Novel paeonol derivatives: Design, synthesis and anti-inflammatory activity in vitro and in vivo

Paeonol has been proved to have potential anti-inflammatory activity, but its clinical application is not extensive due to the poor anti-inflammatory activity (14.74% inhibitory activity at 20 μM). In order to discover novel lead compound with high anti-inflammatory activity, series of paeonol derivatives were designed and synthesized, their anti-inflammatory activities were screened in vitro and in vivo. Structure-activity relationships (SARs) have been fully concluded, and finally (E)-N-(4-(2-acetyl-5-methoxyphenoxy)phenyl)-3-(3,4,5-trimet-hoxyphenyl)acrylamide (compound 11a) was found to be the best active compound with low toxicity, which showed 96.32% inhibitory activity at 20 μM and IC₅₀ value of 6.96 μM against LPS-induced over expression of nitric oxide (NO) in RAW 264.7 macrophages. Preliminary mechanism studies indicated that it could inhibit the expression of TLR4, resulting in inhibiting of NF-κB and MAPK pathways. Further studies have shown that compound 11a has obvious therapeutic effect against the adjuvant-induced rat arthritis model.