*2.3. Cell Culture*

Human tenocytes (#TEN-F; ZenBio Inc.; Durham, NC, USA) were maintained in complete alpha-MEM (EuroClone, Milan, Italy) supplemented with 10% of heat-inactivated FBS (Gibco, ThermoFisher Scientific, Waltham, MA, USA) and 1% penicillin/streptomycin (EuroClone, Milan, Italy) at 37 ◦C and 5% CO2 and used from passage 3 up to passage 6.

#### *2.4. Cell Treatment*

Cells were seeded in 96-well plates (0.5 × 104/well) (ThermoFisher Scientific, Waltham, MA, USA) and left to adhere overnight at 37 ◦C and 5% CO2. In a first set of experiments, tendon-derived cells were treated with increasing concentrations of compounds **1**–**5** in the range 0–100 μM for 24 and 72 h. Compounds were dissolved in DMSO to obtain a 200 mM stock solution, and they were afterwards diluted in complete alpha-MEM (DMSO final concentration = 0.1%) for further analyses. In a second set of experiments, tenocytes were pre-incubated with 100 μM H2O2 for 3 h. After that, the pre-incubation medium was discarded and replaced with a fresh one containing the proper CORM at increasing concentrations for 24 and 72 h. At the established time points, samples were processed for further analyses.
