Novel coumarin derivatives of heterocyclic compounds as lipid-lowering agents

6-methylcoumarin/miR-122 suppresses hepatic Sortilin-mediated ApoB-100 secretion to attenuate aortic atherosclerosis

This study aimed to investigate the effects of hepatic microRNA-122 (miR-122) on Sortilin-mediated apolipoprotein B100 (apoB-100) secretion, and on aortic lipid deposition and atherosclerosis (AS) lesions and to clarify the antiatherosclerotic mechanism of 6-methylcoumarin (6-MC) via the modulation of miR-122. Bioinformatics analysis revealed that miR-122 was putatively overexpressed in a liver-specific manner and was downregulated in steatotic livers. miR-122 was shown to suppress the expression of Sortilin by complementarily pairing to the 3'-untranslated region (3'-UTR) of Sortilin mRNA via bioinformatics and dual-luciferase reporter assays, impeding Sortilin-mediated apoB-100 secretion from HepG2 cells. Administration of 6-MC significantly upregulated hepatocellular miR-122 levels, reducing Sortilin expression and apoB-100 secretion in HepG2 cells. The miR-122 mimic vigorously enhanced 6-MC-depressed Sortilin expression, while miR-122 inhibitor repealed the inhibitory effect of 6-MC on Sortilin expression to some extent in HepG2 cells. After internal intervention with the miR-122 precursor, and 6-MC supplementation alone or in combination with the miR-122 sponge led to the reduction in blood triglyceride (TG) levels, low-density lipoprotein-cholesterol (LDL-C) and apoB-100 and a reduction in aortic lipid deposition and AS lesions in apolipoprotein E-deficient (ApoE-/-) mice fed a high fat diet (HFD). The hepatic levels of Sortilin and apoB-100 expression were also decreased in these treated mice. In conclusion, miR-122 suppresses Sortilin expression and Sortilin-mediated apoB-100 secretion to resist circulating LDL production and aortic AS development, which is enhanced by 6-MC-upregulated miR-122 in the liver.

Preparation of Luvangetin Nanoemulsions: Antimicrobial Mechanism and Role in Infected Wound Healing

Purpose

Incorporation of luvangetin in nanoemulsions for antimicrobial and therapeutic use in infected wound healing.

Patients and Methods

Luvangetin nanoemulsions were prepared by high-speed shear method and characterized based on their appearance structure, average droplet size, polydispersity index (PDI), electric potential, storage stability. Optimized formulation of luvangetin nanoemulsion by Box-Behnken design (BBD). The antimicrobial activity and antimicrobial mechanism of luvangetin nanoemulsions against common hospital pathogens, ie, Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), were investigated using luvangetin nanoemulsions. The biosafety of luvangetin nanoemulsion was evaluated through cytotoxicity, apoptosis, and reactive oxygen species (ROS) assay experiments using human normal epidermal cells and endothelial cells. Finally, the effect of luvangetin nanoemulsion on healing of infected wounds was investigated in B6 mice.

Results

Luvangetin nanoemulsion formulation consists of 2.5% sunflower seed oil, 10% emulsifier Span-20 and 7 minutes of shear time, and with good stability. Luvangetin nanoemulsion produces antibacterial activity against S. aureus and E. coli by disrupting the structure of bacterial cell membranes. Luvangetin nanoemulsion are biologically safe for HaCat and HUVEC. Luvangetin nanoemulsion showed good therapeutic effect on MRSA infected wounds in mice.

Conclusion

For the first time, developed a new formulation called luvangetin nanoemulsion, which exhibited superior antibacterial effects against Gram-positive bacteria. Luvangetin nanoemulsion has a favorable effect in promoting infected wound healing. We have combined luvangetin, which has multiple activities, with nanoemulsions to provide a new topical fungicidal formulation, and have comprehensively evaluated its effectiveness and safety, opening up new possibilities for further applications of luvangetin.

Structure-property modeling of coumarins and coumarin-related compounds in pharmacotherapy of cancer by employing graphical topological indices

Coumarins, a subgroup of colorless and crystalline oxygenated heterocyclic compounds originally discovered in the plant Dipteryx odorata, were the subject of a recent study investigating their quantitative structure-activity relationship (QSAR) in cancer pharmacotherapy. This study utilized graph theoretical molecular descriptors, also known as topological indices, as a numerical representation method for the chemical structures embedded in molecular graphs. These descriptors, derived from molecular graphs, play a pivotal role in quantitative structure-property relationship (QSPR) analysis. In this paper, intercorrelation between the Balban index, connective eccentric index, eccentricity connectivity index, harmonic index, hyper Zagreb index, first path Zagreb index, second path Zagreb index, Randic index, sum connectivity index, graph energy and Laplacian energy is studied on the set of molecular graphs of coumarins. It is found that the pairs of degree-based indices are highly intercorrelated. The use of these molecular descriptors in structure-boiling point modeling was analyzed. Finally, the curve-linear regression between considered molecular descriptors with physicochemical properties of coumarins and coumarin-related compounds is obtained.

Polyphenols: Role in Modulating Immune Function and Obesity

Polyphenols, long-used components of medicinal plants, have drawn great interest in recent years as potential therapeutic agents because of their safety, efficacy, and wide range of biological effects. Approximately 75% of the world's population still use plant-based medicinal compounds, indicating the ongoing significance of phytochemicals for human health. This study emphasizes the growing body of research investigating the anti-adipogenic and anti-obesity functions of polyphenols. The functions of polyphenols, including phenylpropanoids, flavonoids, terpenoids, alkaloids, glycosides, and phenolic acids, are distinct due to changes in chemical diversity and structural characteristics. This review methodically investigates the mechanisms by which naturally occurring polyphenols mediate obesity and metabolic function in immunomodulation. To this end, hormonal control of hunger has the potential to inhibit pro-obesity enzymes such as pancreatic lipase, the promotion of energy expenditure, and the modulation of adipocytokine production. Specifically, polyphenols affect insulin, a hormone that is essential for regulating blood sugar, and they also play a role, in part, in a complex web of factors that affect the progression of obesity. This review also explores the immunomodulatory properties of polyphenols, providing insight into their ability to improve immune function and the effects of polyphenols on gut health, improving the number of commensal bacteria, cytokine production suppression, and immune cell mediation, including natural killer cells and macrophages. Taken together, continuous studies are required to understand the prudent and precise mechanisms underlying polyphenols' therapeutic potential in obesity and immunomodulation. In the interim, this review emphasizes a holistic approach to health and promotes the consumption of a wide range of foods and drinks high in polyphenols. This review lays the groundwork for future developments, indicating that the components of polyphenols and their derivatives may provide the answer to urgent worldwide health issues. This compilation of the body of knowledge paves the way for future discoveries in the global treatment of pressing health concerns in obesity and metabolic diseases.

Study of the DNA damage and cell death in human peripheral blood mononuclear and HepG2/C3A cells exposed to the synthetic 3-(3-hydroxyphenyl)-7-hydroxycoumarin

Hydroxycoumarins are an important source of biologically active compounds. Previous studies have shown that the number and position of the hydroxyl substituents in the scaffold play an important role for the observed biological activity. In the present study, 3-(3-hydroxyphenyl)-7-hydroxycoumarin was synthesized, and potential cytogenotoxic effects determined in human HepG2/C3A cells displaying phase 1 and phase 2 enzymes (metabolizing cell ability) and compared to human peripheral blood mononuclear cells (PBMC) without xenobiotics metabolizing capacity. Cell viability was determined with concentrations between 0.01 and 10 µg/ml of 3-(3-hydroxyphenyl)-7-hydroxycoumarin using MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) and trypan blue tests. Genotoxicity was determined utilizing the comet assay, and the clastogenic/aneugenic potential employing the micronucleus (MN) test. The results of the in vitro cytotoxicity assays showed a significant decrease in cell viability of PBMC following exposure to 10 µg/ml concentration of the studied compound after 48 and 72 hr. Comet assay observations noted significant DNA damage in PBMC after 4 hr treatment. No marked cytogenotoxic effects were found in HepG2/C3A cells. No chromosomal mutations were observed in both cell lines. It is important to note that 3-(3-hydroxyphenyl)-7-hydroxycoumarin may exert beneficial pharmacological actions at the low micromolar range and with half-life less than 24 hr. Therefore, the results obtained encourage the continuation of studies on this new molecule for medicinal purposes, but its potential toxicity at higher concentrations and longer exposure times needs to be investigated in further studies.

Multicomponent Synthesis Strategies, Catalytic Activities, and Potential Therapeutic Applications of Pyranocoumarins: A Comprehensive Review

Fused coumarins, because of their remarkable biological and therapeutic properties, particularly pyranocoumarins, have caught the interest of synthetic organic chemists, leading to the development of more efficient and environmentally friendly protocols for synthesizing pyranocoumarin derivatives. These compounds are the most promising heterocycles discovered in both natural and synthetic sources, with anti-inflammatory, anti-HIV, antitubercular, antihyperglycemic, and antibacterial properties. This review employed the leading scientific databases Scopus, Web of Science, Google Scholar, and PubMed up to the end of 2022, as well as the combining terms pyranocoumarins, synthesis, isolation, structural elucidation, and biological activity. Among the catalysts employed, acidic magnetic nanocatalysts, transition metal catalysts, and carbon-based catalysts have all demonstrated improved reaction yields and facilitated reactions under milder conditions. Herein, the present review discusses the various multicomponent synthetic strategies for pyranocoumarins catalyzed by transition metal-based catalysts, transition metal-based nanocatalysts, transition metal-free catalysts, carbon-based nanocatalysts, and their potential pharmacological activities.

Supramolecular assembly of coumarin 7 with sulfobutylether-β-cyclodextrin for biomolecular applications

Coumarins, in general, exhibit a wide range of photophysical characteristics and are highly sensitive to their microenvironment, and, therefore, their fluorescence characteristics have attracted immense attention as sensors in chemical and biological systems. In the present study, the supramolecular interaction of a bichromophoric coumarin dye, namely, Coumarin 7 (C7) with sulfobutylether-β-cyclodextrin (SBE7βCD) macrocyclic host at different pH conditions has been investigated by using optical spectroscopic techniques such as absorption, steady-state and time-resolved emissions, and circular dichroism measurements and compared with that of βCD. Considerable enhancement in the fluorescence intensity and lifetime of C7 on complexation with SBE7βCD proposes that non-radiative processes like TICT behavior are strictly hindered due to the confinement in the host cavity experienced by the C7 dye. The increase in the rotational correlation time evaluated from the fluorescence anisotropy decay kinetics further confirms the formation of tightly bound inclusion complexes. The binding constant values reveal that the monocationic form of dye at pH 3 shows ∼3 times stronger interaction with SBE7βCD than the neutral form of dye at pH 7 due to strong electrostatic cation-anion interaction. SBE7βCD:C7 exhibits an improved photostability and an upward pK a shift of 0.4 unit compared to the contrasting downward pK a shift of 0.5 with the βCD. The enhanced fluorescence yield and increased photostability have been exploited for bioimaging applications, and better images were captured by staining the Drosophila fly gut with the SBE7βCD:C7 complex. The enhancement in the binding interaction and the emission intensity were found to be responsive to external stimuli such as small competitive binders or metal ions and nearly quantitative dissociation of the complex was demonstrated to release the dye and would find stimuli-responsive applications.

Therapeutic Effects of Coumarins with Different Substitution Patterns

The use of derivatives of natural and synthetic origin has gained attention because of their therapeutic effects against human diseases. Coumarins are one of the most common organic molecules and are used in medicine for their pharmacological and biological effects, such as anti-inflammatory, anticoagulant, antihypertensive, anticonvulsant, antioxidant, antimicrobial, and neuroprotective, among others. In addition, coumarin derivates can modulate signaling pathways that impact several cell processes. The objective of this review is to provide a narrative overview of the use of coumarin-derived compounds as potential therapeutic agents, as it has been shown that substituents on the basic core of coumarin have therapeutic effects against several human diseases and types of cancer, including breast, lung, colorectal, liver, and kidney cancer. In published studies, molecular docking has represented a powerful tool to evaluate and explain how these compounds selectively bind to proteins involved in various cellular processes, leading to specific interactions with a beneficial impact on human health. We also included studies that evaluated molecular interactions to identify potential biological targets with beneficial effects against human diseases.

7,8-Dihydroxy-3-(4'-hydroxyphenyl)coumarin inhibits invasion and migration of osteosarcoma cells

Advances in pharmacy and medicine have led to the development of many anti-cancer and molecular targeted agents; however, there are few agents capable of suppressing metastasis. To prevent cancer recurrence, it is essential to develop novel agents for inhibiting metastasis. Coumarin-based compounds have multiple pharmacological activities including anti-cancer effects. We screened a compound library constructed at Kyoto Pharmaceutical University and showed that 7,8-dihydroxy-3-(4'-hydroxyphenyl)coumarin (DHC) inhibited invasion and migration of LM8 mouse osteosarcoma cells and 143B human osteosarcoma cells in a concentration-dependent manner. DHC decreased intracellular actin filament formation by downregulating Rho small GTP-binding proteins such as RHOA, RAC1, and CDC42, which regulate actin reorganization. However, DHC did not downregulate the corresponding mRNA transcripts, whereas it downregulated Rho small GTP-binding proteins in the presence of cycloheximide, suggesting that DHC enhances the degradation of these proteins. DHC treatment inhibited metastasis and prolonged overall survival in a spontaneous metastasis mouse model. These results indicate that DHC has the potential to suppress metastasis of osteosarcoma cells by downregulating Rho small GTP-binding proteins.

Radical Scavenging Activity and Pharmacokinetic Properties of Coumarin-Hydroxybenzohydrazide Hybrids

Free radicals often interact with vital proteins, violating their structure and inhibiting their activity. In previous studies, synthesis, characterisation, and the antioxidative properties of the five different coumarin derivatives have been investigated. In the tests of potential toxicity, all compounds exhibited low toxicity with significant antioxidative potential at the same time. In this paper, the radical scavenging activity of the abovementioned coumarin derivatives towards ten different radical species was investigated. It was found that all investigated compounds show good radical scavenging ability, with results that are in correlation with the results published in the previous study. Three additional mechanisms of radical scavenging activity were investigated. It was found that all three mechanisms are thermodynamically plausible and in competition. Interestingly, it was found that products of the Double Hydrogen Atom Transfer (DHAT) mechanism, a biradical species in triplet spin state, are in some cases more stable than singlet spin state analogues. This unexpected trend can be explained by spin delocalisation over the hydrazide bridge and phenolic part of the molecule with a low probability of spin pairing. Besides radical-scavenging activity, the pharmacokinetic and drug-likeness of the coumarin hybrids were investigated. It was found that they exhibit good membrane and skin permeability and potential interactions with P-450 enzymes. Furthermore, it was found that investigated compounds satisfy all criteria of the drug-likeness tests, suggesting they possess a good preference for being used as potential drugs.

Design, synthesis, and biological evaluation of coumarin analogs as novel LSD1 inhibitors

The abnormal expression of lysine-specific histone demethylase 1 (LSD1) is associated with different cancer types, and it is increasingly recognized as a potential therapeutic target in oncology. Here, utilizing core hopping and conformational restriction strategies, we designed and synthesized a series of coumarin analogs that were shown to be potent LSD1 inhibitors in the enzyme assay. Furthermore, several potent compounds were selected to evaluate their antiproliferative activity on A549 cells and MGC-803 cells with high expression of LSD1. Among them, YX10 showed an anticlonogenic effect on A549 cells and MGC-803 cells, with IC₅₀ values of 1.52 ± 0.16 and 0.98 ± 0.18 μM, respectively. Modeling suggested that the inhibitors would bind to the active site of the protein located around the key residues of Asp555 and Lys661. Meanwhile, a preliminary druggability evaluation showed that compound YX10 showed favorable liver microsomal and moderate plasma stability and weak inhibitory activity against cytochrome P450 isoforms at 10 μM. All the results indicated that compound YX10 could represent a promising lead compound for further development.

ZnCl2 catalyzed new coumarinyl-chalcones as cytotoxic agents

A new series of coumarin-yl-chalcone derivatives (3a-m) had been designed and synthesized through different reactions such as aromatic addition, cyclization and Claisen-Schmidt reactions in good yields (54–78%). 5-acetyl-4-(2-hydroxyphenyl) -6-methyl-3, 4-dihydropyrimidin-2(1H) -one (1) has been synthesized by multi-component one pot reaction of salicylaldehyde, methyl acetoacetate and urea, which was further reacted with malonic acid employing ZnCl₂ catalyst to yield 5-acetyl-4-(4-hydroxy-2-oxo-2H-chromen-8-yl) -6-methyl-3, 4-dihydropyrimidin-2(1H) -one (2). The title compounds (3a-m) were synthesised by reacting 5-acetyl-4-(4-hydroxy-2-oxo-2H-chromen-8-yl) -6-methyl-3, 4-dihydropyrimidin-2(1H)-one (2) with different aromatic aldehydes in the presence of potassium hydroxide. In silico studies, a preliminary screening method for predicting the anti-cancer activity was performed for the synthesized compounds (3a-m) against Src, Alb tyrosine kinase and homology model protein (PDB ID: 4csv). The derivatives 3h and 3m showed moderate binding energies. The in vitro cytotoxic activity was evaluated for the compounds 3h and 3m by using human cancer cell-line morphology and MTT assay against three human cell-lines A549 (Lung), Jurkat (Leukemia) and MCF-7 (Breast). The results indicate that the derivatives 3h and 3m display significant anti-cancer activity, however it was found to be less cytotoxic when compared to the standard used i.e. Imatinib.

Synergy, Additivity, and Antagonism between Cisplatin and Selected Coumarins in Human Melanoma Cells

(1) Cisplatin (CDDP) is used in melanoma chemotherapy, but it has many side effects. Hence, the search for natural substances that can reduce the dose of CDDP, and CDDP-related toxicity, is highly desired. Coumarins have many biological properties, including anticancer and antiproliferative effects. (2) An in vitro 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay on two human melanoma cell lines (FM55P and FM55M2) examined the antitumor properties of CDDP and five naturally occurring coumarins (osthole, xanthotoxin, xanthotoxol, isopimpinellin, and imperatorin). The antiproliferative effects produced by combinations of CDDP with the coumarins were assessed using type I isobolographic analysis. (3) The most potent anticancer properties of coumarins were presented by osthole and xanthotoxol. These compounds were characterized by the lowest median inhibitory concentration (IC₅₀) values relative to the FM55P and FM55M2 melanoma cells. Isobolographic analysis showed that for both melanoma cell lines, the combination of CDDP and osthole exerted synergistic and additive interactions, while the combination of CDDP and xanthotoxol exerted additive interactions. Combinations of CDDP with xanthotoxin, isopimpinellin, and imperatorin showed antagonistic and additive interactions in two melanoma cell lines. (4) The combination of CDDP and osthole was characterized by the most desirable synergistic interaction. Isobolographic analysis allows the selection of potential candidates for cancer drugs among natural substances.

4-Aminocoumarin derivatives: synthesis and applications

4-Aminocoumarins represent an important class of a versatile scaffold in organic synthesis and have been consistently used as a building block in organic chemistry for the synthesis of different heterocyclic compounds.

A review: Biologically active 3,4-heterocycle-fused coumarins

The combination of heterocycles offers a new opportunity to create novel multicyclic compounds having improved biological activity. Coumarins are ubiquitous natural heterocycle widely adopted in the design of various biologically active compounds. Fusing different heterocycles with coumarin ring is one of the interesting approaches to generating novel hybrid molecules having highlighted biological activities. In the efforts to develop heterocyclic-fused coumarins, a wide range of 3,4-heterocycle-fused coumarins have been introduced bearing outstanding biological activity. The effect of heterocycles annulation at 3,4-positions of coumarin ring on the biological activity of the target structures were discussed. This review focuses on the important progress of 3,4-heterocycle-fused coumarins providing better insight for medicinal chemists on the design and preparation of biologically active heterocycle-fused coumarins with a significant therapeutic effect in the future.

Coumarins and Coumarin-Related Compounds in Pharmacotherapy of Cancer

Cancer is one of the most common causes of disease-related deaths worldwide. Despite the discovery of many chemotherapeutic drugs that inhibit uncontrolled cell division processes for the treatment of various cancers, serious side effects of these drugs are a crucial disadvantage. In addition, multi-drug resistance is another important problem in anticancer treatment. Due to problems such as cytotoxicity and drug resistance, many investigations are being conducted to discover and develop effective anticancer drugs. In recent years, researchers have focused on the anticancer activity coumarins, due to their high biological activity and low toxicity. Coumarins are commonly used in the treatment of prostate cancer, renal cell carcinoma and leukemia, and they also have the ability to counteract the side effects caused by radiotherapy. Both natural and synthetic coumarin derivatives draw attention due to their photochemotherapy and therapeutic applications in cancer. In this review, a compilation of various research reports on coumarins with anticancer activity and investigation and a review of structure-activity relationship studies on coumarin core are presented. Determination of important structural features around the coumarin core may help researchers to design and develop new analogues with a strong anticancer effect and reduce the potential side effects of existing therapeutics.

Design, synthesis, DFT, docking studies and ADME prediction of some new coumarinyl linked pyrazolylthiazoles: Potential standalone or adjuvant antimicrobial agents

The control of antimicrobial resistance (AMR) seems to have come to a dead end. The major consequences of the use and abuse of antibacterial drugs are the development of resistant strains due to genetic mutability of both pathogenic and nonpathogenic microorganisms. We, herein, report the synthesis, characterization and biological activities of coumarin-thiazole-pyrazole (CTP) molecular hybrids with an effort to explore and overcome the increasing antimicrobial resistance. The compounds were characterized by analyzing their IR, Mass, 1H and13C NMR spectral data and elemental analysis. The in vitro antimicrobial activity of the synthesized compounds was investigated against various pathogenic strains; the results obtained were further explained with the help of DFT and molecular orbital calculations. Compound 1b and 1f displayed good antimicrobial activity and synergistic effects when used with kanamycin and amphotericin B. Furthermore, in vitro cytotoxicity of compounds 1b and 1f were studied against HeLa cells (cervical cancer cell) and Hek-293 cells. The results of molecular docking study were used to better rationalize the action and prediction of the binding modes of these compounds.

Syntheses of new 3-thiazolyl coumarin derivatives, in vitro α-glucosidase inhibitory activity, and molecular modeling studies

3-Thiazolylcoumarin derivatives 1-14 were synthesized via one-pot two step reactions, and screened for in vitro α-glucosidase inhibitory activity. All compounds showed inhibitory activity in the range of IC50 = 0.12 ± 0.01-16.20 ± 0.23 μM as compared to standard acarbose (IC50 = 38.25 ± 0.12 μM), and also found to be nontoxic. Molecular docking study was carried out in order to establish the structure-activity relationship (SAR) which demonstrated that electron rich centers at one and electron withdrawing centers at the other end of the molecules showed strong inhibitory activity. All the synthesized compounds were characterized by spectroscopic techniques such as EI-MS, HREI-MS, (1)H NMR and (13)C NMR. CHN analysis was also performed.

Synthesis and Cytotoxic Evaluation of Pyran, Dihydropyridine and Thiophene Derivatives of 3-Acetylcoumarin

A series of coumarin analogues bearing 4H-pyran rings 2a-d, 11a-d and 1,4-dihydropyridine rings 3a-d, 12a-d at position 3 were synthesized starting from either 3-acetyl coumarin (1) or the coumarin acetohydrazide derivative 4. Condensation of 3-acetylcoumarin (1) with 2-cyanoacetohydrazide afforded 2-cyano-N'-{1-[2-oxo-2H-chromen-3-yl]ethylidene}acetohydrazide (4). Reaction of compound 4 with elemental sulfur and either malononitrile or ethyl cyanoacetate afforded the thiophene derivatives 8 and 9, respectively. The structures of the newly synthesized compounds were confirmed on the basis of their spectral data and elemental analyses. All synthesized compounds were screened for their in vitro anticancer activity against six human cancer cell lines and normal fibroblasts. Several compounds showed potent inhibition with an IC50 value of ˂870 nM. Compound 3d exhibited equivalent cytotoxic effect as the standard CHS 828 against a breast cancer cell line (IC50 value=18 nM). Normal fibroblast cells (WI38) were affected to a much lesser extent (IC50 value >10000 nM).

Investigation of binding mechanism of novel 8-substituted coumarin derivatives with human serum albumin and α-1-glycoprotein

Coumarin molecules have biological activities possessing lipid-controlling activity, anti-hepatitis C activity, anti-diabetic, anti-Parkinson activity, and anti-cancer activity. Here, we have presented an inclusive study on the interaction of 8-substituted-7-hydroxy coumarin derivatives (Umb-1/Umb-2) with α-1-glycoprotein (AGP) and human serum albumin (HSA) which are the major carrier proteins in the human blood plasma. Binding constants obtained from fluorescence emission data were found to be KUmb-1=3.1 ± .01 × 10(4) M(-1), KUmb-2 = 7 ± .01 × 10(4) M(-1), which corresponds to -6.1 and -6.5 kcal/mol of free energy for Umb-1 and Umb-2, respectively, suggesting that these derivatives bind strongly to HSA. Also these molecules bind to AGP with binding constants of KUmb-1-AGP=3.1 ± .01 × 10(3) M(-1) and KUmb-2-AGP = 4.6 ± .01 × 10(3) M(-1). Further, the distance, r between the donor (HSA) and acceptor (Umb-1/Umb-2) was calculated based on the Forster's theory of non-radiation energy transfer and the values were observed to be 1.14 and 1.29 nm in Umb-1-HSA and Umb-2-HSA system, respectively. The protein secondary structure of HSA was partially unfolded upon binding of Umb-1 and Umb-2. Furthermore, site displacement experiments with lidocaine, phenylbutazone (IIA), and ibuprofen (IIIA) proves that Umb derivatives significantly bind to subdomain IIIA of HSA which is further supported by docking studies. Furthermore, Umb-1 binds to LYS402 with one hydrogen bond distance of 2.8 Å and Umb-2 binds to GLU354 with one hydrogen bond at a distance of 2.0 Å. Moreover, these molecules are stabilized by hydrophobic interactions and hydrogen bond between the hydroxyl groups of carbon-3 of coumarin derivatives.

Dissociation of protonated N-(3-phenyl-2H-chromen-2-ylidene)-benzenesulfonamide in the gas phase: cyclization via sulfonyl cation transfer

RATIONALE

In the tandem mass spectrometry of protonated N-(3-phenyl-2H-chromen-2-ylidene)benzenesulfonamides, the precursor ions have been observed to undergo gas-phase dissociation via two competing channels: (a) the predominant channel involves migration of the sulfonyl cation to the phenyl C atom and the subsequent loss of benzenesulfinic acid along with cyclization reaction, and (b) the minor one involves dissociation of the precursor ion to give an ion/neutral complex of [sulfonyl cation/imine], followed by decomposition to afford sulfonyl cation or the INC-mediated electron transfer to give an imine radical cation.

METHODS

The proposed reaction channels have been supported by theoretical calculations and D-labeling experiments.

RESULTS

The gas-phase cyclization reaction originating from the N- to C-sulfonyl cation transfer has been first reported to the best of our knowledge.

CONCLUSIONS

For the substituted sulfonamides, the presence of electron-donating groups (R(2) -) at the C-ring effectively facilitates the reaction channel of cyclization reaction, whereas that of electron-withdrawing groups inhibits this pathway.

Coumarin heterocyclic derivatives: chemical synthesis and biological activity

This review highlights the broad range of science that has arisen from the synthesis of coumarin-linked and fused heterocycle derivatives. Specific topics include their synthesis and biological activity.

In vitro inhibition effect of some coumarin compounds on purified human serum paraoxonase 1 (PON1)

Human serum paraoxonase 1 (PON1; EC 3.1.8.1) is a high-density lipoprotein associated, calcium-dependent enzyme that hydrolyses aromatic esters, organophosphates and lactones and can protect the low-density lipoprotein against oxidation. In this study, in vitro effect of some hydroxy and dihydroxy ionic coumarin derivatives (1-20) on purified PON1 activity was investigated. Among these compounds, derivatives 11-20 are water soluble. In investigated compounds, compounds 6 and 13 were found the most active (IC50 = 35 and 34 µM) for PON1, respectively. The present study has demonstrated that PON1 activity is very highly sensitive to studied coumarin derivatives.

Synthesis, in vitro anticancer activity and SAR studies of arylated imidazo[1,2-a]pyrazine–coumarin hybrids

A diverse array of arylated imidazo[1,2-a]pyrazine–coumarin hybrids have been synthesized for in vitro anticancer activities.

Deactivation of 6-aminocoumarin intramolecular charge transfer excited state through hydrogen bonding

This paper presents results of the spectral (absorption and emission) and photophysical study of 6-aminocoumarin (6AC) in various aprotic hydrogen-bond forming solvents. It was established that solvent polarity as well as hydrogen-bonding ability influence solute properties. The hydrogen-bonding interactions between S₁-electronic excited solute and solvent molecules were found to facilitate the nonradiative deactivation processes. The energy-gap dependence on radiationless deactivation in aprotic solvents was found to be similar to that in protic solvents.

Aggregation studies of dipolar coumarin-153 dye in polar solvents: a photophysical study

Photophysical studies have been carried out to explore the aggregation behavior of coumarin-153 (C153) dye in polar organic solvents of both aprotic and protic nature, namely acetonitrile (ACN) and ethanol (EtOH). No unusual behavior is observed in aprotic ACN solvent, suggesting only the monomers of the dye as the single emitting species in the solution. In protic EtOH solvent, however, the dye shows the presence of multiple emitting species in the solution. The concentration-, temperature- and wavelength-dependent changes in the fluorescence decays, and the time-resolved emission spectra (TRES) and area-normalized emission spectra (TRANES) suggest the coexistence of dye aggregates along with the dye monomers in the EtOH solution. Observed results indicate that the emission spectra of the aggregates are substantially blue-shifted compared to the spectra of the monomers, suggesting the H-aggregation of the dye in the present cases. Time-resolved fluorescence anisotropy, ultrafast fluorescence up-conversion measurements and scanning electron microscopy studies support the aggregation of the dye in EtOH solution. Strong dipole-dipole interaction is supposedly responsible for the aggregation of C153 dye (dipole moment ∼6.4 D) and the polar protic solvent EtOH apparently stabilizes the aggregates through solute-solvent hydrogen bonding interaction, which is not possible in aprotic ACN solvent. This is further supported by the time-resolved fluorescence results in a strongly hydrogen bond donating solvent, 2,2,2-trifluoroethanol. Aggregation of C153 dye observed in the present study in polar protic organic solvent is an intriguing finding, as the dye is widely used as a fluorescent probe for various photochemical studies, where overlooking such aggregation will definitely mislead the observed results.

Triglyceride-lowering agents

This review is the first attempt at systematization of the literature data on the structures and activities of triglyceride-lowering agents which used in medical practice or are in development. The effects and mechanisms of action of statins, squalene synthase inhibitors, fibrates, PPARα and PPARα/γ agonists, nicotinic acid, omega-3 fatty acids and some other molecular targets were considered. Unfortunately, to date, harmless and effective triglyceride-lowering drug still does not exist and there is still need for development of better triglyceride-lowering agents.

Photophysics of a coumarin in different solvents: use of different solvatochromic models

This study reported the photophysics of 7-(diethylamino)coumarin-3-carboxylic acid N-succinimidyl ester (7-DCCAE) in different neat solvents of varying polarity using steady-state absorption, fluorescence emission and picosecond time-resolved spectroscopy. In nonpolar solvents, the dye molecule predominantly exists in nonpolar structure and exhibits very low value of nonradiative decay rate constant (k(nr)), demonstrating the emission takes place from S(1) -LE to S(0) ground state. The fluorescence quantum yields, lifetime values of 7-DCCAE in different solvents are rationalized on the basis of intramolecular charge transfer (ICT) followed by twisted intramolecular charge transfer state formation (TICT) as well as specific solute-solvent interactions. Several solvatochromic models (such as Lippert, Dimroth, Kamlet-Taft, Catalán 3P and Catalán 4P models) were used to analyze the solvatochromic shift of 7-DCCAE in different solvents. The different empirical models show that the observed results are better correlate for nonchlorinated solvents and provide statistically significant best-fit result. A comparison was done between comparatively new solvatochromic model (Catalán 3P and Catalán 4P model) with Kamlet-Taft model. The ground state structure of the said molecule was optimized by using Density Functional Theory (DFT).

In vitro inhibition effects of some coumarin derivatives on human erythrocytes glucose-6-phosphate dehydrogenase activities

Inhibitory effects of some synthesized dihydroxycoumarin compounds on purified G6PD were investigated. For this purpose, initially human erythrocyte G6PD was purified 7069-fold in a yield of 33.6% by using ammonium sulfate precipitation and affinity chromatography which includes 2',5'-ADP Sepharose 4B. The purified enzyme showed a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Enzyme activity was determined spectrophotometrically according to Beutler method at 340 nm. 6,7-Dihydroxy-3-(2-methylphenyl)-2H-chromen-2-one (OPC), 6,7-dihydroxy-3-(3-methylphenyl)-2H-chromen-2-one (MPC) and 6,7-dihydroxy-3-(4-methylphenyl)-2H-chromen-2-one (PPC) were used as dihydroxycoumarin compounds. This study has demonstrated that G6PD activity is very highly sensitive to study coumarin derivatives.

A rapid and modified approach for C-7 amination and amidation of 4-methyl-7-nonafluorobutylsulfonyloxy coumarins under microwave irradiation

A rapid approach for the synthesis of an array of 4-methyl-7-substituted coumarins has been developed.

Unusual H-type aggregation of coumarin-481 dye in polar organic solvents

Coumarin-481 (C481) dye shows intriguing time-resolved (TR) fluorescence behavior in polar organic solvents of both protic and aprotic nature, namely, ethanol (EtOH) and acetonitrile (ACN), demonstrating the presence of multiple emitting species in the solution. Following concentration-dependent and wavelength-dependent TR fluorescence measurements and the time-resolved emission spectra (TRES) and time-resolved area-normalized emission spectra (TRANES) subsequently constructed using wavelength dependent decay parameters, we convincingly conclude that in the studied solvents a part of the dissolved dye undergoes H-type of aggregation, even at a very low dye concentration. This is quite an unusual finding because the dye C481 apparently shows reasonably good solubility in these organic solvents. As the TR measurements indicate, major contribution in the fluorescence decays is due to monomeric dye, having reasonably short lifetime (∼0.64-0.68 ns), which is in accordance with the conversion of fluorescent intramolecular charge transfer (ICT) state to nonfluorescent twisted intramolecular charge transfer (TICT) state suggested for the dye in high polarity solvents, causing an efficient nonradiative deexcitation. The minor contributions arising from the aggregated dyes show its clear presence in the decays at the blue edge of the emission spectra and have relatively longer lifetimes (∼1.2-5.2 ns) because the steric hindrance caused by the stacked dyes resists the ICT to TICT conversion. Aggregation of C481 dye as observed in the present study in polar organic solvents is an intriguing finding, as the dye is a widely used fluorescent probe for various photochemical studies, where overlooking such aggregation can mislead the observed results.

Evaluation of the hypolipidemic activity of 6,7-dimethoxycoumarin on placental tissue factor mRNA expression in experimental anti-phospholipid syndrome

Background:

Anti-phospholipid syndrome is a thrombogenic and systemic autoimmune disorder that influences fetal life throughout gestation period. Over expression of tissue factor on the surface of monocyte(s) is reported to be a major causative agent in inducing anti-phospholipid antibody-mediated placental thrombosis and fetal loss in pregnant women. The over expression of tissue factor is proposed to be due to high levels of blood cholesterol and oxidized lipoproteins.

Objective:

In this study, we report the lipid-lowering property and anti-tissue factor activity of one of the naturally occurring coumarin derivates 6,7-dimethoxycoumarin, found aplenty in Chinese medicinal plant Artemisia scoparia, and its effect on tissue factor mRNA expression in experimental anti-phospholipid syndrome.

Materials and Methods:

Adult female mice were immunized with cardiolipin and beta-2-glycoprotein-1 to induce experimental anti-phospholipid syndrome. Female mice with high titer of aCL were allowed to mate with male, and the female mice were treated with 6,7-dimethoxycoumarin on a daily dose of 5 mg/kg body weight from day 3 to day 15 of gestation. On day 18 of pregnancy, all the animals were dissected to measure biochemical parameters in blood, and TF mRNA expression levels were measured in placenta.

Results:

Treatment with 6,7-dimethoxycoumarin significantly reduced the levels of cholesterol and plasma lipids by its potent hypolipidemic property, which eventually reduced the over-expression tissue factor at mRNA levels in placenta. We believe that further studies in animal model would reveal the potential therapeutic properties of 6,7-dimethoxycoumarin against anti-phospholipid syndrome.

Conclusion:

The 6,7-dimethoxycoumarin is capable to reduce the expression of TF in placenta at the mRNA level and thrombus generation indirectly by its potent anti-TF and anti-oxidant activities.