LC–MS/MS-Guided Discovery of Sinapic Acid Derivatives from Lepidium sativum Seeds and Their Anti-inflammatory Activity

Edible seeds of Lepidium sativum are known for their health-promoting properties. A total of 17 sinapic acid derivatives, including 12 previously undescribed compounds, were isolated from L. sativum seeds using an LC-MS/MS-guided strategy. Among them, lepisativutimines A-F (1-6) were identified as rare sinapic acid derivatives featuring a uridine moiety. The structures of the isolated compounds were determined based on mass and NMR data analysis, ¹³C NMR calculations with DP4+ probability analyses, ECD data along with quantum-chemical ECD calculations, and acid hydrolysis followed by acetic derivatization and GC analysis. MS/MS data of the isolated compounds were thoroughly examined, and the characteristic mass fragments of these sinapic acid derivatives were summarized. Compounds 2, 7, and 11-17 presented NO inhibitory activities in LPS-induced RAW264.7 cells, with IC₅₀ values ranging from 16.20 to 86.37 μM. Compound 11 significantly reduced NO production and the levels of TNF-α, IL-6, and PGE₂ in a dose-dependent manner. Additionally, compound 11 dose-dependently reduced the protein expression of COX2, iNOS, MAPK, JNK, and ERK, suggesting that its anti-inflammatory effect may be mediated through the inhibition of iNOS/COX2 and MAPK signaling pathways.