Optimization of antioxidants recovery from wild thyme (Thymus serpyllum L.) by ultrasound-assisted extraction: Multi-response approach

Natural Deep Eutectic Solvent (NADES) Extraction Improves Polyphenol Yield and Antioxidant Activity of Wild Thyme (Thymus serpyllum L.) Extracts

“…On the other hand, luteolin, epicatechin and quercetin were major flavonoids quantified in this sample. Previous studies confirmed that all compounds quantified in this work were identified in wild thyme extracts obtained by UAE [7] and PLE [8]. HPLC results showed that a particularly high content of phenolic acids and flavonoids could be obtained by NADES extraction.…”

“…On the other hand, the highest activity toward DPPH radicals was observed in run 17, the same extract where the highest TP was obtained, suggesting that polyphenols were the main compounds responsible for antioxidant activity. In vitro antioxidant activity in wild thyme extracts obtained by various extraction techniques (conventional solid-liquid, UAE and PLE) was previously investigated elsewhere and the results were expressed as mM equivalents per 100 g plant material [ 7 , 8 ]. However, when these results are calculated on the same units as was given in this work, the radical scavenging capacity of T. serpyllum extracts obtained by conventional solid-liquid extraction, UAE and PLE were 34.37, 63.35 and 79.42 mg TE/g and it could be noted that NADES extraction provides tremendous upgrade on antioxidant capacity of wild time extracts in comparison with other traditional and emerging extraction techniques ( Table 2 ).…”

“…The highest TP was observed in run 17, which was obtained at high levels of independent extraction factors (70 • C, 180 min and 30 g NADES/g plant material). On the other hand, recent work suggested that extraction of polyphenols from wild thyme herbal dust was optimized by other techniques, such as conventional solid-liquid extraction, ultrasound-extraction (UAE) and pressurized-liquid extraction (PLE) [7,8]. According to Mrkonjic et al [7], ethanol concentration was an optimized factor for conventional extraction of T. serpyllum herbal dust and the highest TP observed was 17.35 mg GAE/g, while 43.88 mg GAE/g of TP was obtained by UAE at an optimal set of temperature, extraction time and ethanol concentration.…”

“…On the other hand, recent work suggested that extraction of polyphenols from wild thyme herbal dust was optimized by other techniques, such as conventional solid-liquid extraction, ultrasound-extraction (UAE) and pressurized-liquid extraction (PLE) [7,8]. According to Mrkonjic et al [7], ethanol concentration was an optimized factor for conventional extraction of T. serpyllum herbal dust and the highest TP observed was 17.35 mg GAE/g, while 43.88 mg GAE/g of TP was obtained by UAE at an optimal set of temperature, extraction time and ethanol concentration. In other work, the PLE of wild thyme herbal dust was optimized in two stages (preliminary design and RSM study), and 67.46 mg GAE/g of TP was obtained at an optimal set of PLE conditions [8].…”

“…In addition, conventional solid-liquid, ultrasound-assisted (UAE) and pressurized liquid extractions (PLE) have proven to be a great approach for antioxidant recovery from T. serpyllum herbal dust, using ethanol as an extraction solvent [ 7 , 8 ]. On the other hand, considering the fact that conventional solvents could be flammable, volatile and toxic, their daily use can become problematic for humans and generally for environmental persistence and/or photochemical ozone creation [ 9 ].…”