Enrichment of polyphenol contents and antioxidant activities of Irish brown macroalgae using food-friendly techniques based on polarity and molecular size

► Food-friendly antioxidant extracts were generated from three Irish macroalgae. ► Molecular-weight cut-offs enriched the phenolic and antioxidant profiles of extracts. ► Flash chromatography employed to purify the low molecular weight (LMW) fractions. ► Q-Tof mass analysis suggests phlorotannins may be responsible for antioxidant effect.