Enhanced Antibacterial Activity of Lippia grata Essential Oil by Nanoencapsulation

Abstract

Abstract Background Nanoencapsulation of essential oil with polysaccharides improves the antimicrobial property by reducing the essential oil volatility and imprinting a synergic effect from the polyelectrolyte. This was investigated for Lippia grata essential oil encapsulated in cationic polyelectrolytes chitosan and trimethylchitosan nanoparticles against Escherichia coli and Staphylococcus aureus . Methods Nanoparticles were prepared by ionic gelation and characterized by Dynamic Light Scattering (DLS), encapsulation efficiency (EE), and infrared spectroscopy (FTIR). Techniques such as antibiogram, minimum bactericidal concentration (MBC), minimum inhibitory concentration (MIC), and scanning electron microscopy (SEM) were used to evaluate the antibacterial action. Results DLS analysis for all the samples showed size inferior to 100 nm both for non-encapsulated and that loaded with essential oil at lower concentration (2500 ppm). Hi loaded chitosan nanoparticles (5000 ppm) reached a size of 689 ± 148 nm. In general, EE was near 82%. FTIR changes in NH 2 and OH band patterns were indicative of nanoparticle formation. Essential oil loaded in trimethylchitosan nanoparticles showed the highest antimicrobial activity, with MIC and MBC < 15.62 ppm. SEM images showed that bacteria treated with encapsulated essential oil had irregular and deformed shapes, resulting from extravasation of intracellular contents. Conclusion These findings demonstrate that the encapsulation process stabilized the L. grata essential oil and enhanced the antimicrobial activity.