DESENVOLVIMENTO DE UM FILME DE GOMA XANTANA INCORPORADO COM NANOEMULSÃO DE ÓLEO ESSENCIAL DE Mentha piperita L. COM ATIVIDADE ANTIBACTERIANA CONTRA Pseudomonas aeruginosa

Abstract

Infections caused by Pseudomonas aeruginosa are common in open and long-standing wounds, and the treatment of these wounds is considered a challenge. Dressings are crucial in wound healing, as they have properties to absorb exudate, maintain moisture and accelerate healing, and when associated with essential oils, they can have antimicrobial action. Therefore, this study aimed to formulate a film based on xanthan gum incorporated with nanoemulsion of Mentha piperita L. essential oil (EO) and evaluate its in vitro antimicrobial activity against P. aeruginosa. In this study, the P. aeruginosa strain ATCC 27853 was used and the Minimum Inhibitory Concentration (MIC) test was performed to determine the action concentration of Mentha piperita L. essential oil. After obtaining the MIC, three films based on xanthan gum and propylene glycol were prepared: control film (XG), film with Mentha piperita L. EO nanoemulsion (XG+NMp) and neomycin (XG+Neo), based on a central composite rotational design (DCCR). Then, the films were subjected to physical, antimicrobial and morphological characterization tests by scanning electron microscopy (SEM). In addition, Fourier transform infrared spectroscopy (FTIR), hemolytic and toxicity assays with Tenebrio molitor larvae, as well as ex vivo and in vivo experimental models of infected wounds were performed. It was possible to show that the essential oil presented a MIC of 0.9 mg/mL and neomycin, 0.0078 mg/mL. In electron microscopy, it was possible to observe that the tested compounds were well distributed in the polymer matrix. The average roughness of XG, XG+NMp and XG+Neo was 1.316 ± 0.179, 0.906 ± 0.137 and 1.337 ± 0.218, respectively. The films presented elastic structures that varied from 107.6 to 114.2% and brightness closer to white, with similar tones. In the FTIR, there was the presence of xanthan gum in all films, through the C-O stretching of alkyl ethers and glycosidic bonds. For the XG+NMp film, a bending in the plane of the O-H bond was observed. In the inhibition zone test, it was found that the films incorporated with 1% of the nanoemulsion and 1% of neomycin presented antimicrobial action. The XG+NMp film showed bacteriostatic effect against P. aeruginosa and reduced the bacterial load in an ex vivo experiment. Furthermore, the nanoemulsion had no toxic effect on Tenebrio molitor larvae. The hemolytic action of the XG, XG+NMp and XG+Neo films was, respectively, 2.6%, 5.2% and 10.8%. The XG+NMp film accelerated the healing of infected wounds in vivo with a significant reduction in severity from the 4th day of treatment (p<0.0001). The bacterial load was also significantly reduced by the XG+MNp film (1.329 ± 2.577) when compared to the other groups, XG (-0.8478 ± 0.4458) and XG+Neo (-0.2606 ± 0.9875). Thus, the results obtained in this study show that the films incorporated with the nanoemulsion of M. Piperita L. presented excellent stability, with physicochemical characteristics of the formulation within the required standards and with antimicrobial and healing action on wounds infected by P. aeruginosa, being, therefore, an excellent alternative as a dressing aimed at the treatment of wounds infected by this pathogen.