Dereplication of natural cytotoxic products from Helichrysum oligocephalum using ultra-performance liquid chromatography-quadrupole time of flight-mass spectrometry

In an ongoing project on the Iranian Helichrysum Mill. species (Asteraceae), the phytochemical profiles of the extracts obtained from the flower and leaves of Helichrysum oligocephalum were investigated utilizing ultra-performance liquid chromatography-mass spectrometry (MS) coupled with quadrupole time of flight. In addition, the cytotoxic activity of the extracts was evaluated against different cancerous cell lines by AlamarBlue assay. The apoptotic effects of the fractions were measured by propidium iodide staining and flow cytometry. HPLC-based activity profiling was used to track the cytotoxic constituents. The MS and MSn data were analyzed by MZmine3. Clustering and visualization of the MS data were established by an online platform FreeClust. Concentration-dependent cytotoxicity was observed for dichloromethane fractions. The active constituents were annotated as pyrone and phloroglucinol derivatives by comparing their MS and MSn profiles to an in-house library, available databases, Dictionary of Natural Products, and literature. Additionally, plausible MS fragmentation pathways were suggested for the compounds; this can help in the dereplication process of similar compounds from the genus. In conclusion, this plant is rich in valuable phloroglucinol and pyrone compounds and can be used as a source of active phytochemicals. However, further phytochemical and pharmacological studies are necessary.