Browsing by Author "Abreu, PM"
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- 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.
- Antioxidant and antileishmanial activity of piceatannolPublication . Duarte, N; Figueira, ME; Mota-Filipe, H; Kayser, O; Abreu, PM; Castro, M; Ferreira, MJU
- Bioactive diterpenoids, a new jatrophane and two ent-abietanes, and other constituents from Euphorbia pubescensPublication . Valente, C; Pedro, M; Duarte, A; Nascimento, MSJ; Abreu, PM; Ferreira, MJUA new jatrophane diterpene, pubescenol (1), known ent-abietane lactones, helioscopinolide A (2) and B (3), and taraxerone, 24-methylenecycloartanol, and vanillin have been isolated from Euphorbia pubescens. Diterpenes 1-3 and previously described pubescene D (4) were shown to be moderate inhibitors of the growth of MCF-7, NCI-H460, and SF-268 human tumor cell lines, whereas compounds 2 and 3 also exhibited significant antibacterial activity against Staphylococcus aureus.
- 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.
- Euphopubescenol and euphopubescene, two new jatrophane polyesters, and lathyrane-type diterpenes from Euphorbia pubescensPublication . Valente, C; Pedro, M; Ascenso, JR; Abreu, PM; Nascimento, MSJ; Ferreira, MJUThe structures of euphopubescenol and euphopubescene, two new macrocyclic jatrophane diterpene polyesters, isolated from the whole dried plant of Euphorbia pubescens, were established as 5alpha,8alpha,15beta-triacetoxy-3alpha-benzoyloxy-4alpha-hydroxy-9,14-dioxo-13betaH-jatropha-6(17),11E-diene (1) and 3beta,7beta,8beta,9alpha,14alpha,15beta-hexa-acetoxy-2betaH-jatropha-5E,11E-diene (2) by 1D- and 2D-NMR (COSY, HMQC, HMBC and NOESY), IR, EI-MS and EI-FTICR-MS. Two known lathyrane derivatives, jolkinol A (3) and jolkinol A (4), whose C-13-NMR spectra were assigned, were also isolated. Compounds 1-3 have been evaluated for their ability to inhibit the in vitro growth of three human tumour cell lines representing different tumour types, MCF-7 (breast adenocarcinoma), NCI-H460 (non-small cell lung cancer) and SF-268 (CNS cancer). They inhibited both MCF-7 and NCI-H460 cell lines, with GI(50) values ranging between 40.9 muM and 95.3 muM, but were found to be ineffective as growth inhibitors of the SF-268 cell line.
- New macrocyclic lathyrane diterpenes, from Euphorbia lagascae, as inhibitors of multidrug resistance of tumour cellsPublication . 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 the active lathyrane derivatives 1 -3, compound 2 displayed the highest inhibition of rhodamine 123 efflux of human MDR gene transfected Mouse lymphoma cells when compared to the untreated cells or the positive control verapamil. The new compounds are the first macrocyclic lathyrane diterpenes showing oxidation at C-16, whose structures were characterized by extensive spectroscopic methods, including 2D NMR experiments (H-1-H-1 COSY, HMQC, HMBC and NOESY). The known phenolic Compounds vanillic acid (6), p-salicylic acid (7), isofraxidin (8) and cleomiscosin A (9) were also isolated from this species.
- Pubescenes, jatrophane diterpenes, from Euphorbia pubescens, with multidrug resistance reversing activity on mouse lymphoma cellsPublication . 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-7beta-benzoyloxy-15beta-hydroxy-14-oxo-2betaH-jatropha-5E,12E-diene by spectroscopic methods, including H-1-H-1 COSY, HMQC, HMBC and NOESY.
- Rearranged jatrophane-type diterpenes from Euphorbia species. Evaluation of their effects on the reversal of multidrug resistancePublication . 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 from Euphorbia portlandica and its structure characterised by high-field NMR spectroscopic methods including 2D NMR techniques: COSY, HMQC, HMBC and NOESY. The known diterpene 2, together with aleuritolic acid (4), oleanolic acid (5), and betulin diacetate (6), were also isolated from the same species.
- Study of the secondary metabolites of the methanol extract of Euforbia pubescens. Evaluation of their antibacterial activityPublication . Valente, C; Duarte, A; Ascenso, JR; Abreu, PM; Ferreira, MJU
- Three new jatrophane-type diterpenes from Euphorbia pubescensPublication . Valente, C; Ferreira, MJU; Abreu, PM; Pedro, M; Cerqueira, F; Nascimento, MSJThree new macrocyclic jatrophane diterpene polyesters, named pubescenes A (1), B (2), and C (3), and the known compounds indole-3-aldehyde and scopoletin have been isolated and characterised from the whole dried plant of Euphorbia pubescens. The structures of the new compounds were established by spectroscopic means including 2D-NMR techniques such as COSY, HMQC, HMBC and NOESY experiments. Compounds 1-3 were evaluated for their in vitro effect on the growth of three human cancer cell lines MCF-7 (breast), NCI-H460 (lung) and SF-268 (CNS) as well as for their capacity to interfere with the proliferation of human peripheral blood lymphocytes. They exhibited a moderate growth inhibitory effect on the cancer cell line NCI-H460. No effect was observed on the mitogenic response of human lymphocytes to PHA.