Two new matrine-methyl adducts from Sophora alopecuriodes with anti-inflammatory activity via ROS/HIF-1α regulation

Phytochemical investigation of the seeds of Sophora alopecuroides led to the isolation of two previously undescribed matrine-methyl adducts (1-2). These compounds represent the first naturally occurring methylated derivatives featuring two distinct types of newly constructed C₁₆ matrine-type skeletons, arising from unique CC bond formations at the C-9 and C-3 positions, respectively. Their structures and absolute configurations were established by comprehensive spectroscopic analysis (HR-ESI-MS, 1D/2D NMR) and comparison of experimental electronic circular dichroism (ECD) spectra. Pharmacological assays in LPS-stimulated RAW264.7 cells revealed that both compounds 1 and 2 possess potent anti-inflammatory properties, significantly inhibiting the production of inflammatory mediator NO (IC₅₀ values of 7.9 and 18.2 μM, respectively), TNF-α, and IL-6. Western blot analysis confirmed that both compounds dose-dependently down-regulated the key inflammatory markers iNOS and COX-2. Mechanistic studies revealed that compound 1 attenuates intracellular ROS accumulation and suppresses the HIF-1α signaling pathway. These findings provide new matrine-based molecular templates for the development of anti-inflammatory lead compounds.