Structural characterization of three cytotoxic steroidal saponins from the leaves of Agave desmetiana hort.

Abstract

Three steroidal saponins detected by LC-MS were isolated from the leaves of Agave desmetiana hort. The three saponins were characterized as; Tigogenin 3 – [{O – β – D - xylopyranosyl (1 → 2) – α – L–rhamnopyranosyl (1 → 3)}–β–D– glucopyranoside), Tigogenin– 3 - ([O- α –L–rhamnopyranosyl (1 → 3) – β – D - glalactopyranosyl (1 → 2)] – β – D – glucopyranoside) and Tigogenin– 3 - ([{O – α – L – rhamnopyranosyl (1 → 4)} – β – D - galactopyranosyl (1 → 3) – β – D – xylopyranosyl (1 → 2)] – β – D – glucopyranoside). Identification and structure elucidation of the isolates were done via 1D and 2D NMR techniques, and chemical methods. Cytotoxic activity for the crude saponins and the three isolated compounds were evaluated against Hepg-2 and Mcf-7 cell lines. Compound 2 proved to be the most cytotoxic against tested cell lines with an IC50 2.97 and 2.49 μg/ml respectively.