| Abstract [eng] |
Liquor ice milkvetch (Astragalus glycyphyllos, Fabaceae) leaves have traditionally been used for medicinal purposes and sometimes for tea. It contains various bioactive compounds. The aim of this study was to evaluate the antioxidant activity of Astragalus glycyphyllos using different polarity solvents. It was grounded to 0.2 mm particle size fractions and extracted using solvents such as hexane, acetone, ethanol/water (70:30 %) in Soxhlet extraction, supercritical fluid extraction (SFE-CO₂) and pressurized liquid extraction (PLE) acetone, ethanol/water (70:30). The highest extract yield was obtained using ethanol-water as solvent and has a significant effect in most of cases. Total content of phenolic compounds (TPC) was measured by UV spectrophotometer using Folin-Ciocalteu reagent. The antioxidant capacity of extracts was determined by DPPH, ABTS, FRAP and ORAC assays. In general, the Ethanol/Water extracts possessed significantly higher antioxidant capacity and total phenolic content when compared to other solvents. The QUENCHER method was also employed to evaluate the antioxidant capacity (ABTS, ORAC and TPC) of un-extracted plant Material and (SFE-CO2) residues after extraction. The un-extracted plant material possessed the highest total Phenolic Content, ABTS and ORAC with more effective antioxidant activity compared to residue obtained after SCE-CO2 extraction (TPC, ABTS and ORAC). Characterization of polyphenolic compounds presented in the Soxhlet and SFE-CO2 extracts were executed by the spectral data comparison obtained by UPLC/QTOF. The compounds were identified using different extracts: 12-oxooctadecanoic acid, m-coumaric acid, rutin and linoleic acid. The second part of the experiment was dedicated to evaluate the antimicrobial activities of Astragalus glycyphyllos leaves extracts, obtained using Soxhlet extraction and different solvents (ethanol/water (70:30); acetone and hexane). Additional, the effect of plant leaves bio-treatment using L. sakei under solid state fermentation (SSF) conditions with the following extraction using different solvents has been studied. As control the leaves powder with/without treatment has been used. For this task, different extracts, LAB treated and extracted Astragalus glycyphyllos leaves were tested against five various bacteria (Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, Bacillus subtilis, Bacillus subtilis subspecies spizizenii) and nine fungi (Debaryomyces vanrijiae, Geotrichum fermentants, Candida pelliculosa, Pichia farinose, Pichia fermentans, Candida krusei, Kluyveromyces marxianus, Kluyveromyces lactis var lactis, Aureobasidum pullulans). The highest antibacterial activity showed extracts against Bacillus subtilis in the following order: ethanol/water (70:30) > acetone > hexane and antifungal - against Debaryomyces vanrijiae followed by: acetone > hexane > ethanol/water (70:30). L. sakei fermented in solid-state conditions (50 %) Astragalus glycyphyllos dry powder and extracted showed a wider zone of antibacterial inhibition against Bacillus subtilis as well as antifungal - against Debaryomyces vanrijiae in compare with non-fermented plant raw materials. Thus, results showed, what Astragalus glycyphyllos leaves is a valuable source of antioxidants and their extracts and especially leaves after bio-treatment demonstrated antimicrobial activities; it confirms the perceptiveness of research. |
