Browsing by Author "Madureira, AM"
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- A Diterpene with a Rearranged Jatrofane Skeleton and other Terpenes from Euphorbia portlandicaPublication . Madureira, AM; Ascenso, JR; Ferreira, MJU
- A New abietane quinoide diterpene and a new sesquiterpene-coumarin ether from Euphorbia portlandicaPublication . Madureira, AM; Abreu, P; Ferreira, MJU
- A New Lupane Triterpene from Euphorbia portlandicaPublication . Madureira, AM; Serrão, C; Duarte, MT; Piedade, MFM; Ascenso, J; Ferreira, MJU
- A new sesquiterpene-coumarin ether and a new abietane diterpene and their effects as inhibitors of p-glycoproteinPublication . 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 portlandica. The structures of the new compounds were elucidated from spectral data including 2D-NMR experiments of COSY, HMQC, HMBC and NOESY. When examined for their effects on the reversal of multidrug resistance (MDR) on mouse lymphoma cells, compound 1 proved to be more active than the positive control verapamil and compound 2 was found to be toxic. This is the first report on the isolation of a sesquiterpene-coumarin and a quinoid-type diterpenoid from Euphorbia.
- Compostos Terpénicos Isolados de Euphorbia segetalisPublication . Madureira, AM; Valente, C; Palma, AC; Ascenso, JR; Ferreira, MJU
- Effect of cycloartanes on reversal of multidrug resistance and apoptosis induction on mouse lymphoma cellsPublication . 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 stained with FITC-labeled annexin V and propidium iodide. The majority of the compounds were able to reverse MDR of the tested human MDR1 gene-transfected mouse lymphoma cells. Some of the compounds were able to induce moderate apoptosis in the PAR cell line, but this effect was less effective on multidrug-resistant cells. The results indicate that cycloartanes can be substrates of ABC transporters, which might compete with certain anticancer chemotherapeutics.
- Evaluation of the antiviral and antimicrobial activities of triterpenes isolated from Euphorbia segetalisPublication . Madureira, AM; Ascenso, JR; Valdeira, L; Duarte, A; Frade, JP; Freitas, G; Ferreira, MJUA phytochemical reinvestigation of the whole plant of Euphorbia segetalis yielded five tetracyclic triterpenes: 3 beta- hydroxy- cycloart- 25- en- 24- one ( 1), cycloart- 25- ene- 3 beta, 24- diol ( 2), cycloart- 23- ene- 3 beta, 25- diol ( 3), lanosta-7,9( 11), 24- trien- 3 beta- ol ( 4) and lanosta- 7,9( 11), 24( 31)- trien- 3 beta- ol ( 5). 3 beta- acetoxy- cycloart- 25- en- 24- one ( 1a) and glutinol ( 6), lupenone ( 7), dammaranodienol ( 9), cycloartenol acetate ( 10), 24- methylenecycloartanol acetate ( 11) and beta- sitosterol ( 12), isolated previously, were evaluated for their antiviral activities against Herpes simplex virus ( HSV) and African swine fever virus ( ASFV). Lupenone exhibited strong viral plaque inhibitory effect against HSV- 1 and HSV- 2. The in vitro antifungal and antibacterial activities of 1a, cycloart- 23- ene- 3 beta, 25- diol, 3- acetate ( 3a) and 6 - 12 were also investigated.
- Inhibition of P-glycoprotein transport activity in a resistant mouse lymphoma cell line by diterpenic lactonesPublication . Ferreira, MJU; Gyémánt, N; Madureira, AM; Molnár, Joseph
- Inhibition of P-glycoprotein transport activity in a resistant mouse lymphoma cell line by diterpenic lactonesPublication . 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 superfamily of transporters. The ability of four diterpenic lactones isolated from Euphorbia species to modulate the transport activity of P-gp in mouse lymphoma cells was evaluated by flow cytometry. The reversion of MDR was investigated by using a standard functional assay with rhodamine 123 as a fluorescent substrate analogue of doxorubicin. Verapamil was applied as a positive control. All the compounds were able to reverse the MDR of the tested human MDR] gene-transfected mouse lymphoma cells, in a concentration-dependent manner from 4 to 40 mu g/mL, in a short-term experiment below the cytotoxic doses.
- Isolation and characterization of two new polycyclic jatrophane derivatives from Euphorbia portlandicaPublication . Madureira, AM; Gyémánt, N; Molnár, J; Abreu, P; Ferreira, MJU