**4. Conclusions**

In conclusion, we have successfully obtained three new hybrid molecules containing a furan skeleton and N-heterocycle. The new hybrid molecules were fully characterized using UV, 1H- and 13C-NMR, and HRMS spectrometry. All four of the obtained compounds were in vitro biologically evaluated for their antioxidant, anti-inflammatory, anti-arthritic, and metal-chelating activity. Detailed HRMS analysis showed that the isomers **H3** and **H4** can be easily distinguished from each other. All compounds showed activity in all in vitro biological tests performed. As expected, hybrid molecules **H3** and **H4** show greater metal-chelating activity as well as antioxidant activity than hybrids **H1** and **H2**. The anti-inflammatory activity confirmed by the in silico analysis is also proven by the in vitro biological evaluation, and the hybrids are ranked in the following descending order: **H1** > **H2** > **H4** > **H3**.

**Supplementary Materials:** The following supporting information can be downloaded at: https: //www.mdpi.com/article/10.3390/pr10101997/s1, Figures S1–S4: 1H-NMR spectrum of hybrids 1–4; Figures S5–S8: 13C-NMR spectrum of hybrids 1–4; Figures S9–S12: UV spectrum of hybrids 1–4; Figures S13–S20: HRMS chromatograms of hybrids 1–4.

**Author Contributions:** Conceptualization, I.I. and S.M.; methodology, S.M. and D.B.; software, S.M.; validation, D.B., S.M. and I.I.; formal analysis, S.M., D.B. and P.N.; investigation, S.M.; resources, I.I.; data curation, I.I.; writing—original draft preparation, S.M. and D.B.; writing—review and editing, S.M., D.B. and I.I.; visualization, D.B.; supervision, I.I.; project administration, S.M.; funding acquisition, I.I. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the National Science Fund of the Bulgarian Ministry of Education and Science, grant number KΠ 06 M29/1.

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

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The data presented in this study are available in this article and in the supporting Supplementary Material.

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