Monanchoxymycalins A and B, New Hybrid Pentacyclic Guanidine Alkaloids from the Far-Eastern Marine Sponge Monanchora pulchra.

The new pentacyclic guanidine alkaloids, monanchoxymycalin A (1) and monanchoxymycalin B (2) were isolated from the Far-Eastern marine sponge Monanchora pulchra. Their structures were assigned on the basis of detailed analysis of lD- and 2D-NMR spectroscopic and mass spectrometric data. Compounds 1 and 2 exhibited potent cytotoxic activities against cervical epithelioid carcinoma HeLa cells and breast adenocarcinoma MDA-MB231 cells.

Absolute Configuration and Body Part Distribution of the Alkaloid 6-epi-Monanchorin from the Marine Polychaete Chaetopterus variopedatus.

As a result of the first study on secondary metabolites from the cosmopolitan bioluminescent marine tube polychaete Chaetopterus variopedatus, a new bicyclic guanidine alkaloid, 6-epi-monanchorin (1), along with the previously known monanchorin (2) were isolated. The structure of 1 was elucidated by spectroscopic and chemical methods, including a cleavage of the C1-07 bond to obtain a secondary alcohol (3), which was used to determine the absolute configurations by Mosher's method. It was found that 1 and 2 were mainly accumulated in a secreted mucus special organ of the worm (food net), where green and blue-green microalgae were detected. A biosynthetic pathway to 6-epi-monanchorin and monanchorin from dietary polyeic fatty acid precursors was proposed.

Gramine-derived Bromo-alkaloids Activating NF--kB-dependent Transcription from the Marine Hydroid Abietinaria abietina.

Two new natural products, 6-bromogramine (1) and bis-6-bromogramine (2) were isolated from the marine hydroid A bietinaria abietina and their structures were established using NMR and MS analysis. Compounds 1 and 2 activate NF-cB-dependent transcriptional activity in JB6 Cl 41 NF-KB cells at 1.6 AM concentrations.

New Derivatives of Natural Acyclic Guanidine Alkaloids with TRPV Receptor-Regulating Properties.

The guanidine alkaloids, dihydropulchranin A (2), prepared from pulchranin A from the sponge Monanchora pulchra, and hexadecylguanidine (3), a synthetic analog of pulchranins, were studied for their TRPV channel-regulating activities. Compound 2 was active as an inhibitor of rTRPV1 and hTRPV3 receptors with EC50 values of 24.3 and 59.1 µM, respectively. Hexadecylguanidine (3) was not active against these receptors.

Normonanchocidins A, B and D, New Pentacyclic Guanidine Alkaloids from the Far-Eastern Marine Sponge Monanchora pulchra.

New pentacyclic guanidine alkaloids, normonanchocidins A, B and D (1-3) along with the earlier known monanchocidin A were isolated from the Far-Eastern marine sponge Monanchora pulchra. Structures of 1-3 were elucidated using ID- and 2D-NMR spectroscopic and mass spectrometric data. Compound 1 and a mixture of 2 and 3 (1:1) exhibited cytotoxic activities against human leukemia THP-1 cells with IC50 values of 2.1 µM and 3.7 µM, respectively, and against cervix epithelial carcinoma HeLa cells with IC50 of 3.8 µM and 6.8 µM, respectively.

Monanchomycalin C, a new pentacyclic guanidine alkaloid from the far-eastern marine sponge Monanchora pulchra.

A new pentacyclic guanidine alkaloid, monanchomycalin C (1), along with the earlier known ptilomycalin A (2), were isolated from the Far-Eastern marine sponge Monanchora pulchra. The structure of 1 was elucidated using 1D and 2D NMR spectroscopic and ma ss spectrometric da ta. Compounds 1 and 2 exhibited cytotoxic activities against human breast cancer MDA-MB-231 cells with IC50 values of 8.2 microM and 4.3 pM, respectively.

Pulchranins B and C, new acyclic guanidine alkaloids from the Far-Eastern marine sponge Monanchora pulchra.

New marine natural products, pulchranins B and C (2 and 3), were isolated from the marine sponge Monanchora pulchra and their structures were established using NMR and MS analysis. Compounds 2 and 3 were moderately active as inhibitors of TRPV1 (EC50 value of 95 and 183 microM, respectively) and less potent against TRPV3 and TRPA1 receptors.

New meroterpenoids from the marine sponge Aka coralliphaga.

Three new sulfated meroterpenoids containing sesquiterpene and hydroquinone moieties, namely siphonodictyal A sulfate (1), akadisulfate A (2) and akadisulfate B (3), along with the known siphonodictyal B3 and bis(sulfato)-cyclosiphonodictyol A were isolated from the sponge Aka coralliphaga. Their structures were elucidated on the basis of spectroscopic data. Akadisulfate B and siphonodictyal B3 showed a radical-scavenging activity comparable with that of the known lipophylic antioxidant BHT.

Determination of absolute stereochemistry of natural alicyclic glycosides by 1H NMR spectroscopy without application of chiral reagents--an indication.

A study has been made of the 1H NMR spectra of peracetylated beta-glucopyranosides and alpha-arabinopyranosides obtained by reaction of D- and L-glucoses, and L- and D-arabinoses with either (R)- or (S)-2-octanols. The obtained and literature data show that 1H NMR spectra may be used to determine the absolute configuration of the aglycone moieties of some alicyclic glycosides without the need to synthesize derivatives with chiral reagents, as long as the absolute configuration of their monosaccharide moiety is known or vice versa. Spectra of marine steroid glycosides and their acetates containing glycosylated side chains as alicyclic fragments were also examined. It was shown that analysis of 1H NMR spectra for the determination of the absolute configuration is more applicable in the cases when glycosides have the same substitution in the D-ring of the aglycone moiety.

Three new aaptamines from the marine sponge Aaptos sp. and their proapoptotic properties.

Three new aaptamine-type alkaloids, 2,3-dihydro-2,3-dioxoaaptamine (1), 6-(N-morpholinyl)-4,5-dihydro-5-oxo-demethyl(oxy)aaptamine (2) and 3-(methylamino)demethyl(oxy)aaptamine (3), along with known aaptamines were isolated from the sponge Aaptos sp. Their structures were determined on the basis of detailed analysis of their 1D and 2D NMR spectroscopic and mass spectral data. The isolated compounds induced apoptosis in human leukemia THP-1 cells.