4′-Bromoflavone significantly induces quinone reductase (QR) activity in cultured murine hepatoma 1c1c7 cells (concentration to double activity: 10 nM) and effectively induces the α- and mu-isoforms of glutathione S-transferase in cultured H4IIE rat hepatoma cells with no observed toxicity[1]. 4′-Bromoflavone is a potent inhibitor of cytochrome P4501A1-mediated ethoxyresorufin-O-deethylase activity, with an IC 50 of 0.86 μM. In HepG2 or MCF-7 cells, 4′-Bromoflavone significantly reduces the covalent binding of metabolically activated benzo[a]pyrene to cellular DNA[1].

In short-term dietary studies, 4′-Bromoflavone is also shown to increase QR activity and glutathione levels in rat liver, mammary gland, colon, stomach, and lung in a dose-dependent manner. In studies conducted with female Sprague Dawley rats ,4′-Bromoflavone significantly increases QR activity (phase II enzyme)[1]. In DMBA-treated female Sprague Dawley rats. Dietary administration of 4′-Bromoflavone (2000 and 4000 mg/kg of diet, from 1 week before to 1 week after DMBA) significantly inhibits the incidence and multiplicity of mammary tumors and greatly increases tumor latency[1].