(Rosemary) Extracts Containing Carnosic Acid and Carnosol are Potent Quorum Sensing Inhibitors of Virulence.

is an opportunistic pathogen and a common cause of skin infection. also plays a role in the pathogenesis of the chronic inflammatory skin disease, atopic dermatitis. virulence involves activation of the quorum sensing operon. In this paper, we show that the diterpene carnosic acid, present in . (rosemary) leaves, is a specific inhibitor of expression as low as 5 μM. Carnosol and rosmarinic acid are two other phytochemicals present in rosemary leaves. Carnosol, but not rosmarinic acid, is also a potent expression inhibitor. Natural rosemary extracts containing carnosic acid and carnosol inhibit expression, both in luciferase reporter strains and in wild type strains isolated from patients with atopic dermatitis. Specific inhibition of virulence using topical formulations of rosemary extract may offer a practical approach to preventing and treating flares of atopic dermatitis.