Studies on the antimicrobial activity and brine shrimp toxicity of Zeyheria tuberculosa (Vell.) Bur. (Bignoniaceae) extracts and their main constituents.

BACKGROUND: Due to the indiscriminate use of antimicrobial drugs, the emergence of human pathogenic microorganisms resistant to major classes of antibiotics has been increased and has caused many clinical problems in the treatment of infectious diseases. Thus, the aim of this study was to evaluate for the first time the in vitro antimicrobial activity and brine shrimp lethality of extracts and isolated compounds from Zeyheria tuberculosa (Vell.) Bur., a species used in Brazilian folk medicine for treatment of cancer and skin diseases. METHODS: Using the disc diffusion method, bioautography assay and brine shrimp toxicity test (Artemia salina Leach), we studied the antimicrobial activity and lethality of extracts and isolated compounds against three microorganisms strains, including Gram-positive (Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa) bacteria and yeasts (Candida albicans). RESULTS: In this study, the extracts inhibited S. aureus (8.0 +/- 0.0 to 14.0 +/- 0.0 mm) and C. albicans (15.3 +/- 0.68 to 25.6 +/- 0.4 mm) growth. In the brine shrimp test, only two of them showed toxic effects (LC50 29.55 to 398.05 microg/mL) and some extracts were non-toxic or showed weak lethality (LC50 705.02 to > 1000 microg/mL). From these extracts, four flavones [5,6,7,8-tetramethoxyflavone (1), 5,6,7-trimethoxyflavone (2), 4'-hydroxy-5,6,7,8-tetramethoxyflavone (3), and 4'-hydroxy-5,6,7-trimethoxyflavone (4)] were isolated through bioassay-guided fractionation and identified based on the 1D and 2D NMR spectral data. By bioautography assays, compounds 1 [S. aureus (16.0 +/- 0.0 mm) and C. albicans (20.0 +/- 0.0 mm)] and 3 [S. aureus (10.3 +/- 0.6 mm) and C. albicans (19.7 +/- 0.6 mm)] inhibited both microorganisms while 2 inhibited only S. aureus (11.7 +/- 0.6 mm). Compound 4 did not restrain the growth of any tested microorganism. CONCLUSION: Our results showed that extracts and isolated flavones from Z. tuberculosa may be particularly useful against two pathogenic microorganisms, S. aureus and C. albicans. These results may justify the popular use this species since some fractions tested had antimicrobial activity and others showed significant toxic effects on brine shrimps. However, in order to evaluate possible clinical application in therapy of infectious diseases, further studies about the safety and toxicity of isolated compounds are needed.

Atividade antimicrobiana de extratos hidroalcoólicos de Lafoensia pacari A. St.-Hil., Lythraceae, frente a bactérias multirresistentes de origem hospitalar / Antibacterial activity of the hydro-alcoholic extracts of Lafoensia pacari Saint Hil. against multiresistant bacterial strains from hospital source

Os microrganismos patogênicos multirresistentes apresentam-se como grandes responsáveis por milhões de mortes em todo o mundo, principalmente Pseudomonas aeruginosa e Staphylococcus aureus, responsáveis por grande parte das infecções hospitalares. A preocupação com estas espécies faz com que novas pesquisas busquem alternativas para controlar estes microrganismos de uma forma mais eficiente e também mais econômica. Os extratos fitoterápicos são alternativas promissoras para este fim, visto que são uma imensa fonte de compostos de ação biológica. O objetivo do trabalho foi a elucidação da atividade antimicrobiana do extrato de Lafoensia pacari A. St.-Hil., Lythraceae, frente a linhagens de bactérias multirresistentes (P. aeruginosa, S. aureus) isoladas de pacientes com múltiplas infecções internados na Unidade de Emergência de Maceió. Os testes de atividade antibacteriana foram avaliados pelo método de difusão em meio sólido (Kirby-Bauer) modificado. De acordo com os ensaios in vitro, foi constatado que 96,4 por cento das linhagens de bactérias utilizadas na pesquisa apresentaram-se sensíveis ao extrato da folha da planta, demonstrando atividade antibacteriana. Halos de inibição de crescimento de até 26 mm foram encontrados. Dessa forma, conclui-se que o extrato de Lafoensia pacari apresenta possibilidades de se encontrar substâncias úteis no combate a bactérias multirresistentes.

Multiresistant pathogenic microorganisms are responsible for million of death all the world, mainly Pseudomonas aeruginosa and Staphylococcus aureus that are responsible for great part of hospital infections. The concern with this species does new researches to find out alternatives to control these microorganisms in the way more efficient and more economic. The phytoterapic extracts are promissory alternatives for that purpose because they are an immense source of biological action. The objective of this study was to evaluate the antimicrobial activity of Lafoensia pacari A. St.-Hil., Lythraceae, extract on multiresistant bacterial strains (P. aeruginosa, S. aureus) that have been isolated from patients with multiple infections occupying an Emergency Unit from Maceió in Brazil. The antibacterial activity experiments were evaluated by agar diffusion tests. Agreeable us experiments in vitro, ascertain that 96,4 percent of bacterial strains utilized in this research have showed susceptible to the plant's leaf extract, it means an excellent antibacterial activity. Halos of bacterial inhibition until 26 mm were observed. Thus, it can be concluded that the Lafoensia pacari extract has showed as an excellent product to combat multiresistant bacterial.