Tyrosinase inhibitory and antioxidant potential of eckmaxol isolated from the brown seaweed Ecklonia maxima

Eckmaxol is a natural compound isolated from the brown alga Ecklonia maxima and has been proposed to inhibit tyrosinase. The aim of the present study was to investigate the antioxidant and tyrosinase inhibitory activities of eckmaxol isolated from E. maxima. The antioxidant properties of eckmaxol were determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-di-(3-ethylbenzothiazoline sulfonic acid) (ABTS+), hydrogen peroxide (H2O2) scavenging, and ferric reducing antioxidant power (FRAP). The antioxidant activity of eckmaxol was higher than that of the positive controls (ascorbic acid or Trolox). The tyrosinase inhibitory activity of eckmaxol (IC50 value: 27.95 ± 2.05 μM) was also higher than that of kojic acid (IC50 value: 90.25 ± 1.32 μM) and arbutin (IC50 value: 897.75 ± 76.46 μM). The interaction between eckmaxol and tyrosinase was studied using in silico molecular docking. The AutoDock Vina binding energy results revealed that eckmaxol and kojic acid (positive control) exhibited binding affinity of –7.7 and –5.4 kcal/mol, respectively. Our results suggest that eckmaxol from E. maxima can be used as a potential antioxidant and tyrosinase inhibitory agent for skin-whitening applications.