Cornus officinalis var. koreana Kitam polyphenol extract decreases pro-inflammatory markers in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages by reducing Akt phosphorylation

Abstract Ethnopharmacological relevance Cornus officinalis var. koreana Kitam (CO) is found predominantly in China but also in Korea and Japan and has been used in Eastern medicine for over 2,000 years to treat several conditions including diabetes, cardiovascular disease and kidney disease. Chronic inflammation underlies the pathogenesis of these diseases. The mechanisms by which CO may exert its anti-inflammatory effects have not been well defined. Aim of the study We aimed to determine whether Cornus officinalis var. koreana Kitam extract (COE) attenuate the inflammatory response induced by lipopolysaccharide (LPS) in RAW 264.7 macrophages, and to elucidate the mechanisms which contribute to these anti-inflammatory effects. Materials and methods COE was prepared using ethanolic extraction, followed by solvent evaporation and freeze-drying. RAW 264.7 macrophages were treated with 0, 50, 100, 200 and 400 μg/ml of COE. After 2 h, cells were treated with 100 ng/ml of LPS for 6 h. Cells were then collected for whole cell protein expression analysis of signaling and inflammatory molecules via western blot. Results Pre-treatment with 100, 200 and 400 μg/ml of COE significantly reduced Akt phosphorylation in LPS stimulated macrophages compared to LPS alone (P ≤ 0.003). NF-κB expression was significantly attenuated with 400 μg/ml of COE compared to LPS treatment alone (P = 0.01). LPS induced cyclooxygenase (COX)-2 and inducible nitric oxide synthase (iNOS) expression, which was significantly decreased by treatment with 400 μg/ml COE (P = 0.0001 and 0.02, respectively). COE dose-dependently decreased LPS-induced expression of interleukin (IL)-1β (P ≤ 0.0008) and IL-6 (P = 0.01). Conclusion In summary, COE attenuated the inflammatory response induced by LPS in RAW 264.7 macrophages, likely due to Akt inhibition.