Anti-Inflammatory Mechanisms of Lysilactones and Diketopiperazine Alkaloids From Lysimachia paridiformis.

The whole plant of Lysimachia paridiformis var. stenophylla Franch. (known as "Kod tud vud" in Chinese Miao medicine) has been used for the treatment of inflammation for a long time. However, its bioactive components and underlying mechanisms against inflammation are still unclear. The compounds were extracted and separated using silica gel chromatography, followed by further purification with Sephadex LH-20 and MCI gel CHP 20P. Their structures were identified through physical and chemical characteristics as well as spectral data. Network pharmacology was used to predict the potential anti-inflammatory targets and pathways of these compounds, with the results validated through LPS-induced cell models. A new lysilactone, 2,7,9-trihydroxy-3-methoxy-1-methyl-6H-benzo[c]chromen-6-one (1), has been isolated from "Kod tud vud." In addition, five known compounds were obtained, including three lysilactone compounds, one diketopiperazine-type indole alkaloid, and the diketopiperazine alkaloid 3,6-diisopropyl-2,5-diketopiperazine (6). Compounds 1 and 6 significantly inhibited nitric oxide (NO) production and the expression of interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) in LPS-induced macrophages. Mechanistic studies revealed that these effects were achieved by reducing p65 phosphorylation and preventing its nuclear translocation, thereby decreasing the activation of the NF-κB pathway. Overall, these findings suggest that compounds 1 and 6 may be potential therapeutic agents for inflammation by inhibiting the NF-κB signaling pathway.