Structure assignment of 8 alpha-OH phlegmariurine B - A combined NMR and density functional theory investigation

A combined NMR and density functional theory (B3LYP) investigation was carr ied out on a new alkaloid obtained from Huperzia serrata Thunb(Trev.). The theoretical NMR data of 8 alpha - OH phlegmariurine B are in excellent agre ement with the experimental results. The configuration was then established through analysis of the vicinal coupling constants and 2D NMR(NOESY and CO SY) spectra. This work shows that the quantum chemistry study of NMR can se rve as a promising tool in aiding structural assignment of natural products .