Studies on the Constituents of Scutellaria Species. XVIII. Structures of Neoclerodane-Type Diterpenoids from the Whole Herb of Scutellaria rivularis WALL.

Abstract

Five neoclerodane-type diterpenoid lactones, scuterivulactones A, B, C₁, C₂ and D, have been isolated (scuterivulactone C₂ was separated as the acetate) from the whole herb of Scutellaria rivularis WALL. (Labiaceae), and their structures have been determined based on chemical and physicochemical evidence as follows : scuterivulactone A, (4S, 11S)-11-acetoxy-6α-benzoyloxy-3, 4-epoxy-8β-hydroxy-13(14)-neocleroden-15, 16-olide; scuterivulactone B, (4R, 13R)-11β-acetoxy-6α-benzoyloxy-8β, 13-epoxy-3-oxo-15, 16-neoclerodanolide; scuterivulactone C₁, (4R, 13R)-11β-acetoxy-6α-benzoyloxy-3α, 4β-dihydroxy-8β, 13-epoxy-15, 16-neoclerodanolide; scuterivulactone C₂, (4R^*, 13S^*)-11β-acetoxy-6α-benzoyloxy-3α, 4β-dihydroxy-8β, 13-epoxy-15, 16-neoclerodanolide; and scuterivulactone D, (4R)-6α-benzoyloxy-3α, 4β-dihydroxy-11, 13(14)-neoclerodadien-15, 16-olide.