RESUMO
O óleo essencial das folhas de Lippia gracilis Schauer, Verbenaceae, foi examinado por CG e CG-MS. Quinze constituintes foram identificados, onde o carvacrol, p-cimeno e o γ-terpineno foram as substâncias majoritárias. No estudo in vitro, a solução a 5 por cento do óleo de L. gracilis Schauer apresentou atividade antibacteriana para Staphylococcus aureus isolado de úlcera infectada de paciente diabético. O estudo avaliou a atividade antibacteriana da solução a 5 por cento do óleo de L. gracilis Schauer em modelo experimental em diabetes utilizando ratos albinos Wistar machos com membro pélvico infectado com cepa de Staphylococcus aureus. No experimento foram utilizados 28 ratos Wistar distribuídos em quatro grupos (G1-branco, G2-controle negativo, G3-controle positivo, G4-teste) de sete ratos. Quando comparado o grupo G4 com G3, observou-se que a solução a 5 por cento promoveu uma redução nas CFU/mL após 24h da administração do inóculo (S.aureus sem L. gracilis Schauer 10(8) ± 313 versus S.aureus com L. gracilis Schauer 13,28 ± 4,03). Os resultados foram expressos através do cálculo da média±EPM) e análise de variança (ANOVA). A diferença entre a concentração inibitória mínima no estudo in vitro foi determinada pelo teste Turkey (p<0.05). O teste Newman-Keuls com nível de significância (p<0.05) foi utilizado para o cálculo dos resultados obtidos no experimento in vivo. A solução a 5 por cento do óleo essencial de Lippia gracilis Schauer apresentou boa atividade antibacteriana tanto no estudo in vivo como no in vitro.
The essential oil from Lippia gracilis Schauer (Verbenaceae) leaves was examined by GC and GC-MS. Fifteen constituents were identified. Carvacrol, p-cymene and γ-terpinene were found to be the major components. In the in vitro study, 5 percent solution of the Lippia gracilis Schauer oil presented antibacterial activity against Staphylococcus aureus isolated from diabetic patients with infected ulcers. The study evaluated the antibacterial activity of the 5 percent solution of the Lippia gracilis Schauer oil on the experimental model of diabetic adult male albino Wistar rats with leaft pelvic limb infected by Staphylococcus aureus strain. In this experiment, 28 diabetic Wistar rats were used, randomly distributed in four different groups of seven rats, (G1-white; G2-negative control; G3-positive control and G4-test). When comparing group G4 with G3, it was observed that the 5 percent solution presented a reduced CFU/mL level showing the antibacterial effect of the oil 24 hours after the administration of the inoculum (S .aureus without Lippia gracilis Schauer 108 ±313 versus S.aureus with Lippia gracilis Schauer 13.28±4.03). The results were expressed as mean±S.E.M. One-way analysis of the variance (ANOVA) was used. The differences between the minimum inhibitory concentration in vitro test were determined by the Tukey test (p<0.05). The Newman-Keuls test with level of significance (p<0.05) was used to measure the results in vivo. The findings have shown that 5 percent solution of the Lippia gracilis Schauer oil presented antibacterial activity in vitro and in vivo.
RESUMO
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.