Saengmaeksan inhibits inflammatory mediators by suppressing RIP-2/caspase-1 activation

Background and objectives: Saengmaeksan (SMS) is a Korean herbal prescription consisting of three different herbal drugs: Liriopis Tuber (tuber of Liriope platyphylla, Liliaceae), Ginseng Radix (root of Panax ginseng) and Schisandrae Fructus (fruit of Schisandra chinensis). SMS is commonly used in Korea to treat various diseases that involve the respiratory and cardiovascular systems. However, to date, the mechanism underlying the anti-inflammatory effects of SMS is not clearly understood. In this study, we attempt to determine the effects of SMS on lipopolysaccharide (LPS)-induced inflammatory responses in mouse peritoneal macrophages. Methods: Cell viability was measured by using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and nitric oxide (NO) levels were measured by using Griess reagent. The tumor necrosis factor (TNF)-α and interleukin (IL)-6 levels secreted by the cells were measured using a modified enzyme-linked immunosorbent assay. Expression of cyclooxygenase (COX)-2 and nuclear factor-kappa B (NF-κB), respectively was investigated using a western blot analysis. A caspase colorimetric assay kit was used to assay enzymatic caspase-1 activity. Results: The findings of this study showed that SMS reduced TNF-α and IL-6 production induced by LPS. During the inflammatory process, COX-2 and NO levels were increased in mouse peritoneal macrophages, but SMS decreased the enhanced levels of COX-2 and the production of NO. In addition, SMS suppressed the activation of NF-κB and receptor interacting protein-2/caspase-1. Discussion and conclusion: Our results provide novel insights into the pharmacological actions of SMS, a molecule that can potentially be exploited in the treatment of inflammatory diseases.