Apigenin exerts chemopreventive effects on lung injury induced by SiO 2 nanoparticles through the activation of Nrf2

Apigenin (APG) is a flavonoid widely distributed in fruits, vegetables, and herbs, with comprehensive pharmacological effects. In this paper, we report that APG can elicit a protective effect, which is comparable to those induced by gymnoside II/ n -BuOH extracts of Bletilla striata , on SiO 2 -induced lung injury in vitro and in vivo. In vitro experiments showed that APG (25 μM) could restore the SiO 2 -decreased A549 cell viability and lower the apoptotic rate and the production of intracellular reactive oxygen species (ROS) in A549 cells treated with nm SiO 2 . Western blot results showed that APG (25 μM) could increase the level of Nuclear factor E2-related factor 2 (Nrf2) and its downstream proteins. In vivo experiments showed that APG (20 mg/kg) could potently alleviate the SiO 2 -elicited lung injury by enhancing the Nrf2 expression and thereby suppressing Bax/Bcl-2 pathway. The present study suggests that APG can significantly alleviate the SiO 2 -induced lung injury both in vitro and in vivo through, at least partially, activating Nrf2 expression. Graphic abstract