Quantitative method development for measurement of Maesa lanceolata saponins by LC-MS

Triterpene saponins are a class of plant natural products with a wide range of bioactivities, which make them an interesting research subject. The small tree Maesa lanceolata, growing in African countries, is used in traditional medicine against various diseases. In previous work a triterpenoid saponin mixture was isolated from the leaves of Maesa lanceolata and the compounds were identified [1, 2]. The compounds showed virucidal, haemolytic, molluscicidal and anti-angiogenic activity [3, 4]. Here we report the development of a quantitative LC-MS method to analyse saponin compounds in crude root and leaf extracts of Maesa plants. The crude extract is first purified on a C18ec SPE column. Then the compounds are separated on a reversed phase C18 column (Grace Vydac, 3.2mm x 250mm –300Å) with a H₂O/ACN (0.06% formic acid) gradient before analysis with mass spectrometry (Bruker Daltonics Esquire 3000 plus). This method will be used to screen plants whether or not induced by methyl-jasmonate, or plants such as Medicago truncatula transformed with genes involved in saponin biosynthesis, for the presence of Maesa saponins.

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