Background and Purpose: Non‐small‐cell lung cancer (NSCLC) accounts for up to 80–85% of all lung cancers and has a disappointing prognosis. Flavonoids exert anticancer properties, mostly involving stimulation of ROS production without significant toxicity to normal cells. This study was aimed to delineate the effect of diosmetin, a natural flavonoid, on NSCLC cells and its ability to enhance the antitumour activity of paclitaxel.Experimental Approach: NSCLC cells, normal cell lines HLF‐1 and BEAS‐2B, and immunodeficient mice were chosen as models to study the effects of diosmetin. Changes in cell viability, apoptosis, and ROS were analysed by MTT assay, flow cytometry assay, and fluorescent probe DCFH‐DA. Expression of proteins and mRNA was determined by Western blotting and real‐time RT‐PCR. Growth of xenografted tumours was measured. Spleens and other vital organs were analysed with histological and immunohistochemical techniques.Key Results: Diosmetin induced selective apoptotic death in NSCLC cells but spared normal cells, via ROS accumulation. Diosmetin induced ROS production in NSCLC cells probably via reducing Nrf2 stability through disruption of the PI3K/Akt/GSK‐3β pathway. The in vitro and in vivo xenograft studies showed that combined treatment of diosmetin and paclitaxel synergistically suppressed NSCLC cells. Histological analysis of vital organs showed no obvious toxicity of diosmetin, which matched our in vitro findings.Conclusions and Implications: Diosmetin selectively induced apoptosis and enhanced the efficacy of paclitaxel in NSCLC cells via ROS accumulation through disruption of the PI3K/Akt/GSK‐3β/Nrf2 pathway. Therefore, diosmetin may be a promising candidate for adjuvant treatment of NSCLC.

Acetaminophen (APAP) overdose-induced acute liver damage is mostly due to overwhelmingly increased oxidative stress. Nuclear factor-erythroid 2-related factor2 (Nrf2) plays an important role in alleviating APAP hepatic toxicity. Shikonin (SHK) enhances Nrf2 in multiple lines of normal cells. Nevertheless, whether SHK protects against APAP-induced liver toxicity remains undefined. This study found SHK defended APAP-induced liver toxicity, as well as reversed the levels of serum alanine/aspartate aminotransferases (ALT/AST), liver myeloperoxidase (MPO) activity, and reactive oxygen species (ROS), while it enhanced the liver glutathione (GSH) level in APAP-treated mice. SHK rescued the cell viability and GSH depletion, but neutralized oxidative stress in APAP-treated human normal liver L-02 cells. Mechanically, SHK increased Nrf2 expression in the exposure of APAP at the protein level but not at the mRNA level. Inhibition of Nrf2 blocked the SHK effect in APAP-treated hepatocytes. Furthermore, SHK improved Nrf2 stability through stimulating PI3K/Akt pathway, thus inhibiting GSK-3β. In vivo studies confirmed the close correlation of liver protection of SHK against APAP and Akt/GSK-3β/Nrf2 pathway. In conclusion, this study reveals that SHK prevents APAP hepatotoxicity by upregulation of Nrf2 via PI3K/Akt/GSK-3β pathway. Therefore, SHK may be a promising candidate against APAP-induced liver injury.