Triterpenoid Saponins from Maesa argentea Leaves.

Within an ongoing research program on saponins with potential antileishmanial activity, four previously undescribed saponins were isolated from leaves and identified by LC-MS/MS, GC-MS, and 1D and 2D NMR spectroscopy as 3--{([-D-glucopyranosyl-(1 → 2)--L-rhamnopyranosyl-(1 → 2)--D-galactopyranosyl-(1 → 3)]-[-D-galactopyranosyl-(1 → 2)]--D-glucuronopyranosyl)}-21-angeloyloxy-22-butanoyloxy-13,28-oxidoolean-16,28-diol (), 3--{([-D-glucopyranosyl-(1 → 2)--L-rhamnopyranosyl-(1 → 2)--D-galactopyranosyl-(1 → 3)]-[-D-galactopyranosyl-(1 → 2)]--D-glucuronopyranosyl)}-21,22-angeloyloxy-13,28-oxidoolean-16,28-diol (), 3--{([-D-glucopyranosyl-(1 → 2)--L-rhamnopyranosyl-(1 → 2)--D-galactopyranosyl-(1 → 3)]-[-D-galactopyranosyl-(1 → 2)]--D-glucuronopyranosyl)}-21-angeloyloxy-22-()-cinnamoyloxy-13,28-oxidoolean-16,28-diol (), and 3--{([-L-rhamnopyranosyl-(1 → 2)--D-galactopyranosyl-(1 → 3)]-[-D-galactopyranosyl-(1 → 2)]--D-glucuronopyranosyl)}-21-angeloyloxy-22-()-cinnamoyloxy-13,28-oxidoolean-16,28-diol (). Leaf material was obtained from a germinated seed that was clonally propagated using tissue culturing. Compounds - showed structural similarity with maesasaponins and maesabalides reported before from other spp. All four compounds showed activity against K1 and at micromolar concentrations. However, the observed inhibitory action must be considered nonspecific since they were also cytotoxic in the same concentration range.