Eurycomalactone is an active quassinoid could be isolated from Eurycoma longifolia Jack. Eurycomalactone is a potent NF-κB inhibitor with an IC50 value of 0.5 μM. Eurycomalactone inhibits protein synthesis and depletes cyclin D1. Eurycomalactone enhances radiosensitivity through arrest cell cycle at G2/M phase and delayed DNA double-strand break repair. Eurycomalactone inhibits the activation of AKT/NF‑κB signaling, induces apoptosis and enhances chemosensitivity to Cisplatin (HY-17394).