A nwel tetraqyclicditerpenoid, sarcophytin (1) has been'vrted km the soft emal, SarcaphykM d~gans and its structureelucidatedby 2D NMRspectraldata and suppwtedby X-rsy analysis. @1997Elsevier$cienceLtd.Allrightsreserved.
In continuationof our itttw-est on the bioactive secondarymetabolizesof the soft corals of the Indian0cean,i2 we have undertakenthe chemical exarnind on oftbe species Sarcophylonelegans collected from Havellock(12" 19'N,93Β°4 8'E) ldand of the Anda&n and Nicobar group of Islands of the Indian ocean. Chemical examinationof this species occurring in diffenmt regions of the Pacitk Ocean has been reported to yield polyhydroxysteroids3Γ£nd cembrattoid diterpenoids.' We now report the isolation of a novel tetracyclic ttit+enoi~named sarcophytin(l),' and its stmctme elucidationby spectmldatSittcludingX-ray analysis. The residue from the ethyl acetate extract of tbe organism on column chromatographyover silica gel fimtished StUCOP@ (L 150mg 0.005~0)>w 162-63"C.[UID25 + 0.238 (c. 0.08, CHG). Its molecnl~fortnula wss SSsig13ed ss CZIH300S by elemental amdysisand 'M+362 in its ElMS. Tbe preame of hydmxylic absoq?ti (3520 CTO"]) ~d *O carbonyls;an c+unssturated ester (1708 cm"')and a six membered saturatedketone (1720 cm") was inf-fkomits IR spectmm. Its UV absorptionat 219 run indicatedconjugatism It exhibited ail the 21 carbon signals in its '3CNMR spatmm, which were analysed by @e DEPT spedrum as five medtyl~four metbyl~six methines and six quatemery carbons. The chemical shifts of the respecdve carbons were assignedbased on the cakwtivities noticed in its 2D NMR(13C-'H COSY)spectmm (TabigII). l%eketo (5 210.0, s) md the ester (COOMe,5165.9 and CoO&@,63.73, s) carbonylswere evident tkomthe 13Cand *HNMR spectra. It also showed a trisubstituted doublebond (5 146.0, d and 130.9, s) supported by the presence of the correapon * olefirtic proton at 87.10 es a singlet mmapon&g to a $-proton of an ct,~-umatumted ester. Its 13CNMR spectmm showedtwo oxygenatedcolons; one at 6105.6 (s) assignakto a doubly oxygenatedcyclicketalcarbon and the other at 679.2 (s) as atetti~catboh. All the five oxygetts of the molede could thus be accountedfor. The molecular formula requiring seven double bond equivalence. three of them being accounted for in the two carbonyl Iimctionalitiesand a double bon~indicated its tetracyclic nature. Its 'H NMR spkctmm revealed its ditmpenoid nature by showing five methyl gr~one ~carbomethoxyl(5 3.73, s), two in isopropylgroup