Table 1: Endogenous mediators of oxidative stress.

Leakage of free radicalsMembrane-bound enzymesNADPH oxidase
Electron transport systemsMixed function oxidases

Activation of oxygenSoluble cell constituentsTransition metals, thiol containing proteins, quinine derivatives, epinephrine, metalloproteins, hemeproteins, and flavoproteins
Xenobiotic metabolizing enzymesCyt P450-dependent monooxygenases, Cyt , and NADPH-dependent cytochrome reductases

ROS generation/propagationSoluble cytosolic enzymesXanthine oxidase, superoxide dismutase, catalase
Phagocytic cells Neutrophils, macrophages, and monocytes involved in inflammation, respiratory burst, and removal of toxic molecules
Local ischemiaDamaged blood supply due to injury or surgery