A phytochemical investigation on the alkaloids from water-soluble part of Sophora alopecuroides led to obtain forty matrine-type alkaloids (1-40) including eighteen new ones (1-18), which covers almost all positions of the oxygen substitution in matrine-type structure. Notably, eight compounds (1-8) belong to rare bis-amide matrine-type alkaloid. The new structures were determined based on extensive spectroscopic data, electronic circular dichroism (ECD) calculations, and six instances, verified by X-ray crystallography. Most of isolates showed anti-neuroinflammatory activities based on the expression of tumor necrosis factor (TNF)-α and interleukin (IL)-6 in BV2 microglia cells. Especially, compound 39 can suppress those two mediator secretions in a dose-dependent manner with IC50 values of 21.6 ± 0.5 and 16.7 ± 0.8 μM, respectively. Further mechanistic study revealed that 39 suppressed the phosphorylation of IκBα and p65 subunit to regulate the NF-κB signaling pathway.
Keywords: Anti-neuroinflammatory activity; Matrine-type alkaloid; NF-κB signaling pathway; Sophora alopecuroides; Structural modification; Structure-activity relationship.
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