In reperfusion injury following myocardial ischemia, massive superoxide generation occurs. The MOST dangerous free radical formed from superoxide in the presence of Fe2+ (Fenton reaction) is:
- A Hydrogen peroxide (H2O2)
- B Nitric oxide (NO•)
- C Hydroxyl radical (•OH) ✓
- D Singlet oxygen (1O2)
Correct answer: C. Hydroxyl radical (•OH)
Explanation
The Fenton reaction: Fe2+ + H2O2 → Fe3+ + OH− + •OH (hydroxyl radical). Hydroxyl radical is the most reactive ROS known, with a half-life of ~10−9 seconds and an extremely high reactivity constant. It causes lipid peroxidation (chain reaction destruction of cell membranes), DNA strand breaks (8-oxoguanine formation), and protein carbonylation. During ischemia-reperfusion, xanthine oxidase produces O2•−, which dismutates to H2O2; released Fe2+ from ferritin drives Fenton chemistry generating •OH — a major mechanism of reperfusion injury.
Reference: Harper's Illustrated Biochemistry, 32nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.