Misassigned natural products and their revised structures

Natural products are a major pipeline for drug development and are responsible for more than 50 % of drugs on the market. NMR is a fundamental and powerful tool for the structure determination of natural products. It is essential to provide unambiguous chemical structure information on natural products in drug development research, including the structure–activity relationship, derivatization and pharmacokinetic/pharmacodynamic studies. Advancement of NMR instruments has made it possible to deal with nanomole-scale natural products for structure elucidation, but misinterpretation of NMR spectra still occurs. We review 21 natural products with revised chemical structures and the methods used for those revisions.