Optimizing the extraction of polyphenols from Sideritis montana L. using response surface methodology

Sideritis montana L. endemic of Turkey was screened for its polyphenols content and antioxidant activity. Factor analysis and experimental design have been applied to understand the structure of the separation process, to determine the effective parameters, and to accomplish the performance improvement. Face-centred composite design (FCD) of response surface methodology (RSM) was applied to evaluate the influences of solvent concentration, solvent amount, extraction time, and stirring speed of homogenizer-assisted extraction (HAE) as well as to model and to optimize the HAE. Quadratic models were highly significant (p < 0.0001) for the responses studied with high coefficients of determination (R²) of 0.9440, 0.9415 and 0.9521. The result of the study suggests that 15.02 mL of 22.69% EtOH solution (v/v), 70.16 s, and 9524.52 rpm of mixing speed are the optimal conditions to obtain the highest yield of total polyphenols (TPC) and flavonoids (TFC), and the best antioxidant activity (AA). Rosmarinic acid was identified as the most abundant component.