Role of Natural Radiosensitizers and Cancer Cell Radioresistance: An Update

Figure 1

ROS have superoxide anion, hydrogen peroxide, and hydroxyl radical. Superoxide anion () generated from NADPH oxidation through NADPH oxidases. It reduces to hydrogen peroxide (H₂O₂) where superoxide dismutase (SOD) acts as catalyst. Hydrogen peroxide further reduces to H₂O via catalase/oxidized iron (Fe²⁺) to highly reactive hydroxyl ion (OH⁻). During oxidative stress, when generation of reactive oxygen species spaces out their scavenging system, levels of oxidized reactive oxygen species accumulate and this damages many cellular factors.