Phytochemical constituents from root barks of Eleutherococcus henryi Oliv. and their anti-neuroinflammatory effect

Abstract

Ethnopharmacological relevance: The cortex of Eleutherococcus henryi (EH, Araliaceae), also known as "Wu-Jia-Pi", is known for its effects such as dispelling wind and dampness, calming the mind and enhancing intelligence, removing heat and toxin, strengthening muscles and bones, and nourishing the liver and kidneys. Throughout Chinese history and tradition, it has been used for conditions like amnesia, mental fatigue, arthritis, hepatitis, and rheumatism. However, research evaluating its neuroprotective effects and pharmacological properties remains scarce.

Aim of the study: The goal is to explore the anti-neuroinflammatory properties of EH in vitro and to discover precisely the bioactive natural products within the medicinal plant that are relevant to its traditional usage.

Materials and methods: Utilizing chromatographic techniques, a phytochemical exploration was conducted. The phytochemical structures of the natural products were then elucidated through an analysis involving comprehensive spectra and a comparison with relevant data from published studies. Network pharmacology combined with molecular dynamics simulations (MDs) and docking were applied to forecast potential anti-neuroinflammatory targets of active compounds. In vitro, the anti-neuroinflammatory efficacy was evaluated via the suppression of inflammatory mediators activated by lipopolysaccharide (LPS) in BV2 microglia.

Results: The methanol extract of E.henryi (EHME) restrained the NO release in LPS-activated BV2 microglia, demonstrating anti-neuroinflammatory activity. Subsequently, chemical composition analysis revealed the separation and elucidation of 31 secondary metabolites, comprising 7 new compounds (1-7) and 1 new natural product (8). Based on LPS-induced BV2 cell in vitro activity tests, compounds 4-17, 19, 20, 22, 23, 26, 29 and 31 were found to exhibit potential anti-neuroinflammatory activity, with compound 6 showing the highest efficacy. Furthermore, employing network pharmacology in conjunction with both molecular docking and MDs, potential anti-neuroinflammatory targets of compound 6 were predicted to include TLR4, Src, MAPK, and NF-κB. Finally, validation through in vitro experiments confirmed that the anti-neuroinflammatory mechanism of compound 6 is associated with the TLR4/Src/MAPK p38/NF-κB p65 signaling pathways.

Conclusions: The study affirmed the traditional efficacy of E. henryi and unveiled novel lignans as potent agents against neuroinflammation.

Keywords: Anti-neuroinflammatory; Eleuhenryiside I; Eleutherococcus henryi oliv.; Network pharmacology; Phytochemistry.