel influxes at the plasma membrane. Although multiple channels occur in the membranes of our model system, we find that TrpC6 is specifically required for HGF-induced scattering. We further demonstrate that HGF-induced ion influxes through TrpC6 channels coincide with a transient increase in nuclear factor of activated T-cells (NFAT)-dependent gene transcription and that NFAT-dependent gene transcription is required for HGF-induced cell scattering.

Anti-mitotic potential of 7-diethylamino-3(2'-benzoxazolyl)-coumarin in 5-fluorouracil-resistant human gastric cancer cell line SNU620/5-FU

In this study, we investigate an anti-mitotic potential of the novel synthetic coumarin-based compound, 7-diethylamino-3(2'-benzoxazolyl)-coumarin, in 5-fluorouracil-resistant human gastric cancer cell line SNU-620-5FU and its parental cell SNU-620. It exerts the anti-proliferative effects with similar potencies against both cancer cells, which is mediated by destabilization of microtubules and subsequent mitotic arrest. Furthermore, this compound enhances caspase-dependent apoptotic cell death via decreased expression of anti-apoptotic genes. Taken together, our data strongly support anti-mitotic potential of 7-diethylamino-3(2'-benzoxazolyl)-coumarin against drug-resistant cancer cells which will prompt us to further develop as a novel microtubule inhibitor for drug-resistant cancer chemotherapy.

Salinomycin sensitizes antimitotic drugs-treated cancer cells by increasing apoptosis via the prevention of G2 arrest

Here, we investigated whether Sal could sensitize cancer cells to antimitotic drugs. We demonstrated that Sal sensitized paclitaxcel (PAC)-, docetaxcel (DOC)-, vinblastin (VIN)-, or colchicine (COL)-treated cancer cell lines, suggesting that Sal has the ability to sensitize the cells to any form of microtubule-targeting drugs. Sensitization to the antimitotic drugs could be achieved with very low concentrations of Sal, suggesting that there is a possibility to minimize Sal toxicity associated with human cancer patient treatments. Sensitization by Sal increased apoptosis, which was observed by C-PARP production. Sal sensitized the cancer cells to antimitotic drugs by preventing G2 arrest, suggesting that Sal contributes to the induction of mitotic catastrophe. Sal generally reduced cyclin D1 levels in PAC-, DOC-, and VIN-treated cells. In addition, Sal treatment increased pH2AX levels and reduced p21 levels in antimitotic drugs-treated cells. These observations suggest that the mechanisms underlying Sal sensitization to DNA-damaging compounds, radiation, and microtubule-targeting drugs are similar. Our data demonstrated that Sal sensitizes cancer cells to antimitotic drugs by increasing apoptosis through the prevention of G2 arrest via conserved Sal-sensitization mechanisms. These results may contribute to the development of Sal-based chemotherapy for cancer patients treated with antimitotic drugs.

Synthesis and in vitro evaluation of novel coumarin-chalcone hybrids as potential anticancer agents

A series of coumarin-chalcone hybrids have been synthesized and evaluated for their in vitro cytotoxicity against a panel of four human cancer cell lines and normal fibroblasts (NIH3T3). Among 21 compounds screened, three compounds (23, 25 and 26) showed IC(50) range from 3.59 to 8.12 μM. The most promising compound 26 showed around 30-fold more selectivity towards C33A (cervical carcinoma) cells over normal fibroblast NIH3T3 cells with an IC(50) value of 3.59 μM.