10 documents found, page 1 of 1
Synergistic effects between macrocyclic diterpenes and doxorubicin on resistant...
Duarte, N; Járdánházy, A; Ramalhete, Cátia; Molnar, J; Ferreira, MJUThe aim of this study was to search for new multidrug resistance reversal agents from Euphorbia species. In this way, three new jatophane diterpenes (1 – 3) isolated from E.tuckeyana (Fig. 1) and three new lathyrane esters (4 - 6) obtained through acylation reations of latilagascene B (Fig. 4), have been screened for their potential P-gp modulating properties on mouse resistance cancer cell lines. Furthermore, ...
Novel beta-carboline indole alkaloids from the leaves of Tabernaemontana elegans
Mansoor, TA; Ramalhete, Cátia; Molnar, J; Mulhovo, S; Ferreira, MJUWe have isolated three -carboline indole alkaloids (1-3) from the MeOH extract of the leaves of Tabernaemontana elegans. The chemical structures of these novel entities were established by means of spectroscopic techniques including 2D NMR spectroscopic experiments. The new skeletal features of compounds 1 and 2 were the presence of a two-carbon unit, attached to a structurally related -carboline skeleton, re...
New macrocyclic lathyrane diterpenes, from Euphorbia lagascae, as inhibitors of...
Duarte, N; Gyemant, N; Abreu, PM; Molnar, J; Ferreira, MJUThe new macrocyclic lathyrane diterpenes latilagascenes A and B (1 and 2), the diacetylated derivative of 2, latilagascene C (3), and the known diterpenes ent- 16 alpha,17-dihydroxyatisan-3-one (4) and ent-16 alpha,17-dihydroxykauran-3-one (5), isolated from the methanol extract of Euphorbia lagascae, were examined for their effects on the reversal of multidrug resistance (MDR) oil mouse lymphoma cells. Among t...
Inhibition of multidrug resistance of cancer cells by natural diterpenes, trite...
Molnar, J; Gyemant, N; Tanaka, M; Hohmann, J; Bergmann-Leitner, E; Molnar, P; Deli, J; Didiziapetris, R; Ferreira, MJUThe multidrug resistance (MDR) proteins are member of the ATP-binding cassette superfamily and are present in a majority of human tumors. Their activity is a crucial factor leading to therapeutic failure. It is likely that compounds which inhibit the function of the MDR-efflux proteins such as MDR I will improve the cytotoxic action of anticancer chemotherapy. Therefore, a search for MDR reversing compounds was...
Inhibition of P-glycoprotein transport activity in a resistant mouse lymphoma c...
Ferreira, MJU; Gyemant, N; Madureira, AM; Molnar, JMultidrug resistance (MDR) is believed to be a major reason for the failure of cancer treatment. It is in most cases caused by the activity of the various ABC transporters, multidrug resistance (MDR) gene-encoded p-glycoproteins that pump anticancer drugs out of the cells. P-glycoprotein (P-gp) and multidrug resistance-associated protein (MRP1) are the most important and widely studied members of the ABC superf...
The effects of jatrophane derivatives on the reversion of MDRI- and MRP-mediate...
Ferreira, MJU; Gyemant, N; Madureira, AM; Tanaka, M; Koos, K; Didziapetris, R; Molnar, JMultidrug resistance (MDR) of cancer cells can be the result of a variety of mechanisms that are not completely understood. One of the most significant among them concerns altered membrane transport in tumor cells, often referred to as typical or classic MDR. This mechanism is related to the overexpression of a variety of proteins, that belong to the super family of ABC transporters. The aim or this study was t...
Pubescenes, jatrophane diterpenes, from Euphorbia pubescens, with multidrug res...
Valente, C; Ferreira, MJU; Abreu, PM; Gyemant, N; Ugocsai, K; Hohmann, J; Molnar, JThe macrocyclic jatrophane diterpene polyesters, pubescenes A-D (1-4) were isolated from the whole dried plant of Euphorbia pubescens, and evaluated for multidrug resistance (MDR) reversing activity on mouse lymphoma cells. All the compounds displayed very strong activity compared with the positive control verapamil. Pubescene D (4) is a new compound, whose structure was established as 3beta9alpha,-diacetoxy-7b...
Rearranged jatrophane-type diterpenes from Euphorbia species. Evaluation of the...
Madureira, AM; Ferreira, MJU; Gyemant, N; Ugocsai, K; Ascenso, JR; Abreu, PM; Hohmann, J; Molnar, JThe rearranged jatrophane-type diterpenes (1 - 3), isolated from the Me2CO extracts of Euphorbia portlandica and Euphorbia segetalis, were examined for their effects on multidrug resistance (MDR) in mouse lymphoma cells. Compounds 2 and 3 revealed to be active with the latter being more active than the positive control verapamil, a known resistance modifier. The new compound 1, named portlandicine, was isolated...
A new sesquiterpene-coumarin ether and a new abietane diterpene and their effec...
Madureira, AM; Molnar, A; Abreu, PM; Molnar, J; Ferreira, MJUA new sesquiterpene-coumarin ether (5'beta,9'alpha,10'alpha)-7-O-(3alpha-methoxy-8'(12')-drimen-11'-yl) -scopoletin, designated driportlandin (1) and a new abietane quinoid diterpene 16-hydroxyabieta-8,12-diene-11,14-dione, named portlanquinol (2) together with lupeol, nepehinol, wrightial, formonetin and davidigenin were isolated and characterized from the Me2CO extract of whole dried plant of Euphorbia portla...
Effect of cycloartanes on reversal of multidrug resistance and apoptosis induct...
Madureira, AM; Spengler, G; Molnar, A; Varga, A; Molnar, J; Abreu, PM; Ferreira, MJUThe ability of fifteen cycloartanes, isolated from Euphorbia species, to reverse multidrug resistance (MDR) and apoptosis induction in L5178Y mouse lymphoma cells, including its multidrug-resistant subline, was studied by flow cytometry. Reversion of MDR was investigated using a standard functional assay with rhodamine 123 as a fluorescent substrate analogue. For the evaluation of apoptosis, the cells were stai...