Structural Modification of Alepterolic Acid to Discover New Anti-Inflammatory Agents

Alepterolic acid is a natural compound occurring in Aleuritopteris argentea (Gmél.) Fée. In this study, 12 derivatives of alepterolic acid were obtained by chemical modification and evaluated regarding their effects on nitric oxide (NO) production in RAW264.7 macrophages stimulated by lipopolysaccharide (LPS). Notably, compound 13 exhibited low toxicity while significantly inhibiting LPS-induced NO production. To elucidate its immunomodulatory mechanism, we quantified transcription levels of key cellular inflammatory factors (TNF-α and IL-6) using RT-qPCR and measured protein levels of key cellular inflammatory factor (iNOS) by Western blotting. Additionally, mitochondrial membrane potential and concentrations of reactive oxygen species (ROS) in RAW264.7 cells were analyzed by flow cytometry, and the phosphorylation status of key proteins in the MAPK inflammatory pathway was assessed by Western blotting. The results demonstrate that compound 13 exerts its anti-inflammatory effects by inhibiting MAPK pathway phosphorylation, downregulating LPS-induced transcription of proinflammatory cytokines (TNF-α, IL-6), reducing ROS generation, and delaying the decline of mitochondrial membrane potential. This study provides a basis for the application of alepterolic derivatives in inflammatory diseases.