Preparation and Characterization of Natural Quercetin-Based Mongolia Medicine Sendeng-4 Nanoemulsion (N-QUE-NE) and its Antibacterial Activity

Quercetin is the main active ingredient of Xanthoceras sorbifolia Bunge. Traditional compatibility theory of traditional Chinese medicine has typically reported a synergistic interaction among multiple components, while the synergistic effects of nanoemulsion have not been fully clarified.The paper aims to study the preparation and characterization of quercetin-based Mongolia Medicine Sendeng-4 nanoemulsion (N-QUE-NE) and its antibacterial activity and mechanisms.The morphology of the nanoemulsion was observed by Transmission Electron Microscopy (TEM), and the zeta potential, Polydispersity Index (PDI), and particle size distribution were determined by the nanometer particle size analyze. The stability of nanoemulsion was investigated by light test, high-speed centrifugal test and storage experiment at different temperatures. The combined bacteriostatic effect of N-QUE-NE was studied in vitro by the double-dilution method and checkerboard dilution method.The appearance of N-QUE-NE was pale yellow, clear and transparent. The nanoemulsion particles were spherical and uniformly distributed under TEM. The PDI was 0.052, the average particle size was 19.6nm, and the Zeta potential was -0.2mV. When quercetin nanoemulsion (QUENE) was used in combination with tannin nanoemulsion (TAN-NE) and toosendanin nanoemulsion (TOO-NE), it exhibited a synergistic antibacterial effect. However, the combination of QUE-NE and geniposide nanoemulsion (GEN-NE) exhibited an antagonistic effect. It was revealed that the antibacterial effect was in the order of quercetin-tannin-toosendanin nanoemulsion (QUE-TANTOO- NE) > quercetin-tannin nanoemulsion (QUE-TAN-NE) > QUE-NE > quercetin-tannintoosendanin- geniposide nanoemulsion (QUE-TAN-TOO-GEN-NE).This study explored the preparation and efficacy of N-QUE-NE, and the results showed that quercetin, tannin and toosendanin had satisfactory synergistic antibacterial effects. The antagonistic effect of quercetin and geniposide in nanoemulsion indicated that it is not beneficial to the antibacterial effect of Sendeng-4, and further research needs to be conducted to clarify its antibacterial effect.