The chemistry of (Less.) H. Rob. flowers and its antimicrobial activities.

Twenty-one known specialised metabolites were isolated from the flowers of (Less.) H. Rob., the structures of the compounds were established based on 1 D and 2 D NMR spectroscopic experiments. Others 28 compounds were putatively identified using the dereplication technique by UHPLC-HRMS/MS. Twenty-three of the compounds are being reported for the first time in this species. The mixture of sesquiterpene lactones piptocarphins A and B (), and the flavone velutin () were tested against several microorganisms and showed promising activity against with MIC of 15.6 μg/mL and 31.2 μg/mL, respectively. Furthermore, showed greater cytotoxicity against VERO cells (IC = 7.0 ± 1.73) compared to compound (IC 85.0 ± 10.6 µg/mL). These findings reveal the feasibility of using the UHPLC-ESI-HRMS/MS-based dereplication strategy in complex fractions to identify specialised metabolites, moreover to flowers being a source of compounds with antimycobacterial potential.