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Verificou-se a atividade antimicrobiana in vitro do decocto de Baccharis trimera (Less) D.C., Compositae, (carqueja) por meio de testes-padrão internacionais utilizados para avaliar desinfetantes e anti-sépticos. Determinaram-se a concentração inibitória mínima e a concentração bactericida mínima do decocto frente a várias diluições de inóculos. Os resultados sugerem a possibilidade de se utilizar o decocto de B. trimera como desinfetante e anti-séptico em determinadas situações-problema em produção animal, relacionadas aos agentes transmissíveis estudados.

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The objective of this study was to evaluate in vitro the antimicrobial activity of Brazilian propolis from Urupema, São Joaquim, and Agua Doce (Santa Catarina State) and green propolis from Minas Gerais State, and the effects of propolis on bovine mammary gland explant viability. The propolis samples differed in flavonoid content and antioxidant activity. Green propolis showed the highest content of flavonoids, followed by the sample from São Joaquim. The propolis from Urupema showed the lowest flavonoid content along with the lowest antioxidant activity. The total phenolics were similar across all studied samples. Despite phytochemical differences, the propolis samples from Minas Gerais, São Joaquim, and Urupema presented the same level of antimicrobial activity against Staphylococcus aureus strains. The reduction in S. aureus growth was, on average, 1.5 and 4 log10 times at 200 and 500 μg/mL, respectively. At concentrations of 1,000 μg/mL, all propolis reduced bacterial growth to zero. On the other hand, when the propolis were tested against strains of Escherichia coli, the samples presented weak antimicrobial activity. Mammary explants were maintained in culture for 96h without a loss in viability, demonstrating the applicability of the model in evaluating the toxicity of propolis. The origin and chemical composition of the propolis had an effect on mammary explant viability. We encountered inhibitory concentrations of 272.4, 171.8, 63.85, and 13.26 μg/mL for the propolis from Água Doce, Urupema, São Joaquim, and Mina Gerais, respectively. A clear association between greater antimicrobial activity and toxicity for mammary explants was observed. Of all propolis tested, the Urupema sample was noteworthy, as it showed antimicrobial activity at less toxic concentrations than the other samples, reducing bacterial growth to an average of 9.3 × 10(2) cfu/mL after 6h of contact using 200 μg/mL of extract. The results demonstrate the potential for Brazilian propolis in the treatment of mastitis, although effectiveness is dependent on geographical origin and concentration. The results from the mammary gland explant assays are promising for the investigation of other natural products with antimicrobial and anti-inflammatory properties that can be used in the intramammary treatment of subclinical mastitis and during dry cow therapy.

All extraction procedures presented selective inactivation and/or inhibition capacity on the evaluated bacteria; however, extracts from ethanolic distillation yielded the best results. Salmonella enteritidis had the highest sensitivity, followed by Enterococus faecalis. Later, such agents were subjected to suspension tests, in the same system, in absence or presence of organic matter (bovine serum), under controlled time. Salmonella enteritidis and Enterococus faecalis sensitivity to the different tested Ilex extracts decreased in the presence of organic matter and increased with exposure time.

Determinou-se in vitro a intensidade de atividade de inibição bacteriana e a intensidade de atividade de inativação bacteriana, por meio de testes de diluição e suspensão em sistema de tubos múltiplos, de diferentes extratos, aquosos ou alcoólicos/hidroalcoólicos, de 86 plantas com indicativo etnográfico medicinal ou condimentar acessadas na região metropolitana de Porto Alegre, Rio Grande do Sul, frente a Salmonella spp., ou S. enteritidis ATCC nº 13076, ou S. cholera-suis ATCC nº10708, ou S. gallinarum CPVDF-SAA/RS/BR, em doses-desafio de <10(7)UFC.mL-1. Cinquenta plantas apresentaram alguma atividade seletiva antissalmonela, e 37 nenhuma atividade. Discute-se a validade da ferramenta etnográfica na prospecção de fatores de proteção antibacteriana em plantas, bem como a influência da inibição/inativação na preditividade do diagnóstico bacteriológico.