Identification of Sestrin 2 Modulators from Rosemary (Salvia rosmarinus) in Colitis and Colon Cancer

Rosemary extract is an approved food preservative in the European Union and a Generally Recognized as Safe substance in the United States. Consequently, the individual phytochemicals present in rosemary extract will have greater exposure to the gastrointestinal tract. Therefore, we are interested in determining the effect of rosemary extract and its individual components on gastrointestinal health. Preliminary data from our lab reveals that carnosol, a phenolic diterpene in rosemary, upregulates the expression of sestrin 2 protein in colon cancer cells. Sestrin 2 is a stress response protein that is controlled by a variety of transcription factors to maintain cellular homeostasis. Clinical studies have shown that sestrin 2 is overexpressed in ulcerative colitis patients. Our lab has performed pharmacokinetic studies with carnosic acid and carnosol from rosemary. The results suggest that carnosic acid and carnosol are quickly absorbed into the blood. Additionally, we also found that carnosic acid undergoes enterohepatic recirculation to increase exposure in the body. To determine the effect of rosemary on the development of colitis, we treated RAW 264.7 mouse macrophages with rosemary extract and found that TNF-αproduction in LPS-stimulated macrophages was decreased by approximately 50%. Next, we used a DSS-colitis mouse model to determine the ability of rosemary to prevent colitis development. Rosemary extract at 100 mg/kg significantly reduced the disease activity index in colitis mice. Western blot analysis revealed that the expression of sestrin 2 was increased with DSS administration. However, rosemary extract suppressed sestrin 2 expression in mouse colon lysates. In colon cancer cells, rosemary extract increased sestrin 2 expression and decreased phosphorylation of mTORC1 and 4EBP1, suggesting inhibition of mTOR activity. In a xenograft model, rosemary extract decreased the tumor growth of colon cancer cells by approximately 30%, and sestrin 2 expression was upregulated in tumor lysates from rosemary-treated mice. These results suggest that rosemary extract positively impacts gastrointestinal health and is useful for preventing inflammatory bowel disease.