The effects of Brazilian and Bulgarian propolis in vitro against Salmonella Typhi and their synergism with antibiotics acting on the ribosome

Salmonella enterica serovar Typhi is the causative agent of typhoid fever in humans, and the use of antibiotics is essential for controlling this infection; however, the excessive use of antibiotics may select resistant strains. Propolis is a honeybee product and its antimicrobial activity has been intensively investigated. Thus, the objective of this study was to investigate a possible synergism between propolis (collected in Brazil and Bulgaria) and antibiotics acting on the ribosome (chloramphenicol, tetracycline and neomycin) against Salmonella Typhi in vitro. The synergism was investigated by using 1/2 and 1/4 of the minimum inhibitory concentration for propolis and these antimicrobial agents, evaluating the number of viable cells according to the incubation time. Brazilian propolis showed a bacteriostatic action against S. Typhi, while Bulgarian propolis showed a bactericidal activity and a synergistic effect with the three antibiotics. Variations in the biological assays might be due to the differences in their chemical compositions. Based on the results, one may conclude that Bulgarian propolis showed an important antibacterial action, as well as a synergistic effect with antibiotics acting on the ribosome, which points out a possible therapeutic strategy evaluating the use of propolis preparations for the treatment of Salmonella Typhi infection.

Antibacterial effects of Brazilian and Bulgarian propolis and synergistic effects with antibiotics acting on the bacterial DNA and folic acid

Propolis is a honeybee product that has been used since ancient times because of its therapeutic effects. It can be used in the development of alternative therapies for the treatment of many diseases, and because propolis shows antibacterial action, this work was carried out in order to investigate a possible synergism between propolis and antibiotics acting on DNA (ciprofloxacin and norfloxacin) and on the metabolism (cotrimoxazole) against Salmonella Typhi. Propolis samples collected in Brazil and Bulgaria were compared in these assays, and the synergism was investigated by using 1/2 and 1/4 of the minimal inhibitory concentration for propolis and antibiotics, evaluating the number of viable cells according to the incubation time. Brazilian and Bulgarian propolis showed antibacterial activity, but no synergistic effects with the three tested antibiotics were seen. Previous works by our laboratory have revealed that propolis has synergistic effects with antibiotics, acting on the bacterial wall and ribosome, but it does not seem to interact with antibiotics acting on DNA or folic acid, and only a bacteriostatic action was seen in these assay conditions.

Effects of Brazilian and Bulgarian propolis on bactericidal activity of macrophages against Salmonella Typhimurium

Propolis has been used in folk medicine since ancient times due to its, many biological properties: such as antimicrobial. antinflammatory, antioxidant, immunomodulatory activities, among others. 'Macrophages play an important role in the early phase of Salmonella infection. In this work, macrophages were prestimated with Brazilian or Bulgarian propolis and subsequently challenged with Salmonella Typhimurium at different macrophage/bacteria ratio. After 60 min of incubation. cells were harvested with Triton-X to lyse the macrophages. To assess the bactericidal activity. The number of colony-forming units (CFU) of S. typhimurium was determined by plating 0.1 mL in 'Mueller Hinton agar. After 24 h. CFU were counted. and the percentage of bactericidal activity was obtained. Propolis from Brazil and Bulgaria enhanced the bactericidal activity of macrophages, depending on its concentration. Brazilian propolis seemed to be more efficient than that from Bulgaria. because of their different chemical composition. In Bulgaria, bees collect the material mainly from the bud exudate of poplar tree, while in Brazil, Baccharis dracunculifolia DC. was shown to be the main propolis source. Our data also showed that the increased bactericidal activity of macrophages involved the participation of oxygen (H2O2) and nitrogen (NO) intermediate metabolites. (C) 2004 Elsevier B.V. All rights reserved.

The invisible blackness of Harryette Mullen's poetry: writing, miscegenation and what remais to be seen

Este ensaio aborda a poética de Harryette Mullen, poetisa afro-americana cuja obra questiona os limites que moldam as expectativas pela inteligibilidade acessível na literatura afro-americana. Os poemas de Mullen exploram as bordas da inteligibilidade, avançando para além das expectativas por uma forma visível/ Rev. Let., São Paulo, v.52, n.1, p.101-120, jan./jun. 2012. 119 inteligível de linguagem que abarcaria a experiência da negritude. Argumenta-se que a escrita na poesia de Mullen funciona como um processo de miscigenação ao jogar com a ilegibilidade da negritude, para além de uma linha visível de distinção entre o que é ou que deveria ser considerado como parte apropriada da negritude, o que possibilita novas formas de reflexão sobre a poesia como um instrumento politicamente significativo para se repensar o papel da poetisa e do poeta negros no espaço da diáspora negra.

The Invisible Blackness of Harryette Mullen's Poetry: Writing, Miscegenation, and What Remains to Be Seen

This essay addresses the poetics of Harryette Mullen, an awarded African-American female poet whose work questions the boundaries that shape the expectations for accessible intelligibility in African-American literature. Mullen’s poems skirt the edges of intelligibility by going beyond the expectations for a visible/intelligible form of language that would embrace the experience of blackness. I argue that writing in Mullen’s poetry works as process of miscegenation by playing on the illegibility of blackness, beyond a visible line of distinction between what is or should be considered part of blackness itself, which engages new forms of reflection on poetry as a politically meaningful tool for rethinking the role of the black (female) poet within the black diaspora.