A new cytotoxic triterpene saponin from Lysimachia nummularia L.

• A new triterpene saponin (nummularoside) was isolated from Lysimachia nummularia L.
• Its structure was established on the basis of spectroscopic and chemical methods.
• The compound possesses a 13β,28-epoxy-bridge and a branched pentasaccharide unit.
• Significant cytotoxic activity was seen against five human cancer cell lines.
• The compound does not affect normal cells of respective origin.

A new glycosylated triterpene 1 (named nummularoside) was isolated from the underground parts of Lysimachia nummularia L. Its chemical structure was elucidated as 3-O-β-{{[β-d-xylopyranosyl-(1→2)]-[β-d-xylopyranosyl-(1→4)]-β-d-glucopyranosyl-(1→4)}-[β-d-glucopyranosyl-(1→2)-]-α-l-arabinopyranosyl]}, protoprimulagenin A on the basis of extensive NMR and MS spectral data. The saponin showed significant activity against prostate cancer cells DU145 and PC3 (EC50 1.2 and 7.4 μg/mL, respectively), while it did not affect normal cells (EC50 30 μg/mL), in contrast to the reference compound (mitoxanthrone, EC50 0.45 μg/mL). Glioblastoma cells were also significantly affected by the tested saponin (EC50 6.0 μg/mL), whereas the activity against melanoma cells was moderate (EC50 17.5–23.2 μg/mL).

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