Possibilities of regulating antioxidant activity of medicinal plant extracts

The aim of the paper. The aim of the present paper is to evaluate the effectiveness of extracting biologically active substances of antioxidant action from plant raw materials on the basis of applying different extraction approaches. Materials and methods. We did the chemical research of BAS extracts Lonicera сaerulea L. and Urtica folia L. concerning their migration parameters during fraction division (honeysuckle berries) and changing extraction conditions (dried nettle leaves). Freeze-drying of raw material (by means of a freeze-drying apparatus “Ineye-6” under the following conditions: temperature -50 ± 5 °C, pressure no more than 6 Pa) was applied to preserve the bioactivity in a honeysuckle fraction. The experiment included a wide range of chemical parameters - antioxidant activity (АОА), mass fraction of extractives, phenol compounds, anthocyanins and vitamins. The UFLC Shimadzu Corporation Pump: LC-20AD Detector: SPD-M20A Prominence Diode array detector was used to identify bioactive substances. Results and discussion. The paper studies the influence of various approaches concerning bioactive compounds extraction from Lonicera сaerulea L. and Urtica folia L. The application of ultrasound (US) with frequencies 22 ± 0.6 kHz increases the effectiveness of extraction process. It helps to conduct extraction at low temperatures (60 ± 2 °С) without using chemical reagents. The paper presents the results of water and ethanol extraction obtained from different fractions of honeysuckle and dried nettle leaves. It also provides the results of antioxidant activity analysis of this extraction and a total of antioxidant activity. Urtica folia L extracted by US of 120 W (2,4043 ± 0,084 mg/ml) and a sample based on the water-ethanol extraction agent without an ultrasonic bath (2,5209 ± 0,032 mg/ml) showed higher antioxidant activity. We defined the technological parameters of obtaining a dry extract of Lonicera сaerulea L by means of ultrasound and freeze-drying for preserving the maximum bioactive compounds of raw material (up to 92-85 %). Conclusion. The results of the experiment proved that ultrasound-assisted extraction improves the extraction kinetics and the output of bioactive compounds from the substrate. The extraction technology excludes the infusion stage which reduces energy intensity.