Five new eunicellin-type diterpenoids, briarellins E--I, along with several known diterpenoids of the asbestinane, briarane and eunicellane classes, were isolated from the Caribbean gorgonian octocoral Briareum asbestinum collected in Puerto Rico. The structures of these compounds were established on the basis of spectroscopic evidence.

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Ten new diterpenoid representatives from the briarane skeletal class have been isolated from shallow water colonies of the Caribbean gorgonian octocoral Briareum asbestinum collected at Mona Island near Puerto Rico. The structures of the new secondary metabolites, named briareins C−L (3−12), were defined by chemical and spectroscopic methods. In addition, two known diterpenoids, briareins A (1) and B (2), were among the most abundant compounds isolated. Traces of another known diterpenoid, briarane methyl ester (13), were also isolated from the same gorgonian extracts. In this paper we also establish unambiguously structure 2 for the known diterpene briarein B.

Sixteen new diterpenoids, representative of the asbestinane skeletal class, have been isolated from shallow water colonies of the Caribbean gorgonian octocoral Briareum asbestinum. The structures of these secondary metabolites, named asbestinin-11 [1], asbestinin-12 [3], asbestinin-13 [4], asbestinin-14 [5], asbestinin-15 [7], asbestinin-16 [8], asbestinin-17 [9], asbestinin-18 [10], asbestinin-19 [11], asbestinin-20 [12], asbestinin-21 [13], asbestinin-22 [14], asbestinin-23 [15], 11-acetoxy-4-deoxyasbestinin E [16], 11-acetoxy-4-deoxyasbestinin F [17] and 4-deoxyasbestinin G [18], were defined by chemical and spectroscopic methods. These specimens of B. asbestinum, collected in Puerto Rico, yielded almost exclusively diterpenoids possessing the asbestinane carbon skeleton thus suggesting minor biosynthetic variations for this gorgonian. In this paper, we also revise the structures of the known asbestinin-6 and asbestinin-7 to asbestinanes 2 and 6, respectively.

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Calyxolanes A (1) and B (2) are rare 1,3-diphenylbutanoid compounds isolated from the marine sponge Calyx podatypa collected in Puerto Rico. Their structures, including relative stereochemistry, have been determined by spectroscopic methods. The unique 2,4-diphenyloxolane function in 1 and 2 was established by 2D 1H-1H and 1H-13C NMR correlation experiments and confirmed by mass spectral analysis. A suggestion is made as to their biogenetic origin.

Three new diterpenoid hexose-glycosides, calyculaglycosides A-C (1-3) were isolated from the Caribbean gorgonian Eunicea sp. Calyculaglycosides A-C are rare diterpene glycosides possessing dilophol (4) aglycones related in biosynthetic origin to the elemene-type glycoside class of potent antiinflammatory agents known as fuscosides. The structures of the new compounds, which were assigned on the basis of spectral studies, were further corroborated by molecular modeling studies. Calyculaglycoside B (2) is an effective topical antiinflammatory agent stronger in potency than the industrial standard indomethacin. Calyculaglycoside B inhibits the synthesis of both prostaglandin PGE(2) and leukotriene LTB(4), suggesting it is a nonselective inhibitor of the 5-lipoxygenase and cyclooxygenase pathways. At concentrations of 10(-4)-10(-5)M, calyculaglycoside B produced LC(50)-level differential responses against a majority of the NCI ovarian cancer lines and several of the renal, prostate, and colon tumor lines.

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