Lanostane-Type Saponins from Vitaliana primuliflora

Abstract

The phytochemistry of the genera Androsace, Cortusa, Soldanella, and Vitaliana, belonging to the Primulaceae family is not well studied so far. Hence, in this paper, we present the results of UHPLC-MS/MS analysis of several primrose family members as well as isolation and structure determination of two new saponins from Vitaliana primuliflora subsp. praetutiana. These two nor-triterpenoid saponins were characterized as (23S)-17α,23-epoxy-29-hydroxy-3β-[(O-β-d-glucopyranosyl-(1→2)-O-α-l-rhamnopyranosyl-(1→2)-O-β-d-glucopyranosyl-(1→2)-O-α-l-arabinopyranosyl-(1→6)-β-d-glucopyranosyl)oxy]-27-nor-lanost-8-en-25-one and (23S)-17α,23-epoxy-29-hydroxy-3β-[(O-α-l-rhamnopyranosyl-(1→2)-O-β-d-glucopyranosyl-(1→2)-O-α-l-arabinopyranosyl-(1→6)-β-d-glucopyranosyl)oxy]-27-nor-lanost-8-en-25-one, respectively. Their structures were determined by high resolution mass spectrometry (HRMS), tandem mass spectrometry (MS/MS), one- and two-dimensional nuclear magnetic resonance spectroscopy (1D-, and 2D-NMR) analyses. So far, the 27-nor-lanostane monodesmosides were rarely found in dicotyledon plants. Therefore their presence in Vitaliana and also in Androsace species belonging to the Aretia section is unique and reported here for the first time. Additionally, eleven other saponins were determined by HRMS and MS/MS spectra. The isolated lanostane saponins can be considered as chemotaxonomic markers of the family Primulaceae.

Keywords: Androsace; Douglasia; Primula; Primulaceae; UHPLC screening; Vitaliana; lanostane; primrose; steroid saponins; triterpenoid saponin.

Figure 1

Structures of 12 (R1 = 1-β-D-Glcp) and 13 (R1 = H).

Figure 2

(a) Structure of 12. Solid, one-way arrows represent the key HMBC correlations (violet from methyl groups, red from other hydrogens). (b) Structure of 12. Dashed, blue, two-way arrows represent the key NOESY correlations