DFT Calculations and ROESY NMR Data for the Diastereochemical Characterization of Cytotoxic Tetraterpenoids from the Oleoresin of Abies balsamea
Serge Lavoie, Charles Gauthier, Vakhtang Mshvildadze, Jean Legault, Benoit Roger, André Pichette
Journal of Natural Products
Eight non-carotenoid tetraterpenoids, abibalsamins C–J (3–10), were isolated from the oleoresin of Abies balsamea. Their chemical structures were determined based on analysis of 1D/2D NMR and MS data. The assignment of their relative configurations was accomplished using homonuclear coupling constants in tandem with ROESY data. However, the presence of two stereogenic centers on a flexible side chain complicated the characterization. In silico models and ROESY data were analyzed in order to assign relative configurations of the isolated tetraterpenoids. Abibalsamins B and H–J showed moderate cytotoxicity against human A549 lung carcinoma cells, with IC50 values ranging between 6.7 and 10 μM.
Circular dichroism, Absolute configuration, Natural products