*4.14. Statistical Analysis*

Each independent experiment (*n*) was performed with different primary cell culture batches and cartilage from distinct patients. Replicates within an individual experiment were performed using the same batch of cells and cartilage from a single patient. Data are presented as mean ± standard deviation (SD). Multiple *t* tests were used for comparison between two groups. For more than two groups significance was determined using one-way analysis of variance (ANOVA) with comparison between groups by Dunnett test. Statistical significance was defined as *p* ≤ 0.05 (\*), *p* ≤ 0.005 (\*\*) and *p* ≤ 0.0005 (\*\*\*).

*Mar. Drugs* **2020**, *18*, 624

**Supplementary Materials:** The following are available online at http://www.mdpi.com/1660-3397/18/12/624/s1, Figure S1: Chemical structure, NMR and HRMS data of amentadione (YP); Figure S2: YP reduces the inflammatory response of THP-1 macrophages (THP-1 MOM) stimulated with LPS and hydroxyapatite (HAP); Figure S3: Viability of THP-1 macrophage cells (THP-1 MOM) exposed to different concentrations of amentadione (YP) for 24 h and exposed to different concentrations of HAP for 72 h; Figure S4: Viability of primary human chondrocytes and synoviocytes exposed to different amentadione (YP) concentrations for 24 h; Figure S5: Viability of primary human chondrocytes and synoviocytes exposed to different hydroxyapatite (HAP) concentrations for 72 h; Figure S6: Indication on the time point with increased pIkBα after IL-1β stimulation. Table S1: Modified Mankin score used for histological evaluation of human cartilage explants; Table S2: Gene-specific primers used for gene expression analysis by qPCR.

**Author Contributions:** Conceptualization, N.A., C.S.B.V. and D.C.S.; methodology, N.A. C.S.B.V., J.M., A.R., M.M.C., J.P.S. and H.C., investigation, N.A., C.S.B.V. and D.C.S.; resources, J.M. and E.Z.; writing—original draft preparation, N.A., C.S.B.V. and D.C.S.; writing—review and editing, C.S.B.V., J.M., F.J.B., C.V., E.Z. and D.C.S.; supervision, N.A., C.S.B.V. and D.C.S.; project administration, C.S.B.V. and D.C.S.; funding acquisition, C.S.B.V. and D.C.S. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the Portuguese national funds from FCT—Foundation for Science and Technology through the transitional provision DL57/2016/CP1361/CT0006 and project UIDB/04326/2020. N Araújo is the recipient of the Portuguese Science and Technology Foundation (FCT) fellowship SFRH/BD/111824/2015.

**Acknowledgments:** We would like to acknowledge José L. Enriquez and Alexandra Teixeira from the Centro Hospitalar e Universitário do Algarve (CHUAlgarve), Department of Histopathology, Faro, Portugal, for their collaboration in cartilage tissue paraffin embedding and sectioning.

**Conflicts of Interest:** Dina C. Simes and Carla Viegas are cofounders of GenoGla Diagnostics. The authors declare that there are no conflicts of interest regarding the publication of this paper.
