A New Triterpenoid Saponin from Albizia zygia Induced Apoptosis by Reduction of Mitochondrial Potential Status in Malignant Melanoma Cells.

In our ongoing research program on the proapoptotic function of saponins, two previously undescribed saponins, named zygiaosides E (1: ) and F (2: ), were isolated from the leaves of Albizia zygia. Their structures were established based on extensive analysis of 1D and 2D NMR data, HR-ESI-MS analysis, and by chemical degradation. The proapoptotic effect of zygiaoside E (1: ) was evaluated on human malignant melanoma (A375), human epidermoid cancer (A431), and normal Homo sapiens skin tissue (TE 353.SK.) cell lines by cytometric analysis. Zygiaoside E (1: ) induced apoptosis of the two human cancer cell lines (A375 and A431) in a dose-dependent manner at 1 µM but did not induce apoptosis in noncancerous skin cells (TE 353.Sk), even when treated with concentrations up to 15 µM. The underlying mechanism of the apoptosis induction activity of zygiaoside E (1: ) on the mitochondrial membrane potential status in A375 cells was further assessed by monitoring the uptake rate of DiOC6, a mitochondrial specific and voltage-dependent fluorescent dye. The number of malignant melanoma cells emitting high fluorescence levels was decreased when cells were treated with 3 or 5 µM of zygiaoside E (1: ) during either 12 or 24 h, thereby revealing a drop of mitochondrial membrane potential in A375 cells upon treatment, which indicated mitochondrial perturbation.

New triterpenoid saponin from the stems of Albizia adianthifolia (Schumach.) W.Wight.

As part of our continuing study of apoptosis-inducing saponins from Cameroonian Albizia genus, one new triterpenoid saponin, named adianthifolioside J (1), together with the known gummiferaoside E (2), were isolated from Albizia adianthifolia stems. The structure of the new saponin (1), was established on the basis of extensive analysis of 1 D and 2 D NMR (1H-, 13C-NMR, DEPT, COSY, TOCSY, NOESY, HSQC, HSQC-TOCSY and HMBC) and HRESIMS experiments, and by chemical evidence as 3-O-[ß-D-xylopyranosyl-(1→2)-ß-D-fucopyranosyl-(1→6)-ß-D-glucopyranosyl]-21-O-{(2E,6S)-2-(hydroxymethyl)-6-methyl-6-O-{4-O-[(2E,6S)-2,6-dimethyl-6-O-(ß-D-quinovopyranosyl)octa-2,7-dienoyl]-(ß-D-quinovopyranosyl)octa-2,7-dienoyl]}acacic acid-28-O-ß-D-glucopyranosyl-(1→3)-[5-O-acetyl-α-L-arabinofuranosyl-(1→4)]-α-L-rhamnopyranosyl-(1→2)-ß-D-glucopyranosyl ester (1). The pro-apoptotic activity of the new isolated saponin 1 was evaluated, using Annexin V-FITC binding assay, on the A431 human epidermoid cancer cell. The result showed that adianthifolioside J (1) displayed weak pro-apoptotic activity.

Triterpenoid saponins and others glycosides from the stem barks of Pancovia turbinata Radlk.

In our continuing search of saponins from the plant of Sapindaceae family, phytochemical investigation of the stem barks of Pancovia turbinata Radlk., led to the isolation and structural characterization of two new triterpenoid saponins, named turbinatosides A-B (1-2), one new farnesyl glycoside, named turbinoside A (3), one new coumarin glucoside, named panturboside A (4), together with a known saponin (5). The structures of the new compounds were established, using extensive analysis of NMR techniques, mainly 1D NMR (1H, 13C, and DEPT) and 2D NMR (COSY, NOESY, HSQC, HSQC-TOCSY and HMBC) experiments, HRESIMS and by comparison with the literature data, as 3-O-ß-d-xylopyranosyl-(1 â†’ 3)-α-l-arabinopyranosyl-(1 â†’ 4)-ß-d-glucopyranosyl-(1 â†’ 3)-α-l-rhamnopyranosyl-(1 â†’ 2)-α-l-arabinopyranosylhederagenin 28-O-ß-d-glucopyranosyl ester (1), 3-O-α-l-arabinopyranosyl-(1 â†’ 4)-ß-d-glucopyranosyl-(1 â†’ 3)-α-l-rhamnopyranosyl-(1 â†’ 2)-α-l-arabinopyranosylhederagenin 28-O-ß-d-xylopyranosyl-(1 â†’ 4)-ß-d-glucopyranosyl ester (2), 1-O-{ß-d-glucopyranosyl-(1 â†’ 3)-α-l-rhamnopyranosyl-(1 â†’ 2)-[α-l-rhamnopyranosyl-(1 â†’ 6)]-ß-d-glucopyranosyl}-(2E,6E)-farnes-1,12-diol (3), and 5-O-ß-d-glucopyranosyl-5,6,7-trihydroxy-8-methoxycoumarin (4), respectively. Our findings highlight the presence of -3Rha-2Ara-3hederagenin oligosaccharidic sequence usually described in saponins from Sapindoideae subfamily of Sapindaceae family, as well as farnesol glycosides, and represent therefore a valuable contribution to the chemotaxonomy of the Sapindoideae subfamily.

Structural determination of two new acacic acid-type saponins from the stem barks of Albizia zygia (DC.) J. F. Macbr.

As a continuation of our interest in the study of triterpenoid saponins from Albizia zygia, phytochemical investigation of its stem barks led to the isolation of two new oleanane-type saponins, named zygiaosides C-D (1-2). Their structures were established on the basis of extensive analysis of 1D and 2D NMR (1H-, 13C NMR, DEPT, COSY, TOCSY, ROESY, HSQC and HMBC) experiments, HRESIMS studies, and by chemical evidence as, 3-O-[ ß-d-glucopyranosyl-(1→2)-[α-l-arabinopyranosyl-(1→6)]-ß-d-glucopyranosyl]-21-O-[(2E,6S)-2,6-dimethyl-6-O-(ß-d-quinovopyranosyl) octa-2,7-dienoyl]acacic acid 28-O-α-l-arabinofuranosyl-(1→4)-[ß-d-glucopyranosyl-(1→3)]-α-l-rhamnopyranosyl-(1→2)-ß-d-glucopyranosyl ester (1) and 3- O-[ß-d-glucopyranosyl-(1→2) -[ ß-d-fucopyranosyl-(1→6)]-ß-d-glucopyranosyl]-21-O-[(2E,6S)-2,6-dimethyl-6-O-(ß-D-quinovopyranosyl) octa-2,7-dienoyl]acacic acid 28-O-α-l-arabinofuranosyl-(1→4)-[ß-d-glucopyranosyl-(1→3)]-α-l-rhamnopyranosyl-(1→2)-ß-d-glucopyranosyl ester (2).

New Cytotoxic Triterpenoid Saponins from the Roots of Albizia gummifera (J.F.Gmel.) C.A.Sm.

As part of our search for new bioactive saponins from Cameroonian medicinal plants, two new oleanane-type saponins, named gummiferaosides D and E (1 and 2), along with one known saponin, julibroside J8 (3), were isolated from the roots of Albizia gummifera. Their structures were established on the basis of extensive 1D- and 2D-NMR (1 H- and 13 C-NMR, DEPT, COSY, TOCSY, NOESY, HSQC, HSQC-TOCSY, and HMBC) and HR-ESI-MS studies, and by chemical evidence. 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.