Structural modifications of coumarin derivatives: Determination of antioxidant and lipoxygenase (LOX) inhibitory activity

Aureusidin ameliorates 6-OHDA-induced neurotoxicity via activating Nrf2/HO-1 signaling pathway and preventing mitochondria-dependent apoptosis pathway in SH-SY5Y cells and Caenorhabditis elegans

Movement disorder Parkinson's disease (PD) is the second most common neurodegenerative disease in the world after Alzheimer's disease, which severely affects the quality of patients' lives and imposes an increasingly heavy socioeconomic burden. Aureusidin is a kind of natural flavonoid compound with anti-inflammatory and anti-oxidant activities, while its pharmacological action and mechanism are rarely reported in PD. This study aimed to explore the neuroprotective effects and potential mechanisms of Aureusidin in PD. The present study demonstrated that Aureusidin protected SH-SY5Y cells from cell damage induced by 6-hydroxydopamine (6-OHDA) via inhibiting the mitochondria-dependent apoptosis and activating the Nrf2/HO-1 antioxidant signaling pathway. Additionally, Aureusidin diminished dopaminergic (DA) neuron degeneration induced by 6-OHDA and reduced the aggregation toxicity of α-synuclein (α-Syn) in Caenorhabditis elegans (C. elegans.) In conclusion, Aureusidin showed a neuroprotective effect in the 6-OHDA-induced PD model via activating Nrf2/HO-1 signaling pathway and prevented mitochondria-dependent apoptosis pathway, and these findings suggested that Aureusidin may be an effective drug for the treatment of PD.

Design, synthesis, and pharmacological evaluation of indazole carboxamides of N-substituted pyrrole derivatives as soybean lipoxygenase inhibitors

In this paper, we attempted to develop a novel class of compounds against lipoxygenase, a key enzyme in the biosynthesis of leukotrienes implicated in a series of inflammatory diseases. Given the absence of appropriate human 5-lipoxygenase crystallographic data, solved soybean lipoxygenase-1 and -3 structures were used as a template to generate an accurate pharmacophore model which was further used for virtual screening purposes. Eight compounds (1-8) have been derived from the in-house library consisting of N-substituted pyrroles conjugated with 5- or 6-indazole moieties through a carboxamide linker. This study led to the discovery of hit molecule 8 bearing a naphthyl group with the IC50 value of 22 μM according to soybean lipoxygenase in vitro assay. Isosteric replacement of naphthyl ring with quinoline moieties and reduction of carbonyl carboxamide group resulted in compounds 9-12 and 13, respectively. Compound 12 demonstrated the most promising enzyme inhibition. In addition, compounds 8 and 12 were found to reduce the carrageenan-induced paw edema in vivo by 52.6 and 49.8%, respectively. In view of the encouraging outcomes concerning their notable in vitro and in vivo anti-inflammatory activities, compounds 8 and 12 could be further optimized for the discovery of novel 5-lipoxygenase inhibitors in future. A structure-based 3D pharmacophore model was used in the virtual screening of in-house library to discover novel potential 5-lipoxygenase inhibitors.

Green Synthesis of Thiazolidine-2,4-dione Derivatives and Their Lipoxygenase Inhibition Activity With QSAR and Molecular Docking Studies

Thiazolidinediones are five-membered, heterocyclic compounds that possess a number of pharmacological activities such as antihyperglycemic, antitumor, antiarthritic, anti-inflammatory, and antimicrobial. Conventional methods for their synthesis are often environmentally unacceptable due to the utilization of various catalysts and organic solvents. In this study, deep eutectic solvents were used in the synthesis of thiazolidinedione derivatives that acted as both solvents and catalysts. Initially, a screening of 20 choline chloride-based deep eutectic solvents for thiazolidinedione synthesis, via Knoevenagel condensation, was performed in order to find the most suitable solvent. Deep eutectic solvent, choline chloride, N-methylurea, was proven to be the best for further synthesis of 19 thiazolidinedione derivatives. Synthesized thiazolidinediones are obtained in yields from 21.49% to 90.90%. The synthesized compounds were tested for the inhibition of lipid peroxidation as well as for the inhibition of soy lipoxygenase enzyme activity. The antioxidant activity of the compounds was also determined by the ABTS and DPPH methods. Compounds showed lipoxygenase inhibition in the range from 7.7% to 76.3%. Quantitative structure–activity relationship model (R2 = 0.88; Q2loo = 0.77; F = 33.69) for the inhibition of soybean lipoxygenase was obtained with descriptors Mor29m, G2u, and MAXDP. The molecular docking confirms experimentally obtained results, finding the binding affinity and interactions with the active sites of soybean LOX-3.

Diverse and efficient catalytic applications of new cockscomb flower-like Fe3O4@SiO2@KCC-1@MPTMS@CuII mesoporous nanocomposite in the environmentally benign reduction and reductive acetylation of nitroarenes and one-pot synthesis of some coumarin compounds

In this research, Fe₃O₄@SiO₂@KCC-1@MPTMS@Cu^II as a new cockscomb flower-like mesoporous nanocomposite was prepared and characterized by various techniques including Fourier transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), SEM-based energy-dispersive X-ray (EDX) spectroscopy, inductively coupled plasma-optical emission spectrometry (ICP-OES), thermogravimetric analysis/differential thermal analysis (TGA/DTA), vibrating sample magnetometry (VSM), UV-Vis spectroscopy, and Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) analyses. The as-prepared Fe₃O₄@SiO₂@KCC-1@MPTMS@Cu^II mesoporous nanocomposite exhibited satisfactory catalytic activity in the reduction and reductive acetylation of nitroarenes in a water medium and solvent-free one-pot synthesis of some coumarin compounds including 3,3'-(arylmethylene)bis(4-hydroxy-2H-chromen-2-ones) (namely, bis-coumarins) (3a-n) and 2-amino-4-aryl-7,7-dimethyl-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitriles (6a-n) along with acceptable turnover numbers (TONs) and turnover frequencies (TOFs). Furthermore, the mentioned Cu^II-containing mesoporous nanocatalyst was conveniently recovered by a magnet from reaction environments and reused for at least seven cycles without any significant loss in activity, which confirms its good stability.

3-Phenylcoumarins as a Privileged Scaffold in Medicinal Chemistry: The Landmarks of the Past Decade

3-Phenylcoumarins are a family of heterocyclic molecules that are widely used in both organic and medicinal chemistry. In this overview, research on this scaffold, since 2010, is included and discussed, focusing on aspects related to its natural origin, synthetic procedures and pharmacological applications. This review paper is based on the most relevant literature related to the role of 3-phenylcoumarins in the design of new drug candidates. The references presented in this review have been collected from multiple electronic databases, including SciFinder, Pubmed and Mendeley.

Synthesis, Bioactivity, Pharmacokinetic and Biomimetic Properties of Multi-Substituted Coumarin Derivatives

A series of novel multi-substituted coumarin derivatives were synthesized, spectroscopically characterized, and evaluated for their antioxidant activity, soybean lipoxygenase (LOX) inhibitory ability, their influence on cell viability in immortalized human keratinocytes (HaCaT), and cytotoxicity in adenocarcinomic human alveolar basal epithelial cells (A549) and human melanoma (A375) cells, in vitro. Coumarin analogues 4a-4f, bearing a hydroxyl group at position 5 of the coumarin scaffold and halogen substituents at the 3-phenyl ring, were the most promising ABTS•+ scavengers. 6,8-Dibromo-3-(4-hydroxyphenyl)-4-methyl-chromen-2-one (4k) and 6-bromo-3-(4,5-diacetyloxyphenyl)-4-methyl-chromen-2-one (3m) exhibited significant lipid peroxidation inhibitory activity (IC50 36.9 and 37.1 μM). In the DCF-DA assay, the 4'-fluoro-substituted compound 3f (100%), and the 6-bromo substituted compounds 3i (80.9%) and 4i (100%) presented the highest activity. The 3'-fluoro-substituted coumarins 3e and 4e, along with 3-(4-acetyloxyphenyl)-6,8-dibromo-4-methyl-chromen-2-one (3k), were the most potent lipoxygenase (LOX) inhibitors (IC50 11.4, 4.1, and 8.7 μM, respectively) while displaying remarkable hydroxyl radical scavenging ability, 85.2%, 100%, and 92.9%, respectively. In silico docking studies of compounds 4e and 3k, revealed that they present allosteric interactions with the enzyme. The majority of the analogues (100 μΜ) did not affect the cell viability of HaCaT cells, though several compounds presented over 60% cytotoxicity in A549 or A375 cells. Finally, the human oral absorption (%HOA) and plasma protein binding (%PPB) properties of the synthesized coumarins were also estimated using biomimetic chromatography, and all compounds presented high %HOA (>99%) and %PPB (60-97%) values.

Hydroxylated 3-(pyridin-2-yl)coumarins as radical scavengers with potent lipoxygenase inhibitor activity

Hydroxylated 3-(pyridin-2-yl)coumarins show radical scavenging activity and are able to inhibit soybean lipoxygenase.

Reactions involving aryl methyl ketone and molecular iodine: a powerful tool in the one-pot synthesis of heterocycles

The preparation of heterocyclic compounds has attracted great attention in organic chemistry because of their extensive application in the field of bioactive molecules, materials science, and natural products.

Evaluation of cyrhetrenyl and ferrocenyl precursors as 5-lipoxygenase inhibitors – biological and computational studies

Synthesis and biological evaluation of precursors derived from ferrocene and cyrhetrene as inhibitors of enzyme 5-hLOX.

Multicomponent Synthesis of Iminocoumarins via Rhodium-Catalyzed C-H Bond Activation

We herein establish a multicomponent annulation method for the synthesis of valuable iminocoumarins using aryl thiocarbamates, internal alkynes, and sulfonamides as starting materials, which are safe and readily available. The key step is a Rh-catalyzed and sulfur-directed C-H bond activation. Preliminary mechanistic investigations suggested that the nucleophilic attack of the sulfonamide on an active iminium cation finally completes the imine segment.

Amburana cearensis: Pharmacological and Neuroprotective Effects of Its Compounds

Amburana cearensis A.C. Smith is an endemic tree from Northeastern Brazil used in folk medicine as teas, decocts and syrups for the treatment of various respiratory and inflammatory diseases, since therapeutic properties have been attributed to compounds from its stem bark and seeds. Numerous pharmacological properties of semi-purified extracts and isolated compounds from A. cearensis have been described in several biological systems, ranging from antimicrobial to anti-inflammatory effects. Some of these activities are attributed to coumarins and phenolic compounds, the major compounds present in A. cearensis seed extracts. Multiple lines of research demonstrate these compounds reduce oxidative stress, inflammation and neuronal death induced by glutamate excitotoxicity, events central to most neuropathologies, including Alzheimer’s disease (AD) and Parkinson’s Disease (PD). This review focuses on the botanical aspects, folk medicine use, biological effects and pharmacological activities of A. cearensis compounds and their potential as novel non-toxic drugs for the treatment of neurodegenerative diseases.

Lipoxygenase Inhibition Activity of Coumarin Derivatives-QSAR and Molecular Docking Study

Lipoxygenases (LOXs) are a family of enzymes found in plants, mammals, and microorganisms. In animals and plants, the enzyme has the capability for the peroxidation of unsaturated fatty acids. Although LOXs participate in the plant defense system, the enzyme’s metabolites can have numerous negative effects on human health. Therefore, many types of research are searching for compounds that can inhibit LOXs. The best quantitative structure–activity relationship (QSAR) model was obtained using a Genetic Algorithm (GA). Molecular docking was performed with iGEMDOCK. The inhibition of lipoxygenase was in the range of 7.1 to 96.6%, and the inhibition of lipid peroxidation was 7.0–91.0%. Among the synthesized compounds, the strongest inhibitor of soybean LOX-3 (96.6%) was found to be 3-benzoyl-7-(benzyloxy)-2H-chromen-2-one. A lipid peroxidation inhibition of 91.0% was achieved with ethyl 7-methoxy-2-oxo-2H-chromene-3-carboxylate. The docking scores for the soybean LOX-3 and human 5-LOX also indicated that this compound has the best affinity for these LOX enzymes. The best multiple linear QSAR model contains the atom-centered fragment descriptors C-06, RDF035p, and HATS8p. QSAR and molecular docking studies elucidated the structural features important for the enhanced inhibitory activity of the most active compounds, such as the presence of the benzoyl ring at the 3-position of coumarin’s core. Compounds with benzoyl substituents are promising candidates as potent lipoxygenase inhibitors.

Assessment of the Antitumor Potential of Umbelliprenin, a Naturally Occurring Sesquiterpene Coumarin

Cancer is one of the greatest causes of mortality worldwide. The prevalence rates of different types of cancer is increasing around the world as well. Limitations in chemotherapy and radiotherapy, owing to multiple side effects including cytotoxic effects of antitumor compounds on normal cells as well as the development of resistance to these treatment options in patients, create a serious threat to successful treatment of cancer. The use of natural compounds to prevent and treat cancers has been found to be quite effective, with fewer adverse effects found in patients. Umbelliprenin (UMB) is a naturally occurring sesquiterpene compound found in Ferula species and recently in Artemisia absinthium. Many studies have highlighted the antitumor potential of UMB in different cancer cell lines as well as in animal models. UMB exerts its anticancer actions by regulating extrinsic and intrinsic apoptotic pathways; causing inhibition of the cell cycle at the G0/G1 phase; and attenuating migration and invasion by modulating the Wnt signaling, NF-ĸB, TGFβ, and Fox3 signaling pathways. UMB also affects the key hallmarks of tumor cells by attenuating tumor growth, angiogenesis, and metastasis. This review provides an insight into the role of UMB as a potential antitumor drug for different malignancies and highlights the signaling cascades affected by UMB treatment in diverse tumor cell lines and preclinical models.

Investigation of the cytotoxicity of bioinspired coumarin analogues towards human breast cancer cells

Abstract

Coumarins possess a wide array of therapeutic capabilities, but often with unclear mechanism of action. We tested a small library of 18 coumarin derivatives against human invasive breast ductal carcinoma cells with the capacity of each compound to inhibit cell proliferation scored, and the most potent coumarin analogues selected for further studies. Interestingly, the presence of two prenyloxy groups (5,7-diprenyloxy-4-methyl-coumarin, 4g) or the presence of octyloxy substituent (coumarin 4d) was found to increase the potency of compounds in breast cancer cells, but not against healthy human fibroblasts. The activity of potent compounds on breast cancer cells cultured more similarly to the conditions of the tumour microenvironment was also investigated, and increased toxicity was observed. Results suggest that tested coumarin derivatives could potentially reduce the growth of tumour mass. Moreover, their use as (combination) therapy in cancer treatment might have the potential of causing limited side effects.

Graphic abstract

Electronic supplementary material

The online version of this article (10.1007/s11030-020-10082-6) contains supplementary material, which is available to authorized users.

Novel 3-aryl-5-substituted-coumarin analogues: Synthesis and bioactivity profile

Eighteen 3-aryl-5-substituted-coumarins-six 5-acetyloxy-derivatives, six 5-hydroxy-derivatives, and six 5-geranyloxy-derivatives-were synthesized, structurally characterized and their antioxidant activity, lipoxygenase inhibitory ability, as well as their cytotoxic activity against human neuroblastoma SK-N-SH and HeLa adenocarcinoma cell lines were evaluated. The 5-acetyloxy-compounds 3a-3f were found to be the best cytotoxic agents among all the compounds studied. The bromo-substituted coumarins 3a and 3b were remarkably active against HeLa cell line showing IC₅₀ 1.8 and 6.1 μM, respectively. Coumarin 5e possessing a geranyloxy-chain on position 5 of the coumarin scaffold presented dual bioactivity, while 5-geranyloxy-coumarin 5f was the most competent soybean lipoxygenase inhibitor of this series (IC₅₀ 10 μM). As shown by in silico docking studies, the studied molecules present allosteric interactions with soybean lipoxygenases.

Novel coumarin-pyrazole carboxamide derivatives as potential topoisomerase II inhibitors: Design, synthesis and antibacterial activity

The identification of novel Topoisomerase II (Topo II) inhibitors is one of the most attractive directions in the field of bactericide research and development. In our ongoing efforts to pursue the class of inhibitors, six series of 70 novel coumarin-pyrazole carboxamide derivatives were designed and synthesized. As a result of the evaluation against four destructive bacteria, including Staphylococcus aureus, Listeria monocytogenes, Escherichia coli and Salmonella. Compound 8III-k (MIC = 0.25 mg/L) showed considerable inhibitory activity than ciprofloxacin (MIC = 0.5 mg/L) against Escherichia coli and 8V-c (MIC = 0.05 mg/L) exhibited excellent antibacterial activity than ciprofloxacin (MIC = 0.25 mg/L) against Salmonella. The selected compounds (8III-k, 8V-c and 8V-k) exhibit potent inhibition against Topo II and Topo IV with IC₅₀ values (9.4-25 mg/L). Molecular docking model showed that the compounds 8V-c and 8V-k can bind well to the target by interacting with amino acid residues. It will provide some valuable information for the commercial Topo II inhibiting bactericides.

Pharmacological and Nutritional Effects of Natural Coumarins and Their Structure-Activity Relationships

Coumarins are fused benzene and pyrone ring systems with a wide spectrum of bioactivities, including antitumor, anti-inflammation, antiviral, and antibacterial effects. In this paper, the current development of coumarin-based drugs is introduced, and their structure-activity relationship is discussed by reviewing the relevant literature published in the past 20 years. Coumarin molecules can be customized by the target site to prevent systemic side effects by virtue of structural modification. The ortho-phenolic hydroxyl on the benzene ring has remarkable antioxidant and antitumor activities. Coumarins with aryl groups at the C-4 position have good activities in anti-HIV, antitumor, anti-inflammation, and analgesia. C-3 phenylcoumarins have strong anti-HIV and antioxidant effects. Tetracycline pyranocoumarins can significantly inhibit HIV; osthol structural analogues have antimicrobial activity. Praeruptorin C and its derivatives play an important role in lowering blood pressure and dilating coronary arteries, and khellactone derivatives have significant inhibitory effects on AIDS, cancer, and cardiovascular diseases. It is concluded that the specific site on the core structure of coumarin exhibits one or more activities due to the electronic or steric effects of the substituents. This review is intended to be conducive to rational design and development of more active and less toxic agents with a coumarin scaffold.

Microwave-assisted synthesis, computational studies and antibacterial/ anti-inflammatory activities of compounds based on coumarin-pyrazole hybrid

An efficient, high-yield and rapid synthesis of (E)-1,5-dimethyl-4-((2-((substituted-2-oxo-2H-chromen-4-yl)methoxy)naphthalen-1-yl)methyleneamino)-2-phenyl-1,2-dihydropyrazol-3-one derivatives (3a-3i) containing Schiff base structures under microwave-irradiation has been described. Schiff base is a potential target to discover anti-inflammatory chemotherapeutics, material science, catalysis and molecular magnetism. All the newly synthesized compounds (3a-3i) have been characterized by elemental analysis and spectroscopic techniques. The synthesized compounds (3a-3i) were evaluated for their antibacterial activity by agar-well diffusion method and anti-inflammatory activity by egg albumin denaturation method. The compounds (3e) and (3i) exhibit antibacterial effect with minimum inhibitory concentration (MIC) 0.78 µg ml^-1 and MIC 1.562 µg ml^-1 against Gram-positive Staphylococcus aureus bacterial strain compared with standard ciprofloxacin drug (MIC 6.25 µg ml^-1). The compounds (3c) and (3f) exhibited an inhibition of heat-induced protein denaturation at the concentration (31.25 µg ml^-1) as 53.65% and 67.27%, respectively, and these compounds are more active than standard aceclofenac drug (5.50%). Molecular docking study has been performed for all the synthesized compounds with S. aureus dihydropteroate synthetase and results obtained are quite promising.

Design, synthesis, biological evaluation and docking studies of new 3-(4,5-dihydro-1H-pyrazol/isoxazol-5-yl)-2-phenyl-1H-indole derivatives as potent antioxidants and 15-lipoxygenase inhibitors

New candidates of 3-(4,5-dihydro-1H-pyrazol/isoxazol-5-yl)-2-phenyl-1H-indole derivatives (4-7) were designed combining the pyrazoline/isoxazoline heterocycles and 2-phenylindole to explore its potential as 15-lipoxygenase (15-LOX) inhibitors. The design of the new derivatives was based on utilizing the antioxidant properties of pyrazoline, 2-phenylindole and the good 15-LOX inhibition properties of indolylpyrazoline. The derivatives were synthesized adopting simple and laboratory friendly reaction conditions to give the target compounds in quantitative yields. The resulting indolylpyrazolines/isoxazolines were evaluated as antioxidants against 2,2-diphenyl-1-picrylhydrazyl (DPPH), nitric oxide (NO) and superoxide dismutase (SOD); indolylpyrazoline (4b) was the most potent antioxidant against SOD assay (IC50 = 1.78 μM) to be superior to ascorbic by 2 folds. Consistently, (4b) was the most potent inhibitor when tested against Soybean 15-LOX (IC50 = 3.84 μM) excelling quercetin as standard inhibitor by 1.8 folds. Some of the new derivatives were docked into the active binding site of human 15-LOX (PDB entry 4NRE) emphasizing the most potent derivative (4b) and the least potent one (4c). Docking solutions of compounds (4b), (4c), (5b) and (6c) revealed that (4b) was the only compound that got stabilized into the catalytic pocket of enzyme by π-cation interaction with the catalytic Fe+ and formation of one hydrogen bond with Ile 676 amino acid. Other derivatives including the least potent one variably got stabilized into the active binding pocket by π-cation interaction with the catalytic Fe+ but failed to form hydrogen bond with Ile 676. For the future optimization of the generated inhibitors, (i) antioxidant activity against SOD, (ii) the inhibitor stabilization by π-cation interaction with the catalytic Fe+3 and (iii) formation of hydrogen bond with Ile 676 should be regarded.

Recent development of lipoxygenase inhibitors as anti-inflammatory agents

Inflammation is favorable in most cases, because it is a kind of body defensive response to external stimuli; sometimes, inflammation is also harmful, such as attacks on the body's own tissues. It could be that inflammation is a unified process of injury and resistance to injury. Inflammation brings extreme pain to patients, showing symptoms of rubor, swelling, fever, pain and dysfunction. As the specific mechanism is not clear yet, the current anti-inflammatory agents are given priority for relieving suffering of patients. Thus it is emergent to find new anti-inflammatory agents with rapid effect. Lipoxygenase (LOX) is a kind of rate-limiting enzyme in the process of arachidonic acid metabolism into leukotriene (LT) which mediates the occurrence of inflammation. The inhibition of LOX can reduce LT, thereby producing an anti-inflammatory effect. In this review, the LOX inhibitors reported in recent years are summarized, and, in particular, their activities, structure-activity relationships and molecular docking studies are emphasized, which will provide new ideas to design novel LOX inhibitors.

Novel 6- and 7-Substituted Coumarins with Inhibitory Action against Lipoxygenase and Tumor-Associated Carbonic Anhydrase IX

A series of carboxamide derivatives of 6- and 7-substituted coumarins have been prepared by an original procedure starting from the corresponding 6- or 7-hydroxycoumarins which were alkylated with ethyl iodoacetate, and the obtained ester was converted to the corresponding carboxylic acids which were thereafter reacted with a series of aromatic/aliphatic/heterocyclic amines leading to the desired amides. The new derivatives were investigated as inhibitors of two enzymes, human carbonic anhydrases (hCAs) and soy bean lipoxygenase (LOX). Compounds 4a and 4b were potent LOX inhibitors, whereas many effective hCA IX inhibitors (KIs in the range of 30.2-30.5 nM) were detected in this study. Two compounds, 4b and 5b, showed the phenomenon of dual inhibition. Furthermore, these coumarins did not significantly inhibit the widespread cytosolic isoforms hCA I and II, whereas they were weak hCA IV inhibitors, making them hCA IX-selective inhibitors. As hCA IX and LOX are validated antitumor targets, these results are promising for the investigation of novel drug targets involved in tumorigenesis.

8-Farnesyloxycoumarin induces apoptosis in PC-3 prostate cancer cells by inhibition of 15-lipoxygenase-1 enzymatic activity

Prostate cancer is the second most common cancer in men worldwide. Overexpression of 15-lipoxygenase-1 (15-LOX-1) has been reported in prostate cancer patients. This study aimed to investigate the cytotoxic and anticancer effects of 8-farnesyloxycoumarin (8f), a prenylated coumarin, by inhibition of 15-LOX-1 activity, in prostate cancer cells. The activity of 15-LOX-1 and the inhibitory effects of 8f on this enzyme were first assessed in PC-3 and DU145 prostate cancer cells. The MTT assay was used to examine the cytotoxicity effects of 8f on PC-3 cells following 15-LOX-1 inhibition. To determine the type of cell death, chromatin condensation and DNA damage were examined by DAPI staining and comet assay, respectively. Furthermore, the effects of 8f on the cell cycle were evaluated by PI staining and flow cytometry. The activity of 15-LOX-1 was determined to be higher in PC-3 compared with DU145 cells; thus, this cell line was selected for further experiments. 8f induced cell death in PC-3 cells in a dose-dependent and time-dependent manner, with IC50 values similar to cisplatin, which was used as a control. However, 8f did not significantly affect the viability of HFF3, human foreskin fibroblast cells, under identical conditions. The appearance of apoptotic cells after 8f treatment was confirmed by the presence of PC-3 cells containing condensed chromatin as shown by DAPI staining. The comet assay indicated the induction of DNA damage in cancerous cells compared with normal cells. In addition, 8f induced a potent G1 cell-cycle arrest in PC-3 cells. Our results showed that the antitumor effects of 8f on PC-3 cells were promoted by apoptosis induction, probably via inhibition of 15-LOX-1 activity, thus suggesting that 8f may have therapeutic value in prostate cancer treatment.

Synthesis of 4-aryl-1,2,3-triazolyl appended natural coumarin-related compounds with antiproliferative and radical scavenging activities and intracellular ROS production modification

Diverse natural coumarin-based compounds linked to aryl via a 1,2,3-triazole spacer with antiproliferative activity against K562 cells, radical scavenging activity and a decrease of ROS production were provided.

Organocatalytic condensation–ring opening–annulation cascade reactions between N-Bocindolin-2-ones/benzofuran-2(3H)-ones and salicylaldehydes for synthesis of 3-arylcoumarins

An organocatalytic cascade synthesis of 3-arylcoumarins has been developed.

Synthesis, in vitro anticancer and antibacterial activities and in silico studies of new 4-substituted 1,2,3-triazole-coumarin hybrids

The 4-substituted 1,2,3-triazole core in designed coumarin hybrids (4-35) with diverse physicochemical properties was introduced by eco-friendly copper(I)-catalyzed Huisgen 1,3-dipolar cycloaddition under microwave irradiation. Coumarin-1,2,3-triazole-benzofused heterocycle hybrids emerged as the class of compounds exhibiting the highest antiproliferative activity. The strong relationship between lipophilicity and antiproliferative activities was observed indicating that lipophilic 1,2,3-triazole-coumarin hybrids containing phenylethyl (13), 3,5-difluorophenyl (14), 5-iodoindole (30) and benzimidazole (33 and 35) subunits showed the most potent cytostatic effects. The 7-methylcoumarin-1,2,3-triazole-2-methylbenzimidazole hybrid 33 can be highlighted as a lead that exerted the highest cytotoxicity against hepatocellular carcinoma HepG2 cells with IC₅₀ value of 0.9 μM and high selectivity (SI = 50). This compound induced cell death, mainly due to early apoptosis. Strong antiproliferative effect of 33 could be associated with its inhibition of 5-lipoxygenase (5-LO) activity and perturbation of sphingolipid signaling by interfering with intracellular acid ceramidase (ASAH) activity. Outlined considerable effect of lipophilicity on antiproliferative activity was not observed for antibacterial activity. The compounds with p-pentylphenyl (17), 2-chloro-4-fluorobenzenesulfonamide (23) and dithiocarbamate (27) moiety were endowed with high selectivity against Enterococcus species. Moreover, these compounds were found to be superior in inhibiting the growth of clinically isolated vancomycin-resistant Enterococcus faecium, while the reference antibiotics exhibited the lack of activity. Our findings indicate that coumarin-1,2,3-triazole could be used as the scaffold for structural optimization to develop more potent and selective anticancer agents and encourage further development of novel structurally related analogs of 33 as more effective 5-LO inhibitors.

Optimization of extraction conditions for osthol, a melanogenesis inhibitor from Cnidium monnieri fruits

CONTEXT

Coumarin derivatives have been reported to inhibit melanin biosynthesis.

OBJECTIVE

The melanogenesis inhibitory activity of osthol, a major coumarin of the fruits of Cnidium monnieri Cusson (Umbelliferae), and optimized extraction conditions for the maximum yield from the isolation of osthol from C. monnieri fruits were investigated.

MATERIALS AND METHODS

B16F10 melanomas were treated with osthol at concentration of 1, 3, and 10 μM for 72 h. The expression of melanogenesis genes, such as tyrosinase, TRP-1, and TRP-2 was also assessed. For optimization, extraction factors such as extraction solvent, extraction time, and sample/solvent ratio were tested and optimized for maximum yield of osthol using response surface methodology with the Box-Behnken design (BBD).

RESULTS

Osthol inhibits melanin content in B16F10 melanoma cells with an IC50 value of 4.9 μM. The melanogenesis inhibitory activity of osthol was achieved not by direct inhibition of tyrosinase activity but by inhibiting melanogenic enzyme expressions, such as tyrosinase, TRP-1, and TRP-2. The optimal condition was obtained as a sample/solvent ratio, 1500 mg/10 ml; an extraction time 30.3 min; and a methanol concentration of 97.7%. The osthol yield under optimal conditions was found to be 15.0 mg/g dried samples, which were well matched with the predicted value of 14.9 mg/g dried samples.

CONCLUSION

These results will provide useful information about optimized extraction conditions for the development of osthol as cosmetic therapeutics to reduce skin hyperpigmentation.

Transition metal-free cross-dehydrogenative coupling acylation of coumarins by the K2S2O8/Aliquat 336 catalytic system: a versatile strategy towards 4-aroylcoumarin derivatives

A new and efficient transition metal-free oxidative cross-dehydrogenative coupling (CDC) reaction is described for the preparation of 4-aroylcoumarin derivatives.

QSAR models for antioxidant activity of new coumarin derivatives

This study presents 37 new antioxidant coumarin derivatives and strategies for structural modification to improve their antioxidant activities, the main ferric-reducing antioxidant power (FRAP) assay used to evaluate their antioxidant properties and the generation of validated quantitative structure-activity (antioxidant activity) relationship (QSAR) models. In an attempt to generate QSAR models, structures of all coumarin derivatives in the data set were fully optimized by semi-empirical PM6 method using SPARTAN 10 software. Descriptors were calculated by DRAGON 6.0 software. Multiple linear regression (MLR) models were developed with different training/test set combinations using QSARINS 2.2.1 software. Robustness, reliability and predictive power of the models were tested by internal and external validations. Applicability domain of the best two-descriptor model (nTR = 30; r(2) = 0.924; RMSETR = 0.213; nTEST = 7; r(2)ext = 0.887; RMSEext = 0.255; CCCext = 0.939) was determined. Descriptors appeared in the model revealed that complexity, H-bond donor and lipophilic character are important parameters in describing the antioxidant activity. Apart from the compounds in the data set, we also designed 31 new antioxidant coumarin derivatives and predicted their antioxidant activity using the best two-descriptor model. Most of these compounds are promising antioxidants.

Coumarin-fused coumarin: antioxidant story from N,N-dimethylamino and hydroxyl groups

Two coumarin skeletons can form chromeno[3,4-c]chromene-6,7-dione by sharing with the C ═ C in lactone. The aim of the present work was to explore the antioxidant effectiveness of the coumarin-fused coumarin via six synthetic compounds containing hydroxyl and N,N-dimethylamino as the functional groups. The abilities to quench 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) cationic radical (ABTS(+•)), 2,2'-diphenyl-1-picrylhydrazyl radical (DPPH), and galvinoxyl radical revealed that the rate constant for scavenging radicals was related to the amount of hydroxyl group in the scaffold of coumarin-fused coumarin. But coumarin-fused coumarin was able to inhibit DNA oxidations caused by (•)OH, Cu(2+)/glutathione (GSH), and 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH) even in the absence of hydroxyl group. In particular, a hydroxyl and an N,N-dimethylamino group locating at different benzene rings increased the inhibitory effect of coumarin-fused coumarin on AAPH-induced oxidation of DNA about 3 times higher than a single hydroxyl group, whereas N,N-dimethylamino-substituted coumarin-fused coumarin possessed high activity toward (•)OH-induced oxidation of DNA without the hydroxyl group contained. Therefore, the hydroxyl group together with N,N-dimethylamino group may be a novel combination for the design of coumarin-fused heterocyclic antioxidants.

Crystal structure of 3-[2-(thio-phen-3-yl)ethyn-yl]-2H-chromen-2-one

In the title compound, C15H8O2S, the coumarin moiety is approximately planar (r.m.s. deviation of the 11 non-H atoms = 0.025 Å) and is slightly inclined with respect to the plane of the thio-phen-3-yl ring, forming a dihedral angle of 11.75 (8)°. In the crystal, the three-dimensional architecture features a combination of coumarin-thio-phene C-H⋯π and π-π [inter-centroid distance = 3.6612 (12) Å] inter-actions.

Meglumine catalyzed one-pot, three-component combinatorial synthesis of pyrazoles bearing a coumarin unit

Meglumine has been found to be an efficient catalyst for the synthesis of pyrazolylcoumarins by one-pot three-component reaction of salicylaldehyde, 4-hydroxy-6-methyl-2H-pyran-2-one, and hydrazine.