Apocynin reduces dextran sulfate sodium-induced colonic inflammation in mice

Apocynin, a naturally occurring 4-hydroxy-3-methoxyacetophenone, is used experimentally as an inhibitor of NADPH-oxidase. It can decrease the production of superoxide from activated neutrophils and macrophages, leaving their ability to undergo phagocytosis unaffected [1]. Its anti-inflammatory activity has been demonstrated in a variety of cell and animal models [2]. In this study, we investigated whether apocynin exhibits anti-inflammatory activity on a model of inflammatory bowel disease (IBD) using dextran sulfate sodium (DSS)-induced colitis in mice. Acute colitis was induced in the mice through administration of 5% DSS in water for 7 days. The mice were fed a control diet or a diet supplemented with 2% apocynin or 2% rutin (a flavonoid used as reference) [3]. The animals were sacrificed on day 8 and their colons were removed, immediately snap-frozen on liquid nitrogen, and stored until use. The disease activity index score (DAI) was analyzed taking weight loss, stool blood, and rectal bleeding into account. The removed colons were subjected to extraction of proteins and COX-2 expression was analyzed with the aid of a Western blot assay. Treatment with apocynin ameliorated the course of colonic inflammation with results similar to those of rutin, as can be seen by reductions in the DAI scores (60% reduction for both compounds), colon length (47% and 42% reduction vs. blank, respectively), and COX-2 levels (65% and 75% inhibition, respectively). These results are promising for further experimental studies on treating gastrointestinal diseases and the potential protective effects of apocynin.