39 documents found, page 1 of 4
Isolation of terpenic compounds from the methanolic extract of Euphorbia lagasc...
Duarte, N; Ramalhete, Cátia; Martins, M; Abreu, Pedro; Viveiros, M; Amaral, L; Ferreira, MJUFor as long as man can remember, plants have been used worldwide for the treatment of diseases. Today, many of the drugs currently used are derived from natural products or have dependent upon a natural product for their development and the recent discoveries of the antimalarial artemisinin and the anticancer agent taxol indicate the continuing importance of plant species in drug discovery.2 In recent years, a ...
Screening for antimicrobial activity of plants used in traditional medicine
Ramalhete, Cátia; Duarte, A; Mulhovo, S; Ferreira, MJUInfectious diseases, the leading cause of premature deaths in the world, are killing almost 50.000 people every day.1 Despite the existence of a wide variety of antibacterial agents, the treatment of infectious diseases is a frequent problem in modern-day-medicine due to a significant increase of bacterial resistance to several antibiotics.2 One way to prevent antibiotic resistance is using new compounds that a...
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, ...
Search for antimalarial compounds from Pycnanthus angolensis
Ramalhete, Cátia; Abrantes, M; Mil-Homens, T; Duarte, N; Lopes, D; Cravo, P; Madureira, MC; Ascenso, J; Ferreira, MJUMalaria is one of the most important infectious diseases in underdeveloped countries, particularly in Africa. [1, 2, 3] It affects about 500 million people each year, leading to 1.5 million deaths per year. [2, 3] Multi-resistance to most antimalarials in use is now wide spread, while the cost of effective treatment, through different antimalarial drug combinations, is prohibitive for the majority of the affect...
Screening for antimalarial activity of crude extracts from African medicinal pl...
Ramalhete, Cátia; Lopes, D; Mulhovo, S; Rosário, VE; Ferreira, MJUMalaria a serious parasitic disease, spread by mosquitoes from Anopheles species, is still the most devastating in the world. It has been estimated that in the last 20 years mortality from malaria has doubled (it is currently 3 millions deaths annually), and a major factor responsible for this increase is the resistance of malaria parasites to antimalarial drugs.1 Consequently, there is an urgent need to discov...
Medicinal Plants as a Source of Antiplasmodial Compounds
Ramalhete, Cátia; Lopes, D; Mulhovo, S; Rosário, V; Ferreira, MJUInfectious diseases caused by bacteria, fungi, viruses and parasites are a major threat to public health, despite great progress in therapy. The impact of infectious diseases is especially important in developing countries, where drugs are limited and the emergence of widespread drug resistance is a reality.1 Malaria is a major parasitic disease in the tropical and subtropical regions of the world. It is respon...
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...
Inhibition of P-glycoprotein activity by cucurbitane-type triterpenes and their...
Ramalhete, Cátia; Duarte, N; Capucha, V; Molnár, J; Mulhovo, S; Rosário, V; Ferreira, MJUThe overexpression of P- glycoprotein (P-gp) is one of the mechanisms of multidrug resistance (MDR), responsible for the failure of cancer treatment. One strategy to restore the effectiveness of the anti-cancer drugs is to co-administer compounds that are not toxic themselves, but inhibit these efflux pumps. These compounds have been called MDR inhibitors, MDR modulators, MDR reversal agents or chemosensitizers...
New efflux pumps inhibitors for Gram positive bacteria strains and cancer cells...
Ramalhete, Cátia; Spengler, G; Serley, J; Duarte, N; Viveiros, M; Amaral, L; Molnár, J; Mulhovo, S; Ferreira, MJUAll living cells contain genes encoding multidrug transporters and some of them play an important role in conferring drug resistance in mammalian cancer cells and in microbial pathogens such as Staphylococcus aureus, Enterococcus faecalis, Candida albicans, Plasmodium falciparum, and Leishmania donovani. The over-expression of P- glycoprotein (P-gp) is one of the principal mechanisms of multidrug resistance (MD...
Triterpenoids as antiproliferative agents in classical and atypical multidrug r...
Lage, H; Ramalhete, Cátia; Mulhovo, S; Ferreira, MJUResistance of cancer cells to multiple classes of structurally and mechanistically unrelated antitumor drugs can be defined as multidrug resistance (MDR), and it is one of the major causes of chemotherapy failure. The most significant mechanism of MDR, referred as typical or classical, results from altered cell membrane transport due to overexpression of transporter proteins that act as efflux pumps, such as P-...