New beyerane and isopimarane diterpenoids from Rhizophora mucronata

Chemical examination of the ethyl acetate extract of the roots of Rhizophora mucronata collected from Mangalore Coast resulted in the isolation of three more new diterpenoids, rhizophorins C-E (1-3) in addition to the two, rhizophorin A, (6R,11S,13S)-6,11,13-trihydroxy-2,3-seco-14-labden-2,8-olid-3-oic acid, and rhizophorin B, ent-3beta,20-epoxy-3alpha,18-dihydroxy-15-beyerene, recently reported. The structures of the new diterpenoids have been elucidated by a study of their physical and spectral data as 17-hydroxybeyer-15-en-3-one (1), 3beta,17-diacetoxy-15-beyeren-2-one (2) and 3beta,6alpha-diacetoxy-8(14),15-isopimaradien-2-one (3).