Kapacitet ekstrakta Thymus serpyllum L. za uklanjanje slobodnih radikala u zavisnosti od primenjenih uslova i tehnika ekstrakcije

Abstract

Polyphenols, as plant secondary metabolites, achieve strong antioxidant capacity by scavenging free radicals, chelating metals, and interacting with lipid membranes, proteins and nucleic acids. The aim of the present study was the examination of the applied extraction conditions (particle size of plant material, solvent-to-solid ratio, solvent type, and extraction time) and extraction techniques (maceration, heat- and ultrasound-assisted extractions) on the free radicals' scavenging capacity of Thymus serpyllum polyphenol extracts, determined in ABTS and DPPH methods. According to the results, smaller particle size of herbal drug resulted with better antioxidant potential. However, this effect was statistically significant for heat- and ultrasound-assisted extractions according to ABTS assay, and for maceration and heat-assisted extraction according to DPPH assay. Furthermore, the increase in solvent-to-solid ratio from 10:1 to 30:1 resulted in the extracts with higher antioxidant activity regardless of the type of extraction technique, whereas the scavenging activity of ethanol extracts was higher in comparison to aqueous extracts. In terms of extraction time for achieving the highest free radicals' scavenging capacity, 30 min can be recommended for maceration and heat-assisted extraction, and 5 min for processing by ultrasonic probe. In neutralization of ABTS radicals, there were no statistically significant differences between antioxidant capacity of T. serpyllum extracts obtained by using different extraction techniques, whereas in DPPH scavenging activity, the extracts obtained in ultrasound-assisted extraction have shown statistically significantly higher activity. Due to the free radicals' scavenging properties shown in the present study, T. serpyllum extracts may be used in the formulations in food, pharmaceutical, cosmetic, and chemical industries.