Antioxidant mechanism of Rosmarinus officinalis essential oil ameliorating pulmonary oxidative stress by activating NRF2 signaling pathway

Abstract Oxidative stress is a major transduction intermediator of air pollution-related pulmonary disorders, thus the antioxidants defensed with pulmonary oxidative stress need to be further pursued. Rosemary ( Rosmarinus officinalis ) is widely recognized as a potent natural antioxidant due to its excellent essential oil. However, the application of rosemary essential oil (REO) against oxidative stress has not yet been reported. This study aimed to explore REO’s antioxidant action under pulmonary oxidative stress, and reveal its underlying molecular mechanisms in hydrogen peroxide induced human lung carcinoma (A549) cells. In this paper, REO mainly composed of 1.8-cinelone (54.05%) and α-Pinene (20.67%), showed radical scavenging activity nearly equivalent to that of ascorbic acid, but significantly higher than BTH and BHA in DPPH, ABTS, OH − and O 2 − assays. At the cellular level, REO (12.5–50 µg/mL) evaluated the levels of cell viability, antioxidant metabolic enzymes CAT, SOD, as well as non-enzymatic antioxidant GSH significantly, while reduced the contents of ROS, MDA and GSSG prominently, when compared to H 2 O 2 exposure only. Mechanically, REO relieved oxidative stress via activating Nrf2 signaling pathway and enhancing the protein expression of Nrf2 and its target genes NQO-1, HO-1, which was verified by molecular docking between 1.8-cineole and Kelch domain of KEAP1 further. Therefore, REO could be considered as a potent natural antioxidant with potential strategy in food and pharmaceutical industries.