Effect of solvent, time and method of extraction on the amounts of phenolic, flavonoid and the antioxidant activity of the extract of Ixiolirion tataricum (Pall.) Schult. Schult.f.

Solvent type, extraction time and method are among important parameters in the evaluation of extraction efficiency. The selection of appropriate conditions to increase the extraction efficiency is of great importance. The response surface method (RSM) is a statistical and mathematical technique which can be used to examine the dependence between the responses with variables and also to determine the optimal conditions. In this study, the experimental design of general full factorial (GFF) was used using Minitab 17 software. The variables were time (60, 90 and 120 min), solvent (water, methanol and n-hexane) and method (soxhlet and ultrasound-assisted extraction). The main effects and also interaction terms were investigated on amounts of total phenolic content (TPC), total flavonoid content (TFC) and the antioxidant activity (according to IC50, FRAP and BCB) of the extract of Ixiolirion tataricum (Pall.) Schult. Schult.f.. Under optimal conditions, the best extraction method for the TFC was the ultrasound-based approach, whereas for other responses the soxhlet-based was better. Water was the optimal solvent for TPC, FRAP and BCB, but methanol was found as the best solvent for the determination of TFC and IC50. Also, the extraction time for all of the responses was 90 min. The amounts of TPC, TFC, IC50, FRAP and BCB in the optimum conditions obtained were 22.45 ± 0.60 (mg GAE/g extract), 114.57 ± 1.59 (mg QC/g extract), 0.36 ± 0.08 (mg/mL), 1014.7 ± 12.4 (mmol Fe2+/g extract) and 53.02 ± 0.05, respectively. The R² values for responses were close to unity, which indicates the compatibility between the experimental and the real data. A linear correlation was observed between phenolic compounds and antioxidant activity. Also, the effect of solvent was more important than time and extraction method on the amounts of TPC, TFC, IC50, FRAP and BCB.