Search results for "plastic"
showing 10 items of 7296 documents
Ferrocenyl-Coupled N-Heterocyclic Carbene Complexes of Gold(I)
2016
Four gold(I) carbene complexes featuring 4-ferro-cenyl-substituted imidazol-2-ylidene ligands were investigated for antiproliferative and antivascular properties. They were active against a panel of seven cancer cell lines, including multidrug-resistant ones, with low micromolar or nanomolar IC50 (72 h) values, according to their lipophilicity and cellular uptake. The delocalized lipophilic cationic complexes 8 and 10 acted by increasing the reactive oxygen species in two ways: through a genuine ferrocene effect and by inhibiting the thioredoxin reductase. Both complexes gave rise to a reorganization of the F-actin cytoskeleton in endothelial and melanoma cells, associated with a G1 phase c…
Cytotoxic bufadienolides from the leaves of a medicinal plant Melianthus comosus collected in South Africa.
2020
Abstract From the leaves of South African medicinal plant Melianthus comosus, four previously undescribed bufadienolides, 16β-formyloxymelianthugenin (1), 2β-acetoxymelianthusigenin (2), 2β-hydroxy-3β,5β-di-O-acetylhellebrigenin (3), and 2β-acetoxy-5β-O-acetylhellebrigenin (4) were isolated together with two known bufadienolides. The structural elucidation of the compounds was based on 1D and 2D NMR spectroscopy, high-resolution mass spectrometry, and other spectroscopic methods. The relative configurations were determined by single-crystal X-ray crystallography analysis and NOESY correlations. The isolated compounds displayed strong cytotoxicity against MCF-7 breast cancer cells, sensitive…
Cytotoxic 14-Membered Macrolides from a Mangrove-Derived Endophytic Fungus, Pestalotiopsis microspora.
2016
Seven new 14-membered macrolides, pestalotioprolides C (2), D-H (4-8), and 7-O-methylnigrosporolide (3), together with four known analogues, pestalotioprolide B (1), seiricuprolide (9), nigrosporolide (10), and 4,7-dihydroxy-13-tetradeca-2,5,8-trienolide (11), were isolated from the mangrove-derived endophytic fungus Pestalotiopsis microspora. Their structures were elucidated by analysis of NMR and MS data and by comparison with literature data. Single-crystal X-ray diffraction analysis was used to confirm the absolute configurations of 1, 2, and 10, while Mosher's method and the TDDFT-ECD approach were applied to determine the absolute configurations of 5 and 6. Compounds 3-6 showed signif…
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…
Semisynthesis and cytotoxicity of styryl-lactone derivatives.
1999
The cytotoxicity and the cell-cycle action of altholactone (1), goniofufurone (2), and eight altholactone derivatives (5-12), were determined in vitro on L-1210 cells. Semisyntheses and structure-activity relationships of these compounds are described. The results of this study suggest that the cytotoxicity of altholactone (1), 11-nitro-altholactone (8), and 7-chloro-6,7-dihydroaltholactone (10) is due to the accumulation of the cells in the G2 + M phase of the cell cycle.
Antiproliferative properties and g-quadruplex-binding of symmetrical naphtho[1,2-b:8,7-b’]dithiophene derivatives
2021
Background: G-quadruplex (G4) forming sequences are recurrent in telomeres and promoter regions of several protooncogenes. In normal cells, the transient arrangements of DNA in G-tetrads may regulate replication, transcription, and translation processes. Tumors are characterized by uncontrolled cell growth and tissue invasiveness and some of them are possibly mediated by gene expression involving G-quadruplexes. The stabilization of G-quadruplex sequences with small molecules is considered a promising strategy in anticancer targeted therapy. Methods: Molecular virtual screening allowed us identifying novel symmetric bifunctionalized naphtho[1,2-b:8,7-b’]dithiophene ligands as interesting ca…
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…
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. …