Onognaphalin,a further 5-methyl coumarin from Onoseris gnaphalioides

From the roots of Onoseris gnaphalioides in addition to a known 5-methyl coumarin a new type was isolated. The aerial parts contain a glucoside of 4-hydroxy-5-methyl coumarin. From Gerbera ambigua a compound related to the possible precursor of the 5-methyl coumarins was isolated.     

Cytochemistry of the chromatin replication band in hypotrichous ciliated protozoa staining with silver and thiol-specific coumarin maleimide

A modification of the silver-staining techniques for nucleolar organizing regions (NORs) was used to stain selectively the macronuclear replication bands (RBs) and nucleoli in hypotrichous ciliated protozoa (Euplotes, Stylonychia, and Oxytricha). Silver staining of both types of structures was trypsin-sensitive and DNase I-insensitive, suggesting the involvement of proteins. Silver-staining proteins in the RB were differentially extracted with acid, without any decrease in nucleolar staining. Triton-acid-urea gel electrophoresis of an acid extract of Euplotes macronuclei revealed enhanced silver reaction with a single protein upon selective silver staining. An abundance of thiol groups was also demonstrated in the RBs and nucleoli by the fluorochrome 3-(4-maleimidylphenyl)-7-diethylamino-4-methyl coumarin (coumarin maleimide). Histochemical studies, including blocking thiols with N-ethyl maleimide (NEM), indicated that thiols were not necessary for silver staining, and that proteins in the RBs and nucleoli reacting with coumarin maleimide were not acid extractable.     

The CYP2A3 gene product catalyzes coumarin 7-hydroxylation in human liver microsomes

Three cDNAs, designated IIA3, IIA3v, and IIA4, coding for P450s in the CYP2A gene subfamily were isolated from a lambda gt11 library prepared from human hepatic mRNA. Only three nucleotide differences and a single amino acid difference, Leu160----His, were found between IIA3 and IIA3v, indicating that they are probably allelic variants. IIA4 displayed 94% amino acid similarity with IIA3 and IIA3v. The three cDNAs were inserted into vaccinia virus, and recombinant viruses were used to infect human hepatoma Hep G2 cells. Only IIA3 was able to produce an enzyme that had a reduced CO-bound spectrum with a lambda max at 450 nm. This expressed enzyme was able to carry out coumarin 7-hydroxylation (turnover number of 15 min-1) and ethoxycoumarin O-deethylation. cDNA-expressed IIA3v and IIA4 failed to incorporate heme and were enzymatically inactive. Analysis of IIA proteins in human liver microsomes, using antibody against rat IIA2, revealed two proteins of 49 and 50 kDa, the former of which appeared to correlate with human microsomal coumarin 7-hydroxylase activity. A more striking correlation was found between IIA mRNA and enzyme activity. The rat antibody was able to completely abolish coumarin 7-hydroxylase activity in 12 liver samples. In addition, kinetics of coumarin metabolism in two livers were monophasic over the substrate concentration tested. Km values obtained from human liver (2.3 microM) were similar to those obtained from lysates of hepatoma cells expressing IIA3 (3.6-7.1 microM).(ABSTRACT TRUNCATED AT 250 WORDS)     

Selective induction of coumarin 7-hydroxylase by pyrazole in D2 mice

Pyrazole, was given to DBA/2N (D2), C57BL/6N (B6) and AKR/N mice to study its effects on hepatic drug metabolism. A decrease in the total amount of microsomal cytochrome P-450 as well as in the activities of ethylmorphine demethylase and benzo[a]pyrene hydroxylase was found. On the other hand ethoxycoumarin de-ethylase was increased 1.5-2.5-fold (depending on the strain of mouse) and coumarin 7-hydroxylase as much as sevenfold (but only in D2 mice) after pyrazole treatment. This increase was much higher than that caused by phenobarbital, the only well known inducer of coumarin 7-hydroxylase. By reconstituting the mono-oxygenase complex after purification of cytochrome P-450 we found a 40-fold increase in coumarin 7-hydroxylase and eightfold increase in ethoxycoumarin de-ethylase after pyrazole treatment. This was found only in D2 mice. An antibody previously developed against a cytochrome P-450 fraction from the the D2 strain with a high coumarin 7-hydroxylase activity inhibited the microsomal coumarin 7-hydroxylase almost 100% after pyrazole pretreatment of the animals. In the case of control or phenobarbital-treated mice the inhibition was somewhat weaker. With the reconstituted mono-oxygenase complex the inhibition of coumarin 7-hydroxylase was almost 100% both for control and pyrazole-treated D2 mice. The data indicate that pyrazole causes an induction of the microsomal monooxygenase complex different from that caused by phenobarbital or 3-methylcholanthrene and selective for coumarin 7-hydroxylation or 7-ethoxycoumarin de-ethylation. This induction was strong in D2, weak in B6 and absent in AKR/N mice.     

Omphamurin-a new coumarin from Murraya omphalocarpa

A new coumarin, omphamurin, isolated from the n-hexane extract of the leaves of Murraya omphalocarpa, was characterized as 5,7-dimethoxy-8-(2′-hydroxy-3′-methyl-3′-butenyl) coumarin by chemical evidence and spectral data.     

New bisabolane sesquiterpenes and coumarin from Leontopodium longifolium

From the roots of Leontopotium longifolium, three new bisabolane sesquiterpenes, rel-(1S,4R,5S,6R)-4,5-diacetoxy-6-[(R)-1,5-dimethylhexa-3,5-dienyl]-3-methylcyclohex-2-enyl (Z)-2-methylbut-2-enoate (1), rel-(1S,4R,5S,6R)-4,5-diacetoxy-6-[(R)-5-hydroxy-1,5-dimethylhex-3-enyl]-3-methylcyclohex-2-enyl (Z)-2-methylbut-2-enoate (2), rel-(1R,2S,4R,5S)-4-acetoxy-2-[(R)-5-hydroxy-1,5-dimethylhex-3-enyl]-5-methylcyclohexyl (Z)-2-methylbut-2-enoate (3), and a new coumarin, 2,3-dihydro-5-hydroxy-2-(1-methylethenyl)-7H-pyrano[2,3-g][1,4]benzodioxin-7-one (4) together with nine known compounds have been isolated. The structures of these compounds were established by spectroscopic methods. Compounds 1 and 2 exhibited moderate cytotoxic activities against human promyelocytic leukemia (HL-60) cells.     

Galipein,a coumarin from Galipea trifoliata

In addition to phebalosin and ramosin, the air-dried stem and root barks of Galipea trifoliata contain a third previously unreported coumarin identified as 7-isopentenyloxy-8-(trans-1′,2′-epoxy-3′-methyl-3′-butenyl)coumarin.     

7-Phenylacetoxy coumarin from limonia crenulata

A new coumarin, 7-phenylacetoxycoumarin, has been isolated from Limonia crenulata along with luvangetin, xanthotoxin, umbelliferone and limonin. This is the first report of a coumarin phenol ester from a natural source.     

Analysis of coumarin 7-hydroxylation activity of cytochrome P450 2A6 using random mutagenesis

Cytochrome P450 (P450) 2A6 is an important human enzyme involved in the metabolism of many xenobiotic chemicals including coumarin, indole, nicotine, and carcinogenic nitrosamines. A combination of random mutagenesis and high-throughput screening was used in the analysis of P450 2A6, utilizing a fluorescent coumarin 7-hydroxylation assay. The steady-state kinetic parameters (k(cat) and Km) for coumarin 7-hydroxylation by wild-type P450 2A6 and 35 selected mutants were measured and indicated that mutants throughout the coding region can have effects on activity. Five mutants showing decreased catalytic efficiency (k(cat)/Km) were further analyzed for substrate selectivity and binding affinities and showed reduced catalytic activities for 7-methoxycoumarin O-demethylation, tert-butyl methyl ether O-demethylation, and indole 3-hydroxylation. All mutants except one (K476E) showed decreased coumarin binding affinities (and also higher Km values), indicating that this is a major basis for the decreased enzymatic activities. A recent x-ray crystal structure of P450 2A6 bound to coumarin (Yano, J. K., Hsu, M. H., Griffin, K. J., Stout, C. D., and Johnson, E. F. (2005) Nat. Struct. Mol. Biol. 12, 822-823) indicates that the recovered A481T and N297S mutations appear to be close to coumarin, suggesting direct perturbation of substrate interaction. The decreased enzymatic activity of the K476E mutant was associated with decreases both in NADPH oxidation and the reduction rate of the ferric P450 2A6-coumarin complex. The attenuation is caused in part to lower binding affinity for NADPH-P450 reductase, but the K476E mutant did not achieve the wild-type coumarin 7-hydroxylation activity even at high reductase concentrations.     

Toddasin,a new dimeric coumarin from Toddalia asiatica

A new dimeric coumarin, named toddasin and possessing a cyclohexene ring with a vinylic side-chain interposed between the two coumarin moieties has been isolated from the roots of Toddalia asiatica. It has been characterized as (E)-8,8′-[1″,4″-dimethyl-3″ -cyclohexen-1″,2″-ylene vinylene]-bis-[5,7-dimethoxycoumarin] (1). The proposed structure is supported by the mass fragmentation of its dihydro derivative (2).     

Nonglycosidic analogues of nucleotides. IX. Self-association of 9-(omega'-hydroxyalkyl) adenine omega'-phosphates in aqueous solutions]

The dependence of the NMR spectra of adenosine 5'-phosphate and phosphates of 9-(2'-hydroxyethyl)-, 9-(3'-hydroxypropyl)- and 9-(4'-hydroxybutyl)adenines on temperature and concentration has been investigated in aqueous solutions.     

The hepatoprotective effect of coumarin and coumarin derivates on carbon tetrachloride-induced hepatic injury by antioxidative activities in rats

Coumarins are a vast group of natural compounds and some of them possess antioxidant activities. The comparison of the antioxidant activity of some coumarins with various chemical molecular structure has not been investigated in previous studies. Therefore, this study was aimed to investigate the hepatoprotective effect against carbon tetrachloride (CCl₄) -induced hepatic injury by coumarin (1,2-benzopyrone) and coumarin derivatives, esculetin (6,7-dihydroxycoumarin), scoparone (6,7-dimethoxycoumarin), and 4-methylumbelliferone (7-hyroxy-4-methyl) in male Sprague–Dawley rats. Product of lipid peroxidation, malondialdehyde (MDA), activities of antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT) were evaluated for oxidative stress in hepatic injury. Gamma glutamyl transpeptidase (GGT), lactate dehydrogenase (LDH) were detected in plasma as a biomarker of hepatic injury. Significantly elevated levels of MDA and lowered levels of SOD and CAT activities were observed in liver of rats exposed to CCl₄, when compared to control values. Similarly, administration of CCl₄ increased LDH and GGT levels in serum. Pre-treatment of rats with esculetin (35 mg kg⁻¹, orally) and scoparone (35 mg kg⁻¹, orally) significantly prevented CCl₄-induced decrease in MDA levels and increase in SOD and CAT, whereas 4-methylumbelliferone (35 mg kg⁻¹) and coumarin (30 mg kg⁻¹) had no effect against CCl₄-induced rise in serum enzymes. Esculetin and scoparone also showed protective properties as was evidenced in reduced LDH and GGT levels in serum. The results of this study indicate that the chemical structures of coumarins play an important role in the prevention of oxidative stress.     

Synthesis and biological evaluation of 4-(1,2,3-triazol-1-yl)coumarin derivatives as potential antitumor agents

In this research, a series of 4-(1,2,3-triazol-1-yl)coumarin conjugates were synthesized and their anticancer activities were evaluated in vitro against three human cancer cell lines, including human breast carcinoma MCF-7 cell, colon carcinoma SW480 cell and lung carcinoma A549 cell. To increase the biological potency, structural optimization campaign was conducted focusing on the C-4 position of 1,2,3-triazole and the C-6, C-7 positions of coumarin. In addition, to further evaluate the role of 1,2,3-triazole and coumarin for antiproliferative activity, 9 compounds possessing 4-(piperazin-1-yl)coumarin framework and 3 derivatives baring quinoline core were also synthesized. By MTT assay in vitro, most of the compounds display attractive antitumor activities, especially 23. Further flow cytometry assays demonstrate that compound 23 exerts the antiproliferative role through arresting G₂/M cell-cycle and inducing apoptosis.     

Establishment of the enzymatic protein acetylation independent of acetyl CoA: recombinant glutathione S-transferase 3-3 is acetylated by a novel membrane-bound transacetylase using 7,8-diacetoxy-4-methyl coumarin as the acetyl donor

The current knowledge on biological protein acetylation is confined to acetyl CoA-dependent acetylation of protein catalyzed by specific acetyl transferases and the non-enzymatic acetylation of protein by acetylated xenobiotics such as aspirin. We have discovered a membrane-bound enzyme catalyzing the transfer of acetyl groups from the acetyl donor 7,8-diacetoxy-4-methyl coumarin (DAMC) to glutathione S-transferase 3-3 (GST3-3), termed DAMC:protein transacetylase (TAase). The purified enzyme was incubated with recombinant GST3-3 subunit and DAMC, the modified protein was isolated by sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE) in gel digested with trypsin and the tryptic digest was analyzed by mass spectrometry. The N-terminus and six lysines, Lys-51, -82, -124, -181, -191 and -210, were found to be acetylated. The acetylation of GST3-3 described above was not observed in the absence of either DAMC or TAase. These results clearly establish the phenomenon of protein acetylation independent of acetyl CoA catalyzed by a hitherto unknown enzyme (TAase) utilizing a certain xenobiotic acetate (DAMC) as the active acetyl donor.     

Synthesis, crystal structure and photoluminescent property of an iridium complex with coumarin derivative ligand

Novel iridium complex containing coumarin derivative as a cyclometalated ligand (L) and picolinate (pic) as the ancillary ligand, Ir(III)bis(3-(pyridin-2-yl)coumarinato N,C⁴)(picolinate) [Ir(L)₂(pic)], was synthesized and characterized. It was demonstrated that the iridium (III) ion in Ir(L)₂(pic) is hexacoordinated by two C atoms and two N atoms from 3-(pyridin-2-yl)coumarin ligands and one N atom and one O atom from picolinate ligand, displaying a distorted octahedral coordination geometry. The Ir(L)₂(pic) has very strong absorption and intensive emission at 532 nm. These results show the promising future of that Ir(L)₂(pic) in fabrication organic light-emitting diodes.     

Effect of coumarin and some coumarin derivatives on active transport and passive diffusion of sugars by chicken and rat intestine, in vitro.

The effect of coumarin, 4-hydroxycoumarin, coumarin-3-carboxylic acid and acenocoumarol on the active transport of D-galactose and the passive diffusion of arabinose by intestinal sacs was studied. All these substances, when added to the mucosal medium of incubation at concentrations from 10(-4) to 10(-3) M, inhibit the active transport of D-galactose and increase the diffusion of arabinose. Oxygen uptake by the intestinal tissue is only inhibited by coumarin-3-carboxylic acid. The results suggest that the effects obtained are probably due to an alteration in intestinal permeability, to inhibition of cell metabolism and to molecular size.     

Biosynthesis of coumarin glycosides by transgenic hairy roots of Polygonum multiflorum

To investigate the substrate specificity and regio-selectivity of coumarin glycosyltransferases in transgenic hairy roots of Polygonum multiflorum, esculetin (1) and eight hydroxycoumarins (2-9) were employed as substrates. Nine corresponding glycosides (10-18) involving four new compounds, 6-chloro-4-methylcoumarin 7-O-β-D-glucopyranoside (15), 6-chloro-4-phenylcoumarin 7-O-β-D-glucopyranoside (16), 8-hydroxy-4-methylcoumarin 7-O-β-D-glucopyranoside (17), and 8-allyl-4-methylcoumarin 7-O-β-D-glucopyranoside (18), were biosynthesized by the hairy roots.     

Antimicrobial activity of two novel coumarin derivatives: 3-cyanonaphtho[1,2-(e)] pyran-2-one and 3-cyanocoumarin

The antimicrobial activity of the two novel coumarin derivatives, 3-cyanonaphthol[1,2-(e)]pyran-2-one and 3-cyanocoumarin was determined. The two novel coumarin derivatives showed specific activity against most gram-positive organisms and yeast with lower activity against most gram-negative bacteria. The MIC values of compounds showed that they are largely active against E. coli to a lesser extent against S. aureus and C. albicans.     

分布于日本和中国的鹅观草及其杂种的形态学和细胞学研究

本文对分布于日本的Agropyron tsukushiense(Honda)Ohwi var. transiense(Hack.)Ohwi(2n＝6X＝42）和分布于中国的Roegneria kamoji Ohwi(2n＝6X＝42）及其杂种F1(2n＝6x＝42）进行了形态学及细胞学的研究,并同时探讨了亲本种的亲缘关系。总体来看,亲本材料之间在形态上虽有差异但并不十分显著。杂种F1的形态特征介于其父、母本之间。在减数分裂过程中,亲本种和杂种F1的染色体配对行为均十分正常。但在检查了大量的成熟花粉和穗状花序之后,发现杂种F1有部份不育现象。上述研究结果表明A.tsuku-shiense var.transiens的三个染色体组与R.kamoji的三个染色体组同源。结合形态学和育性等方面的研究资料,作者认为上述两个材料仍应属于同一分类等级。但必须指出,由于长期的地理隔离,他们之间产生了一定的形态变异和生殖障碍。按照国际植物命名法规（ICBN）上述两个材料应组合:Roegneria tsukushiensis(Honda)B．R．Lu,Yen et J.L.Yang 及其变种var.transiens(Hack.)B．R．Lu,Yen et J.L.Yang comb.nov．