Browsing by Author "Soares, M.O."
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- Antibacterial and antimalarial activity of Angolan Cymbopogon citratus essential oilPublication . Pires, P.P. Catarino; Sekhoacha, M.; Matsabisa, M.; Tselanyane, M.; Ferreira da Vinha, Ana; Soares, M.O.Bacterial infections and malaria remain a major public health problem due to the emergence and spread of drug resistant strains. There is an urgent need to investigate new sources of antibacterial and antimalarial drugs, which are more effective. One of the potential sources of antibacterial and antimalarial drugs is traditional medicinal plants. Our ethnopharmacological studies, in several Angolan regions, showed that Cymbopogon citratus (DC) Stapf., has high bioactivity against bacterial infections and malaria. The constituents of Cymbopogon citratus essential oil (CCEO), obtained by hydro-distillation, were analysed by GC and GC-MS and identified from their retention indices and mass spectra. The antimicrobial activity of CCEO and major natural volatile compounds were tested against several bacterial strains. The antimalarial assays where performed in continuous in vitro cultures of asexual erythrocyte stages of P. falciparum using the parasite lactate dehydrogenase assay. CCEO exhibits broad-spectrum antibacterial activity against both Gram-positive and Gram-negative bacteria. Our results showed that multi-resistant Stafilococus aureus (MRSA) isolates were more sensitive to CCEO than non-MRSA. When tested against MRSA resistant to amoxicillin-clavulanic acid combination, penicillin G and methicillin, CCEO shows a significant increase in bactericidal activity when compared with the commercial antibiotics. The same results were obtained using vancomycin resistant S. epidermidis and other strains. Regarding the anti-malaria activity, test samples where considered active for in vitro antimalarial activity exhibiting IC50 values of 5.34±1.01 μg/ml and 7.06±0.47 μg/ml. Our work shows that CCEO has higher antibacterial activity than commercial antibiotics against MRSA strains, as well as antimalarial activity. This offers opportunities for clinical treatments since preliminary in vivo studies showed no toxic effects and high antimalarial activity.
- Antifungal activity of endemic Origanum virens from PortugalPublication . Soares, M.O.; Ferreira da Vinha, Ana; Lima, R.P.; Coutinho, F.; Catarino, P.Origanum virens is widely used in Portuguese, and Mediterranem, cuizin. Althout it is use as food condiment, it is also used in traditional medicin as antiseptic. The antifungal activity of Origanum virens essential oil on Candida albicans ATCC 10231 and physicchemical characterization of several extracts were evaluated.
- Antimicrobial activity of essential oil of Cymbopogon citratus (DC) Stapf. Poaceae-Gramineae from Angola in ATCC and multidrug resistant strainsPublication . Soares, M.O.; Ferreira da Vinha, Ana; Lima, R.P.; Coutinho, F.; Machado, M.; Catarino, P.Cymbopogon citratus (DC) Stapf. Poaceae-Gramineae (C. citratus) is an herb from India, which grows in several countries in tropical and sub-tropical, as the Republic of Angola, where tea is known as caxinde. This tea is consumed, as aromatic drink, as well as in traditional cuisine due to its lemon flavor. Cymbopogon citratus (DC) is widelly used in folk medicine, where infusions and decoctions, feature anti-spasmatic, carminatives and anti-hypertension properties. The essential oil of C. citratus is often applied, in pharmaceutical industry, as flavor and fragrance, and is also used as a source of new phytochemical molecules for the development of new pharmaceutical products.
- Antimicrobial natural productsPublication . Soares, M.O.; Ferreira da Vinha, Ana; Coutinho, F.; Pires, P.C.Our ethnopharmacological studies, in several Angolan regions, showed that Cymbopogon citratus (DC) Stapf., it´s applied in folk medicine to treat several diseases In order to validate antibacterial activity several studies were performed using 12 bacterial strains. The essencial oil samples of Cymbopogon citratus, obtained by hydro-distillation, were analysed by GC and GC-MS. Constituents were identified and tested for their antimicrobial activity by the disc agar diffusion technique and the dilution technique against Staphylococcus aureus (ATCC 25923) and Staphylococcus epidermidis (ATCC 12228) and other bacterial strains. Broad spectrum antibacterial activity was exhibited by the Cymbopogon citratus essential oil against both Gram-positive and Gram-negative bacteria as well as for MRSA that exhibited more sensitive towards the test substance compared to the non-MRSA. Our work was the first to show that Cymbopogon citratus essential oil has higher antibacterial activity against MRSA strains, than commercial antibiotics. These discover opens a new hope to fight against nosocomial infection.
- Antioxidant activity and antimicrobial properties of lemon grass essential oilPublication . Ferreira da Vinha, Ana; Soares, M.O.; Barreira, Sérgio; Castro, A.; Alves, R.C.; Oliveira, M.B.P.P.Essential oils have been explored comprehensively as potential sources of compounds with antioxidant and antimicrobial activities.
- Atividade bioterapêutica de plantas medicinais angolanasPublication . Soares, M.O.; Ferreira da Vinha, Ana; Pires, P.; Catarino, P.Os resultados apresentados neste trabalho demonstram que as plantas medicinais Angolanas têm diversas acções terapêuticas, muitas não descritas no seu uso tradicional. O extracto aquoso do Chá de cachinde apresenta um efeito antioxidante elevado e um efeito bactericida. O presente trabalho foi o primeiro a claramente demonstrar que o óleo essencial de Cymbopogon citratus inibe o crescimento do Staphylococcus aureus MRSA, agente patogénico responsável pela maioria das infecções nosocomiais, com concentrações aproximadas de 0,92mM, assim como o St. epidermidis resistente à vancomicina, e a Escherichia coli, transmitido por contaminação fecal-oral, e causadores de infecções hospitalares, que apresentam elevada sensibilidade a este óleo.
- Caracterização do perfil químico e avaliação do poder redutor dos compostos antioxidantes presentes no Prunus armeniaca L. de origem portuguesaPublication . Ferreira da Vinha, Ana; Coutinho, F.; Machado, M.; Soares, M.O.O stress oxidativo produzido pelo organismo está diretamente relacionado com o aparecimento e/ou desenvolvimento de doenças crónicas. O oxigénio é um componente essencial para os seres vivos, mas a geração de espécies reativas de oxigénio (EROs) é inevitável no metabolismo aeróbio. Nas células, os EROs podem causar a oxidação de lípidos e proteínas e danos na cadeia do DNA.
- Cymbopogon citratus EO antimicrobial activity against multi-drug resistant Gram-positive strains and non-albicans-Candida speciesPublication . Soares, M.O.; Ferreira da Vinha, Ana; Barreira, Sérgio; Coutinho, F.; Aires-Gonçalves, S.; Oliveira, M.B.P.P.; Pires, P.C.; Castro, A.We studied the antibacterial and antifungal activity of Cymbopogon citratus. These properties were studied on hospital isolated multidrug resistant strains Staphylococcus aureus, Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Klebsiella pneumonia and their respective ATCC control strains. Pathogenic Candida albicans, Candida parapsilosis, and Candida tropicalis were also tested. Results of the present investigation provide evidence that the EO of Cymbopogon citratus could have a potential application in the treatment and prevention of diseases caused by Staphylococcus aureus methicillin-resistant strains and by vancomicin-resistant Staphylococcus epidermidis. Cymbopogon citratus EO is also effective against Candida albicans as well as the emerging Candida parapsilosis and Candida tropicalis pointing to its usefulness as an antifungal agent.
- Efeitos sinérgicos entre a cafeína e os fenólicos totais, na capacidade antioxidante de seis plantas usadas na medicina tradicional portuguesaPublication . Costa, A.; Soares, M.O.; Herdeiro, T.; Machado, M.; Ferreira da Vinha, AnaOs chás, de recorrente uso na medicina tradicional, verificam teores significativos de compostos fenólicos, os quais estão relacionados com o elevado potencial antioxidante.
- Estudo comparativo das variações de licopeno, ácido ascórbico e fenólicos totais e sua interacção como compostos antioxidantes em tomates (Lycopersicon esculentum) provenientes de agriculturas convencional e orgânicaPublication . Ferreira da Vinha, Ana; Coutinho, F.; Machado, M; Soares, M.O.; Almeida-Dias, A.Um novo paradigma sobre a dieta e a saúde envolve questões que reforçam a ênfase para os aspetos positivos da dieta alimentar. Atualmente, existe um potencial mercado para os produtos orgânicos, uma vez que existe um grande desconforto por parte da população portuguesa na manutenção do consumo de certos alimentos convencionais, cujo cultivo envolve o emprego de elevados teores de adubos sintéticos e pesticidas.