Butyrolactone I

Dried Astragalus glycyphylos L roots and areal parts (leaves, collected at different vegetation phases) were successively extracted with supercritical carbon dioxide (SFE-CO₂) at 15 and 45 MPa pressures and increasing polarity pressurised liquids (PLE with acetone, ethanol, and water) for the recovery of two lipophilic and three higher polarity fractions. The yield of lipophilic substances was low and varied with applied pressure, plant part, and growth period. PLE obtained the highest yields with water, followed by ethanol and acetone. The antioxidant capacity of the extracts and solids was evaluated using various in vitro assays. In general, antioxidant capacity values of lipophilic extracts were the lowest, and the values determined for the leaves were higher than those for the roots. The total phenolic content and ABTS^•+ scavenging values of PLE-Ac and PLE-EtOH extracts of the aerial parts were similar and significantly higher than those of PLE-H₂O extracts. In the DPPH^•-scavenging assay, PLE-Ac extract of roots was 2-fold more potent than PLE-EtOH and PLE-H₂O extracts. Volatile compounds in the headspace (HS) of dried material and in SFE-CO₂ extracts were collected by solid-phase microextraction (SPME) and analysed by gas chromatography-mass spectrometry. (E,E)-3,5-Octadien-2-one, linalool, and benzaldehyde were dominant among 50 identified dry material compounds, while butyrolactone, 6-methyl-5-hepten-2-one, and (2E)-hexenoic acid were most abundant among 63 compounds characterised in the SFE-CO₂ extracts. Significant differences in volatile composition were observed across vegetation phases and extraction pressures; consequently, this type of fractionation may yield products with varying odour characteristics.