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The chemical investigation of the fresh flowers of Albizia lebbeck (L.) Benth. (Fabaceae, Mimosoideae) led to the isolation of two new echinocystic acid saponins. They were isolated by using chromatographic methods and their structures were elucidated by detailed 1 H and 13 C NMR spectral data including 2 D-NMR (COSY, HSQC, HMBC and APT) spectroscopic techniques, high-resolution electrospray ionization mass spectrometry (HRESIMS) and acid hydrolysis. Their structures were established as 16-hydroxy-3-[[ O - β -D-xylopyranosyl-(1→2)- O - α -L-arabinopyranosyl-(1→6)-2-(acetylamino)-2-deoxy- β -D-glucopyranosyl]oxy]-(3 β ,16 α )-olean-12-en-28-oic acid O -6-deoxy- α -L-mannopyranosyl-(1→4)- O -6-deoxy- α -L-mannopyranosyl-(1→2)- β -D-glucopyranosyl ester ( 1 ) and 16-hydroxy-3-[[ O - β -D-xylopyranosyl-(1→2)- O - α -L-arabinopyranosyl-(1→6)-2-(acetylamino)-2-deoxy- β -D-glucopyranosyl]oxy]-(3 β ,16 α )-olean-12-en-28-oic acid 6- O -[(2 S ,3 R ,4 R )-tetrahydro-3-hydroxy-4-(hydroxymethyl)-2-furanyl]- β -D-glucopyranosyl ester ( 2 ). Additionally, the permeability property and the capacity of interaction with biological membranes of compounds 1 and 2 were investigated.

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 1 H and 13 C 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., (Copyright © 2018 Elsevier Ltd. All rights reserved.)