Vitamin E-derived copolymers continue the challenge to hemodialysis biomaterials

Figure 1 Molecular structure of some forms of vitamin E. A: α-tocopherol (top) and its redox-silent synthetic analogue TPGS 1000 (bottom); B: Some examples of vitamin E analogues with antioxidant activity: the synthetic formsα-tocopherylamine (top) and Trolox (middle), and the hepatic short-chain metabolite α-CEHC (bottom).

Figure 2 Schematic structure of the PS-PVP based copolymer functionalized with α-tocopherol. Kindly provided by the R and D department of Ashai Medical, Tokyo, Japan.

Figure 3 Coupled redox reaction of vitamin E and vitamin C (co-antioxidants) during the reduction (scavenging) of peroxyl radicals (A) and proposed scheme of the mechanisms that may lead vitamin E copolymers to control the flux of reactive oxygen species in the extracorporeal circulation (B). ROS: Reactive oxygen species; Vit C: Ascorbic acid; Vit C^-: Ascorbate anion; Vit C^-*: Ascorbyl radical anion; DHA: Dehydroascorbate; O₂: Molecular oxygen; O₂^-*: Superoxide anion; e^-/H⁺: Electron/proton; T-OH: Tocopherol; T-O*: Tocopheryl radical; ROOH: Peroxyde (reduced form); ROO*: Peroxyl radical.