A new bioactive steroidal saponin, furcreastatin, from the plant Furcraea foetida

Microbial and plant secondary metabolites were screened for compounds that are selectively cytotoxic to mutant p53-expressing mouse fibroblasts. As a result, furcreastatin, a novel steroidal saponin, was isolated from an EtOH extract of the leaves of Furcraea foetida. Furcreastatin consisted of hecogenin as the aglycone and a hexasaccharide containing d-galactose, l-rhamnose and four d-glucose residues. The structure was determined to be (3β,5α,25R)-3-hydroxyspirostan-12-one 3-O-[α-l-Rhap-(1→4)-β-d-Glcp-(1→3)-{β-d-Glcp-(1→3)-β-d-Glcp-(1→2)}-β-d-Glcp-(1→4)-β-d-Galp] by extensive NMR spectroscopic studies. Furcreastatin decreased the viability of mutant p53-overexpressing cells with an ED50 of 4.0 μg/mL, and decreased that of the parental cell-line with an ED50 of 9.6 μg/mL.