2.6.1. HGel-A

The kinetics of release of the indoles in PBS 1× at pH 7.4 or 5.5 was evaluated at room temperature by UV–Vis analysis over 72 h by refreshing the medium every 1 h in the first 6 h and then every 24 h.

#### 2.6.2. HGel-B and HGel-C

The kinetics of release of indole componds (DHICA 5, 10% or MeDHICA 10% from HGel-B and DHICA/MeDHICA 10% from HGel-C) were determined in PBS 1× (pH = 7.4) at 37 ◦C by UV–Vis analysis over time. The medium was repeatedly refreshed every hour over 6 h.

#### *2.7. Stability of DHICA*/*MeDHICA*

Then, 10% HGel-B incorporating DHICA was immersed in PBS 1× at 37 ◦C and the release of the indole was monitored over 6 h without medium refreshing. The decay of free DHICA in the PBS solution at 37 ◦C at the same concentration (based on the estimated incorporation of DHICA in the gelatin as described above) was monitored by HPLC analysis.

#### *2.8. Antioxidant Properties of the DHICA*/*MeDHICA Loaded Gelatins*
