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

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.

Graphical Abstract

Keywords:

• Astragalus glycyphyllos
• saponins
• flavonoids
• neuroprotective activity
• synaptosomes

Acknowledgements

This work was supported by National Scientific Fund at Ministry of Education and Science of Republic of Bulgaria, contract No D H03/6/17.12.2016 and a Grant No D-81/03.05.2018 from Medical Science Council at Medical University of Sofia.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

National Scientific Fund at Ministry of Education and Science of Republic of Bulgaria, contract No D H03/6/17.12.2016 and Medical Science Council at Medical University of Sofia, Grant No D-81/03.05.2018.