Anti biofilm effect of dihydromyricetin-loaded nanocapsules on urinary catheter infected by Pseudomonas aeruginosa.

Nosocomial infections associated with biofilm formation on urinary catheters are among the leading causes of complications due to biofilm characteristics and high antimicrobial resistance. An interesting alternative are natural products, such as Dihydromyricetin (DMY), a flavonoid which presents several pharmacological properties, including strong antimicrobial activity against various microorganisms. However, DMY, has low aqueous solubility and consequently low bioavailability. Nanoencapsulation can contribute to the improvement of characteristics of some drugs, by increasing the apparent solubility and sustained release has been reported among other advantages. The aim of this study was to evaluate, for the first time, the feasibility of DMY nanoencapsulation, and to look at its influence on nanoencapsulation of DMY as well as verify its influence on antimicrobial and antibiofilm activity on urinary catheters infected by Pseudomonas aeruginosa. The physicochemical characterization showed an average diameter less than 170nm, low polydispersity index, positive zeta potential (between +11 and +14mV), slightly acidic pH. The values of the stability study results showed that the best condition for suspension storage without losing physical and chemical characteristics was under refrigeration (4±2°C). The antibiofilm activity of the formulations resulted in the eradication of biofilms both in free DMY formulations and in nanocapsules of DMY during those periods. However, within 96h the results of the inhibition of biofilm by DMY nanocapsules were more effective compared with free DMY. Thus, the nanocapsule formulation containing DMY can potentially be used as an innovative approach to urinary catheter biofilm treatment or prevention.

Validação de metodologia analítica para a determinação de benzofenona-3 nanoencapsulada incorporada em creme gel e estudo da estabilidade físico química / Validation of a method to determine content of nanoencapsulated benzophenone-3 incorporated in a gel cream and study of its physical and chemical stability

The aim of this research was to develop and validatean ultraviolet spectrophotometric method for thequantitative analysis of the content of benzophenone-3(BZ3) nanoencapsulated and incorporated in gel creamand to carry out a study of its stability and determine itsshelf life. The validated method was selective and linearin the range 2?20 ?g/mL, with a correlation coefficientof (r) of 0.999996, precise (relative SD < 2.44%), exact(98.8% - 100.3%) and robust. It can, therefore be usedin the analysis of nanoencapsulated BZ3 gel cream.Gel creams containing nanoencapsulated and free BZ3showed no significant alterations in appearance, colour,smell, pH, viscosity or spreadability, within the 180 dayperiod during which they were exposed to a controlledtemperature of 40 ºC and relative humidity of 75%. Inboth formulations, the BZ3 content fell, but in the freeform it was degraded more quickly (30 days) than inthe nanoencapsulated form (150 days). This indicatesthat the nanocapsules protected the active ingredient.For the gel cream containing the BZ3 nanocapsules, theestimated shelf life was 125 days, and for the free BZ3,69 days.

Este trabalho teve como objetivos validar a metodologia analítica para a quantificação de benzofenona-3 (BZ3) por espectrofotometria na região do ultravioleta, realizar estudo de estabilidade e determinar o prazo de validade deste ativo nanoencapsulado e incorporado em um creme gel. O método validado apresentou-se seletivo, linear na faixa de 2 - 20 ?g/mL, com coeficiente de correlação (R2=0,999993), preciso (DPR < 2,44%), exato (98,8% - 100,3%) e robusto, podendo ser utilizado na quantificação de BZ3 nanoencapsulada em creme gel. Os cremes géis, contendo BZ3 nanoencapsulada e livre não tiveram alterações significativas com relação à aparência, cor, odor, pH, viscosidade e espalhabilidade, durante 180 dias, expostos a temperatura e umidade controlada de 40 ºC e 75% UR. Em ambas as formulações o teor de BZ3 diminuiu, porém, quando na forma livre, o ativo degradou mais rapidamente (30 dias) do que para a forma nanoencapsulada (150 dias), o que nos permite concluir que as nanocápsulas desempenharam um papel de proteção para o ativo. Para o creme gel contendo as nanocápsulas de BZ3 o prazo estimado de validade foi de 125 dias, e para o que continha a BZ3 livre de 69 dias.