Turning Organic Waste into a Valuable Alternative: Evaluation of Total Phenolic Content, Radical and Antioxidant Activity of Medlar Seed Extracts

Abstract

In this study, the potential of medlar seeds, which have no known usage and are considered organic waste, as a natural antioxidant source was investigated. For this purpose, total phenolic, total flavonoid, and anthocyanin contents, which are important in antioxidant activity, were found in aqueous and ethanol extracts of medlar seeds. When the antioxidant activities were examined, the ethanol extract showed 92.38 ± 0.51% activity in 2,2-diphenyl-1-picrylhydrazyl radical (DPPH^•) scavenging at a concentration of 25 µg/mL, slightly better than the synthetic antioxidant butylated hydroxyanisole (BHA) at the same concentration. Also, ethanol extract had 23.30 ± 1.78% of chelating activity, while aqueous extract had 1.04 ± 0.44%. In N,N-dimethyl-p-phenylenediamine (DMPD^+•) scavenging activity, aqueous extract had 36.06 ± 0.89% at 200 µg/mL, while BHA had 41.25 ± 0.1%. In the β-carotene bleaching test, the aqueous extract (1.04 ± 0.02) had slightly better activity than BHA, and the ethanol extract (0.88 ± 0.002) had a somewhat similar activity to BHA. In general, both extracts had considerable antioxidant activity. When the results are examined, it is thought that medlar seeds, which are considered waste, can be made more valuable by using them as a good antioxidant source.