Pro-apoptotic activity of new triterpenoid saponins from the roots of Albizia adianthifolia (Schumach.) W.Wight

Abstract

As part of our study of the proapoptotic function of saponins from Cameroonian's Albizia genus, phytochemical investigation of the roots of Albizia adianthifolia led to the isolation of three new triterpenoid saponins, named adianthifoliosides GI (13). Their structures were established on the basis of extensive analysis of 1D and 2D NMR (¹H-, ¹³C NMR, DEPT, COSY, TOCSY, NOESY, HSQC, HSQC-TOCSY and HMBC) and HRESIMS experiments, and by chemical evidence as 3-O-[β-d-glucopyranosyl-(1 → 2)-β-D-fucopyranosyl-(1 → 6)-β-d-glucopyranosyl]-21-O-{(2E,6S)-2-(hydroxymethyl)-6-methyl-6-O-{4-O-[(2E,6S)-2,6-dimethyl-6-O-(β-D-quinovopyranosyl)octa-2,7-dienoyl]-(β-D-quinovopyranosyl)octa-2,7-dienoyl]}acacic acid-28-O-β-d-xylopyranosyl-(1 → 3)-[5-O-acetyl-α-L-arabinofuranosyl-(1 → 4)]-α-L-rhamnopyranosyl-(1 → 2)-β-d-glucopyranosyl ester (1), 3-O-[β-d-glucopyranosyl-(1 → 2)-β-D-fucopyranosyl-(1 → 6)-β-d-glucopyranosyl]-21-O-{(2E,6S)-2-(hydroxymethyl)-6-methyl-6-O-{4-O-[(2E,6S)-2,6-dimethyl-6-O-(β-D-quinovopyranosyl)octa-2,7-dienoyl]-(β-D-quinovopyranosyl)octa-2,7-dienoyl]}acacic acid 28-O-β-d-xylopyranosyl-(1 → 3)-[α-L-arabinofuranosyl-1 → 4)]-α-L-rhamnopyranosyl-(1 → 2)-β-d-glucopyranosyl ester (2), and 3-O-[β-d-glucopyranosyl-(1 → 2)-β-D-fucopyranosyl-(1 → 6)-β-d-glucopyranosyl]-21-O-{(2E,6S)-2-(hydroxymethyl)-6-methyl-6-O-{4-O-[(2E,6S)-2,6-dimethyl-6-O-(β-D-quinovopyranosyl)octa-2,7-dienoyl]-4-O-[(2E,6S)-2,6-dimethyl-6-O-(β-D-quinovopyranosyl)octa-2,7-dienoyl]-β-D-quinovopyranosyl}-2,6-dimethylocta-2,7-dienoyl}acacic acid 28-O-β-d-xylopyranosyl-(1 → 3)-[α-L-arabinofuranosyl-1 → 4)]-α-L-rhamnopyranosyl-(1 → 2)-β-d-glucopyranosyl ester (3). The apoptotic effect of saponins 1-3 was evaluated on the A431 human epidermoid cancer cell. Flow cytometric analyses showed that saponins 1-3 induced apoptosis of human epidermoid cancer cell (A431) in a dose-dependent manner.

Keywords: Albizia adianthifolia; Human epidermoid cancer cell (A431); Mimosaceae; Proapoptotic activity; Triterpenoid saponins.