Search results for "RESISTANCE"
showing 10 items of 3641 documents
Gold(I) Biscarbene Complexes Derived from Vascular-Disrupting Combretastatin A-4 Address Different Targets and Show Antimetastatic Potential
2014
Gold N-heterocyclic carbene (NHC) complexes are an emerging class of anticancer drugs. We present a series of gold(I) biscarbene complexes with NHC ligands derived from the plant metabolite combretastatin A-4 (CA-4) that retain its vascular-disrupting effect, yet address different cellular and protein targets. Unlike CA-4, these complexes did not interfere with tubulin, but with the actin cytoskeleton of endothelial and cancer cells. For the highly metastatic 518A2 melanoma cell line this effect was accompanied by a marked accumulation of cells in the G1 phase of the cell cycle and a suppression of active prometastatic matrix metalloproteinase-2. Despite these mechanistic differences the co…
Synthesis and biological evaluation of 4-nitro-substituted 1, 3-diaryltriazenes as a novel class of potent antitumor agents
2011
Abstract We describe the synthesis and biological activity of a new class of 1,3-diaryltriazenes, namely 4-nitro-substituted 1,3-diaryltriazenes. Structure–activity relationship analysis reveals that 1,3-diaryltriazenes can be modified from inactive to highly cytotoxic compounds by the introduction of two nitro groups at the para positions of benzene rings and two additional electron-withdrawing groups (bromo, chloro, trifluoromethyl or fluoro substituents) at their ortho position. In order to increase the solubility of the modified compounds, we introduced various acyl groups to their triazene nitrogen. The results of LC-MS/MS analysis showed that N -acyltriazenes can be considered as prod…
Cytotoxicity and modes of action of four naturally occuring benzophenones: 2,2′,5,6′-Tetrahydroxybenzophenone, guttiferone E, isogarcinol and isoxant…
2012
Abstract Introduction The emergence of drug-resistant cancer cells drastically reduces the efficacy of many antineoplasic agents and, consequently, increases the frequency of therapeutic failure. Benzophenones are known to display many pharmacological properties including cytotoxic activities. The present study was aimed at investigating the cytotoxicity and the modes of action of four naturally occurring benzophenones 2,2′,5,6′-tetrahydroxybenzophenone ( 1 ), isogarcinol ( 2 ), isoxanthochymol ( 3 ) and guttiferone E ( 4 ) on a panel of eleven cancer cell lines including various sensitive and drug-resistant phenotypes. Methods The cytotoxicity of the compounds was determined using a resazu…
Furoquinolines and dihydrooxazole alkaloids with cytotoxic activity from the stem bark of Araliopsis soyauxii.
2018
Abstract Two new furoquinoline alkaloids, maculine B (1) and kokusaginine B (2) and one new dihydrooxazole alkaloid, veprisazole (3), along with four known compounds namely, N13-methyl-3-methoxyrutaecarpine (4), flindersiamine (5), skimmianine (6) and tilianin (7) were isolated from the methanol extract of the stem bark of Araliopsis soyauxii Engl. by various chromatographic methods. Their structures were determined using spectrometry and spectroscopic techniques including NMR and MS. The cytotoxicity of the new compounds compared to that of doxorubicin, the reference anticancer compound, was determined on a panel of nine cancer cell lines including sensitive and drug resistant phenotypes. …
Joziknipholones A and B: The First Dimeric Phenylanthraquinones, from the Roots ofBulbine frutescens
2007
From the roots of the African plant Bulbine frutescens (Asphodelaceae), two unprecedented novel dimeric phenylanthraquinones, named joziknipholones A and B, possessing axial and centrochirality, were isolated, together with six known compounds. Structural elucidation of the new metabolites was achieved by spectroscopic and chiroptical methods, by reductive cleavage of the central bond between the monomeric phenylanthraquinone and -anthrone portions with sodium dithionite, and by quantum chemical CD calculations. Based on the recently revised absolute axial configuration of the parent phenylanthraquinones, knipholone and knipholone anthrone, the new dimers were attributed to possess the P-co…
Fluoroquinolone–metal complexes: A route to counteract bacterial resistance?
2014
Abstract Microbial resistance to antibiotics is one of the biggest public health threats of the modern world. Antibiotic resistance is an area of much clinical relevance and therefore research that has the potential to identify agents that may circumvent it or treat resistant infections is paramount. Solution behavior of various fluoroquinolone (FQ) complexes with copper(II) in the presence and absence of 1,10-phenanthroline (phen) was studied in aqueous solution, by potentiometry and/or spectrophotometry, and are herein described. The results obtained showed that under physiological conditions (micromolar concentration range and pH 7.4) only copper(II):FQ:phen ternary complexes are stable.…
Presence and characterisation of verotoxin producing E. coli in fresh Italian pork sausages, and preparation and use of an antibiotic-resistant strai…
2005
One hundred and twenty six samples of fresh pork sausages were analysed-for the presence of verocytotoxigenic Escherichia coli (VTEC). Selective enrichment followed by DNA extraction and PCR amplification of the stx1 and stx2 genes highlighted the occurrence of the above mentioned genes in 20 out of 126 samples screened. From the stx positive enriched cultures, isolation was performed on CT-SMAC agar plates after immuno-magnetic separation of E. coli O157. Fifty three non-sorbitol fermenting isolates were obtained and further characterised, along with the reference strain E. coli ATCC 35150(T). All the isolates were characterised by PCR assays, assessing the presence of stx1, stx2, rfbE(O15…
Thermodynamics and continuum fracture mechanics for nonlocal-elastic plastic materials
2002
Nonlocal elasticity is used as an improved elasticity model which engenders no crack-tip stress singularities and thus makes applicable the classical stress-based failure criteria. Considering nonlocal-elastic plastic materials exposed to softening by particle decohesion in a process surface and to subsequent surface separation by fracture, fracture mechanics is addressed within the framework of irreversible internal-variable thermodynamics in the hypothesis of small strains and arbitrary (but sufficiently regular) fracture surface (crack surface plus process surface). The state equations and the energy dissipation densities are derived for the bulk material and for the process surface, for…
Crack growth analysis at adhesive–adherent interface in bonded joints under mixed mode I/II
2008
The propagation of an interface crack subjected to mixed mode I/II was investigated for two 2024-T351 aluminum thin layers joined by means of DP760 epoxy adhesive produced by 3M©. On the basis of beam theory, an analytical expression for computing the energy release rate is presented for the mixed-mode end loaded split (MMELS) test. The analytical strain energy release rate was compared by finite element (FE) analysis using the virtual crack closure technique (VCCT). Several fatigue crack growth tests were carried out in a plane bending machine to compare the experimental energy release rates to those of the analytical and FE solutions. Experimental results showed the relationship between t…
Strain-Controlled Giant Magnetoresistance in Spin Valves Grown on Shape Memory Alloys
2019
We report a strain-mediated giant magnetoresistance (GMR) in spin valves (SPVs) grown on shape memory alloys (SMAs). The SPVs with a stacking structure of Al2O3/Co90Fe10/Cu/Co90Fe10/IrMn/Pt were de...