Substância antimicrobiana de amplo espectro de Tabebuia caraiba

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

Bacterial infections cause the death of millions of people each year. Studies have shown increased resistance to available antibiotics and the danger of new infectious diseases, which probably cannot be combated with the available drugs. Control is aggravated by the lack of synchronicity between the development of new drugs and the spreading of resistance throughout the world. The search for effective molecules includes the biological potential of vegetable compounds. In this regard, a screening was conducted of the Cerrado Biome Plant Extract Bank of the University of Brasília Farmacognosy Laboratory for human pathogenic bacteria causing nosocomial and community- acquired infections. Two hundred and forty-two crude hexanic and ethanolic extracts, obtained from thirty-seven species belonging to fifteen plant families, were tested in vitro against three Gram negative (Escherichia coli, Pseudomonas aeruginosa and Salmonella choleraesuis) and two Gram positive microorganisms, (Enterococcus faecalis and Staphylococcus aureus) and against a fungus (Candida albicans). The agar-diffusion method was used to evaluate the activity of the extracts, at a concentration of 1000 μg/mL. The results were expressed according to the diameter of the bacterial growth inhibition zone. The hexanic stem bark extract of Tabebuia caraiba was selected for this study due to its significant activity against E. faecalis (inhibition zone: 20 mm; minimum inhibitory concentration/MIC: 31.25 μg/mL), and S. aureus (inhibition zone: 22 mm; MIC: 500 μg/mL). The bioassay-guided fractioning of this extract allowed the selection of the methanolic fraction, which was submitted to a biphasic partition on a silica gel column leading to the creation of 24 groups. An autobiography assay was used to monitor group activity. Of all groups, G2 and G11 were the most active, with promising results for G2. This group allowed the creation of the sub-group SG2-3-4, with a high spectrum of action on other Gram-negative (Salmonella typhimurium, Klebsiella pneumoniae, Enterobacter aerogenes, Serratia marcescens, Proteus mirabilis, Citrobacter koseri) and Gram positive bacteria (Staphylococcus epidermidis). The sub-group, SG2-3-4, presented arilic units, whose spectra allowed us to consider the structural binding capacity of the unit, which appears to be either a aril-cumarine or a benzofuranone. The SG2-3-4 is currently undergoing a purification process to establish the molecular structure.

ASSUNTO(S)

bioma cerrado cerrado biome estudos biomonitorados farmacognosia potencial antimicrobiano extratos de plantas biomonitored studies plant extracts tabebuia caraiba antimicrobial activity tabebuia caraiba

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