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.