Flavonoids and saponins from two Bulgarian Astragalus species and their neuroprotective activity

Publication date: August 2018 Source:Phytochemistry Letters, Volume 26 Author(s): Aleksandar Shkondrov, Ilina Krasteva, Franz Bucar, Olaf Kunert, Magdalena Kondeva-Burdina, Iliana Ionkova Two novel compounds from A. glycyphylloides DC (1–2) and three rare flavonoids from A. spruneri Boiss. (3–5), alongside their neuroprotective activity and possible effects as human monoamine oxidase type B inhibitors were reported. The structural elucidation of the compounds was achieved by chemical, HRESIMS and NMR analyses. Their effects were investigated in vitro on isolated rat brain synaptosomes in 6-hydroxydopamine-induced toxicity. In addition, their effect on human monoamine oxidase type B was explored, using Selegiline as a reference. 3-O-β-d-glucopyranosyl-28-O-[β-d-xylopyranosyl-(1 → 2)-β-d-glucopyranosyl] oleanolic acid (1) and kaempferol-3-O-β-d-glucopyranosyl-(1 → 4)-O-α-l-rhamnopyranosyl-(1 → 6)-O-[β-d-glucopyranosyl-(1 → 2)]-β-d-galactopyranoside (2) were isolated for the first time, alongside three known flavonoids, baimaside (3), isobioquercetin (4) and quercetin-3-O-α-l-rhamnopyranosyl-(1 → 2)-[6-O-(3-hydroxy-3-methylglutaryl)-β-d-galactopyranoside (5). On 6-hydroxydopamine in vitro model in synaptosomes, compounds 1-3 had neuroprotective activity similar to that of Silybin A + B. All compounds exhibited weak activity on the monoamine oxidase type B enzyme. Graphical abstract
Source: Phytochemistry Letters - Category: Chemistry Source Type: research