Chemical composition and antibacterial activity of essential oils from verbenaceae species: alternative sources of (E)-caryophyllene and germacrene-D

Volatile oils from the leaves of Verbenaceae species Aloysia virgata, Lantana camara, Lantana trifolia, Lantana montevidensis, Lippia brasiliensis and Lippia sericea were investigated for its chemical composition and antibacterial activity. The volatile oils were characterized by a high content of sesquiterpenes of which (E)-caryophyllene (10-35%), germacrene-D (5-46%) and bicyclogermacrene (7-17%) were the major components for all studied species. For the flowers, a higher concentration of monoterpenes was observed for the species L. camara, L. trifolia and L. brasiliensis. These compounds probably act as attractive to specific pollinators. The volatile oils from A. virgata was the most active, exhibiting moderate antimicrobial activity against the bacteria Staphylococcus aureus, Bacillus cereus and Escherichia coli

Chemical composition and antibacterial activities from the essential oils of myrtaceae species planted in Brazil

The essential oils of seven Myrtaceae species were investigated for its chemical composition and antibacterial activity. The volatile oils were characterized by a high content of monoterpenoids of which 1,8-cineole (88.0, 65.0 and 77.0% for Melaleuca hypericifolia, Callistemon viminalis and Callistemon citrinus respectively), terpinen-4-ol (47.0 and 49.8% for Melaleuca thymifolia and Callistemon polandii respectively) and α-pinene (54.5% for Kunzea ericoides) were the major components. The oil from M. linariifolia was characterized by a high concentration of methyleugenol (87.2%). The oil from Melaleuca thymifolia was the most active, exhibiting high antimicrobial activity against all tested bacteria

Development of PDA/Phospholipids/Lysine vesicles to detect pathogenic bacteria

The behavior of blue polydiacetylene vesicles was studied in the presence of pathogens to evaluate their application as sensors for the food industry. In this study, lysine-containing vesicles of 10,12-pentacosadyinoic acid (PCDA)/dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC) and PCDA/Sphingomyelin (SPH)/Cholesterol (CHO) were tested to determine the colorimetric response induced by pathogenic bacteria (Staphylococcus aureus,Salmonella Choleraesuis and Escherichia coli). The structures were characterized using the dynamic light scattering technique in which the intensity correlation functions of dilute solutions were fitted using cumulant analysis. The PCDA/DMPC vesicles exhibited improved molecular packing compared to the PCDA/SPH/CHO vesicles, with a particle size of approximately 150 nm for the PCDA/DMPC vesicles compared to 200 nm for the PCDA/SPH/CHO vesicles. Subsequent to the vesicle assembly, their colorimetric response was evaluated. Importantly, the colorimetric response was more pronounced for the PCDA/SPH/CHO/Lysine vesicles than for the PCDA/DMPC/Lysine vesicles, indicating that the SPH/CHO decreased the activation barrier, thus improving the bacterial colorimetric response. The PCDA concentration influenced the vesicle selectivity, with 1 mM PCDA exhibiting a slightly greater sensitivity to S.Choleraesuis than the other bacteria, while 2 mM and 3 mM PCDA exhibited greater selectivity for E. coli and S. aureus. Likewise, 1 mM PCDA and the phospholipids SPH/CHO favored the detection of S. Choleraesuis, and due to the complexity of the bacteria behavior, additional studies were conducted. The colorimetric response was evaluated at various lysine concentrations (6.7 μg ml−1; 35.0 μg ml−1 and 63.0 μg ml−1) and pH values (5.0, 6.0 and 7.0) to improve the PCDA/SPH/CHO/Lysine vesicle specificity. At a lysine concentration of 6.70 μg ml−1, no color change in the PCDA/SPH/CHO/Lysine vesicles was observed in the absence of S. Choleraesuis, indicating that they were suitable for use in the food industry. In terms of pH, the expression of the lysine-dependent system was verified in PCDA/SPH/CO/Lysine vesicles at pH 5.0, although an increase in the pH value to approximately 6.5 provided the highest colorimetric response. Therefore, the PCDA/SPH/CHO/Lysine vesicles demonstrated great potential for use as a biosensor to detect food pathogens in routine analyses.The behavior of blue polydiacetylene vesicles was studied in the presence of pathogens to evaluate their application as sensors for the food industry. In this study, lysine-containing vesicles of 10,12-pentacosadyinoic acid (PCDA)/dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC) and PCDA/Sphingomyelin (SPH)/Cholesterol (CHO) were tested to determine the colorimetric response induced by pathogenic bacteria (Staphylococcus aureus, Salmonella Choleraesuis and Escherichia coli). The structures were characterized using the dynamic light scattering technique in which the intensity correlation functions of dilute solutions were fitted using cumulant analysis. The PCDA/DMPC vesicles exhibited improved molecular packing compared to the PCDA/SPH/CHO vesicles, with a particle size of approximately 150 nm for the PCDA/DMPC vesicles compared to 200 nm for the PCDA/SPH/CHO vesicles. Subsequent to the vesicle assembly, their colorimetric response was evaluated. Importantly, the colorimetric response was more pronounced for the PCDA/SPH/CHO/Lysine vesicles than for the PCDA/DMPC/Lysine vesicles, indicating that the SPH/CHO decreased the activation barrier, thus improving the bacterial colorimetric response. The PCDA concentration influenced the vesicle selectivity, with 1 mM PCDA exhibiting a slightly greater sensitivity to S.Choleraesuis than the other bacteria, while 2 mM and 3 mM PCDA exhibited greater selectivity for E. coli and S. aureus. Likewise, 1 mM PCDA and the phospholipids SPH/CHO favored the detection of S. Choleraesuis, and due to the complexity of the bacteria behavior, additional studies were conducted. The colorimetric response was evaluated at various lysine concentrations (6.7 μg ml−1; 35.0 μg ml−1 and 63.0 μg ml−1) and pH values (5.0, 6.0 and 7.0) to improve the PCDA/SPH/CHO/Lysine vesicle specificity. At a lysine concentration of 6.70 μg ml−1, no color change in the PCDA/SPH/CHO/Lysine vesicles was observed in the absence of S. Choleraesuis, indicating that they were suitable for use in the food industry. In terms of pH, the expression of the lysine-dependent system was verified in CDA/SPH/CO/Lysine vesicles at pH 5.0, although an increase in the pH value to approximately 6.5 provided the highest colorimetric response. Therefore, the PCDA/SPH/CHO/Lysine vesicles demonstrated great potential for use as a biosensor to detect food pathogens in routine analyses

Síntese e avaliação da atividade antimicrobiana de furanonas halogenadas e de compostos análogos aos nostoclídeos Synthesis and evaluation of antimicrobial activity of halogenated furanones and compounds analogues to nostoclides

<abstract language="eng">Considering the broad spectrum of biological activity of gamma-butyrolactone derivatives, we presented the synthesis of 3,4-dihalo-5-arylidenefuran-2(5H)-ones (17-21) and analogues (24-28) of the natural product nostoclide (7,8). Furanones 17-21 were synthesized from the condensation of aromatic aldehydes with lactones 14 and 15, that were obtained from mucobromic and mucochloric acids. Lactone 15 was converted into the intermediate 23 in 36% overall yield. Compound 23 was then transformed into the nostoclide analogues 24-28. Some of the compounds prepared showed antimicrobial activities against Escherichia coli, Staphylococcus aureus and Bacillus cereus comparable to commercial antibiotics

Effect of cleaning treatment on adhesion of Streptococcus agalactiae to milking machine surfaces

Streptococcus agalactiae is a common subclinical mastitis agent in dairy cattle. In this study, the influence of hygiene procedure time on the adhesion of S. agalactiae to rubber and silicone surfaces used in milking machines was evaluated. The effect of hygiene practices on the thermodynamic and microscopic features of both surfaces was also evaluated. The hydrophobicity of milking machines and bacterial surfaces was investigated by measuring the contact angle with a goniometer 0, 30, 90, and 180 days after a full hygiene procedure simulated using rubber and silicone coupons. As the time of cleaning procedures enhanced, there was a reduction in the adhesion of S. agalactiae to both surfaces. The rubber and silicone surfaces were hydrophobic in all treatments (ΔGTOTsws0), which makes the adhesion process difficult. Photomicrographs showed rapid wear of both surfaces, pointing to damages caused by cleaning agents. However, the silicone was more resistant to cleaning and sanitizing treatments. Thus, this work shows that changes caused by hygiene procedures in the thermodynamic and in the morphology of milking surfaces have an enormous importance in the S. agalactiae adhesion and, consequently, in mastitis transmission between cattle herd

Thermodynamic study of colorimetric transitions in polydiacetylene vesicles induced by the solvent effect

We report the synthesis of 10,12-pentacosadyinoic acid (PCDA) and PCDA + cholesterol (CHO) + sphingomyelin (SPH) vesicles dispersed in water and the determination of their colorimetric response induced by small amount of organic solvents. In the absence of solvent, PCDA and PCDA/CHO/SPH vesicles showed an intense blue color. The addition of CHCl 3 , CH 2 Cl 2 , and CCl 4 caused a colorimetric transition (CT) in both structures with the following efficiency: CHCl 3 > CH 2 Cl 2 = CCl 4 . However, CH 3 OH did not cause a blueto-red transition. By microcalorimetric technique we also determined, for the first time, the enthalpy change associated with the CT process and the energy of interaction between solvent molecules and vesicle self- assembly. We observed that the chloride solvents induced a colorimetric transition, but the thermodynamic mechanism was different for each of them. CT induced by CHCl 3 was enthalpically driven, while that caused by CH 2 Cl 2 or CCl 4 was entropically driven