Antioxidant capacity of sweet clover, St. John’s wort and purslane extract mixtures assessed by ABTS assay

Abstract

The development of plant extract compositions with high radical scavenging activity is a promising approach for creating natural antioxidant ingredients for functional foods. This work evaluated individual extracts of sweet clover (Melilotus officinalis), St. John’s wort (Hypericum perforatum) and purslane (Portulaca oleracea), as well as their binary and ternary compositions, using the ABTS assay with expression of results as Trolox equivalent antioxidant capacity (TEAC, µmol TE/g dry weight). Among the individual extracts, St. John’s wort and sweet clover demonstrated higher antioxidant activity, 88.74 and 85.65 µmol TE/g, respectively, whereas purslane showed 70.35 µmol TE/g. The binary compositions had increased TEAC values compared with most single extracts, and the St. John’s wort + purslane combination showed one of the highest values at 94.16 µmol TE/g. The ternary composition with an equal ratio of 33:33:33 demonstrated the maximum antioxidant activity, reaching 99.38 µmol TE/g. These findings indicate that combining the studied plant extracts can enhance antioxidant potential and support their use as natural functional ingredients for fermented dairy products and other food systems.