Targeted Isolation of Cytotoxic Sesquiterpene Lactones from Eupatorium fortunei by the NMR Annotation Tool, SMART 2.0

Small Molecular Accurate Recognition Technology (SMART 2.0) has recently been introduced as a NMR-based machine learning tool for the discovery and characterization of natural products. We attempted targeted isolation of sesquiterpene lactones from Eupatorium fortunei with the aid of structural annotation by SMART 2.0 and chemical profiling. Eight germacrene-type (1-7 and 10) and two eudesmane-type sesquiterpene lactones (8 and 9) were isolated from the whole plant of Eupatorium fortunei. With the guidance of the results of the subfractions from E. fortunei obtained by SMART 2.0, their cytotoxic activities were evaluated against five cancer cells (SKOV3, A549, PC3, HEp-2, and MCF-7). Compounds 4 and 8 exhibited IC₅₀ values of 3.9 ± 1.2 and 3.9 ± 0.6 μM against prostate cancer cells, PC3, respectively. Compound 7 showed good cytotoxicity with IC₅₀ values of 5.8 ± 0.1 μM against breast cancer cells, MCF-7. In the present study, the rapid annotation of the mixture of compounds in a fraction by the NMR-based machine learning tool helped the targeted isolation of bioactive compounds from natural products.