Petasites japonicus has been widely used as a medicinal herb in Korea, Japan, and China. This study investigated the anti-inflammatory activity of hot water extracts of P. japonicus leaves (KP-1) on lipopolysaccharide (LPS)-induced RAW264.7 cells. LPS stimulates the differentiation of monocytes into macrophages and it induces the pro-inflammatory mediators such as nitric oxide (NO), prostaglandin E2 (PGE2), reactive oxygen species (ROS), and cytokines. The results determined that KP-1 did not influence the cytotoxicity of macrophages at 25, 50, and 100 μg/mL. Also, pre-treatment with KP-1 significantly reduced the production of NO and PGE2, and dose-dependently attenuated the ROS levels in the LPS-stimulated cells. In addition, the study evaluated whether fukinolic acid (FA) isolated from KP-1 contributes to the anti-inflammatory properties of KP-1. As a result, FA treatment showed a tendency toward decreased NO production, and inhibited the generation of ROS in activated macrophages. The results suggest that KP-1 has anti-inflammatory activity on the LPS-mediated inflammatory response and may be suitable for the development of potential functional foods.

Keywords: Petasites japonicus, anti-inflammatory activity, macrophages, fukinolic acid