Bioactive compounds from A. dahurica attenuate LPS-induced inflammation via dual inhibition of MAPK and NF-κB signaling pathways

Ethnopharmacological relevance: Angelica dahurica (Hoffm.) Benth. et Hook. f. ex Franch. et Sav. is a perennial, aromatic, herbaceous plant in the family Apiaceae, native to East Asia, and the roots are known as Bai Zhi (Angelicae Dahuricae Radix) in traditional Chinese medicine (TCM). The dried root is used to treat headaches, nasal congestion, rhinosinusitis, toothache, and suppurative skin infections. In TCM, its actions are described as dispelling wind-cold, drying dampness, relieving pain, reducing swelling, and expelling pus; and it serves as a principal component of classical formulas such as Chuan Xiong Cha Tiao San and Xin Yi San. Inflammatory disorders produce proinflammatory cytokines, such as TNF-α and IL-6, and complex inflammatory reactions. The traditional terms "reducing swelling and expelling pus" essentially point to its strong anti-inflammatory and anti-exudative properties, implying the presence of bioactive components that modulate certain inflammatory pathways. Although pharmacological studies of A. dahurica extracts have shown an anti-inflammatory effect, possibly mediated by major constituents such as pyranocoumarin, the mechanisms remain unclear.

Aim of the study: To assess the anti-inflammatory activities of pyranocoumarins, from A. dahurica and elucidate their molecular mechanisms of action systematically using activity-guided isolation.

Materials and methods: Bioactivity-guided isolation was used to obtain specific compound-rich fractions from A. dahurica, which were identified by chromatographic and spectroscopic analyses. Anti-inflammatory activity was evaluated in LPS-stimulated RAW 264.7 macrophages by measuring NO production and the levels of proinflammatory cytokines (TNF-α, IL-6, IL-1β). The involvement of the NF-κB and MAPK signaling pathways was examined by western blotting. Inflammation-related cell death was assessed by flow cytometry and TUNEL assays; antioxidant activity was evaluated using a DPPH assay; and molecular docking was performed to predict interactions between active compounds and inflammation-related targets.

Results: Among the 35 compounds identified, Coumarins, including one newly identified furocoumarin, were the predominant constituents. The most active compounds were (-)-(3'S,4'S)-3'-acetoxy-4'-angeloyloxy-3',4'-dihydroseselin (compound 2) and praeruptorin D (compound 3). Both compounds preserved cell viability, inhibited NO production, downregulated proinflammatory cytokine production in LPS-stimulated macrophages, and inhibited phosphorylation of NF-κB pathway proteins (IKKα, IκBα, and p65) and MAPK pathway proteins (p38, JNK, and ATF2) in Western blot analyses. Moreover, they also reduced LPS-induced Apoptosis, showed dose-dependent DPPH radical-scavenging activity, and exhibited predicted binding to IL-6 in molecular docking analyses.

Conclusion: Pyranocoumarins from A. dahurica exhibit anti-inflammatory activity by modulating NF-κB and MAPK signaling pathways and antioxidant effects, providing mechanistic support for their traditional use in inflammatory conditions, and highlighting pyranocoumarins as bioactive constituents warranting further investigation.

Angelica dahurica; Anti-inflammatory activity; NF-κB/MAPK signaling pathways; Proinflammatory cytokines; Pyranocoumarins.