isoaaptamine and aaptamine

Topics: Animals; Antineoplastic Agents; Apoptosis; Autophagy; Breast Neoplasms; DNA Damage; Dose-Response Relationship, Drug; Female; Flow Cytometry; Humans; Membrane Potential, Mitochondrial; Microscopy, Electron, Transmission; Naphthyridines; Oxidative Stress; Porifera; Reactive Oxygen Species

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.. 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.

Topics: Antineoplastic Agents; Cell Line, Tumor; Cisplatin; Drug Resistance, Neoplasm; Humans; Naphthyridines; Neoplasms, Germ Cell and Embryonal

Aaptamine (1), isoaaptamine (2), and demethylaaptamine (3) were isolated from the marine sponge Aaptossuberitoides collected in Indonesia as inhibitors of the proteasome. They inhibited the chymotrypsin-like and caspase-like activities of the proteasome with IC(50) values of 1.6-4.6 microg/mL, while they showed less inhibition of the trypsin-like activity of the proteasome. The three compounds showed cytotoxic activities against HeLa cells, but their cytotoxicity did not correlate with their potency as proteasome inhibitors, strongly suggesting that their proteasomal inhibitory activity is dispensable to their cytotoxicity.

Topics: Animals; HeLa Cells; Humans; Naphthyridines; Porifera; Protease Inhibitors; Proteasome Inhibitors

Four aaptamines (1-4), 1H-benzo[de][1,6]-naphthyridine alkaloids, were isolated from the marine sponge Aaptos aaptos and their inhibitory activities against sortase A (SrtA), an enzyme that plays a key role in cell wall protein anchoring and virulence in Staphylococcus aureus, were evaluated. Isoaaptamine (2) was a potent inhibitor of SrtA, with an IC(50) value of 3.7+/-0.2 microg/mL. The suppression of fibronectin-binding activity by isoaaptamine (2) highlights its potential for the treatment of S. aureus infections via inhibition of SrtA activity. Our studies have identified a series of SrtA inhibitors, providing the basis for further development of potent inhibitors.

Topics: Aminoacyltransferases; Animals; Anti-Bacterial Agents; Bacterial Proteins; Chromatography, Gel; Chromatography, High Pressure Liquid; Cysteine Endopeptidases; Enzyme Inhibitors; Fibronectins; Microbial Sensitivity Tests; Naphthyridines; Porifera; Protein Binding; Staphylococcus aureus

The marine sponge constituent aaptamine (1) has been converted to the cancer cell growth inhibitor and antibiotic designated hystatin 2 (8a). Herein, we also report results of an initial SAR evaluation of new benzyl derivatives of aaptamine (1). Single benzylation was found to occur at nitrogen N-4 and led to the formation of the 4-benzylaaptamine derivatives 7a-c, whereas double benzylation gave the quaternary 1H-benzo[de][1,6]-naphthyridinium salts 8a-c. The anticancer and antimicrobial properties of these aaptamine derivatives are described. The quaternary ammonium salts 8a (hystatin 2) and 8b exhibited significant inhibitory activity against the murine P388 lymphocytic leukemia and a minipanel of human cancer cell lines. Salts 8a and 8b also had broad spectrum antimicrobial activities and were most potent against Mycobacterium tuberculosis, Neisseria gonorrhoeae, and Micrococcus luteus. Naphthyridinium chloride 8a was selected for further development, and results of an initial cell cycle analysis and a cDNA microarray study showed effects consistent with inhibition of the S-phase of cell growth.

Topics: Animals; Anti-Infective Agents; Antineoplastic Agents; Cell Division; Cell Line, Tumor; Crystallography, X-Ray; Drug Screening Assays, Antitumor; Humans; Mice; Microbial Sensitivity Tests; Molecular Structure; Naphthyridines; Oligonucleotide Array Sequence Analysis; Structure-Activity Relationship

Aaptamine (1) was used as starting material for synthetic transformation to isoaaptamine (2), 9-demethylaaptamine (5), and 4-methylaaptamine (6). A general method for the selective O-demethylation of such 1H-benzo[de][1,6]-naphthyridine (1) marine sponge constituents at position C-9 has been developed. Selective O-demethylation of aaptamine (1) and 1-methylaaptamine (11) with 48% hydrobromic acid led to 9-demethylaaptamine (5) and isoaaptamine (2), respectively. A selection of other aaptamine derivatives were synthesized, and their structures were unambiguously determined by X-ray methods. In addition, their cancer cell growth inhibitory properties were evaluated against the murine P388 lymphocytic cell line and a minipanel of human cancer cell lines. Evaluation as inhibitors of the PKC signal transduction pathway and against a selection of microorganisms was also undertaken. Aaptamine derivatives 3 and 5 had broad-spectrum antimicrobial activities.

Topics: Animals; Antineoplastic Agents; Bacteria; Candida albicans; Cryptococcus neoformans; Drug Screening Assays, Antitumor; Leukemia P388; Mice; Microbial Sensitivity Tests; Molecular Structure; Naphthyridines; Porifera; Structure-Activity Relationship; Tumor Cells, Cultured

A series of 9-O-acylisoaaptamine (3-14) and 4-N-acyl-dihydroaaptamine (16-19) derivatives have been prepared and evaluated for antitumor activity against murine P-388 and human tumor cells including KB16, A549, and HT-29 cell lines. All of compounds showed significant cytotoxicity against P-388 cells. Among them, compounds 9-11 showed potent activity as isoaaptamine (1). There was an apparent lack of linear relationship between cytotoxicity and carbon number of the side chain. The structure and activity relationship for these particular compounds are discussed.

Topics: Animals; Antineoplastic Agents; Drug Screening Assays, Antitumor; Humans; Mice; Molecular Structure; Naphthyridines; Porifera; Spectrum Analysis; Structure-Activity Relationship; Tumor Cells, Cultured