Immune-enhancing screening of fourteen plants on murine macrophage RAW 264.7 cells

Purpose : To investigate the potential immune-enhancing effects of fourteen natural plant extracts on mouse macrophage RAW 264.7 cells. Methods : Fourteen plant extracts from 7 different plants were tested on RAW 264.7 cells to determine their immunostimulant activities. Methylthiazolydiphenyltetrazolium bromide (MTT) and Griess assays were performed to evaluate cell viability and nitric oxide (NO) production, respectively. Then, immune related proteins were measured by western blot analysis, while cytokines and phagocytic activity were determined by enzyme-linked immunosorbent assay (ELISA) method. Results : Among the 14 plant extracts, the hot water extract of Agastache rugose was selected based on the screening results on NO production. The hot water extract of A. rugose significantly increased NO production in a concentration-dependent manner without any cytotoxicity. In addition, the expression levels of proteins (iNOS and COX-2) and cytokines (TNF-α, IL-1β, IL-6 and IL-12) closely related to immune reaction were also significantly upregulated. Furthermore, phagocytic activity of RAW 264.7 cells significantly increased following treatment with A. rugosa . Conclusion : The hot water extract of A. rugosa exhibits significant immune-stimulant activity. Therefore, A. rugosa can be used as a natural resource for immune enhancement or dietary supplement. Keywords : Immune enhancing activity, Macrophage polarization, Natural plant extracts, Agastache rugosa , RAW 264.7