Discovery of new dammarane saponins from Actinostemma lobatum: C-3 monoglucosylation governs α-glucosidase inhibition

Fitoterapia. 2025 Dec:187:106898. doi: 10.1016/j.fitote.2025.106898. Epub 2025 Sep 24.

Abstract

Four new dammarane saponins, named actinostemmosides L-O (1-4), together with five known analogues (5-9), were isolated from the whole plant of Actinostemma lobatum. Their structures were established by HR-ESI-MS, exhaustive 1D/2D-NMR, and chemical methods. All nine saponins exhibited α-glucosidase inhibitory activity (IC50 40.3-150.9 μM), with actinostemmoside L (1) exhibiting an IC50 of 40.3 μM-twice the potency of acarbose (84.6 μM)-while 5 and 6 were equipotent with the drug. These results expand the chemical space of dammarane saponins and establish A. lobatum as a renewable source of α-glucosidase inhibitors.

Keywords: Actinostemma lobatum; Dammarane; Hypoglycemic activity; Triterpenoid saponins; α-Glucosidase inhibitors.

MeSH terms

  • China
  • Dammaranes
  • Glycoside Hydrolase Inhibitors* / chemistry
  • Glycoside Hydrolase Inhibitors* / isolation & purification
  • Glycoside Hydrolase Inhibitors* / pharmacology
  • Molecular Structure
  • Phytochemicals / isolation & purification
  • Phytochemicals / pharmacology
  • Saponins* / chemistry
  • Saponins* / isolation & purification
  • Saponins* / pharmacology
  • Triterpenes* / chemistry
  • Triterpenes* / isolation & purification
  • Triterpenes* / pharmacology
  • alpha-Glucosidases

Substances

  • Saponins
  • Glycoside Hydrolase Inhibitors
  • Dammaranes
  • Triterpenes
  • Phytochemicals
  • alpha-Glucosidases