Activation of intracellular antioxidant master gene Nrf2 by the extracts of Garcinia subelliptica, Ocimum gratissimum L., and Plectranthus ornatus

Body is always exposed to both endogenous and exogenous oxidative stress, and neutralizes them with antioxidant defense system. Imbalance between oxidant and antioxidant produces reactive oxygen and nitrogen species, causing oxidation of protein, lipid, and DNA damage that lead to aging and various types of diseases such as neurodegenerative, pulmonary, or cardiovascular disease. Therefore, antioxidative agents are important for prevention and treatment of these diseases. In this study, we screened Okinawan plant extract library of 80 species to find nuclear factor erythroid-derived two-like-2 (Nrf2)-dependent antioxidant activity by antioxidant response element (ARE)-lucifearase reporter assay. The three species extracts of Garcinia subelliptica, Ocimum gratissimum, and Plectranthus Ornatus dose-dependently induced mRNA and protein expression of HO1, a downstream antioxidant gene of Nrf2. Furthermore, these extracts induced nuclear translocation of Nrf2 and the reduction of reactive oxygen species (ROS). These results suggested that these plants are natural antioxidant sources of Nrf2 activators.