Amentoflavone activates Nrf2 by dissociating Kelch-like epichlorohydrin (ECH)-associated protein 1 (Keap1), subsequently elevating the concentrations of heme oxygenase-1 (HO-1), NAD(P)H-quinone oxidoreductase 1 (NQO1) and γ-glutamylcysteine ligase, which act as an anti-inflammatory and antioxidant, ultimately improving pleurisy and pleural effusion. The gene discussed is HMOX1; the disease is Pleural effusion.