Vascular barrier protective effects of phlorotannins on HMGB1-mediated proinflammatory responses in vitro and in vivo

► HMGB1 is pro-inflammatory cytokine as a mediator of vascular inflammation. ► Phlorotannins inhibited LPS induced HMGB1 release. ► Phlorotannins inhibited HMGB1-mediated hyperpermeability in vitro and in vivo. ► Rutin inhibited HMGB1-mediated inflammatory responses. ► Hydroxyl groups on dieckol positively regulate these vascular barrier protective effects.