Chitosan-Coated Resveratrol and Quercetin Nanoparticles: Synergistical Antibacterial Activities and Improvement of Nutrition Value

OBJECTIVES: Many fresh fruits have short shelf life due to microbial growth. Trans-resveratrol (R) and quercetin (Q) have antimicrobial property, but they are easily degraded and have low bioavailability. These issues can be overcome by biocompatible lipid nanoparticles (NPs) using vitamin E as a hdrophobic core. Coating R and Q NPs (RQ-NPs) with chitosan (CS), can enhance their stability, antibacterial effect, and bioavailability. The objectives of this project are to make and optimize CS-coated R-NPs, Q-NPs and RQ-NPs, measure their characteristics, evaluate their antibacterial effect, investigate fresh-keeping property when coating them on fruits, and determine their bioavailability. METHODS: The size, polydispersity indexes (PDI) and zeta potential of NPs were measured using Zetasizer Pro. Their chemical stability was measured using HPLC. The S. enteritidis, L. monocytogenes, E. coli, and S. aureus were used to evaluate their antibacterial effect. After coating strawberry with NPs, the protective effect was determined by maintained quality. Mice were given NPs via oral gavage, and the bioavailability were determined based on blood R and Q concentrations. RESULTS: The mean particle size of R-NPs, Q-NPs and RQ-NPs was around 50, 30, and 40 nm, and zeta potential was around −2, −10 and −8 mV, respectively. Their PDI were less than 0.3 R-NPs containing 200 μg/mL of R and Q-NPs containing 300 μg/mL of Q significantly inhibited bacteria growth. A a lower concentration of R and Q in RQ-NPs (containing 150 μg/mL of R and 90 μg/mL of Q) exhibited similar antibacterial effect. After coating NPs with CS, their PDI remained under 0.3, but the size of of R-NPs, Q-NPs and RQ-NPs was about 90, 55, 60 nm, and zeta potential was around +30, +15 and +25 mV, respectively. CS-coated NPs were stable at 4°C and 22°C for at least 5 days and 3 days. CS-coated NPs exhibited enhanced antibacterial effect and prolonged the shelf life of strawberry furtherly. Nanoencapsulation also increased oral bioavailability in mice. CONCLUSIONS: RQ-NPs showed a synergistic antibacterial effect, and CS coating increased their stability and antibacterial effect. CS-coated RQ-NPs maintained freshness of strawberry, and showed enhanced bioavailability in mice, indicating their potential implementation in active food packaging. FUNDING SOURCES: NIH 1R15AT010395-01 and American Heart Association 19AIREA34480011.