Immunostimulatory activity of aqueous extract isolated from Prunella vulgaris

Prunella vulgaris (P. vulgaris) has been used as a traditional medicine in the clinical treatment of herpetic keratitis and for its antioxidative and antimicrobial activities. In this study, we examined the immunostimulatory and antitumor activity of P. vulgaris in murine macrophage RAW 264.7 cells. Thus, we investigated the effects of an aqueous extract of P. vulgaris (PVAE) on macrophage function. We found that PVAE stimulated macrophage phagocytic activity, nitric oxide (NO) production and cytostatic activity. In addition, PVAE induced gene expression and production of macrophage-related cytokines such as TNF-α, IL-1β and IL-6. Transient transfection revealed that NF-κB mediated the PVAE-induced increases in macrophage-related cytokine expression levels. Mitogen-activated protein kinases (MAP Kinase) were also significantly activated by the PVAE-induced NF-κB activation. Pretreatment with NF-κB inhibitor and MAP Kinase inhibitors inhibited the NO production and the phagocytic activity induced by PVAE. This demonstrates that PVAE stimulates macrophage activation via NF-κB transactivation and MAP kinase activation.