Xanthohumol D, a natural product isolated and purified from the herbs of Humulus lupulus, is a potent inhibitor of quinone reductase-2 (QR-2) with IC50 of 110μM.

Tigloylgomisin H, a natural product isolated and purified from the fruits of Schisandra chinensis, can significantly induce quinone reductase (QR) activity in Hepa1c1c7 mouse hepatocarcinoma cells. It functions as a monofunctional inducer that specifically upregulates phase II enzymes through the Nrf2-ARE pathway, thus represents a potential liver cancer prevention agent.

S29434 is a potent, nanomolar inhibitor of QR2 with IC₅₀ of 5-16 nM at different organizational levels.