Synthesis And Preliminary Evaluation Of Apocynin Analogues

ObjectivesWe had designed and synthesized a series of novel apocynin analogues and evaluated their biological activities by different assays.Methods1. Synthesized a series of apocynin analogues by modifying different positions.2. Characterized the structure by 1H NMR, ESI-MS and EA3. Investigated the protective activity of apocynin analogues against LPS-induced cytotoxicity by the MTT assay.4. Investigated the ROS-scavenging activity of apocynin analogues in RAW264.7 cells by a fluorescence-based assay.5. Determined the therapeutical effect of apocynin analogues against LPS-induced damage to the lung of rats.Results1. We have designed and synthesized apocynin analogues 2-132. The structures of the new compounds were identified by 1H NMR, ESI-MS and EA.3. Some of the new apocynin analogues have protective effect in LPS-induced cytotoxicity RAW 264.7 cells. The apocynin dimer 12 was the most potent compound in MTT assay.4. At 0.1μM, apocynin significantly reduced ROS; however, at higher concentrations (10μM), apocynin not only did not reduced ROS, it stimulated ROS formation. In contrast, apocynin nitrone 13 strongly reduced the amount of ROS at all concentrations.5. Treatment with apocynin and compound 13 significantly ameliorated the lung inflammation and other damages. In compound 13-treated group, not only inflammatory cell infiltration was significantly decreased, pulmonary alveolus and alveolar saccules were restored to normal. In apocynin-treated group, a little plasmocyte infiltration in focal area was still observed. ConclusionIn this study, we have synthesized a series of novel apocynin analogues and evaluated their biological activity. Compound 13, the nitrone conjugate, had significant activity scavenging ROS, and greatly ameliorated LPS-induced inflammation in the lung of rats. The apocynin dimer 12 was the most potent compound in protecting cells from LPS-induced cytotoxicity. SAR analysis suggests that modification of apocynin with branched or short chain substituents can increase activity.