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Antimicrobial Efficacy of Poly (DL-lactide-co-glycolide) (PLGA) Nanoparticles with Entrapped Cinnamon Bark Extract against Listeria monocytogenes and Salmonella typhimurium

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Direct inquiries to author Gomes (E-mail: carmen@tamu.edu).

Abstract

Nanoencapsulation of active compounds using poly-(d,l-lactide-co-glycolide) (PLGA) is commonly used in the pharmaceutical industry for drug delivery and may have important applications in the food industry. Control of growth of foodborne bacteria with the goals of reducing the number of foodborne illness outbreaks, assuring consumers a safer food supply remains a priority in the food industry. Natural antimicrobials are an excellent way to eliminate pathogens without introducing chemical preservatives that consumers may find undesirable. Cinnamon bark extract (CBE) is an effective pathogen inhibitor isolated from cinnamon spice. PLGA nanoparticles containing CBE were produced using an emulsion-solvent evaporation method and characterized for size, polydispersity, morphology, entrapment efficiency, in vitro release and pathogen inhibition. PLGA with 2 different ratios of lactide to glycolide (65:35 and 50:50) were used to determine how polymer composition affected nanoparticle characteristics and antimicrobial potency. The size of the nanoparticles ranged from 144.77 to 166.65 nm and the entrapment efficiencies of CBE in 65:35 PLGA and 50:50 PLGA were 38.90% and 47.60%, respectively. The in vitro release profile at 35 °C showed an initial burst effect for both types of PLGA followed by a more gradual release of CBE from the polymer matrix. Both types of PLGA nanoparticles loaded with CBE were effective inhibitors of Salmonella enterica serovar Typhimurium and Listeria monocytogenes after 24 and 72 h at concentrations ranging from 224.42 to 549.23 μg/mL. The PLGA encapsulation improved delivery of hydrophobic antimicrobial to the pathogens in aqueous media.

Practical Application

There is an urgent need for new effective antimicrobials for use in the food industry to help prevent foodborne diseases. Nanoencapsulation as a delivery platform offers very promising applications in natural antimicrobial delivery. This study consisted of synthesizing and characterizing PLGA nanoparticles loaded with CBE. These nanoparticles with controlled release characteristics, by virtue of their size and physico-chemical properties, enhanced the absorption/contact of a CBE by the microorganism and consequently antimicrobial activity. The data presented in this study can aid the food industry in developing more efficient and effective application of antimicrobials.

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