Successive Solvent Extraction of Polyphenols and Flavonoids from Cistus creticus L. Leaves

The aim of this study was to evaluate the efficiency of successive extraction (using solvents of increasing polarity, namely hexane, ethyl acetate, acetone, ethanol, and water) of polyphenols from Cistus creticus L. The results were compared with the ones obtained from a single-solvent extraction (ethanol, water, and 50% ethanol: water). According to the results, each solvent used for extraction had a significant effect on the yield of extracted polyphenols and the antioxidant activity of the extracts. The highest extraction yield for successive extraction was achieved with ethanol (95.33 mg GAE/g), whereas a comparable amount could also be extracted with 50% ethanol: water mixture single-solvent extraction (96.51 mg GAE/g). The ethanolic and aqueous extracts had the highest antioxidant activity as indicated by their lowest IC50 values in the DPPH assay, specifically 350.99 μg/mL for ethanolic extract of successive extraction and 341.18 μg/mL for 50% ethanol: water mixture of single-solvent extraction, followed by the extract produced using acetone. However, the acetone extract contained more flavonoids than the other two extracts up to 28.03 mg QE/g. The results obtained were in line with those for the single-solvent extraction. It is concluded that using a range of solvents in succession is a more efficient way of extracting higher amounts of antioxidant compounds with varying antioxidant activity.