Fig. 1.
Case–control (a) and intervention studies (b) suggested that marker of peroxidation could be a more sensitive index of oxidative stress than total antioxidant capacity (TAC). However, some methodological limitations and the relationship between cellular and plasma oxidative stress must be taken into account to properly evaluate the clinical significance of TAC and peroxidation biomarkers in psoriasis (c). TAC methods are strongly influenced by the presence of products of catabolism, such as uric acid and bilirubin, the latter is able to react with thiobarbituric acid (TBARS). The clinical significance of methods based on redox reactions with metal ions must consider the potential detrimental effect of reduced metals in conditions of low levels of antioxidant enzymes (c). The latter, as well as the inflammatory cytokines are regulated at transcriptional levels by cellular redox status. ↑: increased, ↓: decreased/:or ↔: unchanged; ARE: antioxidant responsive elements; CAT: catalase; CHOL: cholesterol; CUPRAC: cupric reducing antioxidant capacity, Fe: iron; FRAP: ferric reducing antioxidant potential; GPX: glutathione peroxidise; H2O2: hydrogen peroxide; NF-kB: nuclear factor- kappa B; Nfr2: nuclear factor-erythroid 2-related factor 2; O2-•: superoxide radical; OH•: hydroxyl radical; ROO•: peroxyl radicals; ROS: reactive oxygen species; SOD: superoxide dismutase; TOC: total oxidant capacity; TOS: total oxidant status