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Reversible chemical covalency provides a path to materials that can degrade and recombine with appropriate stimuli and which can be used for tissue regeneration and repair. However, designing and preparing efficient and quickly self-healing materials has always been a challenge. The preparation strategies of photoresponsive gels attract a lot of attention due to their precise spatial and temporal control and their predetermined response to light stimulation. In this work, the linear copolymer PAC was synthesized via precipitation polymerization of acrylic acid and 7-(2-acrylate-ethoxylated)-4-methylcoumarin. The coumarin groups on the copolymer PAC side chains provide a reversible chemical cross-linking via photostimulation, which achieves reversible regulation of the gel network structure. The concentration of 18 wt% PAC solution produces gelation under irradiation with 365 nm. In contrast, PAC gel is restored to soluble copolymers under irradiation with 254 nm. Meanwhile, the mechanical and self-healing properties of the gel were also explored. It is demonstrated that the cracks of the gel can be repaired simply, quickly, and efficiently. Furthermore, the PAC copolymer shows an excellent adhesion property based on the reversible sol–gel transition. Thus, the PAC gel has considerable potential for applications in engineering and biomedical materials. [ABSTRACT FROM AUTHOR]

Catch and release chemotaxis was studied by using a self‐propelled 6‐methylcoumarin (6‐MC) disk floating on water. A tablet of Na3PO4 placed at the bottom of the water phase acted as a chemical stimulus. The repetition of catch and release chemotaxis, that is, the alternating inversion of the spatial gradient of surface tension, was realized using one 6‐MC disk and one Na3PO4 tablet. Alternating catch and release chemotaxis was observed using two 6‐MC disks and one Na3PO4 tablet. The mechanism of catch and release chemotaxis is discussed in relation to the change in the surface tension of the 6‐MC aqueous phase following the addition of Na3PO4 as the driving force, the spatial concentration gradient of the base dissolved from the tablet in the water phase, and the chemical reaction between 6‐MC and OH−. Understanding this type of chemotaxis system can elucidate the chemotaxis behaviors of living organisms. [ABSTRACT FROM AUTHOR]

Tyrosinase ultimately controls the melanogenesis rate of the skin, and tanning and haircare products generally induce the activation of tyrosinase. Moreover, various enzymes, including tyrosinase, tyrosinase-related protein 1 (TRP1), and tyrosinase-related protein 2 (TRP2), mediate melanogenesis in which microphthalmia-associated transcription factor (MITF) is a master regulator. One coumarin family member 7,8-dihydroxy-4-methylcoumarin (DHMC) shows extensive biological activities with beneficial health effects; however, it also induces cytotoxicity and its melanogenic effect has not been reported yet. Therefore, we first synthesized DHMC derivatives via methylation to obtain 7,8-dimethoxy-4-methylcoumairn (DMMC), and investigated the pro- or anti-melanogenic effects of DHMC and DMMC in B16-F10 melanoma cells as well as the underlying mechanism. DHMC showed cytotoxicity at all tested concentrations, whereas DMMC did not reduce cell viability, even at the high concentration. DMMC also drives the significant increase in intracellular melanin and tyrosinase activity. Moreover, DMMC induced MITF expression by significantly increasing tyrosinase activity, which activates the gene expression of TRP1 and TRP2. Western blotting confirmed that DMMC induced the activation of mitogen-activated protein kinase (MAPK) signaling by the phosphorylation of C-Jun N-terminal kinase (JNK), resulting in the increased melanin production and the decreased phosphorylation of protein kinase B. Collectively, this study showed the pro-melanogenic effect of DMMC and its potential as a safe tanning and dyeing agent. [ABSTRACT FROM AUTHOR]

Cancerous disease phenotype is a leading cause of death and a major source of worry for the health-care system. Despite the huge effort put out to extract, develop and synthesize novel chemotherapeutic drugs, considerable side effects, increasing tumor resistance and poor selectivity continue to be significant obstacles for medicinal chemists. Many natural items’ anti-cancer potential has been studied extensively in recent decades. Coumarin-based substances, which have a wide range of structural variety and pharmacological effects are one type of such product. Hymecromone, also known as 7-hydroxy- 4-methylcoumarin and its derivatives have shown promise in the treatment of multi-drug cancer resistance, the decrease of chemotherapeutic drug side effects and the creation of photo-directed therapeutics, among others. Moreover, numerous synthetic hymecromone-derived compounds have been demonstrated to have a broad antitumor potential, making them effective against a variety of cancers including leukemia, prostate, pulmonary, ovarian and nephro cancers. In this brief review, the authors investigated a number of recently published scientific articles and examined their outcomes in order to highlight structural characteristics of hymecromone-derived compounds that are important or essential for their anticancer activity. The identification of these variables might guide future research interest for designing and synthesizing of new chemotherapeutic agents with better performance. [ABSTRACT FROM AUTHOR]

A Pd‐catalyzed C‐glycosylation reaction was developed by allyl‐allyl coupling process using Achmatowicz rearrangement products as donors and methylcoumarins as acceptors under mild conditions. This method featured regio‐ and diastereoselectivities, stereodivergent synthesis of C‐glycosides. The glycosyl donors with controlled stereodiversity and glycosyl acceptors with fluorescent performace further highlighted this methodology. [ABSTRACT FROM AUTHOR]

Animal models of hemostasis are often extrapolated to humans; however, only a few studies have compared coagulation and fibrinolysis across species. Simultaneous thrombin (TG) and plasmin (PG) generation is useful to assessing coagulation and fibrinolysis within the same sample. In this study, we performed simultaneous TG and PG analysis in blood plasma samples from humans and 6 species commonly evaluated in pre-clinical research. TG and PG were investigated in male and female donor platelet-poor plasmas (PPP) obtained from 28 healthy humans, 10 baboons, 12 rhesus monkeys, 20 Yorkshire pigs, 20 Sprague-Dawley rats, 10 New Zealand White rabbits and 14 Hartley guinea pigs. The continuous generation of the 7-amino-4-methylcoumarin (AMC) from substrates specific to thrombin or plasmin was monitored. The thrombin and plasmin concentration peak heights (PH) and production rates (PR) were calculated. TG and PG parameters from baboon and rhesus macaque plasma approximated that of humans. The other species differed significantly from both human and non-human primates. For example, swine and rat plasmas demonstrated similar TG, but swine plasmas did not generate plasmin. TG and PG parameters from Guinea pig samples were extremely low, while rabbit plasmas showed variable PG curves demonstrating one or two peaks with low and high PR values, respectively. Correlations between PH and PR values were significant with the exceptions of human PG, baboon TG, rat TG and Guinea pig PG. These findings are informative to pre-clinical animal species selection and optimization of coagulation and fibrinolysis translational research. [ABSTRACT FROM AUTHOR]

Effect of a room temperature ionic liquid (RTIL, [pmim][Br]) on the solvation dynamics of a probe covalently attached to a protein (human serum albumin (HSA)) has been studied using femtosecond up-conversion. For this study, a solvation probe, 7-diethylamino-3-(4-maleimidophenyl)-4-methylcoumarin (CPM) has been covalently attached to the lone cysteine group (cys-34) of the protein HSA. Addition of 1.5 M RTIL or 6 M GdnHCl causes a red shift of the emission maxima of CPM bound to HSA by 3 nm and 12 nm, respectively. The average solvation time <τs> decreases from 650 ps (in native HSA) to 260 ps (∼2.5 times) in the presence of 1.5 M RTIL and to 60 ps (∼11 times) in the presence of 6 M GdnHCl. This is ascribed to unfolding of the protein by RTIL or GdnHCl and therefore making the probe CPM more exposed. When 1.5 M RTIL is added to the protein denatured by 6 M GdnHCl in advance, a further ∼5 nm red shift along with further ∼2 fold faster solvent relaxation (<τ> ∼30 ps) is observed. Our previous fluorescence correlation spectroscopy study [D. K. Sasmal, T. Mondal, S. Sen Mojumdar, A. Choudhury, R. Banerjee, and K. Bhattacharyya, J. Phys. Chem. B 115, 13075 (2011)] suggests that addition of RTIL to the protein denatured by 6 M GdnHCl causes a reduction in hydrodynamic radius (rh). It is demonstrated that in the presence of RTIL and GdnHCl, though the protein is structurally more compact, the local environment of CPM is very different from that in the native state. [ABSTRACT FROM AUTHOR]

In the manuscript the first vinylogous, decarboxylative Michael reaction is described. It utilizes 3‐cyano‐4‐methylcoumarins as pronucleophiles undergoing Michael reaction with Michael acceptors activated by the presence of carboxylic acid moiety. Subsequent decarboxylative protonation affords interesting heterocycles in high yields with the reaction realized in the presence of Brønsted base catalyst. Attempts to develop an enantioselective variant of the decarboxylative reaction cascade are also described. [ABSTRACT FROM AUTHOR]

Highlights • A multi-dye (7-amino-4-methylcoumarin/resorufin) containing MOF was developed. • Dyes⊂MOF-801 enabled Cr 2 O 7 2− detection in the presence of interfering ions. • Dyes⊂MOF-801 showed selective removal of Cr 2 O 7 2− of 83 mg/g within 3 min. • Complete Cr 2 O 7 2− removal was confirmed immediately using ratiometric detection. Abstract Among the heavy metals commonly found in wastewater, Cr 2 O 7 2− is considered the most hazardous due to its high toxicity, carcinogenicity, and mutagenicity. Nevertheless, detection and removal of Cr 2 O 7 2− remains a serious challenge as it competes with other metal cations and anions in wastewater. Herein, self-calibration of the emission intensities at two different wavelengths was introduced to microporous media to facilitate the ratiometric detection and simultaneous removal of Cr 2 O 7 2− in the presence of excess interfering ions. Specifically, a multi-dye (7-amino-4-methylcoumarin and resorufin) containing metal-organic framework-801 (Dyes⊂MOF-801) was developed and tested for the detection and removal of Cr 2 O 7 2− from wastewater. Dyes⊂MOF-801 exhibited accurate detection of Cr 2 O 7 2− with high sensitivity in the presence of a 260-fold excess of potentially interfering ions. Its maximum removal capacity was 83 mg/g and was achieved within 3 min, even in the presence of excess metal ions and 10-fold excess concentrations of anions. In addition, the residual concentration of Cr 2 O 7 2− was simultaneously checked using ratiometric detection of Dyes⊂MOF-801, so that the removal of Cr 2 O 7 2− could be immediately confirmed. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • 26 O-alkylcoumarins were synthesized and tested at 100 µM for their in vitro inhibitory potential against cholinesterases. • 12 of them exerted a potent and selective inhibition against BChE. • None of them possessed any potential to inhibit AChE. • MetaCore/MetaDrug analysis and docking simulations were applied the active compounds. Abstract Coumarins of synthetic or natural origins are an important chemical class exerting diverse pharmacological activities. In the present study, 26 novel O-alkylcoumarin derivatives were synthesized and have been tested at 100 µM for their in vitro inhibitory potential against acetylcholinesterase (AChE) and butyrlcholinesterase (BChE) targets which are the key enzymes playing role in the pathogenesis of Alzheimer's disease. Among the tested coumarins, none of them could inhibit AChE, whereas 12 of them exerted a marked and selective inhibition against BChE as compared to the reference (galanthamine, IC 50 = 46.58 ± 0.91 µM). In fact, 10 of the active coumarins showed higher inhibition (IC 50 = 7.01 ± 0.28 µM – 43.31 ± 3.63 µM) than that of galanthamine. The most active ones were revealed to be 7-styryloxycoumarin (IC 50 = 7.01 ± 0.28 µM) and 7-isopentenyloxy-4-methylcoumarin (IC 50 = 8.18 ± 0.74 µM). In addition to the in vitro tests, MetaCore/MetaDrug binary QSAR models and docking simulations were applied to evaluate the active compounds by ligand-based and target-driven approaches. The predicted pharmacokinetic profiles of the compounds suggested that the compounds reveal lipophilic character and permeate blood brain barrier (BBB) and the ADME models predict higher human serum protein binding percentages (>50%) for the compounds. The calculated docking scores indicated that the coumarins showing remarkable BChE inhibition possessed favorable free binding energies in interacting with the ligand-binding domain of the target. Therefore, our results disclose that O-alkylcoumarins are promising selective inhibitors of cholinesterase enzymes, particularly BChE in our case, which definitely deserve further studies. [ABSTRACT FROM AUTHOR]

Abstract Effect of natural and modified cyclodextrins on the absorption and 2D, 3D fluorescence spectra of 7‑hydroxy‑4‑methyl coumarin (HMC) have been investigated in different buffer solutions (pHs – 1.0, 6.5 and 10.0). Both neutral and monoanion species were formed in the ground state, whereas three species such as zwitterion, neutral and monoanion in the excited state in the above mentioned pH ranges. The excited state property of HMC obviously varied with the results from the absorption data. The excited state proton transfer was observed at low pH from the hydroxyl group to carbonyl group of HMC. FT-IR, PXRD, SEM results showed the apparent variation in the natural and modified CDs with the HMC molecule. The results demonstrated that in three pH solutions, HMC forms 1:1 inclusion complex with the three CDs. Finally the proposed structures of the inclusion complexes were predicted using Semi-empirical calculations. Highlights • The excited state proton transfer of 7-hydroxy-4-methylcoumarin encapsulated in natural and modified CDs has been studied. • The zwitterion intensity gradually enhanced with increasing concentration of CDs in acidic pH. • All inclusion complexes formed with 1:1 stoichiometry ratio with all CDs. • The structural information about all inclusion complexes were obtained from PM7 method. [ABSTRACT FROM AUTHOR]

This study explores the excited state prototropic behavior of the fluorophore, 7-hydroxy-4-methylcoumarin (7H4MC), in the [Cnmim][BF4] (n = 2, 4, 6, 8, 10) series of ionic liquid (IL)–water mixtures at low water contents. In pure IL media, 7H4MC exists in the neutral form in both ground and excited states. However, on addition of water to the ILs, the excited neutral form of the dye is gradually converted to the anionic and the tautomeric species, leading to characteristic changes in the emission spectra. The similarity in the spectral features of 7H4MC in the IL–water system with that in a conventional reverse micelle system rather than with organic solvent–water mixtures, suggests that in the presence of water, the ILs are organized into reverse micelle-like structures with the consequent formation of confined water pockets. The results further suggest that formation of water nanoclusters and the ensuing changes in excited state prototropic behavior of the dye, is facilitated by increase in the alkyl chain length of the IL cation. These propositions are supported by time-resolved fluorescence studies. To the best of our knowledge this is the first report on proton transfer reaction in IL–water mixtures at low water contents. Considering that ILs are useful as solvents and surfactants, and IL–water mixtures in particular have applications in chemical extractions and biocatalysis, an understanding of the structural organization and water pool formation in these systems is quite important. The insights obtained from the prototropic transformations of 7H4MC are significant not only for fundamental self-assembly studies, but also for the development of ILs as chemical reaction media. [ABSTRACT FROM AUTHOR]

Ubiquitin (Ub)-based probe Ub-7-amino-4-methylcoumarin is widely used to detect deubiquitinase (DUB) enzymatic activity, but its current synthesis procedures are cumbersome. In this work, we reported a new highly efficient semi-synthetic strategy to prepare Ub-AMC through two facile steps: first, preparation of Ub-thioester through hydrozinolysis-thioesterification of expressed Ub (1-G76C) mutant; second, direct aminolysis of Ub-thioester in a mixed-solvent system which exhibits very low hydrolysis. [ABSTRACT FROM AUTHOR]

In this paper, the effects of gamma irradiation on 7-Methoxy-4-methylcoumarin (7M4MC) molecule, an essential coumarin derivative, which has an inherent variety of biological activities, therapeutic properties and industrial usage were examined. For this purpose, the sample was irradiated with 60Co-gamma ray source for about 100 kGy total doses. Theoretical calculations were performed using GAUSSIAN03 program for the possible radicals that were modeled from two stable conformations with lowest energies. In order to get well-resolved spectra and to determine the radical identity experimentally, EPR spectra of the irradiated 7M4MC sample were recorded at several spectrometer conditions. By considering the molecular structure and EPR spectra, alkyl-type radical was assumed to be formed by gamma irradiation. To support the estimations, simulations were done using theoretical EPR parameters as an initial value. The experimental spectra were well matched with the sum of simulated spectra obtained from two same type modeled radicals of two different conformations. As a result of experimental estimations and theoretical calculations, radiation-induced radicals were identified as two neutral alkyl radicals, , originated from two stable conformations. [ABSTRACT FROM AUTHOR]

In this work we describe the synthesis, docking studies and biological evaluation of a focused library of novel arylpiperazinyl derivatives of 8-acetyl-7-hydroxy-4-methylcoumarin. The new compounds were screened for their 5-HT 1A and 5-HT 2A receptor affinity. Among the evaluated compounds, six displayed high affinities to 5-HT 1A receptors ( 4a -0.9 nM, 6a- 0.5 nM, 10a -0.6 nM, 3b -0.9 nM, 6b -1.5 nM, 10b -1 nM). Compound 6a and 10a bearing a bromo- or methoxy- substituent in ortho position of the piperazine phenyl ring, were identified as potent antagonists of the 5-HT 1A receptors. In the tail suspension test, mice injected with 6a showed a dose-dependent increase in depressive-like behavior that was related to a decrease in locomotor activity. Compound 10a did not decrease or prolong immobility time nor did it affect home cage activity. Molecular docking studies using 5-HT 1A and 5-HT 2A homology models revealed structural basis of the high affinity of ortho -substituted derivatives and subtle changes in amino acid interactions patterns depending on the length of the alkyl linker. [ABSTRACT FROM AUTHOR]

So far, various methods have been proposed to extract the Schottky diode parameters from measured current-voltage characteristics. In this work, Schottky barrier diode with structure of Au/2(3),9(10),16(17),23(24)-tetra(4-(4-methoxyphenyl)-8-methylcoumarin-7 oxy) phthalocyaninatoiron(II) (FePc)/p-Si was fabricated and current-voltage measurements were carried out on it. In addition, current-voltage measurements were also performed on Au/p-Si structure, without FePc, to clarify the influence of the presence of an interface layer on the device performance. The measured current-voltage characteristics indicate that the interface properties of a Schottky barrier diode can be controlled by the presence of an organic interface layer. It is found that the room temperature barrier height of Au/FePc/p-Si structure is larger than that of the Au/p-Si structure. The obtained forward bias current-voltage characteristics of the Au/FePc/p-Si device was analysed by five different analytical methods. It is found that the extracted values of SBD parameters strongly depends on the method used. [ABSTRACT FROM AUTHOR]

A novel environmentally benign condensation of 5,7‐dihydroxy‐4‐methylcoumarin, aryl aldehydes, and ethyl cyanoacetate in the presence of silica sodium carbonate (SSC) has been developed for the synthesis of new pyrano[2,3‐h]coumarins. [ABSTRACT FROM AUTHOR]

Mast cells trigger IgE-mediated allergic reactions by releasing various allergic mediators. 8-Formyl-7-hydroxy-4-methylcoumarin, also called 4μ8C, was originally known as an inositol-requiring enzyme 1 (IRE1) suppressant, but no study has examined its relationship with mast cells and allergic diseases. Therefore, the purpose of this study was to determine whether 4μ8C is effective in suppressing allergic reactions in mast cells and in IgE-mediated allergic animal model. 4μ8C suppressed the degranulation of IgE-mediated mast cells (IC 50 = 3.2 μM) and the production of cytokines such as tumor necrosis factor-α (TNF-α) and interleukin-4 (IL-4) in a dose-dependent manner. 4μ8C also suppressed passive cutaneous anaphylaxis (PCA) in mice (ED 50 = 25.1 mg/kg). In an experiment on mast cell signaling pathways stimulated by antigen, the phosphorylation and activation of Syk was decreased by 4μ8C, and phosphorylation of downstream signaling molecules, such as linker for activated T cells (LAT), Akt, and the three MAP kinases, ERK, p38, and JNK, were suppressed. Mechanistic studies showed that 4μ8C inhibited the activity of Lyn and Fyn in vitro. Based on the results of those experiments, the suppressor mechanism of allergic reaction by 4μ8C involved reduced activity of Lyn and Fyn, which is pivotal in an IgE-mediated signaling pathway. In summary, for the first time, this study shows that 4μ8C inhibits Lyn and Fyn, thus suppressing allergic reaction by reducing the degranulation and the production of inflammatory cytokines. This suggests that 4μ8C can be used as a new medicinal candidate to control allergic diseases such as seasonal allergies and atopic dermatitis. [ABSTRACT FROM AUTHOR]

Hyaluronic acid (HA) is an endogenous polysaccharide that shows intrinsic targetability to CD44+ cancer cells. Here, we developed NIR and UV-responsive degradable nanogels from hyaluronic acid-g-7-N,N-diethylamino-4-hydroxymethylcoumarin (HA-CM) for CD44 targeted and remotely controlled intracellular doxorubicin (DOX) delivery. Nanometer-sized HA-CM nanogels could readily load DOX, and both NIR and UV irradiation could significantly enhance DOX release from the nanogels, resulting from light-triggered cleavage of urethane bonds that connect CM to HA. MTT assays showed that DOX-loaded HA-CM nanogels combined with NIR irradiation induced much higher antitumor activity to MCF-7 cells (CD44+) than to U-87MG cells (CD44-) and free HA pretreated MCF-7 cells. CLSM observations confirmed that DOX-loaded HA-CM nanogels were internalized by CD44+ cells via receptor mediated endocytosis mechanism, and intracellular DOX release was triggered by NIR. These HA-CM nanogels with easy preparation, CD44 targetability and photo-controlled intracellular drug release are interesting for cancer chemotherapy. [ABSTRACT FROM AUTHOR]

We synthesized a series of aryl/heteroarylpiperazinyl derivatives of 8-acetyl-7-hydroxy-4-methylcoumarin and evaluated their antidepressant-like activity. We used a fast, microwave-assisted synthesis protocol and 1 H, 13 C NMR and HRMS spectrometry to confirm the structure of all compounds. We also used radioligand binding assays to determine the affinities towards 5-HT 1A and 5-HT 2A receptors and performed molecular docking studies to rationalize obtained results. Among the evaluated compounds seven displayed high affinity to the 5-HT 1A ( 3a -1.3 nM, 5a -1.6 nM, 10a -1.6 nM, 11a -1.0 nM, 3b -1.0 nM, 5b -0.8 nM and 11b -1.5 nM) as well as significant 5-HT 1A antagonist profiles. The equilibrium dissociation constant values of tested compounds shown differential intrinsic activity ( 3a -190 nM, 3b -28 nM, 5a -48 nM, 5b -23 nM, 10b -180 nM, 11a -99 nM, 11b -38 nM) of antagonist mode. Molecular docking studies using a homology model of 5-HT 1A revealed that ligand 5b is stabilized mainly by hydrogen bonds to Ser190. [ABSTRACT FROM AUTHOR]

The aim of this study is to determine, and to compare the protective effects of eight 4 - methylcoumarins and four related compounds as radical scavengers and chain-breaking antioxidants. The main kinetic parameters of their radical scavenging activity (as % RSA, stoichiometry, n , and rate constants of reaction with DPPH radical, k RSA ) and of chain breaking antioxidant activity (as antioxidant efficiency, PF and reactivity, ID), have been determined and discussed. The RSA study has been conducted at physiological temperature (37 °С) towards DPPH radical and the tested compounds are separated into three main groups: with strong activity (% RSA > 40%); with moderate activity (20% < % RSA > 40%) and with weak activity (% RSA < 20%). Chain-breaking antioxidant activities of the studied compounds have been evaluated during bulk phase lipid (triacylglycerols of sunflower oil, TGSO) autoxidation at 80 °C. All results obtained are compared with those for standard and known inhibitors of oxidation processes, e.g. caffeic and p -coumaric acids, α-tocopherol and butylated hydroxytoluene (BHT). On the basis of a comparative analysis with standard antioxidants, the differences in the radical scavenging and antioxidant abilities of the studied compounds have been discussed and reaction mechanisms proposed. All structures are optimized at UB3LYP/6-31 + G(d,p) level in gas phase and in acetone solution to study the solvation effects. [ABSTRACT FROM AUTHOR]

The photophysical behaviour of 7-mercapto-4-methylcoumarin (C-SH) and derivatives has been studied in different solvents. In contrast to 7-hydroxy-4-methylcoumarin, C-SH shows poor emission, but high fluorescence when the thiol is alkylated. The origin and character of the lowest singlet states are discussed, specifically proposing that the thione-like C=S resonance form plays a key role in excited state deactivation in C-SH. [ABSTRACT FROM AUTHOR]

Four coumarin derivatives were synthesized via the reaction of coumarin by four compounds namely 1,3-dibromopropane, 1,3-bis(bromomethyl)benzene, 1,4-bis(bromomethyl)benzene, and 2,6-bis(bromomethyl)naphthalene. The chemical structures of the prepared compounds were characterized by FTIR, 1 H NMR and mass spectroscopy. The photophysical properties of the prepared compounds were determined by measuring the absorption and emission spectra. The photophysical properties of the prepared compounds were calculated such as: (ε) molecular extinction coefficient; (σ a ) absorption cross section, (φ f ) fluorescence quantum yield, (τ o ) fluorescence life time, ( f ) oscillator strength, ( K isc ) the intersystem crossing rate, (K r ) the radiative decay rate. The prepared compounds exhibited UV–vis absorption spectra in the absorption region of 250–350 nm with a maximum absorption peak at of 321 nm, and emission spectra were obtained in the range of 340–440 nm with different intensities depending on their chemical structures. In vitro microbiological investigation of the prepared coumarin derivatives in dark and UV irradiation was performed. All the compounds exhibited biocidal activities. Antimicrobial assay of the prepared compounds in dark showed their potency against the tested microorganisms. The antimicrobial assay in the presence of UV irradiation showed the photodynamic therapeutic activities of the coumarin derivatives. The photodynamic therapeutic activities were correlated to the photophysical properties of the tested compounds and their interaction by the cellular membranes. [ABSTRACT FROM AUTHOR]

Polymeric micelles in nanomedicine are often cross-linked to prevent disintegration in vivo. This typically requires clinically problematic chemicals or laborious procedures. In addition, cross-linking may interfere with advanced release strategies. Despite this, it is often not investigated whether cross-linking is necessary for efficient drug delivery. We used positron emission tomography (PET) imaging with 64Cu to demonstrate general methodology for real-time in vivo investigations of micelle stability. Triblock copolymers with 4-methylcoumarin cores of ABC-type (PEG-PHEMA-PCMA) were functionalized in the handle region (PHEMA) with CB-TE2A chelators. Polymeric micelles were formed by dialysis and one half was core cross-linked (CL) by UV light and the other half was not (nonCL). Both CL and nonCL were radiolabeled with 64Cu and compared in vivo in tumor-bearing mice, with free 64Cu as control. Accumulation in relevant organs was quantified by region of interest analysis on PET images and ex vivo counting. It was observed that CL and nonCL showed limited differences in biodistribution from each other, whereas both differed markedly from control (free 64Cu). This demonstrated that 4-methylcoumarin core micelles may form micelles that are stable in circulation even without cross-linking. The methodology presented here where individual unimers are radiolabeled is applicable to a wide range of polymeric micelle types. [ABSTRACT FROM AUTHOR]

In the current study, seven compounds (i.e. 1 – 7 ) were found to be novel activators for the N ε -acetyl-lysine deacetylation reaction catalyzed by human histone deacetylase 8 (HDAC8). When assessed with the commercially available HDAC8 peptide substrate Fluor-de-Lys®-HDAC8 that harbors the unnatural 7-amino-4-methylcoumarin (AMC) residue immediately C-terminal to the N ε -acetyl-lysine residue to be deacetylated, our compounds exhibited comparable activation potency to that of TM-2-51, the strongest HDAC8 activator reported in the current literature. However, when assessed with an AMC-less peptide substrate derived from the native HDAC8 non-histone substrate protein Zinc finger protein ZNF318, while our compounds were all found to be able to activate HDAC8 deacetylation reaction, TM-2-51 was found not to be able to. Our compounds also seemed to be largely selective for HDAC8 over other classical HDACs. Moreover, treatment with the strongest activator among our compounds (i.e. 7 ) was found to decrease the K M of the above AMC-less HDAC8 substrate, while nearly maintaining the k cat of the HDAC8-catalyzed deacetylation on this substrate. [ABSTRACT FROM AUTHOR]

Five ruthenium(II) half-sandwich complexes containing arene and coumarin ligands with the general formula [Ru(arene)(L)Cl 2 ] or [Ru(arene)(L 2 )Cl]Cl were synthesized. L: 3-aminocoumarin and 7-amino-4-methylcoumarin were used for the synthesis of complex compounds. The complexes were characterized by 1 H NMR, IR, UV–Vis spectroscopy, electrospray mass spectrometry (ESI MS), elemental analysis and cyclic voltammetry measurement. X-ray crystallography found one molecular structure to be of pseudo-octahedral geometry. All compounds were also tested on Chronic Myelogenous Leukemia (K562), Human Cervix Carcinoma (HeLa), Human Pancreatic Carcinoma (CFPAC) cancer cell lines, and the viability of cells was evaluated by MTT assay. [ABSTRACT FROM AUTHOR]

It is shown that mesoporous hexagonal-ordered silica, containing incorporated nickel particles in the silica matrix (Si/Ni ratio 15), has high catalytic activity in the Pechmann condensation reaction between resorcinol and ethyl acetoacetate and allows one to obtain 7-hydroxy-4-methylcoumarin with high yield and selectivity. [ABSTRACT FROM AUTHOR]

Proteases are found deregulated in many diseases including cancer and neurodegenerative diseases. They thus represent good therapeutical targets for the development of inhibitors mainly small organic molecules. Peptide substrates containing fluorogenic groups constitute central tools for the monitoring of protease activities and inhibitor screening platforms. Amino-methyl coumarin (AMC) is a well-known fluorogenic group that functionalized a huge number of peptide substrates used for kinetics in vitro but also in vivo. However, either autofluorescence or quenching of the AMC fluorescence could compromise selection and accurate evaluation of these inhibitors. It is thus needed to explore alternative spectroscopic tools to unravel these limitations. Here, we investigate whether AMC could constitute a valuable Surface Enhanced Raman Spectroscopy probe in the presence of Creighton' silver colloids under 532-nm excitation to monitor protease activity and to evaluate inhibitors. The kallikrein-related peptidase 8 was used as model of proteolytic enzyme. Band-Target Entropy Minimization analysis was successfully used to validate the present Surface Enhanced Raman Spectroscopy approach. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A facile and an efficient protocol for the synthesis of pyridazinones via molecular-iodine-mediated cleavage of 4-bromomethylcoumarin precursors in the presence of I2in ethanol at 70 °C is reported. The present approach replaced the basic condition (K2CO3) with Lewis acidic condition. [ABSTRACT FROM AUTHOR]

A novel method for synthesis of 7-hydroxy-4-methylcoumarin from resorcinol and ethyl acetoacetate via the Pechmann reaction with polyvinylpyrrolidone-supported phosphotungstic acid (PVP–HPW) catalyst is developed. The catalysts were characterized by FTIR, TGA, elemental analysis, UV–vis and a Hammet acidity function test. HPW protonated PVP to form polymeric cations. The polymeric cations interacted strongly with phosphotungstic anions, leading to an ionic liquid structure. The performance of the PVP–HPW were compared with other catalysts such as HPW, NMP–H 2 SO 4 and PVP–H 2 SO 4 . For PVP–HPW dosage of 9% based on the weight of resorcinol, the yield of 7-hydroxy-4-methylcoumarin reached 96.73% after two hours reflux reaction at 110 °C, which exhibited much higher value than other catalysts. The PVP–HPW can be easily separated from the reaction mixture and retains the activity during recycling. [ABSTRACT FROM AUTHOR]

Gerbera ( Gerbera hybrida) is an economically important ornamental species and a model plant of the Asteraceae family for flower development and secondary metabolism. Gerberin and parasorboside, two bitter tasting glucosidic lactones, are produced in high amounts in nearly all gerbera tissues. Gerbera and its close relatives also produce a rare coumarin, 4-hydroxy-5-methylcoumarin ( HMC). Unlike most coumarins, 5-methylcoumarins have been suggested to be derived through the acetate-malonate pathway. All of these polyketide-derived glucosylated molecules are considered to have a role in defense against herbivores and phytopathogens in gerbera. Gerbera expresses three genes encoding 2-pyrone synthases ( G2 PS1-3). The enzymes are chalcone synthase-like polyketide synthases with altered starter substrate specificity. We have shown previously that G2 PS1 is responsible for the synthesis of 4-hydroxy-6-methyl-2-pyrone (triacetolactone), a putative precursor of gerberin and parasorboside. Here we show that polyketide synthases G2 PS2 and G2 PS3 are necessary for the biosynthesis of HMC in gerbera, and that a reductase enzyme is likely required to complete the pathway to HMC. G2 PS2 is expressed in the leaf blade and inflorescences of gerbera, while G2 PS3 is strictly root specific. Heterologous expression of G2 PS2 or G2 PS3 in tobacco leads to the formation of 4,7-dihydroxy-5-methylcoumarin, apparently an unreduced precursor of HMC, while ectopic expression in gerbera leads to HMC formation in tissues where nontransgenic tissue does not express the genes and does not accumulate the compound. Using protein modelling and site-directed mutagenesis we identified the residues I203 and T344 in G2 PS2 and G2 PS3 to be critical for pentaketide synthase activity. [ABSTRACT FROM AUTHOR]

Catechol- O -methyltransferase (COMT), one of the most important phase II drug metabolizing enzymes, plays important roles in the metabolism of endogenous and xenobiotic catechols. In this study, a highly selective fluorescent probe for sensing activities of catechol- O -methyltransferase in complex biological samples was discovered and well characterized. Under physiological conditions, COMT selectively catalyzes the conversion of the probe (7,8-dihydroxy-4-methylcoumarin, DHMC ) to 7-hydroxy-8-methoxy-4-methylcoumarin ( HMMC ), which brings a strong turn-on fluorescence signal at 520 nm. The probe substrate has been used for monitoring the real activities of COMT in complex biological samples, as well as for rapid screening of potential COMT inhibitors which are useful in the treatment of Parkinson's diseases Furthermore, the probe has been successfully used to monitor endogenous COMT in living cells for the first time, and the results demonstrate that DHMC is cell membrane permeable and low toxic to the cells. All these features of DHMC suggested that this probe holds great promise for COMT-related regulation and inhibition assays in drug discovery, as well as for further investigation on the biological functions of COMT in living cells. [ABSTRACT FROM AUTHOR]

A fluorescent responsive BMP32C10-based cryptand host was successfully synthesized by introducing a 4-methylcoumarin group to the third arm of the cryptand. The cryptand was able to undergo [2+2] photodimerization on UV irradiation (λ = 365 nm) and, based on the photodimerization and host–guest interaction, a new supramolecular polymer was constructed in a convenient manner. [ABSTRACT FROM AUTHOR]

5-[2-( N,N -dimethylamino)ethoxy]-4,7-dimethylcoumarin ( 1 ) and 6-acetyl-5-[2-( N,N -dimethylamino)ethoxy]-4,7-dimethylcoumarin ( 2 ), structurally related, were synthesized using both conventional and microwave-assisted approach. An impact of acetyl groups on the molecular structure of coumarin derivatives has been examined. Crystals of 2 were investigated using single crystal and powder X-ray diffraction techniques. Compound 2 crystallizes forming two polymorphs (denoted as 2_1 and 2_2), both belonging to P 2 1 / c space group. Both polymorphs are comparably stable and can be formed simultaneously during crystallization process. The solid state structure was also analysed using the fully resolved 13 C CP/MAS NMR. The double signals with the intensity ratio of about 1:1 which were observed in the 13 C CP/MAS NMR spectrum of compound 1 must arise due to the presence of two conformers of 1 . In contrast, NMR spectrum recorded for powder mixture of two polymorphs of compound 2 displays no signal splitting. This is related to structural similarities of molecules in both polymorphs. [ABSTRACT FROM AUTHOR]

The copper-catalyzed methylation of coumarin by using di- tert-butyl peroxide (DTBP) has been described. The reaction provides direct access to a wide range of 3-methylcoumarins in moderate to good yields. In this procedure, it is noteworthy that DTBP was employed not only as the oxidant, but also as the methyl source. [ABSTRACT FROM AUTHOR]

The design and synthesis is reported of 7-(9 H-carbazol-9-yl)-4-methylcoumarin (Cz-Cm), comprising a carbazole donor moiety and a 4-methylcoumarin acceptor unit, for use in a blue organic light-emitting diode. A detailed solid state, theoretical and spectroscopic study was performed to understand the structure-property relationships. The material exhibits deep-blue emission and high photoluminescence quantum yield both in solution and in a doped matrix. A deep-blue electroluminescence emission at 430 nm, a maximum brightness of 292 cd m−2 and an external quantum efficiency of 0.4 % was achieved with a device configured as follows: ITO/NPD (30 nm)/TCTA (20 nm)/CzSi(10 nm)/10 wt % Cz-Cm:DPEPO (10 nm)/TPBI (30 nm)/LiF (1 nm)/Al [ITO=indium tin oxide, NPD= N, N′-di(1-naphthyl)- N, N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine, TCTA=tris(4-carbazoyl-9-ylphenyl)amine, CzSi=9-(4- tert-butylphenyl)-3,6-bis(triphenylsilyl)-9 H-carbazole, DPEPO=bis[2-(diphenylphosphino)phenyl]ether oxide, TPBI=1,3,5-tris( N-phenylbenzimidazol-2-yl)benzene]. [ABSTRACT FROM AUTHOR]

The synthesis of N1and N2coumarin substituted 1,2,3-triazole isomers from terminal alkynes, sodium azide, and 4-bromomethylcoumarins in the presence of triethylamine as a base and CuI as a catalyst in good yield are reported. The molecular structure of compounds3gand5dare established by single-crystal analysis. [ABSTRACT FROM PUBLISHER]

Heteroaromatic thiols and thiones attracted the attention of chemists, pharmacologists and biochemists because of participation in the interception of free radicals. For the first time offered independent and reliable methods for evaluating of the antioxidant activity of thioamides-derivatives of pyridine, quinoline, imidazole, triazole, tetrazole, pyrimidine, pyrrolidine and 7-mercapto-4-methylcoumarin -based on kinetic parameters of the thioamide reaction with chromogenic radical (rate constant, M −1 min −1 and time to decrease concentration of test free radical by 50%, T EC50 , min) or thermodynamics of the thioamides reaction with molecular iodine (extent of thioamide conversion, %). To compare the antioxidant activity of thioamides and widely used standard-antioxidant Trolox (6-Hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid) we have proposed to use a value of relative antioxidant activity constant. As it was established, the kinetics of interaction between the chromogenic radical and thioamides in the presence of an excess of 2,2′-diphenyl-1-picrylhydrazyl (DPPH) is described by the kinetics of the pseudo first order with respect to the reacting components. A kinetic-spectrophotometric method for the quantification of heteroaromatic thioamides is elaborated and was tested in the analysis of urine. Thioamides were detected at concentrations of 1.53 μg ml −1 , RSD=4.6% (2-mercaptoimidazole, V), 2.08 μg ml −1 , RSD=1.8% (1-methylimidazoline-2-thione, VI), 1.45 μg ml −1 , RSD=4.3% (2-mercaptopyridine, IX).The proposed procedures show good precision and accuracy of the results obtained. [ABSTRACT FROM AUTHOR]

The effective fragment potential (EFP) method of solvation interfaced with the density functional theory (DFT) was applied to investigate the hydrogen bonding (HB) sites of 7-hydroxy-4-methylcoumarin (4MU (4-methylumbelliferone)) and 7-methoxy-4-methylcoumarin (MMC) in water. The original EFP model (EFP1) was used to form 4MU–(H2O)5, 4MU−–(H2O)5, 4MUT–(H2O)5 (keto tautomer of 4MU) and MMC–(H2O)2 complexes. A hydrogen bond network was formed by three water molecules between the oxygen of the carbonyl group and hydrogen (oxygen) of the hydroxyl group. Five HBs were formed by 4MU and 4MUT with water molecules; two C=O…H (B type), one C–O…H (B′ type), one by the oxygen of the pyrone ring with the hydrogen of the hydroxyl group or water molecule (B′′ type) and one O–H…O (type C). 4MU− also formed five HBs; two B type, two B′ type and one B′′ type. Two HBs are formed by MMC; one B type and one B′ type. The excited state properties were computed using the state-specific time dependent density functional theory (SS-TDDFT) combined with the polarizable continuum model (PCM) and EFP1 method. The excited state hydrogen transfer (ESHT) was found in the first excited (S1) state of 4MU. C–OH bond contracting, O–H bond stretching and O–H…O HB strengthening suggests the possibility of hydrogen transfer from the hydroxyl group to a water molecule and water molecule to the carbonyl group at the S1 state. Natural charge analysis manifests the intramolecular charge transfer (ICT) of 4MU chromophore in the S1 state, and the calculated electronic absorption and fluorescence spectra of 4MU, 4MU− and 4MUT in water revealed the tendency of hydrogen transfer in the S1 state. The change in HB energy between the 4MU–(H2O)5 complex at the S0 state and the 4MUT–(H2O)5 complex at the S1 state confirms the formation of the 4MUT–(H2O)5 complex at the first excited state. [ABSTRACT FROM AUTHOR]

In the search for new environmental-friendly antifoulants for replace metallic biocides, 7-hydroxy-4-methylcoumarin was synthesized according to green chemistry procedures. This compound was characterized by current organic analysis and its antifouling properties were firstly evaluated on the bivalve Mytilus edulis platensis in the laboratory. In the second stage, a soluble matrix antifouling coating formulated with this compound was assayed in marine environment. Laboratory experiments showed that 7-hydroxy-4-methylcoumarin was effective in inhibiting both the settlement as well as the byssogenesis of mussels. In addition, after exposure time in the sea, painted panels containing this compound showed strong antifouling effect on conspicuous species of the fouling community of Mar el Plata harbor. In conclusion, green-synthesized coumarin could be a suitable antifoulant candidate for marine protective coatings. [ABSTRACT FROM AUTHOR]

Context: Cancer is a leading cause of death worldwide and novel chemotherapeutic agents with better efficacy and safety profiles are much needed. Coumarins are natural polyphenolic compounds with important pharmacological activities, which are present in many dietary plants and herbal remedies. Objectives: The objective of this study is to investigate natural and synthetic coumarin derivatives with considerable anticancer capacity against three human cancer cell lines. Materials and methods: We synthesized 27 coumarin derivatives (mostly having 4-methyl moiety) and examined their cytotoxic effect on three human cancer cell lines, K562 (chronic myelogenous leukemia), LS180 (colon adenocarcinoma), and MCF-7 (breast adenocarcinoma) by MTT reduction assay. Screened compounds included 7-hydroxy-4-methylcoumarins (7-HMCs), 7-acetoxy-4-methylcoumarins (7-AMCs), and different dihydroxy-4-methylcoumarin (DHMC) and diacetoxy-4-methylcoumarin (DAMC) derivatives. Some compounds with methoxy, amine, and bromine substitutions were also examined. Results: 7,8-DHMCs bearing alkyl groups at C3 position were the most effective subgroup, and of which, the most potent is compound11, with ann-decyl chain at C3, which had IC50values of 42.4, 25.2, and 25.1 µM against K562, LS180, and MCF-7 cells, respectively. The second most active subgroup was 7,8-DAMCs containing ethoxycarbonylmethyl and ethoxycarbonylethyl moieties at C3 position. Compound27(6-bromo-4-bromomethyl-7-hydroxycoumarin), the only derivative containing bromine also showed reasonable cytotoxic activities (IC50range: 32.7–45.8 µM). Discussion and conclusion: This structure–activity relationship (SAR) study of 4-methylcoumarins shows that further investigation of these derivatives may lead to the discovery of novel anticancer agents. [ABSTRACT FROM PUBLISHER]

On heating with zinc in acetic acid 2-(N-arylamino)chromone-3-carbaldehydes produce 2-(N-arylamino)-3-methylchromones, whereas 2-(N-alkylamino)chromone-3-carbaldehydes produce 4-hydroxy-3-methylcoumarin in moderate yields. Reduction of an aldehyde function to a methyl group has been achieved under very mild reaction conditions. [ABSTRACT FROM AUTHOR]

To develop PSA peptide substrates with improved specificity and plasma stability from the known substrate sequence glutaryl-Hyp-Ala-Ser-Chg-Gln, systematic replacements of the N-terminal segment with D-retro-inverso-peptides were performed with the incorporation of 7-amino-4-methylcoumarin (7- AMC) after Gln for convenient fluorometric determination and ranking of the PSA substrate activity. The D-retro-inverso-peptide conjugates with P2-P5 D-amino acid substitutions were moderate but poorer PSA substrates as compared to the original peptide, suggesting that inversion of the amide bonds and/or incorporation of the additional atom as in the urea linker adversely affected PSA binding. However, P5 substitution of Hyp with Ser showed significant improvements in PSA cleavage rate; the resulting AMC conjugate, glutaryl-Ser-Ala-Ser-Chg-Gln- AMC ( 11), exhibited the fastest PSA cleavage rate of 351 pmol/min/100 nmol PSA. In addition, GABA← mGly-Ala-Ser-Chg-Gln- AMC (conjugate 6) was the second best PSA substrate and released 7- AMC at a rate of 225 pmol/min/100 nmol PSA as compared to 171 pmol/min/100 nmol PSA for the control conjugate glutaryl-Hyp-Ala-Ser-Chg-Gln- AMC. Incubations of selected AMC conjugates with mouse and human plasma revealed that GABA←D-Ser- ψ[ NH- CO- NH]-Ala-Ser-Chg-Gln- AMC ( 5) and GABA← mGly-Ala-Ser-Chg-Gln- AMC ( 6) were most stable to non- PSA-mediated proteolysis. Our results suggest that the PSA specificity of glutaryl-Hyp-Ala-Ser-Chg-Gln is improved with Ser and mGly substitutions of Hyp at the P5. [ABSTRACT FROM AUTHOR]

The excited-state multiple proton transfer (ESMPT) reaction has been investigated for tautomerization of the 7-hydroxy-4-methylcoumarin·(NH3)3 (7H4MC·(NH3)3) cluster by means of time-dependent density functional theory. In the 7H4MC·(NH3)3 cluster, our results have demonstrated that four intermolecular hydrogen bonds are strengthened in the first excited state upon photoexcitation. This mechanism can remarkably facilitate the releasing of the proton from the phenolic group of the 7H4MC moiety to the hydrogen-bonded ammonia wire (NH3…NH3…NH3). Subsequently, an intermediate transition conformer (A·(NH3)3H+) appears on the excited-state proton-transfer energy curve. In the A·(NH3)3H+ conformer, the intramolecular charge transfer process is revealed due to the proton motion. This process is able to effectively trigger the subsequent ESMPT reaction. Therefore, the different types of excited-state hydrogen-bonded dynamics mechanisms orderly provide two driving forces for the ESMPT reaction in the 7H4MC·(NH3)3 cluster. In addition, the mechanism of the ESMPT processes in the 7H4MC molecule along different kinds of hydrogen-bonded wires (ammonia and water) has been elucidated, and the internal property of transformation is discussed in detail. [ABSTRACT FROM AUTHOR]

Condensation of equimolar amount of 8-formyl-7-hydroxy-4-methylcoumarin (fhmc) and hydrazides [benzoylhydrazide (bhz), isonicotinoylhydrazide (inh), nicotinoylhydrazide (nah) and furoylhydrazide (fah)] in methanol results in the formation of potential ONO tridentate ligands H 2 fhmc-bhz ( I ), H 2 fhmc-inh ( II ), H 2 fhmc-nah ( III ), and H 2 fhmc-fah ( IV ), respectively. Reaction of these ligands with [Mo VI O 2 (acac) 2 ] in refluxing methanol gives dioxidomolybdenum(VI) complexes, [Mo VI O 2 (fhmc-bhz)(MeOH)] ( 1 ), [Mo VI O 2 (fhmc-inh)(MeOH)] ( 2 ), [Mo VI O 2 (fhmc-nah)(MeOH)] ( 3 ) and [Mo VI O 2 (fhmc-fah)(MeOH)] ( 4 ), respectively. The structures of the obtained ligand and their respective metal complexes were elucidated by elemental analyses, spectroscopic techniques (IR, electronic, 1 H and 13 C NMR) and thermogravimetric analyses. Single crystal X-ray analysis of complex 1a confirms the chelation of the ligand to the metal ion through two oxygen and a nitrogen atoms. These metal complexes have been tested against oxidative bromination of monoterpene (thymol) to yield 2-bromothymol, 4-bromothymol and 2,4-dibromothymol using H 2 O 2 as an oxidant therefore they act as functional models of vanadium dependent haloperoxidases. The effects of various factors, such as amounts of catalyst, oxidant, KBr, HClO 4 and different solvents have been considered to optimize the reaction conditions for the maximum brominated products. [ABSTRACT FROM AUTHOR]

A popular thermal-stability assay developed especially for the study of membrane proteins uses a thiol-specific probe, 7-diethylamino-3-(4-maleimidophenyl)-4-methylcoumarin (CPM). The fluorescence emission of CPM surges when it forms a covalent bond with the side chain of a free Cys, which becomes more readily accessible upon protein thermal denaturation. Interestingly, the melting temperatures of membrane proteins determined using the CPM assay in literature are closely clustered in the temperature range 45-55 °C. A thorough understanding of the mechanism behind the observed signal change is critical for the accurate interpretation of the protein unfolding. Here we used two α-helical membrane proteins, AqpZ and AcrB, as model systems to investigate the nature of the fluorescence surge in the CPM assay. We found that the transition temperatures measured using circular-dichroism (CD) spectroscopy and the CPM assay were significantly different. To eliminate potential artifact that might arise from the presence of detergent, we monitored the unfolding of two soluble proteins. We found that, contrary to current understanding, the presence of a sulfhydryl group was not a prerequisite for the CPM thermal-stability assay. The observed fluorescence increase is probably caused by binding of the fluorophore to hydrophobic patches exposed upon protein unfolding. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

SIRT6, as one of these seven sirtuins, has been shown to have the therapeutic potentials for treating several human diseases. A fluorogenic assay for SIRT6 has been developed to screen their small molecule modulators based on the recent discovery that SIRT6 is a defatty-acylase (removing long chain fatty acyl groups). However, this assay uses a fluorogenic peptide containing 7-amino-4-methylcoumarin (AMC), which becomes the cause of false positive hits from screenings. To overcome this, we have developed an alternative method called a FRET-based assay suitable for screening SIRT6 modulators, which will be reliable and useful in a high-throughput format since no AMC group present in this assay. [ABSTRACT FROM AUTHOR]

5-[2-( N,N -diethylamino)ethoxy]-4,7-dimethylcoumarin ( 1 ) and 6-acetyl-5-[2-( N,N -diethylamino)ethoxy]-4,7-dimethylcoumarin ( 2 ) were synthesized in a traditional way and microwave-assisted synthesis. Crystals of 2 in form of hydrochloride salt ( 3 ) were investigated using single crystal X-ray diffraction technique. In the crystal lattice of 3 there is only one type of strong hydrogen bond present involving protonated amino group and chloride anion. The whole structure is dominated by weak C–H…Cl − , C–H…O contacts. There is also visible aggregation of cations in stacks due to π–π interactions. The solid state structures of 1 and 2 derived from 13 C CP/MAS NMR spectra were also proposed. [ABSTRACT FROM AUTHOR]