Rapid quantification of 14 saponins of Maesa lanceolata by UPLC-MS/MS

Abstract

Triterpene saponins are a class of plant natural products with a wide range of bioactivities, and therefore they are a promising research subject. In previous work a triterpenoid saponin mixture was isolated from the leaves of Maesa lanceolata and the compounds were identified [1,2]. These compounds showed virucidal, haemolytic, molluscicidal and anti-angiogenic activity [3,4]. Maesasaponin II displays the highest anti-angiogenic activity, but is only present in very small amounts in the plant. To increase this amount, a platform of combinatorial biosynthesis in the plant was developed. By introducing genes involved in saponin biosynthesis we are attempting to identify new active compounds, and a higher production of the known compounds. In the first phase of the project, only small amounts of transgenic plant material are available. Therefore it is important to use very sensitive analytical methods. For the fast and sensitive analysis of the extracted and purified plant samples, ultra-performance liquid chromatography (UPLC) was coupled to a triple-quad mass spectrometer for MS/MS detection (TQD). The intensity of the signal obtained by fragmentation of the sodium adducts of the saponins was optimized by addition of sodium acetate to the mobile phase. The method was linear over the investigated concentration range with a correlation coefficient higher than 0.99. Furthermore the method was shown to be repeatable and accurate and therefore suitable for screening of the saponin production of plants transformed with genes involved in saponin biosynthesis.