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PubMed1975

The resolution of thermal oedema at various temperatures under coumarin treatment.

The treatment of thermal oedema with coumarin (a benzopyrone) has been found to be most effect when fast moving air of 20 degrees was blown over the burnt animals. Coumarin has two main effects: one is to cause vascular injury thus allowing extra protein and fluid into the tissues; the other is to stimulate phagocytosis, enzyme production and thus proteolysis and a subsequent removal of protein and fluid from the injured tissues. At lower temperatures the injurious nature of coumarin is prominent. At medium range temperatures the proteolytic actions of coumarin outweigh its injurious nature. Resolution thus proceeds much more rapidly. At high temperatures resolution is slowed. This is a consequence of the antioxidant effect of coumarin on adrenaline and ambient temperature on peripheral dilatation. The results obtained tie in well with those obtained by workers using water of equivalent temperature.

Air Movements↗

PubMed1975

Effect of coumarins on mitochondrial function.

Several derivatives of coumarin inhibited mitochondrial respiration and ATPase activity. The extent of inhibition depended on the concentration of the coumarins as well as on the substituents of the coumarin ring. Some of the coumarins stimulated ATPase activity, but all of them inhibited uncoupler-stimulated ATPase activity. Coumarins with free or substituted phenolic groups were found to exert profound effects on respiration and ATPase activity.

Adenosine Triphosphatases↗

PubMedDate not supplied

Structural requirements of hydroxylated coumarins for in vitro anti-Helicobacter pylori activity.

We have previously found that a 7-hydroxycoumarin derivative has potent anti-Helicobacter pylori (H. pylori) activity, comparable with metronidazole. In this report, we describe the structural requirement for the anti-H. pylori activity of several hydroxylated coumarins (1-23). It was found that 7-hydroxy-4-methylcoumarin (6), 6,7-dihydroxy-4-methylcoumarin (8), 6-hydroxy-7-methoxy-4-methylcoumarin (10) and 5,7-dihydroxycyclopentanocoumarin (21) showed comparable anti-H. pylori activity with metronidazole. The presence of 7- and/or 6-hydroxyl groups seems to be essential to display higher anti-H. pylori activity. Their activities depended on the number and position of the hydroxyl group on the benzenoid ring of the coumarin system. Methylation of the hydroxy group generally diminished the activity. In hydroxylated coumarins, the methyl group at C-4 position enhanced the activity. The inhibitory activity of coumarins (1-23) against jack bean urease was examined, but no coumarins showed any inhibition at 160 micrograms/mL.

Coumarins↗

PubMed1992

Immunological and antitumor effects of coumarin and some derivatives.

Coumarin and its 4-OH and 7-OH derivatives, as well as o-, m- and p-coumaric acid were tested against P-815 and P-388 tumor cells in vitro. In addition, the compounds were investigated in various in vitro immunological test systems and genuine coumarin was tested furthermore against the Sarcoma-180 in CD1 mice. In vivo, coumarin showed only a moderate antitumor effect against the allogeneic Sarcoma-180 at concentrations of 10 and 40 mg/kg, with inhibition rates of 49 and 60%, respectively. However, both concentrations were markedly toxic. In vitro all compounds were more or less cytotoxic against P-815 and P-388 tumor cell lines starting at a concentration of 100 micrograms/ml. At subtoxic concentrations (less than or equal to 10 micrograms/ml) the samples showed no mitogenic activity against murine spleen lymphocytes and PHA costimulated human peripheral blood lymphocytes. Furthermore, with the coumarin derivatives neither cytotoxic macrophages could be induced against P-815 tumor cells nor an increased release of Il-2 and TNF-alpha could be observed. Only 7-OH coumarin, in concentrations of 2 and 20 micrograms/ml, caused a strong increase in phagocytosis of 124 and 84% in both, human peripheral blood granulocytes and murine peritoneal macrophages, respectively.

Animals↗

PubMedDate not supplied

Rapid analysis of coumarins using surface plasmon resonance.

Coumarin molecules are ubiquitous in nature. Several have come to prominence as potential clinical therapeutic candidates. The principal example is warfarin, which is a very widely prescribed anticoagulant. Other coumarin derivatives, such as aflatoxin B1, are insidious contaminants in crop-derived foodstuffs. Extreme potency is a common feature of all biochemically active coumarins and, thus reliable methods for their rapid and sensitive detection are of paramount importance. Accordingly, this review examines the current methods used in the analysis of these molecules and compares them with immunoassay-based strategies. As a case study, we report on our experiences with using coumarin-specific polyclonal, monoclonal, and recombinant antibodies in conjunction with a surface plasmon resonance-based biosensor for analysis of coumarins. We chart the assay development process and demonstrate high sensitivity and reproducibility that compares favorably with established methodologies.

Aflatoxin B1↗

PubMed1976

The ineffectiveness of coumarin treatment on thermal oedema of macrophage-free rats.

The administration of silica prevents coumarin-stimulated lysis of accumulated abnormal protein. This impairs the resolution of thermal oedema which is normally increased with coumarin administration. Evidence suggests that there is a rapid differentiation and infiltration of monocytes into the tissues and that these are selectively retained. This is aided by coumarin which increases tissue permeability. Coumarin also injures the vascular endothelium of some vessels, allowing extra protein and fluid into the tissues. Death of recently differentiated macrophages and subsequent release of their lysosomal contents into the extra-cellular spaces may be responsible for the changes in serum enzyme levels. It would seem that macrophages are the only cells in which coumarin stimulates increased phagocytosis, enzyme production and proteolysis.

Animals↗

PubMed1989

Effects of coumarin (1,2-benzopyrone) and cimetidine on peripheral blood lymphocytes, natural killer cells, and monocytes in patients with advanced malignancies.

The combination of coumarin and cimetidine has yielded objective tumor regressions in patients with metastatic renal cell carcinoma and malignant melanoma. While the mechanism of action of cimetidine appears to be immunomodulatory, coumarin appears to have direct effects on tumor cells as well as immunomodulatory activity. We utilized monoclonal antibody labeling techniques to monitor peripheral blood lymphocyte, natural killer (NK) cell, and monocyte phenotypes in patients treated with coumarin and cimetidine. Patients received coumarin 100 mg orally daily for 14 days; on day 15 cimetidine 300 mg four times daily was added and both drugs were continued until disease progression. Studies were performed pre treatment and at 2, 4, and 8 weeks on therapy. There were no alterations in T-cells, helper/inducer T-cells, cytotoxic/suppressor T-cells, B-cells, Ia + lymphocytes, or NK cells. However, an increase was noted by 2 weeks on therapy in the percentage of monocytes and the percentage of DR+ monocytes. This change in the monocyte population occurred in the presence of coumarin alone, before the institution of cimetidine. While this treatment appears to increase DR expression by monocytes, further studies with larger numbers of patients are needed to determine if this observed change is related to antitumor response.

Adult↗

PubMed1979

Genetic regulation of coumarin hydroxylase activity in mice. Biochemical characterization of the enzyme from two inbred strains and their F1 hybrid.

Hydroxylation of coumarin to 7-hydroxycoumarin by liver microsomes from control or phenobarbital-pretreated mice is 5- to 10-fold higher in the DBA/2J strain compared to the AKR/J strain, while activities of nine other cytochrome P-450 mediated oxidations show only minor differences. Mixing experiments with whole liver homogenates and subcellular fractionations do not reveal the presence of enzyme activators or inhibitors or competing enzyme reactions in either strain. Comparisons of pH optima (pH 7.6), heat stability at 52 degrees C (6 to 8 min for 50% inactivation), and Km values (0.45 to 0.50 microM coumarin) for coumarin hydroxylase show no significant differences in the two strains of mice or their F1 hybrid. Similarly, only minor differences in inhibition of coumarin hydroxylase by carbon monoxide, SKF-525A, menadione, and several other inhibitors of microsomal mixed function oxidase reactions are observed in the two strains. In contrast to these data, aniline and metyrapone, two compounds which bind to the heme iron of cytochrome P-450 to form ferrihemochromes, show differential and opposite patterns of inhibition of enzyme activity in the DBA/2J and AKR/J mouse strains. This latter observation suggests that a structurally different cytochrome P-450 may hydroxylate coumarin in these two inbred mouse strains.

Aniline Compounds↗

PubMed1977

An integration of the modes of action of coumarin. An explanation of its effectiveness as a therapy for thermally injured tissue.

The mode of action of coumarin is well suited to the relief of high-protein oedemas. It binds rapidly to the serum albumins, and the protein binding capacity of a substance provides insight into its interaction with sites of biological activity. Together with proteins, inflowing through the damaged capillary endothelium after thermal injury, it is taken up by the monocytes in the inflamed tissues and by the resident macrophages. Coumarin can stimulate these cells to enhanced proteolysis of the engulfed protein which is digested to debris of molecular weight less than 1000. This is on the other hand readily utilisable protein for the large number of monocytes to mature and differentiate into macrophages. Coumarin may dissociate from protein in the tissue and cause local site activation or even activate all cell sites increasing cell numbers or rejuvenate older phagocytic cells and stimulate the reticulo-endothelial system (RES). A passing histamine-like effect of coumarin and other benzopyrones is an indirect stimulant for the RES. The released injurious amines open additional numbers of endothelial intercellular junctions, allowing extra protein and fluid into the interstitial tissues. A reinforced phagocytosis follows and results in more rapid and complete digestion. The action of the drug in causing the opening of intercellular junction is very beneficial. The extra protein is of little consequence, since its inflow is more than compensated for by the other actions of the drug which results in its lysis. Coumarin has also a number of other important actions on the vascular system. It causes constriction of the precapillary sphincters and a dilatation of the arterio-venous anastomosis. The result is an increased blood pressure and flow, and a better oxygen supply of the area. It is able to restore the deformability of the red blood cell to near normal levels and to protect the thrombocyte by membrane stabilizing. The result is a reduced likelihood of thrombosis and embolism. By increasing the glucose uptake and transport the benzopyrones can improve the chance of survival of those cells in stagnant areas of the circulation.

Animals↗

PubMed1997

[Acute cytolytic hepatitis caused by coumarin. 2 cases].

Coumarin is a drug which is extensively used to treat lymphedema. We report two cases of acute hepatitis probably due to coumarin. Two women, 40 year and 45 year-old, were treated with 90 mg/d of coumarin for 5 months. Clinical features included jaundice, pruritus, and diarrhea. A marked increase in serum aminotransferases was observed (ALT: 30 and 100 times the upper limit of normal, respectively). Coumarin withdrawal was rapidly followed by a favorable outcome in both cases. Rechallenge in one case induced a relapse of symptoms and liver test abnormalities. Coumarin can induce acute cytolytic hepatitis.

Acute Disease↗

PubMed1997

[Coumarin combined with low-dose acetylsalicylic acid in the prevention of thromboembolic complications in patients with mitral and aortic valve prostheses].

Authors studied the effect of coumarin, and its combination with low-dose (125 mg/day) acetylsalicylic acid in the prevention of thromboembolic complication during a 10-year period (average 4.7 years) in a randomized trial of 296 patients aged 18-60 year with tilting disc type prosthetic heart valve (159 mitral and 137 aortic) in sinus rhythm. In the group treated with coumarin (152 patients, 743.4 patient-years) 4 cases (2 of them fatal) of valve thrombosis, 12 cases of peripheral embolism and 9 cases (3 intracranial, 3 among them fatal) of major bleeding were observed; in the group treated with coumarin plus acetylsalicylic acid (144 patients, 638.7 patient-years) 2 cases (1 of them fatal) of valve thrombosis, 4 cases of peripheral embolism and 14 cases (3 of them fatal) of major bleeding were observed. In the case of valve thromboses the difference between the two groups was non-significant but still clinically remarkable; peripheral embolism occurred in significantly higher number (p < 0.05). There was no statistically significant difference of bleeding complications between the two groups. The results suggest that the combination of coumarin plus low-dose acetylsalicylic acid is more effective in the prevention of thromboembolic complications in patients with mitral and aortic prosthetic heart valve than coumarin alone; the danger of bleeding complications seems to be acceptable with adequate control.

Adolescent↗

PubMed1998

[Microcirculatory consequences of a venous striction in the rat. Effect of a coumarine-rutine association].

The aim of this study was to investigate the consequences of a venous striction on capillary red blood cell distribution and venular blood return and the effect of a coumarin derivative-rutoside combination. The study was conducted, in vivo, in the rat cremaster muscle using intravital microscopy. The striction lasted thirty minutes and was obtained by clamping the epigastric vein. This mechanical constraint was sufficient to induce microcirculatory modifications without disrupting microvessels. Before the striction (t-5 min), the velocities and diameters of the veins and arteries were comparable in all groups. After the striction (t5 min), in the control group, venous blood flow decreased by 60%, from 0.48 +/- 0.09 mm3/s (t-5 min) to 0.20 +/- 0.06 mm3/s (t5 min). The results showed that after thirty minutes reperfusion, venular blood flow in the control animals was only 34% of initial blood flow. The mean red blood cell velocity dropped by 56%, the percentage of low perfused capillaries increased from 7.5% to 50%. Treatment of animals with a coumarin derivative-rutoside combination, particularly at 4 mg/kg coumarin derivative-100 mg/kg rutoside, has significantly improved the microcirculation. After thirty minutes reperfusion venular blood flow was 60% and the percentage of low perfused capillaries was only 10%. The effect seemed to be more pronounced for rutoside than coumarin derivatives. The interest of this study was to set up an experimental model of a venous striction not too severe to induce micro-hemorrages but enough to modify microcirculation. This model was used to quantify the beneficial effects of a coumarin derivative-rutoside combination.

Animals↗

PubMed1985

Comparison of kidney, lung and liver coumarin 7-hydroxylases in phenobarbital pretreated DBA/2J and C57BL/6J mice.

In this paper we describe catalytic and immunological properties of coumarin 7-hydroxylase, a cytochrome P-450 dependent enzyme activity, in the liver, kidney and lung of C57BL/67 and DBA/2J mice. Coumarin 7-hydroxylase activity was higher in D2 than in B6 mice in all three organs. For both strains of mice, liver had the highest enzyme activity when expressed per milligram of microsomal protein. However, when expressed per nmole cytochrome P-450 there was no difference in the enzyme activity between the tissues. Inhibition of microsomal coumarin 7-hydroxylase by antibodies previously developed in our laboratory against a cytochrome P-450 fraction from D2 and B6 mouse liver, associated with coumarin 7-hydroxylase, occurred as follows. In D2 mice both antibodies caused approximately 50% inhibition of the enzyme activity of all three organs. In B6 mice, however, the only organ where considerable inhibition took place was the liver, and only when antibody against B6 cytochrome P-450 was used. Ouchterlony immunodiffusion analysis revealed a 100% crossreactivity between the two strains of mice when similar organs were compared. The 100% crossreactivity was also found between the liver and lung in both strains of mice. However, only a 50% crossreactivity was found between kidney and liver or kidney and lung in B6 and between the kidney and lung in D2. The data demonstrate interorgan and interstrain differences in the immunological and catalytical properties of cytochrome(s) P-450 catalysing coumarin 7-hydroxylation.

Animals↗

PubMed2005

Allelic variants of cytochrome P450 2C9 modify the interaction between nonsteroidal anti-inflammatory drugs and coumarin anticoagulants.

INTRODUCTION: Cytochrome P450 (CYP) plays a key role in the metabolism of coumarin anticoagulants and nonsteroidal anti-inflammatory drugs (NSAIDs). Because CYP2C9 is a genetically polymorphic enzyme, genetic variability could play an important role in the potential interaction between NSAIDs and coumarins. We investigated whether NSAIDs were associated with overanticoagulation during therapy with coumarins and evaluated the effect of the CYP2C9 polymorphisms on this potential interaction. METHODS: We conducted a population-based cohort study among patients of an anticoagulation clinic who were treated with acenocoumarol or phenprocoumon between April 1, 1991, and May 31, 2003, and whose CYP2C9 status was known. Patients were followed up until an international normalized ratio (INR) of 6.0 or greater was reached or until the end of treatment, death, or the end of the study. Proportional hazards regression analysis was used to estimate the risk of an INR of 6.0 or greater in relation to concomitant use of a coumarin anticoagulant and NSAIDs after adjustment for several potentially confounding factors. To study effect modification by CYP2C9 genotype, stratified analyses were performed for wild-type patients and patients with a variant genotype. RESULTS: Of the 973 patients in the cohort, 415 had an INR of 6.0 or greater. Several NSAIDs increased the risk of overanticoagulation. The risk of overanticoagulation was 2.98 (95% confidence interval, 1.09-7.02) in coumarin-treated patients taking NSAIDs with a CYP2C9*2 allele and 10.8 (95% confidence interval, 2.57-34.6) in those with a CYP2C9*3 allele. CONCLUSIONS: Several NSAIDs were associated with overanticoagulation. For NSAIDs that are known CYP2C9 substrates, this risk was modified by allelic variants of CYP2C9. More frequent INR monitoring of patients taking NSAIDs is warranted.

Acenocoumarol↗

PubMed2003

Decreased coumarin 7-hydroxylase activities and CYP2A6 expression levels in humans caused by genetic polymorphism in CYP2A6 promoter region (CYP2A6*9).

One of seven poor metabolizers of coumarin found in Thai subjects was previously genotyped as heterozygote for the CYP2A6*4 (whole deletion) and CYP2A6*9. Thus, we aimed to investigate the relationship between the genetic polymorphism in the TATA box of the CYP2A6 gene (CYP2A6*9), expression levels of CYP2A6 mRNA and coumarin 7-hydroxylase activities in human livers. Levels of CYP2A6 mRNA were quantified by real-time quantitative reverse transcriptase-polymerase chain reaction. The mean expression levels of CYP2A6 mRNA in individuals with CYP2A6*1/*4, CYP2A6*1/*9 and CYP2A6*4/*9 were 58%, 71% and 21% of the individuals genotyped as CYP2A6*1/*1, respectively. The mean in-vitro coumarin 7-hydroxylase activities in subjects carrying CYP2A6*1/*4, CYP2A6*1/*9 and CYP2A6*4/*9 were 41%, 71% and 12%, respectively, compared to those of the subjects judged as wild-type. Vmax values for coumarin 7-hydroxylation in the liver microsomes from human subjects with genotypes of CYP2A6*1/*1, CYP2A6*1/*4, CYP2A6*1/*9 and CYP2A6*4/*9 were 0.58, 0.26, 0.44 and 0.13 nmol/min/nmol total P450, respectively. CYP2A6 protein levels in human liver microsomes with the CYP2A6*4 and the CYP2A6*9 alleles were markedly decreased. These results suggest that the genetic polymorphism in the promoter region of the CYP2A6 gene (CYP2A6*9) reduced the expression levels of CYP2A6 mRNA and protein in human livers, resulting in the decrease of coumarin 7-hydroxylase activities. Individuals judged as CYP2A6*4/*9 were expected to be poor metabolizers, having extremely low activity of CYP2A6.

Adult↗

PubMed1975

The reaction of coumarins with horseradish peroxidase.

The peroxidase catalyzed oxidation of indole-3-acetate is inhibited by naturally occurring coumarins such as scopoletin. This inhibition is due to the preferential reactivity of the coumarins with the peroxidase compounds I, II, and III. In view of the possible growth regulatory role of coumarins in plants, the mechanism of oxidation of scopoletin by horse-radish peroxidase has been investigated.Peroxidase catalyzed coumarin oxidation requires either an electron donor and molecular oxygen or hydrogen peroxide. If peroxide is present, the reaction is mediated by peroxidase compound II which reacts rapidly and stoichiometrically with scopoletin. Different oxidation products are formed, depending on whether IAA or hydrogen peroxide promotes the reaction. A scopoletin-free radical intermediate has been isolated from the peroxide reaction mixture but was not detected in the peroxide-free system.When indole-3-acetate is the electron donor, reduced peroxidase combines with molecular oxygen to give peroxidase compound III. Added scopoletin is cooxidized with indole-3-acetate. Compared to the scopoletin peroxidation, this reaction is slower and yields fewer coumarin oxidation products. The differences observed between the two scopoletin oxidation pathways reflect: (a) the competition between indole-3-acetate and scopoletin for peroxidase compounds; (b) the lower reactivity of scopoletin with peroxidase compound III compared with peroxidase compound II. The peroxide-promoted reaction is eliminated by catalase, while the indole-3-acetate initiated oxidation is not affected by excess quantities of either catalase or superoxidase dismutase.

Journal Article↗

PubMed2006

Synthesis of coumarin or ferrocene labeled nucleosides via Staudinger ligation.

BACKGROUND: Reaction of azides with triaryl phosphines under mild conditions gives iminophosphoranes which can react with almost any kind of electrophilic reagent, e.g. aldehydes/ketones to form imines or esters to form amides. This so-called Staudinger ligation has been employed in a wide range of applications as a general tool for bioconjugation including specific labeling of nucleic acids. RESULTS: A new approach for the preparation of labeled nucleosides via intermolecular Staudinger ligation is described. Reaction of azidonucleosides with triphenylphosphine lead to iminophosphorane intermediates, which react subsequently with derivatives of coumarin or ferrocene to form coumarin or ferrocene labeled nucleosides. Fluorescent properties of coumarin labeled nucleosides are determined. CONCLUSION: New coumarin and ferrocene labeled nucleosides were prepared via intermolecular Staudinger ligation. This reaction joins the fluorescent coumarin and biospecific nucleoside to the new molecule with promising fluorescent and electrochemical properties. The isolated yields of products depend on the structure of azidonucleoside and carboxylic acids. A detailed study of the kinetics of the Staudinger ligation with nucleoside substrates is in progress.

Journal Article↗

PubMed2026

Enzymatic innovations in Angelica pubescens reveal dual coumarin biosynthetic pathways driving metabolic diversification.

Coumarins are structurally diverse phenylpropanoid derivatives with ecological and pharmacological significance, yet the biosynthetic logic underlying their diversification remains incompletely understood in non-model medicinal plants. Angelica pubescens (Apiaceae), widely used in traditional Chinese medicine, accumulates a rich repertoire of furanocoumarins and dihydrofuranocoumarins, making it an ideal system to investigate this metabolic complexity. Here, we combined chromosome-level genome assembly, transcriptome and metabolite profiling, phylogenetics, and heterologous expression assays to dissect coumarin biosynthesis in A. pubescens. We identified two functionally specialized O-methyltransferases, ApOMT1 and ApOMT2, which catalyze regioselective methylation of xanthotoxol and bergaptol to yield the furanocoumarins xanthotoxin and bergapten. We also characterized ApCYP736A121, a cytochrome P450 enzyme that converts osthenol to the dihydrofuranocoumarin columbianetin via a previously unknown mechanism. Gene expression and metabolite accumulation patterns across tissues and developmental stages revealed functional partitioning among pathway branches. Phylogenetic and syntenic analyses indicated that ApOMT1 and ApOMT2 arose through subfunctionalization following gene duplication, whereas ApCYP736A121 evolved via neofunctionalization from a distantly related CYP736 ancestor. Together, our findings uncover dual biosynthetic routes to structurally distinct coumarins in A. pubescens and provide insights into the evolutionary mechanisms contributing to metabolic innovation in Apiaceae. This work lays a foundation for future efforts to engineer coumarin pathways and understand their ecological functions in medicinal plants.

Coumarins↗