Aspilia africana C. D. Adams inhibits the production of lipopolysaccharide-induced inflammatory mediators in murine macrophage RAW264.7 cells by suppressing the NF-κB and PI3K/Akt pathways

Abstract

Aspilia africana C. D. Adams (A. africana) is used in African folk medicine as a wound healing remedy. In this study, the potential anti-inflammatory effects of A. africana were investigated in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. The cytotoxicity of A. africana was assessed in RAW264.7, human embryonic kidney 293, and HaCaT cells using the WST-1 assay. The results indicated that concentrations up to 400 μg/mL were safe for all cell lines studied. Further analyses, such as the nitric oxide (NO) assay, quantitative reverse transcription polymerase chain reaction (qRT-PCR), and western blotting, were performed to evaluate the anti-inflammatory potential of A. africana. The results of NO analysis showed that A. africana inhibited NO production, while the results of western blot analysis showed that the expression levels of important inflammatory enzymes, such as inducible nitric oxide synthase and cyclooxygenase-2, and pro-inflammatory cytokines (tumor necrosis factor-α, interleukin [IL]-6, and IL-1β) were significantly suppressed by A. africana. The results also demonstrated that A. africana prevents the activation of the nuclear factor κB (NF-κB) and phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) pathways by inhibiting phosphorylated (p)-p65 NF-κB, p-Akt, p-IκBα, and p-PI3K. qRT-PCR analysis revealed that A. africana affects the expression of pro-inflammatory cytokines at the gene level. The results of this study showed that A. africana prevents the production of inflammatory mediators in RAW264.7 cells stimulated with LPS by regulating the NF-κB and PI3K/Akt signaling pathways.