Search results for "coumarin"
showing 10 items of 116 documents
New umbelliferone sesquiterpene ethers from roots ofLigularia persica
1991
An extract of roots of Ligularia persica yielded thirteen umbelliferone sesquiterpene ethers, among them the new ones ligupersin A (11) and ligupersin B (13).
Coumarin derivatives from Pedilanthus tithymaloides as inhibitors of conidial germination in Magnaporthe oryzae
2012
In a screening for inhibitors of infection-related morphogenesis in the rice blast fungus Magnaporthe oryzae, a series of 10 coumarin derivatives were isolated from Pedilanthus tithymaloides (Euphorbiaceae). Seven of these compounds turned out to be known while three represent previously unreported natural products. Their structures were established on the basis of spectroscopic data and X-ray crystallography. Nine out of 10 coumarin derivatives were found to inhibit conidial germination in the phytopathogenic fungus at low concentrations.
Synthesis of Lamellarin D Trimethyl Ether and Lamellarin H via 6π-Electrocyclization.
2015
An electrocyclic ring closure of a 2-azapentadienyl anion generated in situ from a chalcone and glycine ester is the key step of an efficient synthesis of the pyrrole core of the lamellarin alkaloids. A recently developed scalable one-pot procedure provides multigram quantities of a 3,5-diaryl-4-iodopyrrole-2-carboxylate intermediate which is transformed in four further high-yielding operations including a one-pot Pomeranz–Fritsch alkylation/cyclization and an Ullmann-type lactone ring closure into the pentacyclic lamellarin skeleton.
New insights into the water-solubilization of thiol-sensitive fluorogenic probes based on long-wavelength 7-hydroxycoumarin scaffolds
2014
Abstract The synthesis and photophysical properties of novel water-soluble phenol-based fluorophores derived from 3-benzothiazolyl-7-hydroxycoumarin and emitting in the range 485–631 nm are described. Further conversion into thiol-sensitive fluorogenic probes through the chemical modification of their hydroxyl group was next investigated. Depending on the type of thiol-reactive quenching moiety used (2,4-dinitrobenzenesulfonyl ester, 2,4-dinitrophenyl ether or benzoquinone-type Michael acceptors) and the water-solubilizing group(s) pre-introduced into the coumarin core, dramatic differences in the thiol-induced fluorescence activation of these pro-fluorophores under physiological conditions…
Inhibition of Plant Lactate Dehydrogenase Isoenzymes by Benzoic Acid and Cinnamic Acid Derivatives
1976
Summary Several phenolic compounds such as derivatives of benzoic and cinnamic acid were investigated with respect to their inhibitory effect on potato tuber lactate dehydrogenase isoenzymes. Ki values were determined and it was found that they were in the range of 10−2 M for several benzoic acid derivatives while they were in the range of 10−5 M for several hydroxylated cinnamic acid derivatives such as 3,4-dihydroxy cinnamic acid, p(m)nitrocinnamic acid, and 7,8-dihydroxy-4-methyl coumarin as well as kynurenic acid. Also coumaric acid derivatives revealed a very strong inhibition: The K1 values for coumarin and p-coumaric acid were in the range of 10−4 M. The inhibition by all aromatic co…
Singlet oxygen generation in PUVA therapy studied using electronic structure calculations
2009
Abstract The ability of furocoumarins to participate in the PUVA (Psoralen + UV-A) therapy against skin disorders and some types of cancer, is analyzed on quantum chemical grounds. The efficiency of the process relies on its capability to populate its lowest triplet excited state, and then either form adducts with thymine which interfere DNA replication or transfer its energy, generating singlet molecular oxygen damaging the cell membrane in photoactivated tissues. By determining the spin–orbit couplings, shown to be the key property, in the intersystem crossing yielding the triplet state of the furocoumarin, the electronic couplings in the triplet–triplet energy transfer process producing …
Photoinduced Cluster Formation of Coumarin-Labeled Organosilicon Micronetworks
2000
Molecular docking and oxidation kinetics of 3-phenyl coumarin derivatives by human CYP2A13
2021
CYP2A13 enzyme is expressed in human extrahepatic tissues, while CYP2A6 is a hepatic enzyme. Reactions catalysed by CYP2A13 activate tobacco-specific nitrosamines and some other toxic xenobiotics in lungs.To compare oxidation characteristics and substrate-enzyme active site interactions in CYP2A13 vs CYP2A6, we evaluated CYP2A13 mediated oxidation characteristics of 23 coumarin derivatives and modelled their interactions at the enzyme active site.CYP2A13 did not oxidise six coumarin derivatives to corresponding fluorescent 7-hydroxycoumarins. The Km-values of the other coumarins varied 0.85���97 ��M, Vmax-values of the oxidation reaction varied 0.25���60 min���1, and intrinsic clearance var…
In vitro glucuronidation of 7-hydroxycoumarin derivatives in intestine and liver microsomes of Beagle dogs
2019
Beagle dog is a standard animal model for evaluating nonclinical pharmacokinetics of new drug candidates. Glucuronidation in intestine and liver is an important first-pass drug metabolic pathway, especially for phenolic compounds. This study evaluated the glucuronidation characteristics of several 7-hydroxycoumarin derivatives in beagle dog's intestine and liver in vitro. To this end, glucuronidation rates of 7-hydroxycoumarin (compound 1), 7-hydroxy-4-trifluoromethylcoumarin (2), 6-methoxy-7-hydroxycoumarin (3), 7-hydroxy-3-(4-tolyl)coumarin (4), 3-(4-fluorophenyl)coumarin (5), 7-hydroxy-3-(4-hydroxyphenyl)coumarin (6), 7-hydroxy-3-(4-methoxyphenyl)coumarin (7), and 7-hydroxy-3-(1H-1,2,4-t…
Substrate Selectivity of Coumarin Derivatives by Human CYP1 Enzymes: In Vitro Enzyme Kinetics and In Silico Modeling
2021
Of the three enzymes in the human cytochrome P450 family 1, CYP1A2 is an important enzyme mediating metabolism of xenobiotics including drugs in the liver, while CYP1A1 and CYP1B1 are expressed in extrahepatic tissues. Currently used CYP substrates, such as 7-ethoxycoumarin and 7-ethoxyresorufin, are oxidized by all individual CYP1 forms. The main aim of this study was to find profluorescent coumarin substrates that are more selective for the individual CYP1 forms. Eleven 3-phenylcoumarin derivatives were synthetized, their enzyme kinetic parameters were determined, and their interactions in the active sites of CYP1 enzymes were analyzed by docking and molecular dynamic simulations. All cou…