Stereoisomers of Eudesmane Sesquiterpene From Cleome droserifolia.

The present study reports the chemical investigation on the aerial parts of Cleome droserifolia yielding the related eudesmane sesquiterpene solyraterpenoid A (1) and the novel cledrone A (2) from the acetonitrile fraction of the dichloromethane extract. These compounds were separated by column chromatography, centrifugal thin layer chromatography (CTLC) followed by semipreparative reversed-phase high performance liquid chromatography (RP-HPLC). The chemical structure of these compounds was determined by mono and bidimensional NMR techniques, IR spectroscopy, and HRESIMS, while the absolute configuration was established by computational analysis of ECD spectra. Furthermore, the structure and absolute configuration of both 1 and 2 were unambiguously confirmed via single crystal X-ray diffraction (scXRD). Both compounds showed antibacterial activity against Escherichia coli and Pseudomonas aeruginosa strains, with compound 2 being more active.