Flavonoid Glycosides from Endemic Bulgarian <i>Astragalus aitosensis</i> (Ivanisch.)

• Main Authors: Hristo Vasilev, Samir Ross, Karel Šmejkal, Petr Maršík, Dagmar Jankovská, Jaroslav Havlík, Ondřej Veselý
• Format: Article
• Language: English
• Published: MDPI AG 2019-04-01
• Series: Molecules
• Subjects: <i>Astragalus aitosensis</i>; flavonoid; glycoside
• Online Access: https://www.mdpi.com/1420-3049/24/7/1419

<i>Astragalus</i> is a very interesting plant genus, well-known for its content of flavonoids, triterpenes and polysaccharides. Its secondary metabolites are described as biologically active compounds showing several activities, e.g., immunomodulating, antibacterial, antiviral and hepatoprotective. This inspired us to analyze the Bulgarian endemic <i>A. aitosensis</i> (Ivanisch.) to obtain deeper information about its phenolic components. We used extensive chromatographic separation of <i>A. aitosensis</i> extract to obtain seven phenolic compounds (<b>1</b>&#8211;<b>7</b>), which were identified using combined LC-MS and NMR spectral studies. The 1D and 2D NMR analyses and HR-MS allowed us to resolve the structures of known compounds <b>5</b>&#8211;<b>7</b> as isorhamnetin-3-<i>O</i>-robinobioside, isorhamnetin-3-<i>O</i>-(2,6-di-<i>O</i>-&#945;-rhamno-pyranosyl-&#946;-galactopyranoside), and alangiflavoside, respectively, and further comparison of these spectral data with available literature helped us with structural analysis of newly described flavonoid glycosides <b>1</b>&#8211;<b>4</b>. These were described in plant source for the first time.