Chemical constituents of Indian mangrove plants part 1 - Five diterpenoids(agallochins A-E) from the mangrove plant Excoecaria agallocha Linn

Chemical examination of the hexane extract of the roots of Excoecaria agall ocha Linn collected from the Godavari estuary resulted in the isolation of altogether eleven diterpenoids of which five (1-5) are new. The structures of the new diterpenoids have been elucidated by a study of their physical a nd spectral (UV, IR, H-1, C-13, DEFT, H-1-H-1 COSY, NOESY, HMQC, HMBC and M ASS) data as 3-oxo-ent-13epi-8(13)-epoxy-15-chloro-14-hydroxylabdane (1), e nt-15-chloro-13,14-dihydroxylabd-8(9)-en-3-one (2), ent-15-chloro-labd-8(9) ene-3 alpha ,13,14-trio (3), ent-11 beta -hydroxy-8(14),15-isopimaradien-3- one (4), 8,13-epoxy-3-nor-2,3-seco-14-epilabden-2,4-olide (5). The six know n diterpenoids have been characterised respectively as ent-3-oxo-13-epi-man oyl oxide (6), ent-3 beta -hydroxy-13-epi-manoyl oxide (7), (13R,14S)-ent-8 alpha ,13;14,15-diepoxy-13-epi-labdan-3-one (8), ent-16-hydroxy-3-oxo-13-e pimanoyl oxide (9), ent-15-hydroxylabda-8(17),13E-dien-3-one (10), labda-8( 17),13E-diene-3 beta ,15-diol (11) by a comparative study of their spectral data with the literature values. (C) 2000 Elsevier Science Ltd. All rights reserved.