Effects of glycerol monolaurate on growth and physiology of chicks consuming diet containing fumonisin.

Glycerol monolaurate (GML) is composed of lauric acid and glycerol. Research has shown that such organic acids can minimize negative effects caused by mycotoxins. Therefore, the objective of this study was to determine whether adding GML (free or encapsulated) to chick feed minimizes the effects of natural contamination by fumonisin (Fusarium verticillioides), evaluating parameters such as biochemistry, antioxidant properties, histological analysis and chick growth. Were weighed 84 chicks of the Cobb 500 strain and randomly distributed them into six groups of two replicates each (n = 14). The F group consumed feed containing fumonisin (levels 400 ppb), with no performance enhancer; F + ZB- feed with fumonisin (levels 400 ppb) + zinc bacitracin; F + GLM100 - feed with fumonisin (levels 400 ppb) + 100 mg of GML/kg of feed; F + NGLM4 - feed with fumonisin (levels 400 ppb) + 4 mg GML/kg in nanocapsules added to the feed; F + NGLM8 - fumonisin feed (levels 400 ppb) + 8 mg GML/kg in nanocapsules in the feed; and F0 - fumonisin-free feed (negative control) + zinc bacitracin. The body weights of birds fed with feed fumonisin-contaminated feed (F, F + ZB, F + GLM100, F + NGLM4 and F + NGLM8) were significantly lower (P < 0.05) than those of the negative control (F0), despite the use of GML (free and nanoencapsulated). Serum levels of triglycerides, globulins and cholesterol were significantly lower in the F0 group than in the other groups (P < 0.05), except for the F + NGLM8 group. Significantly greater levels of lipid peroxidation were observed in livers in the groups that consumed fumonisin than in the control group (F0) (P < 0.05). Serum levels of reactive oxygen species were significantly lower in groups F + NGLM8 and F0 than in the other treatments (P < 0.05). Superoxide dismutase activity was significantly greater in groups F + NGLM8 and F0 than in groups F, F + ZB and F + NGLM4. Hepatic catalase activity was significantly lower in birds that consumed contaminated feed (F, F + ZB, F + GLM100, F + NGLM4 and F + NGLM8) than in the control group (F0). Greater hepatic glutathione S-transferase activity was observed in the F + NGLM8 group than in the F0 group. Despite changes in cellular lesions in the liver, no histological changes were observed in the liver or intestines, even though visually there was yellowing of the liver. Taken together, the data suggest that free or nano-encapsulated GML did not minimize oxidative stress caused by fumonisin, and consequently, these birds had less weight gain.

Ecotoxicology of Glycerol Monolaurate nanocapsules.

Glycerol Monolaurate (GML) is a compound with known antimicrobial potential, however it is not much used due to its low solubility in water and high melting point. The nanoencapsulation of some drugs offers several advantages such as improved stability and solubility in water. The present study aimed to produce, characterize, and evaluate the ecotoxicity of GML nanocapsules. The nanocapsules were produced and presented a mean diameter of 210nm, polydispersity index of 0.044, and zeta potential of -23.4mV. The electron microscopy images showed the nanometric size and spherical shape. The assay in soil showed that GML has a high toxicity while the GML nanocapsules showed decreased toxic effects. Nanostructuration also protected the Rhamdia quelen against the toxic effects of GML. Concluding, the formulation shows positive results and is useful to predict the success of development besides not damaging the soil.

In vivo bactericidal effect of Melaleuca alternifolia essential oil against Aeromonas hydrophila: Silver catfish (Rhamdia quelen) as an experimental model.

Aeromonas hydrophila is one of the main causative agent of high mortality and significative economic losses in aquaculture and has become increasingly resistant to conventional antibiotics. One feasible alternative to control and treat it is the use of essential oils. This study aimed to evaluate A. hydrophila susceptibility to tea tree oil (TTO-Melaleuca alternifolia) in vivo, and the effect of this treatment. In vivo tests were performed using silver catfish (Rhamdia quelen) as the experimental model. Silver catfish were treated with TTO at 25 and 50 µL/L for seven days before infection. After seven days, the fish were inoculated with A. hydrophila via intramuscularly. Treatment with TTO at 50 µL/L was able to extend longevity of infected fish, and showed 88% of therapeutic success, even though it did not show curative efficacy. TTO treatment was not toxic under these tested concentrations, since biomarkers of hepatic and renal functions were not affected, and the concentration of 50 µL/L was able to prevent increased levels of aspartate aminotransferase. There was no significative differences regarding hematological parameters (p < 0.05). Treatment with TTO 50 µL/L was able to reduce histopathological alterations usually caused by this type of bacteria in the gills, but it was unable to reduce hepatic histopathological alterations. Our results showed, for the first time, that TTO has high activity against A. hydrophila and proved to be a natural alternative to prevent and control this pathogen.

Evaluation of antimicrobial activity of glycerol monolaurate nanocapsules against American foulbrood disease agent and toxicity on bees.

The American Foulbrood Disease (AFB) is a fatal larval bee infection. The etiologic agent is the bacterium Paenibacillus larvae. The treatment involves incineration of all contaminated materials, leading to high losses. The Glycerol Monolaurate (GML) is a known antimicrobial potential compound, however its use is reduced due to its low solubility in water and high melting point. The nanoencapsulation of some drugs offers several advantages like improved stability and solubility in water. The present study aimed to evaluate the antimicrobial activity against P. larvae and the toxicity in bees of GML nanoparticles. The nanocapsules were produced and presented mean diameter of 210 nm, polydispersity index of 0.044, and zeta potential of -23.4 mV demonstrating the acceptable values to predict a stable system. The microdilution assay showed that it is necessary 142 and 285 µg/mL of GML nanocapsules to obtain a bacteriostatic and bactericidal effect respectively. The time-kill curve showed the controlled release of compound, exterminating the microorganism after 24 h. The GML nanocapsules were able to kill the spore form of Paenibacillus larvae while the GML do not cause any effect. The assay in bees showed that the GML has a high toxicity while the GML nanoparticles showed a decrease on toxic effects. Concluding, the formulation shows positive results in the action to combat AFB besides not causing damage to bees.

Influence of Melaleuca alternifolia oil nanoparticles on aspects of Pseudomonas aeruginosa biofilm.

The Pseudomonas aeruginosa is a gram-negative bacillus and frequent cause of infection. This microorganism is resistant intrinsically to various drugs. The P. aeruginosa is associated with the biofilm formation, which causes worsen the prognosis and difficulty the treatment. The influence of Melaleuca alternifolia oil or "tree of tee" oil (TTO) and TTO nanoparticles on adhesion of P. aeruginosa in buccal epithelial cells was investigated. Also was determined the antimicrobial and antibiofilm activity against this microorganism. The TTO nanoparticles were produced by deposition of preformed polymer and the physic-chemical properties of nanoparticles were measured by electrophoresis and dynamic light scattering. The characterization of nanoparticle showed acceptable values for diameter and zeta potential. The evaluation of antimicrobial and antibiofilm activity against P. aeruginosa PAO1 was performed by microdilution indicating the minimal inhibitory concentration, and the potential antibiofilm. It was verified the action on virulence factors such the motility, besides the influence on adhesion in buccal epithelial cells. Both oil and nanoparticles showed a decrease in adhesion of microorganisms to buccal cells, decrease of biofilm and interfering on P. aeruginosa PAO1 motility. The nanostructuration of TTO, shows be a viable alternative against formed biofilm microorganisms.