ABSTRACT: Surface contamination by pathogenic and deteriorating microorganisms is a constant concern in the food industry. Therefore, in this study we evaluated the antimicrobial activity of silver nanoparticles (AgNPs), produced using the essential oil of Lippia origanoides Kunth and ethanolic extract of Hymenaea martiana Hayne, against bacteria used in milk processing. For this, AgNPs were synthesized and their antimicrobial activity was evaluated for minimum inhibitory and bactericidal concentrations, time-kill, interference on the biofilm, and application on the surfaces of different materials. AgNPs showed bacteriostatic and bactericidal activity against Staphylococcus aureus (ATCC 25923), Staphylococcus aureus (ATCC 33591), Escherichia coli (ATCC 25922), Salmonella enterica subsp. enterica serovar Choleraesuis (ATCC 10708), Listeria monocytogenes, Escherichia coli, Salmonella spp.,andPseudomonas aeruginosa,and interfered with biofilm formation more than with consolidated biofilms. A 1hour period was sufficient to reduce the bacterial cells, whereas a Minimum Duration for Killing (MDK) of 99% was reached after approximately 30 min. AgNPs were effective against bacteria attached to stainless steel and polyethylene, but ineffective on tile surfaces. Thus, owing to the growing microbial resistance and the need to develop new products based on the concepts of green chemistry, these AgNPs are presented as a new possibility for cleaning processes in the food industry.

RESUMO: A contaminação de superfícies por micro-organismos patogênicos e deteriorantes é uma preocupação constante na indústria de alimentos. Dessa forma, o objetivo deste trabalho foi avaliar a atividade antimicrobiana de nanopartículas de prata (AgNPs) produzidas utilizando óleo essencial de Lippia origanoides Kunth e extrato etanólico da Hymenaea martiana Hayne, frente a bactérias de importância na contaminação em áreas de processamento do leite. Para isso, as AgNPs foram sintetizadas e sua atividade antimicrobiana foi avaliada através das concentrações inibitória e bactericida mínimas, tempo de morte, interferência sobre o biofilme, e por fim, a sua aplicação sobre superfícies de diferentes materiais. As AgNPs apresentaram atividade bacteriostática e/ou bactericida frente à Staphylococcus aureus (ATCC 25923), Staphylococcus aureus (ATCC 33591), Escherichia coli (ATCC 25922), Salmonella enterica subsp. enterica serovar Choleraesuis (ATCC 10708), Listeria monocytogenes, Escherichia coli, Salmonella spp. e Pseudomonas aeruginosa, e interferiram na formação do biofilme mais do que sobre o biofilme consolidado. O tempo de uma hora foi o suficiente para reduzir as populações bacterianas, enquanto o Minimum Duration for Killing MDK 99% foi atingido próximo a 30 minutos. As AgNPs foram eficientes contra bactérias aderidas ao inox e ao polietileno. Assim, tendo em vista a crescente resistência microbiana e o desenvolvimento de novos produtos baseados nos conceitos da química verde, essas nanopartículas de prata apresentam-se como uma nova possibilidade de uso nos processos de higienização da indústria de alimentos.

RESUMO: Considerando a necessidade de terapias alternativas para a mastite bovina, uma inflamação, normalmente de causa infecciosa, de alta prevalência e de alto impacto econômico nas fazendas leiteiras, avaliou-se a eficácia antimicrobiana, in vivo, de uma formulação intramamária à base de polipirrol (PPy) solúvel, um polímero condutor promissor para aplicações biomédicas, especialmente como potente antibacteriano. Neste ensaio, quartos mamários de vacas holandesas sadias (n = 8) foram inoculados com Staphylococcus aureus e tratados, por via intramamária, com formulação experimental à base de PPy solúvel (5%) e com formulação comercial à base de sulfato de gentamicina. O efeito desses tratamentos foi avaliado com a realização de lactoculturas, da Contagem Bacteriana Total (TBC), da Contagem de Células Somáticas (SCC) e da análise da composição do leite das amostras obtidas de quartos mamários, em sete momentos experimentais. Avaliação hematológica dos animais também foi realizada. A aplicação intramamária de três doses da formulação experimental à base de PPy solúvel resultou em maiores log/mL da TBC e da SCC quando comparadas ao grupo controle positivo e ao grupo que recebeu sulfato de gentamicina. A administração da formulação experimental não induziu alterações na composição do leite e nos parâmetros hematológicos. Alguns fatores farmacocinéticos e farmacodinâmicos do PPy solúvel podem ser atribuídos a ineficácia antimicrobiana da pomada experimental. Outras pesquisas devem ser realizados em prol do desenvolvimento de formulações que permitam a atuação antibacteriana do PPy solúvel no ambiente intramamário de vacas leiteiras.

ABSTRACT: Given the need for alternative therapies for bovine mastitis, an infectious disease of high prevalence and significant economic impact in dairy farms, this study evaluated the in vivo antimicrobial efficacy of an intramammary formulation based on soluble polypyrrole (PPy), a promising conductive polymer for biomedical applications, especially as an effective antimicrobial agent. In this assay, mammary quarters of healthy Holstein Friesian cows (n = 8) were inoculated with Staphylococcus aureus and treated, via the intramammary route, with an experimental formulation based on soluble PPy (5%) and a commercial formulation based on gentamicin sulfate. The effect of these treatments was evaluated based on milk cultures, Total Bacterial Count (TBC), Somatic Cell Count (SCC), and milk composition analysis of mammary quarter samples in seven experimental moments. In addition, hematological evaluations of the animals were also performed. The intramammary application of three levels of the experimental formulation based on soluble PPy resulted in higher log/mL of the TBC and SCC compared to a positive control group and a group that received gentamicin sulfate. The experimental formulation did not induce changes in milk composition or in hematological parameters. Certain factors related to pharmacokinetics, such as the type of carrier used in the formulation and the pharmacodynamics of soluble PPy, may have contributed to the antimicrobial ineffectiveness of the experimental formulation. The results of this study neither define nor decrease the antimicrobial potential of soluble PPy. Further research is required to develop formulations that enable the antibacterial action of soluble PPy in the intramammary environment of dairy cows.

Abstract Melatonin (MLT) reportedly reduces side effects associated with certain antineoplastic agents. Accordingly, we investigated the effect of MLT on cisplatin (CP)-induced gastric emptying (GE) delay. Mice were intraperitoneally pretreated with vehicle (ethanol 5%; control group), MLT (5, 10, or 20 mg/kg), or N-acetylcysteine (NAC; 150 mg/kg), followed by CP treatment (5 mg/kg). Pharmacological modulation was analyzed using relevant receptor antagonists (luzindole: non-selective MT1/MT2 antagonist; 5 mg/kg or 4-P-PDOT: selective MT2 antagonist; 4 mg/kg) before treatment with MLT plus CP. All treatments were performed once daily for three days. GE was assessed using phenol red. Gut morphology was examined using scanning electron microscopy and optical microscopy. Compared with the control, CP decreased GE. Pretreatment with NAC and MLT (5 and 10 mg/kg) did not prevent CP-induced gastric dysmotility; however, pretreatment with 20 mg/kg MLT prevented this effect. In addition, luzindole and 4-P-PDOT suppressed MLT-mediated gastroprotection against cytotoxic effects of CP. CP caused degeneration of the gut mucosa, which was attenuated by MLT treatment. Thus, 20 mg/kg MLT prevented the GE delay and decreased CP-induced adverse effects on the gut mucosa. In addition, the gastroprotective activity was mediated via the MT2 receptor.

RESUMO A atividade antibacteriana de nanopartículas metálicas (e em especial de prata) vem sendo explorada ao longo do tempo em diferentes formulações químicas para agentes biológicos livres de antibióticos. A produção dessas partículas por rotas ambientalmente responsáveis representa uma estratégia extremamente relevante por apresentar baixo custo, favorecer a escalabilidade e ter mínimos impactos ambientais. O uso de óleos essenciais como agentes redutores em síntese verde de nanopartículas de prata introduz a sinergia de um agente intrinsicamente antibacteriano e que favorece a nucleação/crescimento das nanopartículas. Esta revisão apresenta o estado da arte da síntese verde de nanopartículas de prata por óleos essenciais assim como discute os mecanismos mais relevantes desse processo de formação e ação antibacteriana.

ABSTRACT The antibacterial activity of silver nanoparticles has been explored over time in different chemical formulations for antibiotic-free agents. The production of these particles by environmentally friendly routes represents an extremely relevant strategy for presenting low cost, favoring scalability and having minimal environmental impacts. The use of essential oils as reducing agents in green synthesis of silver nanoparticles introduces the synergy of an intrinsically antibacterial agent that favors the nucleation / growth of the nanoparticles. This review presents the state-of-the-art of green synthesis of silver nanoparticles by essential oils as well as discusses the most relevant mechanisms of formation process and antibacterial action.

Abstract Some species of Lactobacillus have demonstrated beneficial health effects being applied in the production of food supplements. Thus, the incorporation of viable cells as encapsulated probiotics represents an essential condition to be considered in new strategies for the controlled release of microorganisms. Herein, the massive encapsulation of Lactobacillus paracasei is provided by the use of alternative electrospinning technique. Is spite of the high voltage required for the production of fibers, a high density of viable cells is observed into the polymeric electrospun web, allowing the controlled release at targeted pH (characteristic of Eudragit® L100 polymer support). The reported procedure circumvents typical drawbacks of degradation of microorganisms under adverse conditions (storage, package and low pH) and preserves its biologic action after complete release from polymer fibers.

Abstract The development of polypyrrole-based nanocomposites as alternative antibacterial agents represents a promising strategy to be applied against the prevailing multi-resistant bacteria. Herein, it is reported the most recent development of antibacterial materials based on the combination of polypyrrole and different fillers (metal nanoparticles, carbon nanotubes, and polysaccharides) and strategies to improve their action (such as light and electrical stimulus). The synergistic interaction of electrostatic forces provided by charged polypyrrole combined with the permeation of nanoparticles through the cell wall favors the leakage of cytoplasmic components and reinforces the antibacterial activity of the resulting material, observed in all-organic composites of polypyrrole and chitosan that reached superior performance against Escherichia coli (108 CFU) or metal-polymer composites (polypyrrole-palladium) with an outstanding performance against different types of bacteria. The development of binary and ternary composites is explored to potentialize the antibacterial synergy of components.

RESUMO: Este trabalho teve como objetivo analisar o potencial das soluções de óxido de zinco e de nitrato de prata como alternativa para antissepsia de tetos de bovinos (in situ), considerando a escassez de literatura a respeito do uso destes compostos na profilaxia de mastites. Primeiramente foram realizados ensaios de microdiluição e CBM (Concentração Bactericida Mínima) a fim de verificar a atividade antimicrobiana das soluções de óxido de zinco e de nitrato de prata sobre 30 isolados de Staphylococcus spp., obtidos de casos de mastite. Todos os isolados apresentaram sensibilidade às duas soluções testadas, mas a solução de nitrato de prata apresentou menores valores de CBMs (3,05 a 97,65 μg/mL), quando comparada as CBMs da solução de óxido de zinco (97,65 a 6.250μg/mL). Posteriormente, foram conduzidos os ensaios de antissepsia dos tetos (in situ) através da imersão dos mesmos nas soluções antimicrobianas testadas. Para isso, foram utilizados 40 tetos (n=40) oriundos de vacas abatidas, os quais foram divididos em 4 grupos de 10 tetos, destinados ao teste das solução de óxido de zinco a 3% (30mg/mL), de nitrato e prata 1% (10mg/mL) e seus respectivos controles. Os tetos foram submetidos à contagem de microrganismos mesófilos na superfície dos tetos (UFC/cm2) antes e após a imersão nas soluções testadas. Como resultado, todas as soluções (de óxido de zinco e de nitrato de prata) apresentaram significativa redução de UFC/cm2 até aos 60 minutos após a imersão (M 0’ a M 60’). A solução de nitrato de prata apresentou redução de UFC/cm2 significativamente maior, quando comparado ao grupo testado com solução de óxido de zinco. Tais resultados validam o potencial das soluções de óxido de zinco e nitrato de prata para utilização no pré e pós-dipping em vacas leiteiras.

ABSTRACT: This study aimed to analyze the zinc oxide and silver nitrate solutions as an alternative antiseptic for cow teats (in situ), considering the lack in the literature about these compounds uses in mastitis prophylaxis. First microdilution tests med and MBC (Minimal Bactericidal Concentration were perfor in order to determine the antimicrobial activity of zinc oxide and silver nitrate solutions over 30 Staphylococcus spp. isolates, obtained from cows with mastitis. All strains tested showed sensitivity to both solutions, but the silver nitrate solution had lower MBC values (3,05 to 97,65ug/ml) compared with zinc oxide solution MBCs (97,65 to 6,250 ug/ml). Subsequently, the antiseptic teat tests were conducted (in situ) by immersing the teats in same antimicrobial solutions tested in the first experiment. Therefore, 40 teats were used (n = 40) originating from slaughtered cows were divided into 4 groups of 10 teats, to test test zinc oxide 3% (30mg/mL) and silver nitrate 1% (10mg/mL) solutions and their respective controls. The teats were submitted to mesophilic count on the teat surface (CFU/cm2) before and after immersion in tested solutions. As a result, all the solutions (zinc oxide and silver nitrate) had a significant reduction in CFU/cm2 until 60 minutes after immersion (M 0’ to 60 M’). Silver nitrate solution showed a reduction of CFU/cm2 significantly higher compared to the group treated with zinc oxide solution. These results validate the potential use of zinc oxide and silver nitrate solutions in dairy cows as a pre- and post-dipping antiseptic.

In this paper, we analyze the use of electrical impedance spectroscopy applied to determination of cloud point. The slope of admittance measured at 100 kHz is reduced to temperature above the critical value which characterizes the phase transition, in a strong indication that this process is activated during the clouding. Additionally to this study we explored the influence of parameters such as additives and temperature on the performance of phase separation of residues (silver nanoparticles) by cloud point extraction. The interaction with salt maximizes the separation of chemical residues in a progressively reduced temperature.