Ultrasound Extraction of Polyphenolic Compounds from Thymus serpyllum

Abstract

Aromatic plant species of family Lamiaceae are important medicinal plants because of their antioxidant, antimicrobial, antispasmodic, expectorant, stimulant and diuretic properties. In this study T. serpyllum herba was evaluated as a source of polyphenolic compounds, which are extracted by the application of ultrasound probe instead of the traditional solvent extraction. Ultrasound extraction has become a good alternative extraction method when compared to classical methods due to its high efficiency, low energy and solvent consumption. Ultrasound assisted extraction is a well established method in the processing of plant material, particularly to extract bioactive substances such as polyphenols. Optimization of the extraction was carried out through varying degrees of fragmentation (0.3, 0.7 and 1.5), time of extraction (3, 7 and 10 minutes) and ratio drugs:solvent (1:10, 1:20 and 1:30) in 30% ethanol as an extraction medium. Extraction efficiency was expressed via total polyphenols content (Folin-Ciocalteu method) and antioxidant activity (DPPH method). The highest total polyphenols content and antioxidant activity were recorded in extract with a degree of fragmentation of 0.3 and ratio drug:solvent 1:30 after 3 minutes, 23.03 mg/L GA and IC50 3.00 mg/ml, respectively. The lowest total polyphenols content and antioxidant capacity were obtained in extract with a degree of fragmentation of 1.5 and ratio drug:solvent 1:10 (12.06 mg/L GA and IC50 4.78 mg/ml, respectively). This study found that both total polyphenols and antioxidant activities determined were significantly affected by the degree of fragmentation and ratio drugs:solvent. Also, the levels of total soluble phenolic compounds were positively correlated with free radical scavenging activities against DPPH radicals.