The Structure of Graucin A, a New Bitter Limonoid from Evodia grauca Miq. (Rutaceae)

Abstract Graucin A, a new bitter limonoid, has been isolated from the root bark of Evodia grauca Miq. as well as the known limonoids limonin, rutaevin and limonin diosphenol. Its structural and stereochemical assignments were made using NMR (COSY and NOESY), and CD spectroscopy, which indicated the uncommon 5β-H configuration of this new compound. Rutaevin was also recognized to be a 5β-H limonoid.