Serra do Cipó is part of a Brazilian bioma recently qualified as a "hotspot for conservation priority," an area featuring exceptional concentrations of endemic species and experiencing exceptional loss of habitat. The in vitro antimicrobial activity of 20 plant species occurring in this habitat was evaluated against 4 bacteria and 2 fungal strains. About 75% of the species were active against at least one microorganism. None of the species inhibited the growing of Pseudomonas aeruginosa, Escherichia coli and Saccharomyces cerevisae. The activities of Lavoisiera cordata and Xyris pilosa extracts against Staphylococcus aureus were comparable to that of the pure antibiotic used as a positive control. The preliminary toxicity of the active extracts was evaluated by the brine shrimp lethality test and only three plants showed LD 50 values greater than 1000 mg/ml, suggesting that they are relatively non-toxic. Some of the assayed plants are endangered species, presenting different degrees of extinction risk. According to our data, the plant activity against more than one microorganism seems to be advantageous to the evaluated species in protecting them against extinction.

RESUMO: "Atividade antimicrobina de Trembleya lanifl ora, Xyris platystachia e Xyris pterygoblephara". As espécies Trembleya lanifl ora (Melastomataceae), Xyris platystachia (Xyridaceae) e Xyris pterygoblephara foram coletadas na Serra do Cipó, região considerada hotspot para conservação de biodiversidade. A atividade antimicrobiana dessas espécies foi avaliada em ensaios in vitro de difusão em ágar frente a linhagens padronizadas de Staphylococcus aureus e Micrococcus luteus. Todos os extratos, avaliados na concentração de 2000 g/disco, foram ativos contra M. luteus, enquanto a inibição de crescimento de S. aureus somente foi observada para os extratos de T. lanifl ora (folhas) e X. platystachia (partes aéreas). A partição dos extratos brutos entre solventes imiscíveis resultou na obtenção de frações ativas, oriundas de extratos originalmente inativos frente a S. aureus, observando-se atividade principalmente para as frações de baixa e média polaridade. O extrato de folhas de T. lanifl ora foi adicionalmente fracionado por cromatografi a em coluna de sílica gel e as frações resultantes apresentaram atividade antimicrobiana e perfi s por CLAE distintos daquelas obtidas pela partição entre solventes imiscíveis. Unitermos:Trembleya lanifl ora, Xyris platystachia; Xyris pterygoblephara, atividade antimicrobiana. ABSTRACT: Trembleya lanifl ora (D. Don) Cogn. (Melastomataceae), Xyris platystachiaAlb. Nilss. (Xyridaceae) and Xyris pterygoblephara Kunth., Brazilian species collected from a biodiversity hotspot for conservation priority, had their antimicrobial activity evaluated against standardized strains of Staphylococcus aureus and Micrococcus luteus, by the agar diffusion assay. All extracts, assayed in the concentration of 2000 g/disc, were active against M. luteus, whereas S. aureus growth was inhibited only by T. lanifl ora leaves and X. platystachia aerial parts. Fractionation of the extracts by partition between immiscible solvents resulted in active fractions from extracts originally inactive against S. aureus. Activity was mainly found in low and medium polar fractions. The extract of T. lanifl ora leaves was also fractionated by silica gel column chromatography and both the HPLC fi ngerprint and antimicrobial activity of the obtained fractions were distinct of those originated from the partition process.

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This feature focuses on a reagent chosen by a postgraduate, highlighting the uses and preparation of the reagent in current research 3-Methyl-2-Butenal Compiled by Claiton Pires VenturaClaiton Pires Ventura was born in Minas Gerais, Brazil in 1978. He received his B.Sc. degree in pharmacy from the Universidade Federal de Minas Gerais in 2001 and his M.Sc. in pharmacy from the same university in 2003. He is currently working toward his Ph.D. under the supervision of Professor Rosemeire Brondi Alves. His research interests focus on the synthesis of pterocarpans from 2H-chromenes.