Structural characterization of a complex triterpenoid saponin from Albizia lebbeck and investigation of its permeability property and supramolecular interactions with membrane constituents

As part of the ongoing efforts in discovering potentially bioactive natural products from medicinal plants, the present study was conducted to isolate a new complex triterpenoid saponin from the barks of Albizia lebbeck. It was isolated by using chromatographic methods and its structural elucidation was performed using detailed analyses of 1H and 13C NMR spectra including 2D-NMR (COSY, TOCSY, HSQC and HMBC) spectroscopic techniques, high-resolution electrospray ionization mass spectrometry (HRESIMS) analysis and chemical conversions. Its structure was established as 21-[[(2E,6S)-6-[6-deoxy-4-O-[(2E,6S)-6-hydroxy-2-(hydroxymethyl)-6-methyl-1-oxo-2,7-octadienyl]-[(β-d-glucopyranosyl)oxy]-2-(hydroxymethyl)-6-methyl-1-oxo-2,7-octadienyl]-[(β-d-glucopyranosyl)oxy]-2,6-dimethyl-1-oxo-2,7-octadienyl]oxy]-16-hydroxy-3-[[O-β-d-xylopyranosyl-(1 → 2)-O-α-l-arabinopyranosyl-(1 → 6)-2-(acetylamino)-2-deoxy-β-d-glucopyranosyl]oxy]-(3β,16α,21β)-olean-12-en-28-oic acid O-α-l-arabinofuranosyl-(1 → 4)-O-[β-d-glucopyranosyl-(1 → 3)]-O-6-deoxy-α-l-mannopyranosyl-(1 → 2)-β-d-glucopyranosyl ester (1). Additionally, this study aimed to investigate the permeability property of 1, its activity on membrane integrity and supramolecular interactions with cellular constituents using in vitro experimental models. [Display omitted] •A new complex triterpenoid saponin was isolated from Albizia lebbeck.•The chemical structure was established by spectroscopic techniques and chemical methods.•The permeability property was investigated using in vitro experimental models.•The compound exhibited powerful capacity of interaction with membranes.•Supramolecular interactions of the compound with cellular components were observed.