Twelve extracts obtained from nine plants belonging to six different genera of Clusiaceae were analyzed against Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus and Enterococcus faecalis) bacteria using the microdilution broth assay. Tovomita aff. longifolia, T. brasiliensis, Clusia columnaris, Garcinia madruno, Haploclathra paniculata, and Caraipa grandifolia extracts showed significant results against the bacteria. The organic extract obtained from the leaves of T. aff. longifolia showed minimal inhibitory concentration (MIC) = 70 µg/ml and minimal bactericidal concentration (MBC) = 90 µg/ml against E. faecalis and the organic extract made with the stem of C. columnaris showed MIC = 180 µg/ml and MBC = 270 µg/ml against P. aeruginosa. None of the antibacterial extracts showed lethal activity against brine shrimp nauplii. On the other hand, both aqueous and organic extracts obtained from the aerial organs of Vismia guianensis that were cytotoxic to brine shrimp nauplii did not show a significant antibacterial activity in the assay.Key words: antibacterial -cytotoxicity -Clusiaceae -Amazon rain forest -Brazil Natural products are considered an important source of new antibacterial agents. Drugs derived from unmodified natural products or drugs semi-synthetically obtained from natural sources corresponded to 78% of the new drugs approved by the FDA between 1983 and 1994(Cragg et al. 1997). This evidence contributes to support and quantify the importance of screening natural products. Previous screening works were done with more than 700 Amazon rain forest plant extracts, and results can be seen elsewhere (Frana & Suffredini 2002, Suffredini et al. 2002a, b 2004, Nepomuceno et al. 2003.Less than 20% of the Angiospermae have been screened for biological activity, and taking the Brazilian rain forests in concern, not much has been done so far. Brazil is home to more than 20% of the world's biodiversity, and the Amazon rain forest concentrates 17% of the biodiversity found within the country (Wilson & Peter 1988). For this reason, our research team has been systematically studying the antibacterial activity of organic and aqueous plant extracts obtained from plants native to the rain forest against Gram-positive Staphylococcus aureus ATCC 29213 (Sau) and Enterococcus faecalis ATCC 29212 (Efae) and Gram-negative Pseudomonas aeruginosa ATCC 27853 (Psa) and Escherichia coli ATCC 25922 (Ecol) with the aim of discovering new natural product compounds that can be used as antibiotics. Twelve aqueous and organic extracts obtained from plants belonging to six different genera of Clusiaceae (Vismia, Garcinia, Haploclathra, Tovomita, Caraipa, and Clusia) were submitted to the determination of the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) using the microdilution broth assay (Suffredini et al. 2004). The extracts were also tested against brine shrimp nauplii in order to evaluate their potential as cytotoxic agents and to determine if ...

2003 ResumoO extrato orgânico obtido do caule de Tovomita sp. apresentou atividade antibacteriana significativa contra Staphylococcus aureus (CIM = 460 ?µg/mL e CBM = 490 µg/mL), Enterococcus faecalis (CIM = 500 ?µg/ mL e CBM = 540 µg/mL) e Pseudomonas aeruginosa (CIM = 300 ?µg/mL e CBM = 400 µg/mL). As frações obtidas do extrato orgânico apresentaram atividade antimicrobiana contra E. faecalis (CIM F1 = 570 µg/ mL e CBM F1 = 840 µg/mL; CIM F2 = 480 µg/mL e CBM F2 = 720 µg/mL, respectivamente) e contra P. aeruginosa (CIM F1 = 310 µg/mL e CBM F1 = 570 µg/mL; CIM F2 = 310 µg/mL e CBM F2 = 460 µg/mL, respectivamente). AbstractThe organic extract obtained of the stem of Tovomita sp. did it present significant antibacterial activity against Staphylococcus aureus (CIM = 460 µg/mL and CBM = 490 µg/mL), Enterococcus faecalis (CIM = 500 µg/mL and CBM = 540 µg/mL) and Pseudomonas aeruginosa (CIM = 300 µg/mL and CBM = 400 µg/ mL). The obtained fractions of the organic extract present antibacterial activity against E. faecalis (CIM F1 = 570 µg/mL and CBM F1 = 840 µg/mL; CIM F2 = 480 µg/ mL and CBM F2 = 720 µg/mL, respectively) and against P. aeruginosa (CIM F1 = 310 µg/mL and CBM F1 = 570 µg/mL; CIM F2 = 310 µg/mL and CBM F2 = 460 µg/mL, respectively).O conhecimento sobre determinadas espécies vegetais com propriedades antimicrobianas tem sido revisto e ampliado, devido aos crescentes problemas associados ao uso de diversos antibióticos, como o limitado espectro de ação e os efeitos colaterais. Quanto ao potencial antibiótico, destacam-se os resultados obtidos com óleos essenciais, alcalóides, cumarinas, triterpenos, citral, mirceno, timol, xantanol, ácido caurêmico, entre outros que, em baixas concentrações, exercem inibição sobre o crescimento de bactérias gram- O gênero Tovomita tem 60 espécies conhecidas na América do Sul 2 e é conhecido por conter xantonas, benzofenonas, triterpenos e esteróides. Chás preparados a partir das flores de outras espécies de Tovomita como a T. brasiliensis e a T. laurina apresentaram uma ação benéfica no controle da diarréia 3 .Devido aos resultados obtidos na avaliação da atividade antibacteriana, EO de Tovomita sp. foi selecionado para um estudo que possibilitará obter conhecimentos em relação à sua composição química e seu potencial antibacteriano.Na avaliação da atividade antibacteriana de EO os resultados obtidos de CIM e CBM para E. faecalis foram de 500 e 540 mg/m, respectivamente. Contra S.aureus foram observadas doses de 460 mg/m para CIM e 490 mg/m para CBM e contra P. aeruginosa, doses de 300 mg/m para CIM e 400 mg/mL para CBM. EO apresentou, portanto, atividade mais efetiva contra P.aeruginosa.As frações F1 e F2 foram submetidas ao ensaio antibacteriano. A fração F1 apresentou CIM de 570 mg/mL e CBM de 840 mg/mL contra E. faecalis e contra P. aeruginosa as doses de CIM e CBM foram de 310 e 570 mg/mL, respectivamente. Para a fração F2, as doses de CIM e CBM contra E. faecalis foram de 480 e 720 mg/mL e contra P. aeruginosa de 310 e de 460 mg/mL, respectivamente. CIM e CBM de F1 e...