Resveratrol seems most effective at low concentrations. However, BDO-3,4DHB shows stable results from 31 days onwards, whereas for the other systems, most OITs decline sharply between the end of the first month and the third one. Then, despite its lower initial efficacy, YI of materials based on resveratrol (Figure ) or BDO-3,4DHB (Figure ) increase sharply over time, with values reaching 45. In the case of resveratrol, this is due to the presence of two aromatic rings per molecule and a styrene double bond. The concentration of conjugated bonds in these molecules is therefore higher than in Irganox 1076. According to the literature, these conjugated bonds are responsible for the coloration of TPOs, as well as the presence of two OH groups per aromatic ring, as in BDO-3,4DHB. Indeed, after radical capture, these antioxidants are stabilized in a quinone form that is highly chromophoric . Moreover, the synthesis of BDO-3,4DHB requires a temperature of 100 °C for 24 h, which induces an initial notable coloration for this molecule.