Rosmarinic acid in perilla extract inhibits allergic inflammation induced by mite allergen, in a mouse model

Summary Background Perilla and its constituent rosmarinic acid have been suggested to have anti‐allergic activity. However, few studies have examined the effects on allergic asthma. Objective The purpose of this study was to evaluate the effect of oral administration of perilla leaf extract, which contains high amount of rosmarinic acid, on a murine model of allergic asthma induced by house dust mite allergen. Methods C3H/He mice were sensitized by intratracheal administration of Dermatophagoides farinae (Der f). Mice were orally treated with rosmarinic acid in perilla extract (PE) (1.5 mg/mouse/day). Results Der f challenge of sensitized mice elicited pulmonary eosinophilic inflammation, accompanied by an increase in lung expression of IL‐4 and IL‐5, and eotaxin. Daily treatment with rosmarinic acid in PE significantly prevented the increases in the numbers of eosinophils in bronchoalveolar lavage fluids and also in those around murine airways. Rosmarinic acid in PE treatment also inhibited the enhanced protein expression of IL‐4 and IL‐5, and eotaxin in the lungs of sensitized mice. Der f challenge also enhanced allergen‐specific IgG1, which were also inhibited by rosmarinic acid in PE. Conclusion These results suggest that oral administration of perilla‐derived rosmarinic acid is an effective intervention for allergic asthma, possibly through the amelioration of increases in cytokines, chemokines, and allergen‐specific antibody.