Anti-inflammatory, antioxidant, and antibacterial activity of tea saponin-based Zanthoxylum bungeanum essential oil nanoemulsions against bovine mastitis pathogens

To enhance the applicability of Zanthoxylum bungeanum essential oil (ZEO) from Wudu, China, a tea saponin (TS)-stabilized nanoemulsion (ZEO-NE) was developed. Its composition was analyzed, and the physical properties, stability, and bioactivities were systematically evaluated. GC-MS analysis identified linalool (24.833 %), linalyl acetate (16.076 %), and d-limonene (14.019 %) as the principal constituents. An oil-in-water ZEO-NE was prepared using the natural surfactant tea saponin (TS) as an emulsifier via ultrasonication. The average particle size, zeta potential, and polydispersity index of ZEO-NE were 188.49 ± 6.15 nm, −26.02 ± 0.47 mV, and 0.17 ± 0.04, respectively. The physical properties and biological activity of ZEO-NE were evaluated. ZEO-NE behaved as a non-Newtonian fluid and demonstrated stability over 30 days of storage, within a temperature range of 4–50°C, and under centrifugation at 2000–6000 rpm. Compared to free ZEO, ZEO-NE demonstrated improved scavenging capacities against DPPH, ABTS, and hydroxyl radicals, along with enhanced antibacterial activity against Escherichia coli , Staphylococcus aureus , and S. dysgalactiae . The antibacterial mechanism involved the disruption of bacterial cell walls and membranes. Furthermore, ZEO-NE provided superior protection to bovine mammary epithelial cells against bacterial-induced damage and effectively downregulated the expression of the pro-inflammatory cytokines TNF-α and IL-1β in these cells. These findings demonstrate that nanoencapsulation of ZEO using TS enhances its antioxidant, antibacterial, and anti-inflammatory activities. Consequently, ZEO-NE shows promise as a natural antioxidant for food preservation and holds potential therapeutic value for the treatment of bovine mastitis. • Wudu-sourced Z. bungeanum essential oil exhibits multiple bioactivities. • A tea saponin-stabilized nanoemulsion of the essential oil was prepared. • Tea saponin-based nanoemulsion enhances the bioactivity of Z. bungeanum essential oil.