Apigenin exerts chemopreventive effects on lung injury induced by SiO2 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 SiO2-induced lung injury in vitro and in vivo. In vitro experiments showed that APG (25 μM) could restore the SiO2-decreased A549 cell viability and lower the apoptotic rate and the production of intracellular reactive oxygen species (ROS) in A549 cells treated with nm SiO2. 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 SiO2-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 SiO2-induced lung injury both in vitro and in vivo through, at least partially, activating Nrf2 expression.