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Browsing CEBIMED - Books and Book Chapters/ Livros e Capítulos de Livros by Subject "Antibacterial activity"
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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.
- 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.
- Coffee industrial waste as a natural source of bioactive compounds with antibacterial and antifungal activitiesPublication . Silva, Carla Sousa e; Gabriel, Carla; Cerqueira, Fátima; Manso, M. Conceição; Vinha, A. F.Coffee is one of the most popular and consumed beverages in the world, which leads to a high contents of solid residue known as spent coffee grounds (SCG). As is known, coffee beans contain several classes of health related chemicals, including phenolic compounds, melanoidins, diterpenes, xanthines and carotenoids which are associated with therapeutic and pharmaceutical effects, due to antimicrobial, antioxidant, anti-infectious and antitumour activities. Considering that this coffee industrial waste has no commercial value and are currently disposed as a solid waste or employed as fertilizers, we intend to highlight the use of SCG as a raw material with potential interest to the food and pharmaceutical industries. Moreover, this work seems to be valuable to promote the use of SCG as natural and an inexpensive food supplements or pharmaceutical additive. The phytochemical compounds content among the crude aqueous extracts of SCG followed this order: phenolics > flavonoids > carotenoids (mg/ g dry waste), respectively. Caffeine content found in SCG was ~ 0.82 g/100 g dry waste, 70 % lower than coffee roasting beans. Coffee ground extracts showed inhibition to S. aureus and E. coli growth for concentrations of 1.0 mg/ mL and a stronger inhibition was also observed against C. albicans, C. krusei and C. parapsilosis growth using lower concentration (0.5 mg/ mL).