Mining secondary metabolites of chassalia curviflora leaves using SIRIUS and high-resolution mass spectrometry data

Chassalia curviflora Thwaites is a flowering plant from Rubiaceae family. Previous phytochemical investigations on Chassalia species led to the isolation of benzoic acid, benzoquinone derivatives, flavonoids, monoterpenoid, indole alkaloids and its essential oil composition. However, these are still scarce in terms of scientific reports on the studied species. This study was carried out to investigate the fast screening of secondary metabolites by using data-dependent acquisition (DDA) LC-MS/MS analysis of methanolic extract of the leaves of C. curviflora in positive ionization mode. The data were analysed using the computational mass spectrometry method from the molecular structure database search implemented in Sirius. This led to the discovering of 13 known secondary metabolites from distinct tandem MS data. De novo molecular formula annotation and predictions from SIRIUS suggested five major class compounds classified as coumarins, benzofuran, fatty acids, esters, and triterpenes. Stigmasterol 12 and β-sitosterol 13 were successfully isolated, thus used to verify the data obtained from the Sirius. With our results, we advocate the MS-based approach as a useful starting method for the dereplication of compounds from the complex crude extract of plants. Keywords: Rubiaceae; Chassalia curviflora; dereplication; SIRIUS; orbitrap