Carnosol, a dietary diterpene from rosemary ( Rosmarinus officinalis ) activates Nrf2 leading to sestrin 2 induction in colon cells

Rosemary is abundant with phytochemicals and has recently been approved as an antioxidant food preservative in the European Union. The safety of rosemary is well established, however, the benefits on gastrointestinal health are less known. Our overall hypothesis is that the phytochemicals in rosemary including carnosol have the potential to promote gastrointestinal health by activation of the antioxidant sestrin-2 when consumed in our diet. Colon cells HCT116 and SW480 were treated with carnosol and evaluated by MTT, immunofluorescence, ELISA, and Western blot analysis to understand the modulation of the PERK/Nrf2/Sestrin-2 pathway. Carnosol was found to modulate PERK and increase the concentration of nuclear Nrf2. Furthermore, a downstream marker of Nrf2 expression, Sestrin-2 was shown to be upregulated. Based on these observations carnosol modulates the PERK and Nrf2 pathways along with increased expression of sestrin-2, a known stress inducible antioxidant.