Figure 3.

Proposed antioxidant mechanisms of inositol derivatives. Phytic acid (IP₆) chelates and sequesters Fe³⁺, redirecting Fe²⁺ via the Fenton reaction to oxidation with O_2. Four molecules of Fe²⁺ are necessary to oxidize one molecule of O₂, which generates O₂⁻, which is later converted in H₂O₂, and finally inactive H₂O. Reactive oxygen species (ROS) are scavenged by the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). Inositols upregulate antioxidant enzyme levels and activity. The activation of insulin signaling in the endothelium results in increased NO production. l-quebrachitol and 3,4-dibutyryl-d-chiro-inositol scavenge peroxynitrite (ONOO⁻) and ROS species, respectively, although the mechanisms of this have not been unveiled yet.