Meroterpenoids from the alga-derived fungi Penicillium thomii Maire and Penicillium lividum Westling

Ten new austalide meroterpenoids (1-10) were isolated from the alga-derived fungi Penicillium thomii KMM 4645 and Penicillium lividum KMM 4663. Their structures were elucidated by extensive spectroscopic analysis and by comparison with related known compounds. The absolute configurations of some of the metabolites were assigned by the modified Mosher's method and CD data. Compounds 1, 2, 8, and 9 were able to inhibit AP-1-dependent transcriptional activity in JB6 Cl41 cell lines at noncytotoxic concentrations. Austalides 1-5, 8, and 9 exhibited significant inhibitory activity against endo-1,3-β-D-glucanase from a crystalline stalk of the marine mollusk Pseudocardium sachalinensis.

Quinone-carbohydrate nonglucoside conjugates as a new type of cytotoxic agents: synthesis and determination of in vitro activity

We have found that 2-methoxy-1,4-naphthoquinones easily react with primary alcohols to produce the corresponding 2-alkoxyderivatives. Using this reaction, we synthesized methyl-6-O-(naphthalene-1,4-dione-2-yl)-α-D-glucopyranosides, a new type of water soluble quinone-carbohydrate nonglucoside conjugates. The resulting conjugates induced apoptosis in human cancer HeLa and normal mouse JB6 P(+) Cl41 cells with simultaneous inhibition of p53-dependant transcriptional activity, suggesting that the observed cell death was p53-independent. Furthermore, we analyzed structure-activity relationship and bioactivity of 2-hydroxy- and 2-methoxy-1,4-naphthoquinones as well as carbohydrate nonglucoside conjugates. All compounds containing a quinone moiety were able to inhibit p53-dependant transcriptional activity and exerted moderate inhibitory effects on HeLa cell colony formation. Investigations of structure-activity relationships revealed that cytotoxicity depended on the type of substituent at C-2 of the quinone moiety, decreasing in the following order: methoxyderivatives > carbohydrate nonglucoside conjugates > hydroxyderivatives. Furthermore, cytotoxicity depended on the position of the hydroxy substituent in the quinone moiety in all derivatives and decreased in the following order: 8- > 5- > 5,8-derivatives. In conclusion, this is the first report on synthesis and biological structure-activity relationships of the new class of quinone-carbohydrate nonglucoside conjugates.

Activity of aaptamine and two derivatives, demethyloxyaaptamine and isoaaptamine, in cisplatin-resistant germ cell cancer

We analyzed the effects of all three marine alkaloids aaptamine, demethyloxyaaptamine and isoaaptamine in NT2-R, a cisplatin-resistant subline of the human embryonal carcinoma cell line NT2. All aaptamines were found to be equally effective in both cell lines, excluding cross-resistance between aaptamines and cisplatin in vitro. At the inhibitory concentration (IC50), aaptamine exerted an antiproliferative effect, whereas demethyloxyaaptamine and isoaaptamine were strong inducers of apoptosis. We analyzed the changes in the proteome of NT2-R cells treated with these compounds. 16-22 proteins were found to be significantly altered, of which several were validated by Western blotting and two-dimensional Western blotting analysis. Changes in the proteome pattern frequently resulted from post-transcriptional protein modifications, i.e. phosphorylation or hypusination in the case of eIF5A. Although the lists of altered proteins were heterogeneous and compound-specific, gene ontology analyses identified rather similar profiles regarding the affected molecular functions. Ingenuity pathway analysis by IPA put the following factors in a central position of the hypothetical networks: myc and p53 for aaptamine; tumor necrosis factor (TNF) for demethyloxyaaptamine; and all three, myc, p53, and TNF for isoaaptamine. Our results represent an important step towards a better understanding of the molecular basis underlying the observed bioactivity of these promising marine compounds.

BIOLOGICAL SIGNIFICANCE

We characterized the mode of action of three aaptamines, marine natural compound with anti-tumor activity, using a functional proteomics approach and the cisplatin-resistant pluripotent human embryonal carcinoma cell line NT2-R. The manuscript is of particular scientific interest, as we could reveal the similarities and differences of the modes of action. Furthermore, we were able to identify several new targets of these promising compounds. We found hypusination of eIF5A to be a prominent feature exclusively of aaptamine treatment, as this was not observed upon treatment with demethyloxyaaptamine or isoaaptamine. Our results are a step towards unraveling the mode of action of these interesting compounds.

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.

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 mass spectrometric data. Compounds 1 and 2 exhibited cytotoxic activities against human breast cancer MDA-MB-231 cells with IC50 values of 8.2 μM and 4.3 μM, respectively.

Isolation, structures, and biological activities of triterpenoids from a Penares sp. marine sponge

Six new triterpenoids (1-6) and the previously known penasterone, acetylpenasterol, and ergosta-4,24(28)-dien-3-one were isolated from a Penares sp. sponge collected from Vietnamese waters. Structures of the obtained compounds were established by extensive 1D and 2D NMR spectroscopy and mass spectrometry. Configurations of the triterpene epoxy lactones (1-4) were determined on the basis of NOESY and CD data and calculation of spin coupling constants and confirmed by X-ray crystallographic analysis of compound 2. The isolated triterpenoid 6 was cytotoxic against human leukemia HL-60 cells (IC₅₀ = 9.7 μM).

A New Antimicrobial and Anticancer Peptide Producing by the Marine Deep Sediment Strain “Paenibacillus profundus” sp. nov. Sl 79

A new linear glyceryl acid derived heptapeptide (1), together with known isocoumarin antibiotic, Y-05460M-A (2), were isolated from the culture of the deep sea sediment strain Sl 79 classified as “ Paenibacillus profundus” sp. nov. Their structures were determined by 1D- and 2D- NMR techniques and ESI-MS/MS experiments. HPLC analysis of the Marfey derivatives in comparison to their analogs of authentic amino acids revealed that all amino acids in peptide 1, with an exception of Val, have the D-configuration. The compound 1 showed inhibitory activity against Staphylococcus aureus, Staphylococcus epidermidis, Bacillus subtilis, Enterococcus faecium as well as cytotoxic and moderate colony growth inhibitory activity against SK-MEL-28 cell line.

A new antimicrobial and anticancer peptide producing by the marine deep sediment strain "Paenibacillus profundus" sp. nov. Sl 79

A new linear glyceryl acid derived heptapeptide (1), together with known isocoumarin antibiotic, Y-05460M-A (2), were isolated from the culture of the deep sea sediment strain SI 79 classified as "Paenibacillus profundus" sp. nov. Their structures were determined by 1D- and 2D- NMR techniques and ESI-MS/MS experiments. HPLC analysis of the Marfey derivatives in comparison to their analogs of authentic amino acids revealed that all amino acids in peptide 1, with an exception of Val, have the D-configuration. The compound 1 showed inhibitory activity against Staphylococcus aureus, Staphylococcus epidermidis, Bacillus subtilis, Enterococcus faecium as well as cytotoxic and moderate colony growth inhibitory activity against SK-MEL-28 cell line.

Mycalamide A shows cytotoxic properties and prevents EGF-induced neoplastic transformation through inhibition of nuclear factors

Mycalamide A, a marine natural compound previously isolated from sponges, is known as a protein synthesis inhibitor with potent antitumor activity. However, the ability of this compound to prevent malignant transformation of cells has never been examined before. Here, for the first time, we report the isolation of mycalamide A from ascidian Polysincraton sp. as well as investigation of its cancer preventive properties. In murine JB6 Cl41 P⁺ cells, mycalamide A inhibited epidermal growth factor (EGF)-induced neoplastic transformation, and induced apoptosis at subnanomolar or nanomolar concentrations. The compound inhibited transcriptional activity of the oncogenic nuclear factors AP-1 and NF-κB, a potential mechanism of its cancer preventive properties. Induction of phosphorylation of the kinases MAPK p38, JNK, and ERK was also observed at high concentrations of mycalamide A. The drug shows promising potential for both cancer-prevention and cytotoxic therapy and should be further developed.

Proteomic profiling of germ cell cancer cells treated with aaptamine, a marine alkaloid with antiproliferative activity

Aaptamine is a marine compound isolated from the sponge Aaptos aaptos showing antiproliferative properties via an undefined mode of action. We analyzed the effects of aaptamine treatment on the proliferation and protein expression of the pluripotent human embryonal carcinoma cell line NT2. Effects on proliferation, cell cycle distribution, and induction of apoptosis were analyzed. At lower concentrations, including the IC50 of 50 μM, aaptamine treatment resulted in a G2/M phase cell cycle arrest, whereas at higher concentrations, induction of apoptosis was seen. Differentially expressed proteins were assessed by 2D-PAGE and mass spectrometry, followed by verification and analysis of protein modifications of the most significantly up- and down-regulated proteins. Aaptamine treatment at the IC50 for 48 h resulted in alteration of 10 proteins, of which five each showed up- and down-regulation. Changes in the 2D map were frequently noticed as a result of post-transcriptional modifications, e.g., of the hypusine modification of the eukaryotic initiation factor 5A (eIF5A). Observed alterations such as increased expression of CRABP2 and hypusination of eIF5A have previously been identified during differentiation of pluripotent cells. For the first time, we describe changes in protein expression caused by aaptamine, providing valuable information regarding the mode of action of this compound.

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.

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.

Monanchocidin: a new apoptosis-inducing polycyclic guanidine alkaloid from the marine sponge Monanchora pulchra

Monanchocidin (1), a guanidine alkaloid with an unprecedented skeleton system derived from a polyketide precursor, (ω-3)-hydroxy fatty acid, and containing a 2-aminoethyl- and 3-aminopropyl-substituted morpholine hemiketal ring, has been isolated from the sponge Monanhora pulchra. The structure of 1 was assigned on the basis of detailed analysis of 1D and 2D NMR spectra, mass spectrometry, and results of chemical transformations. Compound 1 shows pro-apoptotic and cytoxic activities.

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.

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.

Aaptamine Alkaloids from the Vietnamese Sponge Aaptos sp

A series of aaptamines, including one new alkaloid (1), were isolated from the marine sponge Aaptos sp. collected in Vietnamese waters. The structure of 1 was elucidated using NMR and HRESIMS, as well as by chemical transformation of 1 to the previously known aaptamine and established as 3-N-morpholinyl-9-demethyl(oxy)aaptamine. The isolated compounds showed a potential cancer preventive activity.

Aaptamine alkaloids from the Vietnamese sponge Aaptos sp

A series of aaptamines, including one new alkaloid (1), were isolated from the marine sponge Aaptos sp. collected in Vietnamese waters. The structure of 1 was elucidated using NMR and HRESIMS, as well as by chemical transformation of 1 to the previously known aaptamine and established as 3-N-morpholinyl-9-demethyl(oxy)aaptamine. The isolated compounds showed a potential cancer preventive activity.