Studies on coumarins from the root of Angelica decursiva FR. et SAV. II. Sterostructures of decursin, decursidin, and other new pyranocoumarin derivatives.

Abstract

The stereostructures of pyranocoumarin derivatives named decursin (I), decursidin (II), AD-I (III), AD-II (IV) isolated from the root of the titled plant have been elucidated on the basis of chemical and physicochemical evidence. Decursin is expressed as 3'(S)-senecioyloxy-3', 4'-dihydroxanthyletin (I) and decursidin as -3'(S), 4'(R)-disenecioyloxy-3', 4'-dihydroxanthyletin (II). AD-I has been revealed to be a mixture of two diastereoisomers being isomeric at C-4' and is expressed as 3'(S)-angeloyloxy-4'(R and S)-isovaleroyloxy-3', 4'-dihydroxanthyletin (III). Finally, AD-II has been established to be -3'(S)-angeloyloxy- 4'(R)-senecioyloxy-3', 4'-dihydroxanthyletin (IV) and it has been suggested on the basis of close similarity of the physical properties of AD-II with those of andelin that the structure proposed for andelin by Avramenko, et al. might be revised.