Phenotype-specific apoptosis induced by three new triterpenoid saponins from Albizia glaberrima (Schumach. & Thonn.) Benth

As part of our search of new bioactive saponins from Cameroonian medicinal plants, phytochemical investigation of the roots of Albizia glaberrima led to the isolation of three new oleanane-type saponins, named glaberrimosides A–C (1–3). Their structures were established by direct interpretation of their spectral data, mainly HRESIMS, 1D NMR (1 H, 13C NMR, and DEPT) and 2D NMR (COSY, ROESY, HSQC and HMBC) as 3-O-[α-l-arabinopyranosyl-(1 → 6)-[β-d-glucopyranosyl-(1 → 2)]-β-d-glucopyranosyl]-28-O-[β-d-glucopyranosyl-(1 → 6)-[β-d-glucopyranosyl-(1 → 2)]-β-d-glucopyranosyl]-oleanolic acid (1), 3-O-[α-l-arabinopyranosyl-(1 → 6)-[β-d-glucopyranosyl-(1 → 2)]-β-d-glucopyranosyl]-28-O-[β-d-glucopyranosyl-(1 → 6)-β-d-glucopyranosyl]-oleanolic acid (2), and 3-O-[β-d-glucopyranosyl-(1 → 2)-β-d-glucopyranosyl]-28-O-[β-d-glucopyranosyl-(1 → 6)-[β-d-fucopyranosyl-(1 → 2)]-β-d-glucopyranosyl]-oleanolic acid (3). The pro-apoptotic effect of the three saponins was evaluated on three human cell lines (pancreatic carcinoma AsPC-1, hematopoietic monocytic THP-1, and human fibroblast cell line BJ). Saponins 1–3 specifically induced apoptosis of pancreatic carcinoma cell (AsPC-1) in a dose-dependent manner. More interestingly, there were inactive on monocytic (THP-1) and normal human fibroblast (BJ) cell lines.

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