Search results for "relationship"
showing 10 items of 3616 documents
Synthesis and preliminary antibacterial evaluation of Linezolid-like 1,2,4-oxadiazole derivatives
2012
In the present study the synthesis of new Linezolid-like molecules has been achieved by substitution of the oxazolidinone central heterocyclic moiety with a 1,2,4-oxadiazole ring. Two series of 1,2,4-oxadiazoles, bearing different side-chains and containing a varying number of fluorine atoms, were synthesized and preliminarily tested for biological activity against some Gram-positive and Gram-negative bacteria using Linezolid and Ceftriaxone as reference drugs
Phytochemical Profile and Apoptotic Activity of Onopordum cynarocephalum.
2012
A phytochemical investigation of acetone and chloroform extracts of the aerial parts of Onopordum cynarocephalum Boiss. et Blanche was carried out. It led to the isolation of two new sesquiterpenes, the elemane aldehyde (2) and the eudesmane (11), together with 15 known compounds: two lignans (1 and 15) and 13 sesquiterpenes (3–10, 12–14, 16, 17). The structures were elucidated by spectroscopic analyses, especially 1D and 2D NMR spectra. The anti-growth effect against three human melanoma cell lines, M14, A375, and A2058, of the different extracts and compounds of O. cynarocephalum was also investigated. Among them, the chloroform extract exhibited the strongest biological activity, while t…
Tetrandrine and Isotetrandrine, Two Bisbenzyltetrahydroisoquinoline Alkaloids from Menispermaceae, with Rat Uterine Smooth Muscle Relaxant Activity
1992
Abstract The effects of two bisbenzyltetrahydroisoquinoline alkaloids, 1S, 1′S tetrandrine and its isomer 1R, 1′S isotetrandrine, were investigated in rat isolated uterus in order to identify the mechanism of relaxant action and to study the influence of the absolute configuration on the activity of these alkaloids. Both inhibited the uterine contraction induced by high K+, acetylcholine and oxytocin. In Ca2+-free medium, isotetrandrine relaxed the sustained contraction induced by oxytocin but tetrandrine did not. The relaxant effects of the alkaloids may be due to blockade of calcium influx through specific channels. Tetrandrine and isotetrandrine modify the calcium channel in a nonreversi…
Efficient synthesis of hexahydroindenopyridines and their potential as melatoninergic ligands.
2014
Hexahydroindenopyridine (HHIP) is an interesting tricyclic piperidine nucleus that is structurally related to melatonin, a serotonin-derived neurohormone. Melatonin receptor ligands have applications in several cellular, neuroendocrine and neurophysiological disorders, including depression and/or insomnia. We report herein an efficient two-step method to prepare new HHIP via enamine C-alkylation-cyclization. The influence of substituents on the benzene ring and the nitrogen atom on melatoninergic receptors has been studied. Among the 25 synthesized HHIPs, some of them containing methylenedioxy (series 2) and 8-chloro-7-methoxy substituents (series 4) on the benzene ring revealed affinity fo…
Specific interactions of monotetrahydrofuranic annonaceous acetogenins as inhibitors of mitochondrial complex I.
2000
Annonaceous acetogenins (ACG) are a wide group of cytotoxic compounds isolated from plants of the Annonaceae family. Some of them are promising candidates to be a future new generation of antitumor drugs due to the ability to inhibit the NADH:ubiquinone oxidoreductase of the respiratory chain (mitochondrial complex I), main gate of the energy production in the cell. ACG are currently being tested on standard antitumor trials although little is known about the structure activity relationship at the molecular level. On recent studies, the relevance of several parts of the molecule for the inhibitory potency has been evaluated. Due to the great diversity of skeletons included in this family of…
Stereoselective synthesis and determination of the cytotoxic properties of spicigerolide and three of its stereoisomers.
2003
Stereoselective syntheses of the naturally occurring, cytotoxic lactone spicigerolide and three nonnatural stereoisomers thereof are described. The commercially available sugar l-rhamnose was in all cases the chiral starting material. Key steps in each of these syntheses were asymmetric Brown allylations and ring-closing metatheses. The cytotoxic activities of the four lactones against a range of tumoral lines were then determined.
Cytotoxic activity of some natural and syntetic sesquiterpene lactones
2006
Several natural and synthetic sesquiterpene lactones with different skeletons were tested and found to be active against nine cancer cell lines. Elemane (4), heliangolane (5) and their hydroxy analogues 9 and 10, all containing an α,β-unsaturated aldehyde substituent, were the most potent compounds.
Antibodies directed to drug epitopes to investigate the structure of drug-protein photoadducts. Recognition of a common photobound substructure in ti…
2001
Drug-induced photoallergy is an immune adverse reaction to the combined effect of drugs and light. From the mechanistic point of view, it first involves covalent binding of drug to protein resulting in the formation of a photoantigen. Hence, determination of the structures of drug-protein photoadducts is of great relevance to understand the molecular basis of photoallergy and cross-immunoreactivity among drugs. Looking for new strategies to investigate the covalent photobinding of drugs to proteins, we generated highly specific antibodies to drug chemical substructures. The availability of such antibodies has allowed us to discriminate between the different modes by which tiaprofenic acid (…
Anti-Inflammatory Activity of Unusual Lupane Saponins fromBupleurum fruticescens
1998
Extracts from Bupleurum fruticescens were examined for oral and topical anti-inflammatory activities. The BuOH extract proved to be active against carrageenan and tetradecanoylphorbol acetate acute edemas and allowed the isolation of three saponins identified by spectroscopic techniques as 3 beta-O-(O-alpha-L-rhamnopyranosyl-(1-->4)-O-[beta-D-glucopyranosyl- (1-->6)]-O-beta-D-glucopyranosyl)lup-20(29)-ene-23,28-dioic acid (fruticesaponin A), 3 beta-O-(O-alpha-L-rhamnopyranosyl-(1-->4)-O-beta-D-glucopyranosyl) lup-20(29)-ene-23,28-dioic acid 28-O-beta-D-glucopyranosyl ester (fruticesaponin B), and 3 beta-O-(O-alpha-L-rhamnopyranosyl-(1-->4)-O-[beta-D-glucopyranosyl- (1-->6)]-O-beta-D-glucopy…
Design, synthesis and biological evaluation of new oligopyrrole carboxamides linked with tricyclic DNA-intercalators as potential DNA ligands or topo…
2007
In the context of the design and synthesis of minor groove binding and intercalating DNA ligands some new oligopyrrole carboxamides were synthesized. These hybrid molecules (combilexins) possess a variable and conformatively flexible spacer at the N-terminal end. As intercalating tricyclic systems acridone, acridine, anthraquinones and in a special case iminostilbene terminate the N-terminal end of the pyrrole chain. The cytotoxicity was examined by the NCI antitumor screening, furthermore, biophysical as well as biochemical studies were performed in order to get some information about the DNA binding properties and topoisomerase inhibition effect of this new series of molecules.