LC-MS analysis of 13,28-epoxy-oleanane saponins in Maesa spp. extracts with antileishmanial activity
2009
Foubert, Kenn | Vermeersch, Marieke | Theunis, Mart | Apers, Sandra | Cos, Paul | Claeys, Magda | Puyvelde, Luc van | Pieters, Luc | Maes, Louis
INTRODUCTION: Saponins are natural products that are well known for a wide range of biological activities. For saponins of Maesa balansae, selective antileishmanial activity has been described. OBJECTIVE: In view of their pharmacological interest, several Maesa species from the National Botanical Garden of Meise (Belgium) and wild-grown plants from Vietnam were screened for their antileishmanial potential and saponin content. METHODOLOGY: Different parts of the plants (mainly leaves and twigs) were collected, dried and extracted. Plant extracts were evaluated by liquid chromatography/mass spectrometry (LC-MS) using electrospray ionisation in the negative ion mode and their saponin content was compared with those of Maesa balansae (maesabalides) and Maesa lanceolata (maesasaponins). RESULTS: Several Maesa species (M. ambigua, M. argentea, M. brevipaniculata, M. japonica and M. perlarius) showed potent antileishmanial activity (<0.1 μg/mL) and indeed contained known maesasaponins and maesabalides. However the leaves of M. argentea also revealed two new compounds. Two saponins with [M - H]⁻ ions at m/z 1465 and 1477 were characterised. Their mass spectrometric fragmentation pattern revealed a structure that was the same or closely related to maesasaponin V.3 and VI.2, respectively, but had a glycan part with one additional hexose residue. CONCLUSION: Several known as well as new saponins from Maesa species active against leishmaniasis were characterised using LC-MS.
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