LC-MS analysis of 13,28-epoxy-oleanane saponins in **Maesa spp.** extracts with antileishmanial activity
Faculty of Pharmaceutical, Biomedical and Veterinary Sciences. Pharmacy
Phytochemical analysis. - Chichester
, p. 159-167
University of Antwerp
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.