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Objective: This research aimed to delineate the pharmacological mechanisms of 7-Hydroxycoumarin (7-HC) on ulcerative colitis (UC) employing network pharmacology and experimental validation. Methods: To investigate the therapeutic effects of 7-HC on UC, a UC mouse model was established through the unrestricted intake of 3.0% dextran sulfate sodium (DSS) in their drinking water. Subsequently, we predicted the core targets and signaling pathways of 7-HC for the treatment of UC using the network pharmacology approach. Finally, the insights gained from network pharmacology were further validated by molecular docking, molecular dynamics simulation as well as in vivo experiments. Results: Administering 7-HC orally to mice with UC led to a marked improvement in colitis indicators. Furthermore, 7-HC significantly lowered the levels of inflammatory cytokines (TNF-α, IL-1β) in the colon and modulated oxidative stress markers (MPO, SOD). Subsequent studies identified 2 core targets (AKT1 and EGFR) in the colon of UC mice that were inhibited by 7-HC. Network pharmacology and experimental validation showed that 7-HC can reduce the expression of MAPK pathway markers P38, JNK, ERK, and their phosphorylation; 7-HC can also ameliorate UC by regulating the gut microbiome. Conclusion: 7-HC demonstrates considerable efficacy in alleviating UC in mice, primarily through substantial diminution of tissue inflammation and oxidative stress. This is the first time that 7-HC has been found to treat UC by inhibiting the MAPK pathway and modulating the gut microbiota, providing a fresh perspective on the pharmacological mechanisms through which 7-HC operates in the management of UC. [ABSTRACT FROM AUTHOR]

Abstract Objective This research aimed to delineate the pharmacological mechanisms of 7-Hydroxycoumarin (7-HC) on ulcerative colitis (UC) employing network pharmacology and experimental validation. Methods To investigate the therapeutic effects of 7-HC on UC, a UC mouse model was established through the unrestricted intake of 3.0% dextran sulfate sodium (DSS) in their drinking water. Subsequently, we predicted the core targets and signaling pathways of 7-HC for the treatment of UC using the network pharmacology approach. Finally, the insights gained from network pharmacology were further validated by molecular docking, molecular dynamics simulation as well as in vivo experiments. Results Administering 7-HC orally to mice with UC led to a marked improvement in colitis indicators. Furthermore, 7-HC significantly lowered the levels of inflammatory cytokines (TNF-α, IL-1β) in the colon and modulated oxidative stress markers (MPO, SOD). Subsequent studies identified 2 core targets (AKT1 and EGFR) in the colon of UC mice that were inhibited by 7-HC. Network pharmacology and experimental validation showed that 7-HC can reduce the expression of MAPK pathway markers P38, JNK, ERK, and their phosphorylation; 7-HC can also ameliorate UC by regulating the gut microbiome. Conclusion 7-HC demonstrates considerable efficacy in alleviating UC in mice, primarily through substantial diminution of tissue inflammation and oxidative stress. This is the first time that 7-HC has been found to treat UC by inhibiting the MAPK pathway and modulating the gut microbiota, providing a fresh perspective on the pharmacological mechanisms through which 7-HC operates in the management of UC.

CYP2A7 is one of the most understudied human cytochrome P450 enzymes and its contributions to either drug metabolism or endogenous biosynthesis pathways are not understood, as its only known enzymatic activities are the conversions of two proluciferin probe substrates. In addition, the CYP2A7 gene contains four single-nucleotide polymorphisms (SNPs) that cause missense mutations and have minor allele frequencies (MAFs) above 0.5. This means that the resulting amino acid changes occur in the majority of humans. In a previous study, we employed the reference standard sequence (called CYP2A7*1 in P450 nomenclature). For the present study, we created another CYP2A7 sequence that contains all four amino acid changes (Cys311, Glu169, Gly479, and Arg274) and labeled it CYP2A7-WT. Thus, it was the aim of this study to identify new substrates and inhibitors of CYP2A7 and to compare the properties of CYP2A7-WT with CYP2A7*1. We found several new proluciferin probe substrates for both enzyme variants (we also performed in silico studies to understand the activity difference between CYP2A7-WT and CYP2A7*1 on specific substrates), and we show that while they do not act on the standard CYP2A6 substrates nicotine, coumarin, or 7-ethoxycoumarin, both can hydroxylate diclofenac (as can CYP2A6). Moreover, we found ketoconazole, 1-benzylimidazole, and letrozole to be CYP2A7 inhibitors. [ABSTRACT FROM AUTHOR]

Background. The rejection of antibiotics in animal husbandry encourages the search for new more effective alternatives, one of which is phytochemicals – small molecules with pronounced bioactive effect. Materials and methods. The article discusses the physiological properties of quercetin, 7-hydroxycoumarin, vanillin, trans-cinnamon aldehyde, as active substances from extracts of some plants. Their biological certification was carried out in the bacterial luminescence inhibition test using a recombinant strain of Escherichia coli K12 TG1 in comparison with the antibiotic drug tetracycline. Results. Effective concentrations of quercetin, 7-hydroxycoumarin, vanillin, trans-cinnamic aldehyde, suppressing 80, 50 and 20 % luminescence in two media – H2O and scar fluid, respectively, have been established. 9,8×10-4; 4,9×10-4; 6,1×10-5 mol/l for trans-cinnamon aldehyde; 3.9×10-3; 1.9×10-3; 4.9×10-4 mol/l for vanillin; 2,5×10-1; 1,2×10-1; 9,8×10-4 mol/l for quercetin dihydrate; 1,6×10-2; 9,8×10-4; 4,9×10-4 mol/l for 7-hydroxycoumarin. Conclusion. Trans-cinnamon aldehyde, vanillin, 7-hydroxycoumarin and quercetin have a pronounced bactericidal or bacteriostatic effect and can be used as an alternative to antibiotic preparations in feeding farm animals, including cattle. In particular, synergistically increasing suppression of the bacterial strain is observed in the environment of the scar content.

Umbelliferone (UMB), a natural coumarin compound, has been reported to possess anti-rheumatic effects on rheumatoid arthritis (RA) experimental models, but its potential role of UMB in regulating migration, invasion and inflammation of RA fibroblast-like synoviocytes (FLS) remain unclear. Herein, MTT assay was performed to confirm the non-cytotoxic concentrations (10, 20, and 40 μ M) and the treatment time (24 h) of UMB on TNF- α -stimulated RA FLS (MH7A cells) in vitro. Results of wound-healing, transwell and phalloidin staining assays revealed that UMB inhibited TNF- α -induced migration, invasion and F-actin cytoskeletal reorganization in MH7A. Results of ELISA, western blot and gelatin zymography indicated that UMB decreased the productions of pro-inflammatory factors, including IL-1 β , IL-6, IL-8, MMP-2 and MMP-9, and inhibited MMP-2 activity in TNF- α -stimulated MH7A cells. In vivo, UMB (25 mg/kg and 50 mg/kg) relieved the joint damage and synovial inflammation in rats with adjuvant-induced arthritis (AIA). Mechanistically, UMB could suppress Wnt/ β -catenin signaling both in TNF- α -induced MH7A cells and in AIA rat synovium, evidenced by decreasing Wnt1 protein level, activating GSK-3 β kinase by blocking GSK-3 β (Ser9) phosphorylation, and reducing the protein level and nuclear translocation of β -catenin. Importantly, combined use of lithium chloride (a Wnt/ β -catenin signaling agonist) eliminated the inhibitory effects of UMB on migration, invasion and inflammation in vitro and the anti-arthritic effects of UMB in vivo. We concluded that UMB inhibited TNF- α -induced migration, invasion and inflammation of RA FLS and attenuated the severity of rat AIA through its ability to block Wnt/ β -catenin signaling pathway. [ABSTRACT FROM AUTHOR]

Cardiovascular diseases (CVD) are the deadliest noncommunicable disease worldwide. Hypertension is the most prevalent risk factor for the development of CVD. Although there is a wide range of antihypertensive drugs, there still remains a lack of blood pressure control options for hypertensive patients. Additionally, natural products remain crucial to the design of new drugs. The natural product 7-hydroxycoumarin (7-HC) exhibits pharmacological properties linked to antihypertensive mechanisms of action. This study aimed to evaluate the vascular effects of 7-HC in an experimental model of essential hypertension. The isometric tension measurements assessed the relaxant effect induced by 7-HC (0.001 μM–300 μM) in superior mesenteric arteries isolated from hypertensive rats (SHR, 200–300 g). Our results suggest that the relaxant effect induced by 7-HC rely on K+-channels (KATP, BKCa, and, to a lesser extent, Kv) activation and also on Ca2+ influx from sarcolemma and sarcoplasmic reticulum mobilization (inositol 1,4,5-triphosphate (IP3) and ryanodine receptors). Moreover, 7-HC diminishes the mesenteric artery's responsiveness to α1-adrenergic agonist challenge and improves the actions of the muscarinic agonist and NO donor. The present work demonstrated that the relaxant mechanism of 7-HC in SHR involves endothelium-independent vasorelaxant factors. Additionally, 7-HC reduced vasoconstriction of the sympathetic agonist while improving vascular endothelium-dependent and independent relaxation. [ABSTRACT FROM AUTHOR]

7-Hydroxycoumarin's FT-IR solid phase spectra were observed at 4000–400 cm−1. The spectra were analyzed in aspects of significant approaches. DFT was used to optimize the structure of the compound and its structural properties. The molecular properties were also determined by the HF/3-21G level. The bond lengths and bond angles were obtained by the computational study of the optimized geometry. The vibrational frequencies were determined in all these approaches, which were then matched to experimental frequencies, yielding an excellent agreement between measured and estimated frequency ranges. The UV–visible spectrum of 7HC was obtained and the electronic characteristics HOMO and LUMO energies were monitored by the time-dependent TD-DFT method. The spectral behavior of 7-Hydroxycoumarin was studied using fluorescence spectroscopy in a wide range of polar and non-polar solvents. Solvatochromic effect was observed in both the fluorescence and absorption spectra. The structural properties, energies, IR intensities, absorption wavelengths, and harmonic vibrational frequencies were compared with the obtainable experimental information of the molecule. [ABSTRACT FROM AUTHOR]

In this paper, a kind of fluorescent anti-counter feiting acrylate pressure-sensitive adhesive (PSA) label was prepared using 7-hydroxycoumarin and acrylate monomer. First,7-hydroxycoumarin was reacted with 3-bromopropylene and coumarin derivatives were prepared. And thio-terminated intermediate-mercaptan A was obtained by the reaction of the mercaptan group of 2,2ʹ-(Ethylenedioxy) diethanethiol with the double bond. Then, mercaptan A was reacted with acrylate and a novel fluorescent anti-counterfeiting acrylate PSA was prepared. Finally, a novel fluorescent anti-counterfeiting acrylate PSA label was prepared by coating the adhesive on the PET label. The experimental results showed that with the increasing of mercaptan A content, the tensile strength, shear resistance, thermal stability property and fluorescence of mercaptan A-acrylate PSA were improved. When the content of mercaptan A was 5 wt %, the tack,180° peel strength and shear resistance of mercaptan A-acrylate PSA were No.5 ball, 0.54 KN/m and 87 h, respectively. The mercaptan A-acrylate PSA showed bright blue fluorescence under the ultraviolet lamp. [ABSTRACT FROM AUTHOR]

Breast cancer is the most common malignancy worldwide; therefore, the development of new anticancer agents is essential for improved tumor control. By adopting the pharmacophore hybridization approach, two series of 7-hydroxyl-4-methylcoumarin hybridized with thiosemicarbazone (V–VI) and thiazolidin-4-one moieties (VII–VIII) were prepared. The in vitro anticancer activity was assessed against MCF-7 cells adopting the MTT assay. Nine compounds showed significant cytotoxicity. The most promising compound, VIIb, induced remarkable cytotoxicity (IC50 of 1.03 + 0.05 µM). Further investigations were conducted to explore its pro-apoptotic activity demonstrating S-phase cell cycle arrest. Apoptosis rates following VIIb treatment revealed a 5-fold and 100-fold increase in early and late apoptotic cells, correspondingly. Moreover, our results showed caspase-9 dependent apoptosis induction as manifested by an 8-fold increase in caspase-9 level following VIIb treatment. Mechanistically, VIIb was found to target the PI3K-α/Akt-1 axis, as evidenced by enzyme inhibition assay results reporting significant inhibition of examined enzymes. These findings were confirmed by Western blot results indicating the ability of VIIb to repress levels of Cyclin D1, p-PI3K, and p-Akt. Furthermore, docking studies showed that VIIb has a binding affinity with the PI3K binding site higher than the original ligands X6K. Our results suggest that VIIb has pharmacological potential as a promising anti-cancer compound by the inhibition of the PI3K/Akt axis. [ABSTRACT FROM AUTHOR]

The effective fraction of coumarin glycosides from Hydrangea paniculata Sieb (HP) has been under development for the treatment of chronic kidney disease for years. Skimmin and apiosylskimmin are the main coumarin glycosides of HP, and the major metabolites in rats are 7‐hydroxycoumarin (7‐HC) and 7‐hydroxycoumarin glucuronide (7‐HCG). In this study, a sensitive and reliable liquid chromatography–Orbitrap mass spectrometry method was developed for the simultaneous determination of skimmin, apiosylskimmin, 7‐HC and 7‐HCG in rat plasma. The chromatographic separation was performed on a Zobax SB C18 column (2.1 × 100 mm, 3.5 μm) at a flow rate of 0.3 ml/min with a gradient mobile phase of water and acetonitrile containing 0.2% formic acid. Skimmin, apiosylskimmin and 7‐HCG were detected in targeted‐selected‐ion‐monitoring mode at positive ions m/z of 325.0911, 457.1331 and 339.0703, respectively. 7‐HC and the internal standard were detected in parallel‐reaction‐monitoring mode at m/z 163.0387 → 119.0492 and 260.1641 → 116.1071 to overcome the carryover of 7‐HC. Linearity was obtained for the analytes within the ranges 20–2,000 ng/ml for skimmin, 5–500 ng/ml for apiosylskimmin and 7‐HC and 100–10,000 ng/ml for 7‐HCG. Validation parameters were all in line with the criteria of international guidance. The method has been applied to the pharmacokinetic study of HP in rats. [ABSTRACT FROM AUTHOR]

Coumarin is a naturally occurring component of food products but is of clinical interest for its potential hepatotoxicity in humans. In the current study, the pharmacokinetics of coumarin in humanized-liver mice after oral and intravenous administrations (30 mg/kg) were investigated for its transformations to metabolically active coumarin 3,4-epoxide (as estimated by the levels of o-hydroxyphenylacetic acid) and to excretable 7-hydroxycoumarin. After oral administration, control mice metabolized coumarin to o-hydroxyphenylacetic acid at roughly the same rate as that to 7-hydroxycoumarin (total of unconjugated and conjugated forms). In contrast, the in vivo biotransformation of coumarin to o-hydroxyphenylacetic acid by humanized-liver mice was around two orders of magnitude less than that to conjugated and unconjugated 7-hydroxycoumarin. After intravenous administrations of coumarin, differences were observed in the plasma concentrations of o-hydroxyphenylacetic acid between humanizedliver mice treated with furafylline (daily oral doses of 13 mg/kg for 3 days) and untreated humanized-liver mice. The mean values of the areas under the plasma concentration versus time curves and the maximum concentrations for o-hydroxyphenylacetic acid were significantly lower in the group treated with furafylline (45% and 57% of the untreated values, respectively). These results suggested that the metabolic activation of coumarin in humans was mediated mainly by P450 1A2, which was suppressed by furafylline, and that humanized-liver mice orally treated with furafylline might constitute an in vivo model for metabolically inactivated P450 1A2 in human hepatocytes transplanted into chimeric mice. [ABSTRACT FROM AUTHOR]

Cardiovascular diseases (CVD) are the deadliest noncommunicable disease worldwide. Hypertension is the most prevalent risk factor for the development of CVD. Although there is a wide range of antihypertensive drugs, there still remains a lack of blood pressure control options for hypertensive patients. Additionally, natural products remain crucial to the design of new drugs. The natural product 7-hydroxycoumarin (7-HC) exhibits pharmacological properties linked to antihypertensive mechanisms of action. This study aimed to evaluate the vascular effects of 7-HC in an experimental model of essential hypertension. The isometric tension measurements assessed the relaxant effect induced by 7-HC (0.001 μM–300 μM) in superior mesenteric arteries isolated from hypertensive rats (SHR, 200–300 g). Our results suggest that the relaxant effect induced by 7-HC rely on K+-channels (KATP, BKCa, and, to a lesser extent, Kv) activation and also on Ca2+ influx from sarcolemma and sarcoplasmic reticulum mobilization (inositol 1,4,5-triphosphate (IP3) and ryanodine receptors). Moreover, 7-HC diminishes the mesenteric artery’s responsiveness to α1-adrenergic agonist challenge and improves the actions of the muscarinic agonist and NO donor. The present work demonstrated that the relaxant mechanism of 7-HC in SHR involves endothelium-independent vasorelaxant factors. Additionally, 7-HC reduced vasoconstriction of the sympathetic agonist while improving vascular endothelium-dependent and independent relaxation.

Dietary-derived coumarin is of clinical interest for its potential hepatotoxicity in humans because such toxicity is especially evident in rats. In this study, the oxidative metabolism of coumarin to active coumarin 3,4-epoxide (as judged by the formation rates of o-hydroxyphenylacetic acid) and excretable 7-hydroxycoumarin was investigated in liver fractions from rats and humans. In rat liver microsomes, the formation rate of o-hydroxyphenylacetic acid (~6 pmol/min/mg microsomal protein) from coumarin at 10 μM was dependent on the presence of liver cytosolic fractions. Rat hepatocytes mediated similar formation rates of o-hydroxyphenylacetic acid and 7-hydroxycoumarin (~0.1 nmol/hr/106 cells) at 0.20-20 μM coumarin. Human hepatocytes mediated the biotransformation of coumarin to o-hydroxyphenylacetic acid at roughly similar rates to those of rat hepatocytes. In contrast, the formation rates of 7-hydroxycoumarin by human hepatocytes were around 10-fold higher at ~1 nmol/hr/106 cells. In the presence of human liver cytosolic fractions, the oxidative formation rate of o-hydroxyphenylacetic acid was relatively high in cytochrome P450 (P450) 1A2-rich human liver microsomes. The inhibitory effects of furafylline/α-naphthoflavone and 8-methoxypsoralen, P450 1A2 and 2A6 inhibitors, respectively, were seen on the rates of o-hydroxyphenylacetic and 7-hydroxylation formations, respectively, in pooled human liver microsomes. Human liver microsomes selectively inactivated for P450 1A2 and 2A6 showed low rates of o-hydroxyphenylacetic acid and 7-hydroxylation formation (~20-30% of control), respectively. Among the P450 isoforms tested, recombinant human P450 1A2 predominantly mediated o-hydroxyphenylacetic formation. These results suggested that the metabolic activation and deactivation of coumarin were mediated mainly by P450 1A2 and 2A6 enzymes, respectively. The metabolic oxidation of coumarin via 3,4-epoxidation forming o-hydroxyphenylacetic acid could inform individual human risk assessments of dietary-derived coumarin, for which hepatotoxicity is especially evident in rats. [ABSTRACT FROM AUTHOR]

Breast cancer is the most common malignancy worldwide; therefore, the development of new anticancer agents is essential for improved tumor control. By adopting the pharmacophore hybridization approach, two series of 7-hydroxyl-4-methylcoumarin hybridized with thiosemicarbazone (V–VI) and thiazolidin-4-one moieties (VII–VIII) were prepared. The in vitro anticancer activity was assessed against MCF-7 cells adopting the MTT assay. Nine compounds showed significant cytotoxicity. The most promising compound, VIIb, induced remarkable cytotoxicity (IC50 of 1.03 + 0.05 µM). Further investigations were conducted to explore its pro-apoptotic activity demonstrating S-phase cell cycle arrest. Apoptosis rates following VIIb treatment revealed a 5-fold and 100-fold increase in early and late apoptotic cells, correspondingly. Moreover, our results showed caspase-9 dependent apoptosis induction as manifested by an 8-fold increase in caspase-9 level following VIIb treatment. Mechanistically, VIIb was found to target the PI3K-α/Akt-1 axis, as evidenced by enzyme inhibition assay results reporting significant inhibition of examined enzymes. These findings were confirmed by Western blot results indicating the ability of VIIb to repress levels of Cyclin D1, p-PI3K, and p-Akt. Furthermore, docking studies showed that VIIb has a binding affinity with the PI3K binding site higher than the original ligands X6K. Our results suggest that VIIb has pharmacological potential as a promising anti-cancer compound by the inhibition of the PI3K/Akt axis.

Purpose: To investigate the anticancer effects of 7-hydroxycoumarin against cisplatin-resistant ovarian cancer cell line, and the underlying mechanism(s). Methods: Cell proliferation was determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. The 4',6-diamidino-2-phenylindole (DAPI) and acridine orange/ethidium bromide (AO/EB) dual staining methods were used for measuring cell apoptosis in terms of DNA damage. Flow cytometry was used for analysis of mitosis of cancer cells, while protein expression levels were assayed with western blotting. Results: The 7-hydroxycoumarin preferentially inhibited the proliferation of the ovarian cancer cells, but had significantly less prominent effects on normal cells (p < 0.05). The decrease in cell proliferation was due to induction of cell apoptosis via caspase-linked apoptotic pathway. Treatment with 7-hdoxycoumarin further led to the arrest of cancer cell cycle at G2/M stage (p < 0.05) via down-regulation of the expressions of regulatory proteins that promote mitotic entry. Conclusion: 7-Hydroxycoumarin exerts significant anticancer effect against cisplatin-resistant ovarian cancer cells via decrease in cell proliferation, induction of apoptosis and mitotic cell cycle arrest. Thus, the compound could emerge as a vital lead molecule in the treatment of cisplatin-resistant type of human ovarian cancer. [ABSTRACT FROM AUTHOR]

Colistin has been considered as the last line of defense against Gram-negative bacterial infections, however, the potential nephrotoxicity limited its clinical use. 7-Hydroxycoumarin (7-HC) possesses many beneficial pharmacological activities. This study aimed to investigate the nephroprotective effects of 7-HC against colistin-induced kidney injury. In vivo experiments showed that 7-HC alleviated kidney injury induced by colistin, as indicated by lower levels of serum neutrophil gelatinase-associated lipocalin, blood urea nitrogen and creatinine levels. Both in vivo and in vitro results demonstrated that 7-HC alleviated oxidative stress and apoptosis induced by colistin, as shown by decreased malondialdehyde levels, decreased caspase-3 and caspase-9 activities, and increased superoxide dismutase and catalase activities. We also found that colistin significantly induced histone deacetylase (HDAC) 1 expression that deacetylated histone 3 at Lys27 acetylation (H3K27AC) of Nrf2 promoter region and hence inhibiting Nrf2 signaling. 7-HC treatment restored histone acetylation at the Nrf2 promoter region and hence promoted Nrf2 expression. These results suggested that 7-HC alleviates colistin-induced renal injury and this effect was achieved by enhancement of renal antioxidant capacity with the decreased level of HDAC1 and the activation of Nrf2 signaling pathway.

A novel additive, 7‐hydroxycoumarin (7‐HC), is employed to construct a stable interface film on the LiNi0.5Mn1.5O4 cathode to improve the cyclic stability of Li/LiNi0.5Mn1.5O4 cells at elevated temperature (ca. 55 °C). In the 0.01 wt% 7‐hydroxycoumarin‐containing electrolyte, the capacity retention of Li/LiNi0.5Mn1.5O4 cell increases from 78.15 % to 95.64 % at elevated temperature after 100 cycles at 1 C rate. Through theoretical calculations and ex‐situ analysis, it suggests that 7‐HC is susceptible to oxidation than other components of the electrolyte to form a thin and stable film on the surface of LiNi0.5Mn1.5O4 cathode. The thin and stable film can effectively reduce the interface oxidation reaction and the "cross‐talk" between the positive electrode and negative electrode and effectively inhibit the structural changes of LiNi0.5Mn1.5O4 caused by dissolved transition metals in subsequent cycles, thereby improving the cyclic stability of the cell at elevated temperature. [ABSTRACT FROM AUTHOR]

Coumarin is a dietary-derived substance that is extensively metabolized by human liver to excretable 7-hydroxycoumarin. Although coumarin under daily dietary consumption is generally regarded as nontoxic, the substance is of toxicological and clinical interest because of its potential association with hepatotoxicity, which is especially evident in rats. In this study, the pharmacokinetics of coumarin were modeled after virtual oral administration in humans. The adjusted monitoring equivalents of coumarin, along with the biotransformation of coumarin to o-hydroxyphenylacetic acid (via 3,4- epoxidation) based on reported plasma concentrations from rat studies, were scaled to human coumarin equivalents using known species allometric scaling factors. Using rat and human liver preparations, data on the rapid in vitro metabolic clearance for humans (~50-fold faster than in rats) were obtained for in vitro-in vivo extrapolation. For human physiologically based pharmacokinetic (PBPK) modeling, the metabolic ratios to o-hydroxyphenylacetic acid and 7-hydroxycoumarin were set at minor (0.1) and major (0.9) levels for the total disappearance of coumarin. The resulting modeled plasma concentration curves in humans generated by simple PBPK models were consistent with reported simulated coumarin maximum concentrations. These results provide basic information to simulate plasma levels of coumarin and its primary metabolite 7-hydroxycoumarin or its secondary activated metabolite o-hydroxyphenylacetic acid (via 3,4-epoxidation) resulting from dietary foodstuff consumption. Under the current assumptions, little toxicological impact of coumarin was evident in humans, thereby indicating the usefulness of forward dosimetry using PBPK modeling for human risk assessment. [ABSTRACT FROM AUTHOR]

Drug resistance in malaria parasites is one of the major stumbling blocks hindering the goal of malaria elimination. One of the major strategies to counter drug resistance is the development of new potent antimalarial drugs. In the present study, a series of novel sulfonamide based coumarin-[1,2,3]-triazole conjugates have been synthesized via Huisgen reaction between azidosulfonamides and 4-hydroxy- or 7-hydroxymethylcoumarinoalkynes. All the compounds have been characterized spectroscopically and screened for their in vitro antimalarial activity against P. falciparum 3D7 strain. Out of the twenty five synthesized compounds, four compounds displayed significant activity (IC50 <10 µM) with the most active compound having an IC50 of 3.64 µM. [ABSTRACT FROM AUTHOR]

Sulfonation is an important high affinity elimination pathway for phenolic compounds. In this study sulfonation of 7-hydroxycoumarin and 13 its derivatives were evaluated in liver cytosols of human and six animal species. 7-hydroxycoumarin and its derivatives are strongly fluorescent, and their sulfate conjugates are nonfluorescent at excitation 405 nm and emission 460 nm. A convenient fluorescence based kinetic assay of sulfonation was established. The sulfonation rate of most of the 7-hydroxycoumarin derivatives was low in liver cytosol of human and pig, whereas it was high with most compounds in dog and intermediate in rat, mouse, rabbit, and sheep. Sulfonation of the 7-hydroxycoumarin derivatives followed Michaelis-Menten kinetics with Km values of 0.1–12 µM, Vmax of 0.005–1.7 µmol/(min * g protein) and intrinsic clearance (Vmax/Km) of 0.004–1.9 L/(min * g cytosolic protein). Fluorescence based measurement of sulfonation of 7-hydroxycoumarin derivatives provides a sensitive and convenient high-throughput assay to determine sulfonation rate in different species and tissues and can be applied to evaluate sulfonation kinetics and inhibition. [ABSTRACT FROM AUTHOR]

Colistin has been considered as the last line of defense against Gram-negative bacterial infections, however, the potential nephrotoxicity limited its clinical use. 7-Hydroxycoumarin (7-HC) possesses many beneficial pharmacological activities. This study aimed to investigate the nephroprotective effects of 7-HC against colistin-induced kidney injury. In vivo experiments showed that 7-HC alleviated kidney injury induced by colistin, as indicated by lower levels of serum neutrophil gelatinase-associated lipocalin, blood urea nitrogen and creatinine levels. Both in vivo and in vitro results demonstrated that 7-HC alleviated oxidative stress and apoptosis induced by colistin, as shown by decreased malondialdehyde levels, decreased caspase-3 and caspase-9 activities, and increased superoxide dismutase and catalase activities. We also found that colistin significantly induced histone deacetylase (HDAC) 1 expression that deacetylated histone 3 at Lys27 acetylation (H3K27AC) of Nrf2 promoter region and hence inhibiting Nrf2 signaling. 7-HC treatment restored histone acetylation at the Nrf2 promoter region and hence promoted Nrf2 expression. These results suggested that 7-HC alleviates colistin-induced renal injury and this effect was achieved by enhancement of renal antioxidant capacity with the decreased level of HDAC1 and the activation of Nrf2 signaling pathway. [ABSTRACT FROM AUTHOR]

Umbelliferone (UMB) is a natural coumarin that has diverse biological activities. However, its potential to protect against liver fibrosis has not been reported yet. This study aimed to investigate the protective effect of UMB against carbon tetrachloride (CCl4)-induced liver fibrosis in rats. Rats received CCl4 and UMB for 8 weeks and samples were collected for analyses. CCl4 induced a significant increase in serum levels of liver function markers and pro-inflammatory cytokines. Treatment with UMB significantly ameliorated liver function markers and pro-inflammatory cytokines and prevented CCl4-induced histological alterations. CCl4 promoted significant upregulation of α-smooth muscle actin (SMA), collagen I, collagen III, NF-κB p65, TGF-β1, and p-Smad3. Masson's trichrome staining revealed a significant fibrogenesis in CCl4-induced rats. Treatment with UMB suppressed TGF-β1/Smad3 signaling and downregulated α-SMA, collagen I, collagen III, and NF-κB p65. In addition, UMB diminished malondialdehyde and nitric oxide levels, boosted reduced glutathione and antioxidant enzymes, and upregulated the expression of PPARγ. In conclusion, our results demonstrated that UMB prevented CCl4-induced liver fibrosis by attenuating oxidative stress, inflammation, and TGF-β1/Smad3 signaling, and upregulating PPARγ. Therefore, UMB may be a promising candidate for preventing hepatic fibrogenesis, given that further research is needed to delineate the exact molecular mechanisms underlying its antifibrotic efficacy. [ABSTRACT FROM AUTHOR]

Coumarins are well known secondary metabolites widely found in various plants. However, the degradation of these compounds in the environment has not been studied in detail, and, especially, the initial stages of the catabolic pathways of coumarins are not fully understood. A soil isolate Pseudomonas mandelii 7HK4 is able to degrade 7-hydroxycoumarin (umbelliferone) via the formation of 3-(2,4-dihydroxyphenyl)propionic acid, but the enzymes catalyzing the α-pyrone ring transformations have not been characterized. To elucidate an upper pathway of the catabolism of 7-hydroxycoumarin, 7-hydroxycoumarin-inducible genes hcdD, hcdE, hcdF, and hcdG were identified by RT-qPCR analysis. The DNA fragment encoding a putative alcohol dehydrogenase HcdE was cloned, and the recombinant protein catalyzed the NADPH-dependent reduction of 7-hydroxycoumarin both in vivo and in vitro. The reaction product was isolated and characterized as a 7-hydroxy-3,4-dihydrocoumarin based on HPLC-MS and NMR analyses. In addition, the HcdE was active towards 6,7-dihydroxycoumarin, 6-hydroxycoumarin, 6-methylcoumarin and coumarin. Thus, in contrast to the well-known fact that the ene-reductases usually participate in the reduction of the double bond, an alcohol dehydrogenase catalyzing such reaction has been identified, and, for P. mandelii 7HK4, 7-hydroxycoumarin degradation via a 7-hydroxy-3,4-dihydrocoumarin pathway has been proposed.

A novel compound, Cou-platin, composed of 7-hydroxycoumarin and a platinum(IV) moiety derived from cisplatin was designed and synthesized. Significantly, Cou-platin exhibited more potent in vitro antitumor activity against all tested cancer cell lines than that of cisplatin, which was mainly attributed to the liberation of cisplatin and 7-hydroxycoumarin upon reduction with a biomolecular agent. Besides, cellular accumulation of Cou-platin was dramatically increased among several cancer cells in contrast to cisplatin. Flow cytometry study revealed that Cou-platin arrested cell cycle at G2 phase and induced cell apoptosis. Western blots results indicated that it not only activated cell apoptosis pathway, but also inhibited extracellular regulated protein kinases/mitogen-activated protein kinase pathway. In vivo tests showed that Cou-platin, at equimolar dose to cisplatin, could inhibit tumor growth in nude mouse HCT116 tumor xenograft models almost as cisplatin and oxaliplatin, but with less toxicity. [ABSTRACT FROM AUTHOR]

Highly specific and ultrasensitive fluorescent probes for tracking the intracellular native hypochlorous acid (HOCl) levels are urgently needed owing to its important molecular functions in the biological systems. In this contribution, a simple thiocarbamate-caged 7-hydroxycoumarin ( TCHC ) was developed as fluorescent probe for monitoring HOCl in live cells. Probe TCHC exhibited preeminent specificity towards HOCl over other various bioactive substances. Importantly, probe TCHC could sensitively detect HOCl in the range of 0–175 pM with the detection limit of 17 pM, which was attributed to the multiple fluorescence sensing mechanisms including photo-induced electron transfer (PET), intramolecular charge transfer (ICT), and the chlorination. Furthermore, probe TCHC displayed an instant response towards HOCl (<3 s), and thus the real-time detection of HOCl could be achieved. Finally, probe TCHC was successfully applied to monitor native HOCl and the fluctuations of endogenous HOCl levels in live cells. [ABSTRACT FROM AUTHOR]

Hepatic encephalopathy (HE) is a serious neuropsychiatric complication that occurs as a result of liver failure. Umbelliferone (UMB; 7-hydroxycoumarin) is a natural product with proven hepatoprotective activity; however, nothing has yet been reported on its protective effect against hyperammonemia, the main culprit behind the symptoms of HE. Here, we evaluated the effect of UMB against ammonium chloride (NH 4 Cl)-induced hyperammonemia, oxidative stress, inflammation and hematological alterations in rats. We demonstrated the modulatory role of UMB on the glutamate-nitric oxide (NO)-cGMP pathways in the cerebrum of rats. Rats received intraperitoneal injections of NH 4 Cl (3 times/week) for 8 weeks and concomitantly received 50 mg/kg UMB. NH 4 Cl-induced rats showed significantly elevated blood ammonia and liver function markers. Lipid peroxidation and NO were increased in the liver and cerebrum of rats while the antioxidant defenses were declined. UMB significantly reduced blood ammonia, liver function markers, lipid peroxidation and NO, and enhanced the antioxidant defenses in NH 4 Cl-induced rats. UMB significantly prevented anemia, leukocytosis, thrombocytopenia and prolongation of PT and aPTT. Hyperammonemic rats showed elevated levels of cerebral TNF-α, IL-1β and glutamine as well as increased activity and expression of Na + /K + -ATPase, effects that were significantly reversed by UMB. In addition, UMB down-regulated nitric oxide synthase and soluble guanylate cyclase in the cerebrum of hyperammonemic rats. In conclusion, this study provides evidence that UMB protects against hyperammonemia via attenuation of oxidative stress and inflammation. UMB prevents hyperammonemia associated hematological alterations and therefore represents a promising protective agent against the deleterious effects of excess ammonia. [ABSTRACT FROM AUTHOR]

Methyl glyoxal (MG), a major precursor of advanced glycation end-products, has been identified as significant in the progression of several diseases including aging, diabetes and neurodegenerative diseases as well as causing hepatic damages. 7-hydroxycoumarin (7-HC), a natural-occurring derivative of coumarin from fruits and plants, has been reported to exert antioxidant and free radical-scavenging properties, protecting cells from aldehydes and oxidants. In this study, the ability of 7-HC to protect human HepG2 cells against MG-induced toxicity and oxidative stress was investigated. Results show that 7-HC pretreatment significantly attenuates MG-induced cytotoxicity, apoptotic changes and ROS accumulation and that this protection is shown to be associated with the induction of the nuclear factor erythroid 2-related factor 2 (NRF2) and its downstream detoxifying enzymes. In response to 7-HC, NRF2 protein translocates from cytosol to the nuclei. In addition, depletion of NRF2 by siRNA significantly reduces the protective effect of 7-HC against MG, suggesting that NRF2 plays an important role in the protective function of 7-HC. These findings highlight the potential for the interventional activation of the NRF2 induction via the non-toxic natural phytochemical 7-HC as a novel therapeutic approach towards the detoxification of MG, with the aim of halting the progression of diseases in which MG has been implicated. [ABSTRACT FROM AUTHOR]

Umbelliferone (UMB) is a coumarin derivative with promising hepatoprotective effects. In this study, we examined the possible protective effects of UMB against cyclophosphamide (CP)-induced hepatotoxicity, addressing the question of the possible role of nuclear factor erythroid 2-related factor 2 (Nrf2) and peroxisome proliferator activated receptor gamma (PPARγ). Wistar rats were orally administered UMB at doses 50 and 100 mg/kg two weeks prior to CP injection. Five days after CP administration, the rats were sacrificed and samples were collected for analyses. CP induced a significant increase in circulating liver marker enzymes and pro-inflammatory cytokines. Hepatic lipid peroxidation and nitric oxide levels, and nuclear factor-kappaB (NF-κB) and inducible nitric oxide synthase (iNOS) expression were significantly increased following CP administration. UMB supplementation attenuated CP-induced inflammation and oxidative stress as assessed by restoration of the activity and expression of the antioxidant defenses, and suppression of pro-inflammatory cytokines. Histological examination also showed that UMB could significantly reduce CP-induced alterations. CP-induced rats showed significant down-regulation of Nrf2, HO-1 and PPARγ, an effect that was markedly reversed by UMB. In conclusion, the hepatoprotective effects of UMB appear to depend on co-activation of PPARγ and Nrf2, and subsequent suppression of oxidative stress and inflammation. [ABSTRACT FROM AUTHOR]

A gene cluster, denoted as hcdABC, required for the degradation of 3-(2,4-dihydroxyphenyl)-propionic acid has been cloned from 7-hydroxycoumarin-degrading Pseudomonas mandelii 7HK4 (DSM 107615), and sequenced. Bioinformatic analysis shows that the operon hcdABC encodes a flavin-binding hydroxylase (HcdA), an extradiol dioxygenase (HcdB), and a putative hydroxymuconic semialdehyde hydrolase (HcdC). The analysis of the recombinant HcdA activity in vitro confirms that this enzyme belongs to the group of ipso-hydroxylases. The activity of the proteins HcdB and HcdC has been analyzed by using recombinant Escherichia coli cells. Identification of intermediate metabolites allowed us to confirm the predicted enzyme functions and to reconstruct the catabolic pathway of 3-(2,4-dihydroxyphenyl)-propionic acid. HcdA catalyzes the conversion of 3-(2,4-dihydroxyphenyl)-propionic acid to 3-(2,3,5-trihydroxyphenyl)-propionic acid through an ipso-hydroxylation followed by an internal (1,2-C,C)-shift of the alkyl moiety. Then, in the presence of HcdB, a subsequent oxidative meta-cleavage of the aromatic ring occurs, resulting in the corresponding linear product (2E,4E)-2,4-dihydroxy-6-oxonona-2,4-dienedioic acid. Here, we describe a Pseudomonas mandelii strain 7HK4 capable of degrading 7-hydroxycoumarin via 3-(2,4-dihydroxyphenyl)-propionic acid pathway.

A novel series (13) of isoxazoline functionalized coumarins was synthesized through 1,3-dipolar cyclization of nitrile oxides with Allylated coumarins. Synthesis of effective and target selective immunostimulators through conjugation of diversely substituted isoxazolines and 7-hydroxycoumarins is the focus of the present article. The proposed synthetic scheme was observed to be highly regiospecific yielding attempted conjugates in good yield (>90%). Kinetic resolution of the racemates was carried out by employing lipase B from Candida antarctica (CALB). The synthesized compounds were screened in vitro and in vivo for their biological activities viz . toxicity and impact on splenocyte proliferation (T- and B-cell proliferation), antibody production (HA titre), delayed-type hypersensitivity reaction (DTH), T-cell subtypes (CD4 and CD8), cytokine production (IL-2, IFN-γ, and IL-4) and NO (macrophage) production. Our results establish that isoxazoline functionalized coumarins exhibit excellent immune potentiating activity especially compounds 2 , 4 and 8 whose activity is more than that of Levimasole as standard. The structure activity relations are explained in light of the structural/functional aspects of tested compounds. To the best of our knowledge the presented work is first of its kind and is presaged to prove very useful for the design and synthesis of bis -heterocycle based novel, therapeutically selective and effective immunopotentiators. [ABSTRACT FROM AUTHOR]

In this study, effects of chemical structure and molecular size of the anticancer drugs 5-fluorouracil and 7-hydroxycoumarin on their release from MCM-48 nanoparticles were investigated. Nanoparticles of the mesoporous silicate material, MCM-48, were prepared and characterized by XRD, SEM and FTIR. Loading of 5-fluorouracil and 7-hydroxycoumarin onto the nanoparticles was confirmed by FTIR and TGA measurements, and loading capacities of about 24 and 14 % were achieved, respectively. Release experiments for 5-fluorouracil were conducted in buffer solutions at pH = 7.4 and 5.2. However, due to the instability of 7-hydroxycoumarin in basic media, release experiments were conducted only in acidic buffer solution at pH = 5.2. The release of 5-fluorouracil was slightly affected by the pH of the release medium, and it was almost complete in about 2 h. However, the release of 7-hydroxycoumarin which has a larger size and higher acidity followed a prolonged release mode over a period of 12 h. Graphical Abstract: The prolonged release of 7-hydroxycoumarin from MCM-48 nanoparticles points out to the potential use of this system as sustained release delivery carrier. [ABSTRACT FROM AUTHOR]

In this work, two high selective and sensitive fluorescent probes for ClO − , 7-Hydroxycoumarin and 4-Hydroxycoumarin were designed. The reaction mechanism that we speculated was the oxidized ring opening reaction and hydrolysis. The detection could be realized in quasi-aqueous phase and the detection limits of probe [7] and probe [4] for ClO − were found to be 56.8 nM and 70.5 nM. Furthermore, the probes can be used to cell imagings. [ABSTRACT FROM AUTHOR]

Ultraviolet B (UVB) irradiation alters multiple molecular pathways in the skin, thereby inducing skin damage. Human dermal fibroblasts (HDFa) were subjected to single UVB-irradiation (18 mJ/cm 2 ) resulting in reactive oxygen species (ROS) generation, oxidative DNA damage and upregulation of nuclear factor kappa B (NF-κB) expression. Further, it has been observed that there was a significant cytokine production (TNF-α and IL-6) in UVB irradiated HDFa cells. Our results show that 7-hydroxycoumarin (7-OHC) prevents UVB-induced activation of NF-κB thereby subsequently preventing the overexpression of TNF-α and IL-6 in HDFa cells. Further, 7-OHC prevents UVB-induced activation of cyclooxygenase-2 (COX-2) expression, an inflammatory mediator in skin cells. Moreover, 7-OHC inhibited mRNA expression pattern of matrix metalloproteinases (MMP-1 and MMP-9) in UVB irradiated skin cells. Furthermore, 7-OHC restored antioxidant status, thereby scavenging the excessively generated ROS; consequently preventing the oxidative DNA damage. It has also been noticed that 7-OHC prevents UVB mediated DNA damage through activation of DNA repair enzymes such as XRCC1 and HOGG1. In this study, we treated HDFa cells with 7-OHC before and after UVB irradiation and we found that pretreatment showed better results when compared to posttreatment. Further, 7-OHC showed 9.8416 sun protection factor (SPF) value and it absorbs photons in the UVB wavelength rage. Thus, it has been concluded that sunscreen property, free radical scavenging potential and prevention of NF-κB activation play a role for photoprotective property of 7-OHC. [ABSTRACT FROM AUTHOR]

Activation of β 1 -adrenoceptor stimulates myocardial membrane destabilization in isoproterenol induced rats. Male albino Wistar rats were pre and co-treated with 7-hydroxycoumarin (16 mg/kg body weight) daily for 8 days. Myocardial infarction was induced into rats by the subcutaneous administration of isoproterenol (100 mg/kg body weight) at an interval of 24 h daily for a period of two days (7th and 8th day). The levels/activities of serum cardiac troponin-T, lactate dehydrogenase and the concentrations of heart lipid peroxidation products were significantly increased and the antioxidant status was significantly decreased in isoproterenol induced rats. Furthermore, the activity of sodium/potassium-dependent adenosine triphosphatase was significantly decreased and the activities of calcium and magnesium-dependent adenosine triphosphatases were significantly increased in the heart of isoproterenol induced myocardial infarcted rats. Isoproterenol induced rats also revealed increased concentrations of sodium and calcium and decreased concentrations of potassium in the heart. 7-hydroxycoumarin pre- and co-treatment showed considerable impact on all biochemical parameters assessed. Also, 7-HC greatly reduced the infarct size of the myocardium. The in vitro study confirmed its potent free radical scavenging activity. Thus, the present study revealed that 7-HC attenuates myocardial membrane destabilization by reinstating the activities/levels of adenosine triphosphatases and minerals in isoproterenol induced rats by inhibiting oxidative stress. These effects are attributed to the membrane stabilizing and free radical scavenging properties of 7-hydroxycoumarin. [ABSTRACT FROM AUTHOR]

This study evaluates the protective effects of 7-hydroxycoumarin (7-HC) on dyslipidemia and cardiac hypertrophy in isoproterenol (ISO) induced myocardial infarction (MI) in rats. Rats were preand co treated with 7-HC (16 mg/kg) daily for 8 days. ISO (100 mg/kg) was subcutaneously injected into rats on seventh and eighth days to induce MI. Increased activity/levels of serum creatine kinase-MB (CK-MB), troponin-T, plasma lipid peroxidation products, and altered levels of lipids in the serum and heart and serum lipoproteins were noted in ISO-induced rats. ISO-induced myocardial infarcted rats revealed increased hypertrophy (cardiac and left ventricular) and hepatic 3-hydroxyl 3-methylglutaryl-coenzyme-A reductase (HMG-CoA reductase) activity. Pre and cotreatment with 7-HC revealed significant protective effects on all the biochemical parameters evaluated. The in vitro study demonstrated its free radical scavenging property. Thus, 7-HC protects ISO-induced MI in rats by its free radical scavenging and antihyperlipidaemic and antihypertrophic properties. [ABSTRACT FROM AUTHOR]

In order to find out the truth of influence of solution chemistry on the oxidation efficiency of a goethite-catalyzed Fenton-like reaction, the amount of hydroxyl radicals ( OH) was quantified by using coumarin as its trapping agent to produce the only fluorescent derivative 7-hydroxycoumarin (7-HC), because OH was the reactive species responsible for the oxidation activity of Fenton reactions. The concentration of OH achieved maximum at solution pH of 3 and decreased with an increase of solution pH value. However, considerable amount of OH can also generate at near neutral pH (i.e. pH 6 and 7). The concentration of OH was increased both with increasing of goethite and H 2 O 2 dosages, but H 2 O 2 could compete with coumarin to scavenge OH to reduce the formation of 7-HC when the concentration of H 2 O 2 was too high. Anions inhibited OH generation followed an order of H 2 PO 4 − > SO 4 2− > Cl − > NO 3 − > ClO 4 − . Higher concentrations of Cl − and SO 4 2− resulted in greater inhibition of OH generation. Results of this study demonstrated that the influence of solution chemistry on the oxidation efficiency of the goethite-catalyzed Fenton-like reaction was greatly attributed to the effect of solution chemistry on the amount of OH formed in the process of reaction. [ABSTRACT FROM AUTHOR]

An impressive body of evidence has been accumulated now on sound beneficial effects of mitochondrial uncouplers in struggling with the most dangerous pathologies such as cancer, infective diseases, neurodegeneration and obesity. To increase their efficacy while gaining further insight in the mechanism of the uncoupling action has been remaining a challenge. Encouraged by our previous promising results on lipophilic derivatives of 7-hydroxycoumarin-4-acetic acid (UB-4 esters), here, we use a 7-hydroxycoumarin-3-carboxylic acid scaffold to synthesize a new series of 7-hydroxycoumarin (umbelliferone, UB)-derived uncouplers of oxidative phosphorylation – alkyl esters of umbelliferone-3-carboxylic acid (UB-3 esters) with varying carbon chain length. Compared to the UB-4 derivatives, UB-3 esters proved to be stronger uncouplers: the most effective of them caused a pronounced increase in the respiration rate of isolated rat heart mitochondria (RHM) at submicromolar concentrations. Both of these series of UB derivatives exhibited a striking difference between their uncoupling patterns in mitochondria isolated from liver and heart or kidney, namely: a pronounced but transient decrease in membrane potential, followed by its recovery, was observed after the addition of these compounds to isolated rat liver mitochondria (RLM), while the depolarization of RHM and rat kidney mitochondria (RKM) was rather stable under the same conditions. Interestingly, partial reversal of this depolarization in RHM and RKM was caused by carboxyatractyloside, an inhibitor of ATP/ADP translocase, thereby pointing to the involvement of this mitochondrial membrane protein in the uncoupling activity of both UB-3 and UB-4 esters. The fast membrane potential recovery in RLM uncoupled by the addition of the UB esters was apparently associated with hydrolysis of these compounds, catalyzed by mitochondrial aldehyde dehydrogenase (ALDH2), being in high abundance in liver compared to other tissues. Protonophoric properties of the UB derivatives in isolated mitochondria were confirmed by measurements of RHM swelling in the presence of potassium acetate. In model bilayer lipid membranes (liposomes), proton-carrying activity of UB-3 esters was demonstrated by measuring fluorescence response of the pH-dependent dye pyranine. Electrophysiological experiments on identified neurons from Lymnaea stagnalis demonstrated low neurotoxicity of UB-3 esters. Resazurin-based cell viability assay showed low toxicity of UB-3 esters to HEK293 cells and primary human fibroblasts. Thus, the present results enable us to consider UB-3 esters as effective tissue-specific protonophoric mitochondrial uncouplers. [Display omitted] • Alkyl esters of umbelliferone-3-carboxylic acid (UB-3 esters) uncoupled mitochondria. • The uncoupling was transient in rat liver, but stable in rat heart mitochondria (RHM). • The ATP/ADP translocase inhibitor caused a reversal of RHM uncoupling by UB-3 esters. • RHM swelling in KAcetate showed protonophoric activity of UB-3 esters in mitochondria. • UB-3 esters also displayed protonophoric activity in pyranine-loaded liposomes. [ABSTRACT FROM AUTHOR]

Coumarins have attracted intense interest in recent years due to their apoptogenic effects. The aim of the present study was to determine whether 7-hydroxycoumarin (7-HC) induces changes in caspase-3 (C.3) activity in A549 human lung carcinoma cells. A range of analytical techniques, including colorimetric and fluorometric assays, western blotting, single-cell microinjection, fluorescence microscopy and image analysis were conducted to elucidate the effects of 7-HC. A 24-h exposure to 1.85 mM 7-HC induced a 65% increase in C-3 activity, and a notable conversion of procaspase-3 to C.3, in addition to poly(ADP-ribose)polymerase cleavage. Furthermore, morphological changes associated with apoptosis were observed. Exposure of the cells to 7-HC for 3 or 6 h increased calcium conductance by 27%. By performing the single-cell microinjection of a specific fluorescent substrate of C-3 into previously 7-HC-exposed cells, a typical enzymatic kinetic profile of C-3 activation was identified a number of hours prior to the morphological and biochemical changes associated with apoptosis being observed. These results suggest that the rapid in vivo activation of C-3 is induced by 7-HC, the most relevant biotransformation product of coumarin in humans. [ABSTRACT FROM AUTHOR]

A novel, simple, selective and sensitive spectrofluorimetric method was developed and validated for the determination of perindopril erbumine using 7-hydroxycoumarin. Perindopril erbumine was found to react with 7-hydroxycoumarin in acetonitrile resulting in a new fluorescent product with about 58 nm blue shifted emission. The fluorescence of the complex was measured at 440 nm after excitation at 350 nm in acetonitrile. Under the optimum conditions, the fluorescence intensity was linear over a concentration range of 2.0-16.0 μg/mL (R = 1) with a detection limit of 0.054 μg/mL. The proposed method was fully validated and successfully applied to the analysis of perindopril erbumine in pure form and tablets. Statistical comparison of the results obtained by the proposed and reference method revealed no significant differences in the performance of the two methods regarding the accuracy and precision respectively. The method was shown to be highly specific in the presence of indapamide, a diuretic that is commonly combined with perindopril erbumine. A proposal for the reaction pathway with 7-hydroxycoumarin was postulated. [ABSTRACT FROM AUTHOR]

The new Cu(II) complexes with 6-acetyl-7-hydroxy-4-methylcoumarin (HL1) and 8-acetyl-7-hydroxy-4-methylcoumarin (HL2) have been obtained by the electrochemical method. The density functional theory calculations and X-ray absorption spectroscopy techniques have been used to geometrically describe a series of new compounds. The studies have been focused on the coordination mode of the hydroxy ligands to the metallic centre. The complexes, Cu(HL1) 2 and Cu(HL2) 2 ⋅ 0.5H 2 O, have flat square geometry with oxygen atoms in the first coordination sphere. Two bidentate anionic coumarins are bonded to the metal cation via the acetyl and deprotonated hydroxyl O atoms. Biological activity, including microbiological and cytotoxic, has been evaluated and found to be enhanced in comparison with the parent ligands. Moreover, the Cu(II) complex with 8-acetyl-7-hydroxy-4-methylcoumarin shows similar antifungal activity as commercially used fluconazole. [ABSTRACT FROM AUTHOR]

[Display omitted] • Alkyl esters of umbelliferone-4-acetic acid (UB-4 esters) uncoupled mitochondria. • Uncoupling of isolated rat liver mitochondria by UB-4 esters disappeared in minutes. • This recoupling was apparently due to hydrolysis of UB-4 esters catalyzed by ALDH2. • UB-4 esters had protonophoric activity in planar BLM and pyranine-loaded liposomes. • UB-4 esters showed antimycobacterial activity, the decyl ester being the most potent. A great variety of coumarin-related compounds, both natural and synthetic, being often brightly fluorescent, have shown themselves beneficial in medicine for both therapeutic and imaging purposes. Here, in search for effective uncouplers of oxidative phosphorylation, we synthesized a series of 7-hydroxycoumarin (umbelliferone, UB) derivatives combining rather high membrane affinity with the presence of a hydroxyl group deprotonable at physiological pH - alkyl esters of umbelliferone-4-acetic acid (UB-4 esters) differing in alkyl chain length. Addition of UB-4 esters to isolated rat liver mitochondria (RLM) resulted in their rapid depolarization, unexpectedly followed by membrane potential recovery on a minute time scale. According to TLC and HPLC data, incubation of RLM with UB-4 esters caused their hydrolysis, which led to disappearance of the uncoupling activity (recoupling). Both mitochondrial recoupling and hydrolysis of UB-4 esters were suppressed by inhibitors of mitochondrial aldehyde dehydrogenase (ALDH2), disulfiram and daidzin, thus pointing to the involvement of this enzyme in the recoupling of RLM incubated with UB-4 esters. The protonophoric mechanism of mitochondrial uncoupling by UB-4 esters was proved in experiments with artificial bilayer lipid membranes (BLM): these compounds induced proton-selective electrical current across planar BLM and caused dissipation of pH gradient on liposomes. UB-4 esters showed antibacterial activity against Bacillus subtilis, Staphylococcus aureus and Mycobacterium smegmatis. [ABSTRACT FROM AUTHOR]

Benzoxazine derivatives are typically synthesized by condensation reaction of a phenol with two equivalents of formaldehyde and various primary amines (aliphatic or aromatic) as starting materials either by employing solution or solvent-free conditions. In this work, coumarin Mannich bases were synthesized using 7-hydroxycoumarin as phenol and were obtained with moderate to very good yields. [ABSTRACT FROM AUTHOR]

Abstract: A novel reaction-based probe for the dual signaling of hydrogen sulfide (H2S) was investigated. The selective H2S-induced cleavage of the ether linkage of the 7-nitro-2,1,3-benzoxadiazole (NBD) and 7-hydroxycoumarin conjugate resulted in a dual signaling behavior. The colorimetric and fluorogenic signaling behaviors were attributed to the H2S-induced generation of 7-nitrobenzo-2,1,3-oxadiazole-4-thiol (NBD-SH) and 7-hydroxycoumarin, respectively. The signaling behavior was analyzed by ratiometry. The selective signaling of H2S over other common metal ions and anions was possible with a detection limit of 1.6×10−6 M in an aqueous DMSO solution. [Copyright &y& Elsevier]

7-Hydroxycoumarin exhibits antioxidative, lipoxygenase inhibitive and anti-tumourigenic effects. Density and viscosity measurements have been carried out for the solutions of 7-hydroxycoumarin in mixture solvents of water and ethanol or 1-propanol at T = (293.15, 298.15, 303.15, 308.15 and 313.15) K. The measured data have been used to evaluate apparent molar volumes ( Vϕ), limiting apparent molar volumes ( $$ V_{\phi }^{0} $$ V ϕ 0 ), viscosity B-coefficients of the Jones–Dole equation and variation of B with temperature (d B/d T). The values of $$ V_{\phi }^{0} $$ V ϕ 0 and B-coefficients are positive and pass through their corresponding maxima at about 18 mol·kg −1 ethanol molality and 20 mol·kg −1 1-propanol molality, respectively. Besides, the values of $$ V_{\phi }^{0} $$ V ϕ 0 and B-coefficients decrease with increasing temperature. Molar refractive indices ( RD) of the ternary solutions at the temperature of 298.15 K have also been determined from measured refractive indices ( nD). There is an obvious increase of RD with increasing molality of the solvent. These parameters have been interpreted in terms of solute–solvent interactions and structure making/breaking ability of components in the aqueous solution. The temperature and concentration dependences of the weak interactions in the solution systems have also been discussed. [ABSTRACT FROM AUTHOR]

Highlights: [•] 7-Hydroxycoumarin derivatives modulate the oxidative metabolism of human neutrophils. [•] 7-Hydroxycoumarin impairs degranulation of neutrophils and killing of Candida albicans. [•] Myeloperoxidase oxidizes 7-hydroxycoumarin to highly reactive free radicals. [•] In the absence of MPO, the 7-hydroxycoumarin derivatives display antioxidant effect. [•] 7-Hydroxycoumarin derivatives inhibit superoxide anion generation by neutrophils. [Copyright &y& Elsevier]