Procyanidin A2, A Polyphenolic Compound, Exerts Anti-Inflammatory And Anti-Oxidative Activity In Lipopolysaccharide-Stimulated Raw264.7 Cells

Procyandin A2 (PCA2) is a polyphenolic compound which is isolated from grape seeds. It has been reported that PCA2 exhibits antioxidative and anti-inflammatory effects, but its molecular mechanism is still poorly understood. This study tests the hypothesis that PCA2 suppresses lipopolysaccharide (LPS)-induced inflammation and oxidative stress through targeting the nuclear factor-kappa B (NF-kappa B), mitogen-activated protein kinase (MAPK), and NF-E2-related factor 2 (Nrf2) pathways in RAW264.7 cells. PCA2 (20, 40, 80 mu M) exhibited no significant cytotoxicity in RAW264.7 cells and showed an inhibitory effect on an LPS-induced nitrite level. Pro-inflammatory cytokines like tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), prostaglandin E2 (PGE2), nitric oxide (NO), and reactive oxygen species (ROS) were suppressed by PCA2 with a concentration range of 0-80 mu M. The mRNA levels of TNF-alpha and IL-6 were inhibited by PCA2 (80 mu M). The hallmark-protein expression of the NF-kappa B (p-IKK alpha/beta, p-I kappa B alpha, and p-p65) and MAPK (p-p38, p-JNK, and p-ERK) pathways were decreased by PCA2 in LPS-stimulated RAW264.7 cells. In addition, immunofluorescence results indicated that PCA2 (80 mu M) promoted the translocation of NF-kappa B/p65 from the cytoplasm into the nucleus. PCA2 upregulated the expressions of Nrf2 and HO-1 and downregulated the expression of Keap-1. Simultaneously, PCA2 (80 mu M) reversed LPS-induced Nrf2 translocation from the nucleus into the cytoplasm. Collectively, PCA2 protect cells against the damage from inflammation and oxidative injury, which suggest a potential therapeutic strategy for inflammatory and oxidative stress through targeting NF-kappa B, MAPK, and Nrf2 pathways in RAW264.7 cells.