**4. Conclusions**

In this study, the flavonoid contents of PUL were investigated, and the PUL were discovered to be rich in flavonoids, such as rutin, hyperoside, and isoquercitrin. Extraction using different DESs based on CC and dicarboxylic acids was found to effectively improve the extraction efficiency of the three flavonoids from the PUL. Among the different DESs tested, the DES based on CC and GA exhibited the highest extraction efficiency. The extraction conditions were optimized using the BBD analysis. According to these conditions, the highest extraction efficiency (217.515 μg/mL) could be achieved by performing the extraction of PUL for 1 h at a temperature of 30 ◦C and stirring speed of 1113.1 rpm, using the DES based on CC and GA at a concentration of 30.85 wt.%. The extraction efficiency

achieved using the DES was more than twice as high as that of aqueous extraction. In addition, the PUL extract obtained using the DES synthesized from CC and GA exhibited appreciable antioxidant activity, which was approximately 1/6 that of L-ascorbic acid. The potential utility of the PUL extracts as antioxidants was, thus, demonstrated. The PUL extract obtained using the DES synthesized from CC and GA significantly inhibited NO generation (up to 26.1%) at a concentration of 0.1%. These results indicated the antiinflammatory properties of the active components of the PUL extracted using the DES.

**Supplementary Materials:** The following supporting information can be downloaded at: https: //www.mdpi.com/article/10.3390/molecules27092798/s1: Figure S1: liquid chromatogram of PUL extract and mass spectra of flavonoid peaks; Figure S2: effect of extraction conditions on extraction efficiency of DES.

**Author Contributions:** Conceptualization, H.Y.P. and J.P.; methodology, J.W.L.; validation, J.W.L.; resources, H.Y.P.; writing—original draft preparation, J.P.; writing—review and editing, J.P. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the National Institute of Biological Resources (NIBR), funded by the Ministry of Environment (MOE) of the Republic of Korea, grant number NIBR202219101, and the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT), grant number 2019R1F1A1058645.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** This work was supported by a grant from the National Institute of Biological Resources (NIBR), funded by the Ministry of Environment (MOE) of the Republic of Korea (NIBR202219101) and a National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (2019R1F1A1058645).

**Conflicts of Interest:** The authors declare no conflict of interest.

**Sample Availability:** Not applicable.
