Antioxidant and structure–activity relationship of acylphloroglucinol derivatives from the brown alga Zonaria tournefortii

This study aimed at isolating acylphloroglucinol derivatives with potential antioxidant effect from the brown alga Zonaria tournefortii and to ascertain their structure–activity relationship (SAR). Fractionation HPLC purification led isolation of four major metabolites that were screened for activity via five complementary methods. Results indicated all tested compounds proved have activities. In DPPH ABTS methods, acylphloroglucinols found be most active IC50 values 42.76 ± 0.26 50.46 0.12 µg cm−3 in assay 12.04 1.60 12.73 1.47 assay, respectively. contrast, β-carotene CUPRAC chromone revealed high activities 23.76 0.63 20.99 2.70 19.06 0.11 17.72 However, metal chelating method investigated demonstrated potent ferrous ion-chelating capability, approximately same level activity.