Hippocampus reidi extract, a marine natural product, attenuates NF-kB expression and suppresses inflammatory activity in vitro and in vivo

Summary. Seahorses ( Hippocampus reidi ) are used in Brazilian folk medicine to treat asthma and other inflammatory conditions. In this study, we explored the chemical profile as well as the anti-inflammatory potential of H. reidi hydroalcoholic extract in vitro and in vivo . First, we explored the chemical profile of this extract using high performance liquid chromatography and high-resolution mass spectrometry, a combinatorial analysis that demonstrated that the H. reidi is rich in peptides. Then, the cytotoxic activity of H. reidi on spleen cells, its modulatory effect on cytokines and nitric oxide production and its stabilizing capacity of red blood cell membranes was evaluated in vitro . Finally, we evaluated NF-kB gene expression. In vivo studies were performed using a peritonitis mouse model. Leukocyte recruitment to the peritoneum was evaluated, and IL-6 was measured by ELISA. The H. reidi  extract attenuated the production of Th2 and Th1 cytokines and modulated the immunoregulatory cytokine. In addition, we observed a reduction in nitric oxide production as well as a stabilization of the erythrocyte membrane in addition to an inhibition of transcriptional factor NF-kB. The  H. reidi  extract showed an anti-inflammatory effect in vivo by reducing the total leukocyte and neutrophil migration and IL-6 concentration in the peritoneal cavity. Thus, our study revealed that H. reidi  hydroalcoholic extract possesses anti-inflammatory activity in  vitro  and in vivo  and may be a candidate for the isolation of molecules for further study and that H. reidi  hydroalcoholic extract might also represent a component of a therapeutic arsenal of inflammatory disorders. Industrial Relevance. H. reidi has been commonly used in folk medicine for the treatment of inflammatory disorders. This study is the first to demonstrate the anti-inflammatory activity of Hippocampus reidi in vitro and in vivo. Additional work is needed to confirm which molecules are responsible for the observed effects and better understand the mechanisms whereby such effects occur. Keywords. Natural Products; Hippocampus reidi; Anti-inflammatory; Peptides.