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

Publication date: August 2018Source: Phytochemistry Letters, Volume 26Author(s): Aleksandar Shkondrov, Ilina Krasteva, Franz Bucar, Olaf Kunert, Magdalena Kondeva-Burdina, Iliana IonkovaAbstractTwo 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 - July 11, 2018 Category: Chemistry Source Type: research