A new tetracyclic saponin from Astragalus glycyphyllos L. and its neuroprotective and hMAO-B inhibiting activity

Nat Prod Res. 2020 Feb;34(4):511-517. doi: 10.1080/14786419.2018.1491040. Epub 2018 Nov 23.

Abstract

A new tetracyclic saponin, 17(R),20(R)-3β,6α,16β-trihydroxycycloartanyl-23-carboxylic acid 16-lactone 3-O-β-D-glucopyranoside (1) together with one known flavonoid, camelliaside A (2) were isolated from the aerial parts of Astragalus glycyphyllos L. Their structures were determined by chemical, HRESIMS and NMR methods. On 6-hydroxydopamine in vitro model on isolated rat brain synaptosomes, compounds 1-2 had statistically significant neuroprotective activity similar to that of Silibinin, tested at 100 μM. Saponin 1 possessed the most prominent neuroprotective and antioxidant effects in this in vitro model. On human recombinant monoamine oxidase type B enzyme compound 1 displayed strong inhibiting activity, compared to Selegiline (1 μM). It could be concluded that the new epoxycycloartane saponin 1 could be a promising leading structure in respect of neurodegenerative diseases.

Keywords: Astragalus glycyphyllos; flavonoids; neuroprotective activity; saponins; synaptosomes.

MeSH terms

  • Animals
  • Antioxidants / chemistry
  • Antioxidants / isolation & purification
  • Antioxidants / pharmacology
  • Astragalus Plant / chemistry*
  • Flavonoids / chemistry
  • Flavonoids / isolation & purification
  • Flavonoids / pharmacology
  • Humans
  • Magnetic Resonance Spectroscopy
  • Molecular Structure
  • Monoamine Oxidase / drug effects
  • Neuroprotective Agents / chemistry
  • Neuroprotective Agents / isolation & purification
  • Neuroprotective Agents / pharmacology
  • Rats
  • Saponins / chemistry
  • Saponins / isolation & purification*
  • Saponins / pharmacology
  • Synaptosomes / drug effects

Substances

  • Antioxidants
  • Flavonoids
  • Neuroprotective Agents
  • Saponins
  • Monoamine Oxidase