Immunostimulatory effects of three traditional Okinawan vegetable extracts on activation of macrophage-like cells, and tumor growth suppression by Crepidiastrum lanceolatum Nakai in mice

Abstract

To clarify the effects of traditional Okinawan vegetable extracts on the activation of immunocompetent cells, we prepared methanol extracts from lyophilized powders of Crepidiastrum lanceolatum Nakai (hosoba-wadan), Peucedanum japonicum Thunb. (botan-bofu) and Artemisia indica Willd. var. orientalis (Pamp.) H. Hara (nishi-yomogi). We examined nitric oxide and cytokine production and phagocytosis of macrophage-like J774.1 cells following stimulation with extracts as activation indices. Moreover, we investigated the effect of the hosoba-wadan extract on tumor growth in tumor-bearing mice. IL-6 and TNF-α production and incorporation of microbeads in the 3 µg/ml hosoba-wadan extract group were significantly higher than in the other groups. We also observed that intraperitoneal administration (30 mg/mouse) of the hosoba-wadan extract significantly suppressed tumor growth compared with the saline group. Moreover, the hosoba-wadan extract resulted in significant increases of serum TNF-α and IFN-γ concentrations in the mice. These results suggest that the hosoba-wadan extract activated immunocompetent cells and enhanced host immunity.