Water-soluble matrine-type alkaloids with potential anti-neuroinflammatory activities from the seeds of Sophora alopecuroides

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.

Five matrine-type alkaloids from Sophora tonkinensis

Five matrine-type alkaloids (1‒5) including two new compounds (1 and 3) and a new natural product (2) were isolated from the roots of Sophora tonkinesis. Their structures were identified by extensive spectroscopic analysis (UV, IR, HRESIMS and NMR). The absolute configurations of 2 and 3 were determined by X-ray diffraction. Compounds 1‒5 were evaluated their activity against inflammatory cytokines TNF-α and IL-6 levels on LPS-induced RAW 264.7 macrophages, and compound 1 showed the most significant activity, potent than that of matrine, the representative ingredient from Sophora plants.