LC-MS Analysis of 13,28-Epoxy-Oleanane Saponins in Maesa spp. Extracts with Antileishmanial Activity

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 mu g/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. Copyright (C) 2009 John Wiley & Sons, Ltd.