Methodological Approach to the Elaboration of the Analytical Procedure of the Antioxidant Activity Determination of the Schisandra chinensis (Turcz) Baill. Extracts

Abstract

The DPPH assay provides an easy and rapid way to evaluate the antioxidant activity of herbal preparations. The most important stage of the elaboration of the analytical procedure of total antioxidant activity measured by the DPPH test is to select the volume of an extract or its appropriate dilution for the determination of the reliable total antioxidant activity of the extract. If the concentration of antioxidants is too high in an extract, the kinetic curves of antioxidant activity changes on time are more parallel to axis X (time) and what is more, the total antioxidant activity does not depend on the volume of the extract. The analytical procedure of the antioxidant activity determination of the Schisandra chinensis (Turcz) Bail. extracts was elaborated, namely a volume and dilution of the extract was selected, rutin was chosen for the calibration curve. The calibration curve was plotted in the concentration range of 95–305 mg/L (y=0.228x+7.0992, R²=0.9945). The results suggest that the leaves of S. chinensis are a valuable source of antioxidant compounds with significant antioxidant activity. The antioxidant activity was evaluated by the DPPH test. It was equal to 227.2–443.6 mg/L in the extracts or 1.14–2.22 mg/g in the leaves of rutin-equivalents depending on the particle size. Additionally, it was established that particle size in the range of 2 to 3 mm was optimal for the preparation of Schisandra chinensis extracts as the antioxidant activity was the highest. The ethanol absorption coefficient is a main technological parameter in the pharmaceutical manufacture of extracts. The absorption coefficient of the Schisandra chinensis leaves for 70 % ethanol was in the range of 3.4 to 6.5 ml/g and depended on the particle size.