Background: 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.
Objective: To study preparation and characterization of quercetin-based Mongolia Medicine Sendeng-4 nanoemulsion (NQUE-NE) and its antibacterial activity and mechanisms.
Methods: 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
temperature. The combined bacteriostatic effect of N-QUE-NE was studied in vitro by double-dilution method and
checkerboard dilution method.
Results: 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 (QUE-NE) 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
order of quercetin-tannin-toosendanin nanoemulsion (QUE-TAN-TOO-NE) ＞ quercetin-tannin nanoemulsion (QUE-TANNE) ＞ QUE-NE ＞ quercetin-tannin-toosendanin-geniposide nanoemulsion (QUE-TAN-TOO-GEN-NE).
Conclusion: 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.