Comparative study on antioxidative and macrophage-stimulating activities of polyguluronic acid (PG) and polymannuronic acid (PM) prepared from alginate

► PG and PM from alginate show potent O2- and OH scavenging activities. ► PG and PM have no scavenging activity on hydrogen peroxide. ► Both PM and PG induce NO production from mouse macrophage cell line RAW 264.7. ► NO-inducing activity of PG is stronger than PM.