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Nine triterpene saponins, acutangulosides A−F (2−7), and acutanguloside D−F methyl esters (5a−7a) and a single triterpene aglycone (1) were isolated from a water extract of the bark of Barringtonia acutangula. Their structures were assigned on the basis of spectroscopic data.

Three new marine natural products, dysinosins B−D (1−3), were isolated from the sponge Lamellodysidea chlorea and their structures determined by 1D and 2D NMR spectroscopy. These compounds are inhibitors of the blood coagulation cascade serine proteases factor VIIa and thrombin. These analogues, dysinosins B−D (1−3), allowed identification of two structural motifs within the structures that contribute to binding to the proteases, factor VIIa and thrombin.

Naturally occurring cembranes 1−4 have been isolated from a Sarcophyton sp. These compounds have not previously been found to occur in nature but had been obtained as intermediates in a synthetic modification from tobacco. The absolute stereochemistries of 3 and 4 were determined. Compounds 1 and 2 inhibited the binding of [³H]8-cyclopentyl-1,3-dipropylxanthine to rat-brain adenosine A1 receptors.

Chemical investigation of a Great Barrier Reef ascidian, Aplidium tabascum, has resulted in the isolation of three new cis-decahydroquinoline alkaloids, lepadins F−H (4−6). The three new compounds differ from the previously isolated lepadins A−C (1−3) in that they contain a fully saturated 5-hydroxyoctyl side chain attached at C-5, an unsaturated eight-carbon ester moiety attached to C-3, and opposite stereochemistry at C-5 and C-3. Lepadins G (5) and H (6) are epimers at C-2. NMR and molecular modeling studies indicated that the three new compounds adopt a chair−chair conformation in which the nitrogen equatorially substitutes the cyclohexyl ring. This contrasts with lepadins A−C (1−3), which adopt a chair−chair conformation in which the nitrogen axially substitutes the cyclohexyl ring.

Four cheilanthane sesterterpenoids, 25-hydroxy-13(24),15,17-cheilanthatrien-19,25-olide (1), 13,16-epoxy-25-hydroxy-17-cheilanthen-19,25-olide (2), 25-hydroxy-13(24),17-cheilanthadien-16,19-olide (3), and 16,25-dihydroxy-13(24),17-cheilanthadien-19,25-olide (4), were isolated from the marine sponge Ircinia sp. Compounds 1, 3, and 4 are new natural products. The four compounds inhibit MSK1 (mitogen and stress activated kinase) and MAPKAPK-2 (mitogen activated protein kinase activated protein kinase), two protein kinases involved in mitogen and stress signal transduction.

The combined CH2Cl2 and MeOH crude extract of a new species of the marine sponge Dysidea, collected in Northern Australia was found to inhibit the binding of [I125] interleukin-8 [IL-8] to the human recombinant IL-8 receptor type A at 500 μg/mL. Bioassay-guided fractionation led to the isolation of three new polyoxygenated sterols 3, 4, and 5. Their structures were assigned on the basis of 1D and 2D NMR experiments, and relative stereochemistries were established by ROESY correlations and analysis of coupling constants. The IC50 values for inhibition of IL-8Ra for sterols 3, 4, and 5 were 20, 5.5, and 4.5 μM, respectively.

The Australian sea pen Anthoptilum cf. kukenthali has afforded five new briarane-type diterpenes, anthoptilides A−E. Their structures were determined on the basis of their spectroscopic data. Single-crystal X-ray determination was performed on anthoptilide A. Anthoptilides B and C inhibited the binding of [³H]1,3-dipropyl-8-cyclopentylxanthine ([³H]DPCPX) on adenosine A1 receptors.

Chemical investigation of a Great Barrier Reef ascidian, Aplidium longithorax has resulted in the isolation of two new para-substituted cyclofarnesylated hydroquinone compounds, longithorols C (1) and D (2), and a novel macrocyclic chromenol, longithorol E (3). Longithorol C (1) had its absolute stereochemistry determined by the advanced Mosher method and all compounds had their structures determined by interpretation of spectroscopic data.

The CH2Cl2 extract of the marine sponge Xestospongia testudinaria inhibited [³H]DPCPX binding to rat-brain adenosine A1 receptors. Bioassay-guided fractionation led to the isolation of a known brominated acetylenic fatty acid 1 as the active component. Also isolated were two novel sterol esters 2 and 3. All structures were determined on the basis of their spectroscopic data.

Five novel lamellarin-class alkaloids have been isolated from a Great Barrier Reef ascidian, Didemnum chartaceum. The structures of the 20-sulfated derivatives of lamellarins B, C, and L (1−3); the 8-sulfated derivative of lamellarin G (4), plus a nonsulfated compound, lamellarin Z (5), were identified by interpretation of spectroscopic data. Lamellarin G 8-sulfate (4) is the first example of this class of compounds sulfated at the C-8 position, while lamellarin Z (5) is the first example of a dimethoxylated lamellarin. The known lamellarins A, B, C, E, G, and L (6−11), plus the triacetate derivatives of lamellarins D (12) and N (13), were also isolated. An aberration in the integration of signals in the ¹H NMR spectra of the 20-sulfated derivatives of lamellarins B, C, and L (1−3) led to NMR relaxation studies. T1 values were calculated for all protons in the sulfated lamellarins (1−4) and their corresponding nonsulfated derivatives (7, 8, 10, 11). Interestingly, the protons ortho to the sulfate group in compounds (1−4) had T1 values up to five times larger than the corresponding protons in their nonsulfated derivatives (7, 8, 10, 11).