Ultrasound-mediated release of iron from ferritin

We investigated the release of iron from ferritin in aqueous solutions exposed to high-frequency ultrasound (US). Our data suggests that superoxide produced as a result of ultrasonic cavitation acts as a reducing agent, enabling the release of iron from ferritin. We also found that the release of ferritin iron during US exposure is enhanced by the addition of 5-hydroxy-1,4-naphthoquinone. We hypothesize that this quinone is ultrasonically transformed into a semiquinone radical capable of directly and indirectly reducing Fe(3+) in ferritin to soluble Fe(2+). Our proposed mechanism for the release of iron from ferritin adds new insight to the synergistic effect of quinone-containing cancer drugs with US.