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.

Novel resveratrol-based flavonol derivatives: Synthesis and anti-inflammatory activity in vitro and in vivo.

In order to discover novel anti-inflammatory agents, total thirty-seven new resveratrol-based flavonol derivatives were designed and synthesized. All compounds have been screened for their anti-inflammatory activity by evaluating their inhibition effect of LPS-induced NO production in RAW 264.7 macrophages. Their toxicity was also assessed in vitro. Structure-activity relationships (SARs) have been concluded, and finally 2-(2,4-dimethoxy-6-(4-methoxystyryl)phenyl)-3-hydroxy-4H-chromen-4-one was found to be the most active scaffold with low toxicity. This compound could significantly decrease productions of NO, IL-6 and TNF-α with IC50 values of 1.35, 1.12 and 1.92 µM, respectively in RAW 264.7 macrophages. Preliminary mechanism studies indicated that it could inhibit the expression of TLR4 protein, resulting in activation of the NF-ĸB cell signaling pathway. The in vivo anti-inflammatory activity of this compound could reduce pulmonary inflammation by mouse model of LPS-induced acute lung injury (ALI). We believe these findings would further support studies of rational design of more efficient acute lung injury regulatory inhibitors.

Novel Pyrazolo[4,3- d]pyrimidine as Potent and Orally Active Inducible Nitric Oxide Synthase (iNOS) Dimerization Inhibitor with Efficacy in Rheumatoid Arthritis Mouse Model.

In order to discover novel anti-inflammatory agents for treatment of arthritis and based on preliminary structure-activity relationships, four series (A-D) of total 90 new pyrazolo[4,3- d]pyrimidine compounds were designed and synthesized. All the compounds have been tested for their anti-inflammatory activities by inhibiting of LPS-induced NO production. A clear structure-activity relationship has been concluded step by step, and finally 3,4,5-trimethoxystyryl-1 H-pyrazolo[4,3- d]pyrimidine was found to be the most active scaffold. Among them, compound D27 was discovered as the most potent anti-inflammatory agent (IC50 = 3.17 µM) with low toxicity and strong inhibitory of NO release (IR = 90.4% at 10 µM). This compound also showed potent inhibition of iNOS with IC50 value of 1.12 µM. Preliminary mechanism studies indicated that it could interfere with the stability and formation of active dimeric iNOS. The anti-inflammatory effect of this compound was determined by adjuvant-induced arthritis in rat model. We believe these findings would further support the study of rational design of more efficient iNOS inhibitors in the future.