Aaptocarbamates A-G, chlorinated terpene carbamates with antiosteoclastogenic activities from the marine sponge Aaptos sp.

Six undescribed chlorinated sesquiterpene carbamates, aaptocarbamates A-F, and a chlorinated tris-norsesquiterpene carbamate, aaptocarbamate G, were isolated from the marine sponge Aaptos sp. collected in Indonesia. Aaptocarbamates D-F and G possess tetrahydrofurans and a tetrahydrofuranone, respectively. The relative configurations of the tetrahydrofuran units were determined by the NOE correlations and DFT-based calculation of the 13C chemical shifts. This is the first time that chlorinated terpene carbamates have been reported from natural sources. Various aaptamine derivatives have been reported from the Aaptos sponges so far, the isolation of chlorinated terpene carbamates is very rare. Aaptocarbamates A, B, and D showed 60% inhibition of the RANKL-induced formation of multinucleated osteoclasts in RAW264 macrophages at 20 µM.

Cyclopsammocinamides A and B, Enantiomeric Cyclic Peptides of Cyclocinamide A, from the Marine Sponge Psammocinia sp.

LC-MS and molecular networking analyses of the extract of the marine sponge Psammocinia sp. indicated the presence of two new compounds with multiple halogens. LC-MS-guided isolation yielded cyclic peptides, cyclopsammocinamides A (1) and B (2), in an enantiomeric relationship to cyclocinamide A (3). Planar structures of 1 and 2 were elucidated by NMR and mass spectroscopic analyses and the absolute configurations of the amino acid residues were determined using Marfey's method with their acid hydrolysates. The sponge extract exhibited cytotoxicity and the bioassay-guided isolation afforded a dimeric dilactone macrolide, swinholide A, as the cytotoxic compound.

Phytochemical and Antioxidant Activities of Eucheuma spinosum as Natural Functional Food from North Sulawesi Waters, Indonesia.

BACKGROUND AND OBJECTIVE: Research to find functional food from new natural sources has caught the attention of many researchers through the characterization of phytochemicals and biological activities. One potential source of natural ingredients is the red alga Eucheuma spinosum, which has been used as a daily source of natural food. The purpose of this study was to obtain a prospective new source of natural antioxidants from various extracts of tropical red alga (E. spinosum) through several tests, which were used as determinants of whether the alga can be used as a functional food source. MATERIALS AND METHODS: Algal sample was extracted with organic solvents (methanol, n-hexane, ethyl-acetate and water) and purified by a combination of normal and reverse phase chromatography methods. RESULTS: The algal extracts had antioxidant compounds based on free radical scavenging activities using 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) and superoxide dismutase (SOD). The ethyl acetate extract of E. spinosum scavenged DPPH and SOD free radicals, so that this extract was indicated contained powerful antioxidants. The result of the isolation of the antioxidant compound showed the presence of pure compound 3-(3-methoxyphenyl) propanal. CONCLUSION: This study concluded that red algae E. spinosum contained natural antioxidants which have the potential to be developed as a functional food and disease prevention and treatment. In addition, the components of these antioxidant compounds from the algae have the potential to be used as natural sources of new functional ingredients.

Fluorescent image-based high-content screening of extracts of natural resources for cell cycle inhibitors and identification of a new sesquiterpene quinone from the sponge, Dactylospongia metachromia.

Natural products are important sources for drug development. Discovery of natural products that inhibit cell cycle progression significantly contributes to the progress of cancer biology and the development of new antitumor agents. In this study, cell cycle inhibitory activity was evaluated with our extract library of natural resources, including marine invertebrates, fungi, and bacteria, using HeLa/Fucci2 cells which allow classification of the cell cycle phases of living cells. Screening of the extract library revealed that the extract of the marine sponge Dactylospongia metachromia inhibited cell cycle progression at S/G2/M phases. Bioassay-guided fractionation afforded a new sesquiterpene quinone, neoisosmenospongine (1), and four known compounds, nakijiquinone I, N, and Q (2-4) and (-)-dictyoceratin-C (5). The chemical structure of 1 was elucidated by interpretating the NMR and mass spectroscopic data, and the absolute configuration was determined by comparison of the experimental and calculated ECD spectra. Fluorescent imaging of HeLa/Fucci2 cells revealed that 1-4 inhibited the cell cycle progression at S/G2/M phases. This study demonstrated that fluorescent image-based high-content screening using HeLa/Fucci2 cells is an effective approach for isolating cell cycle inhibitors from natural resources.

Absolute Structures of Wedelolide Derivatives and Structure-Activity Relationships of Protein Tyrosine Phosphatase 1B Inhibitory ent-Kaurene Diterpenes from Aerial Parts of Wedelia spp. Collected in Indonesia and Japan.

Two sesquiterpene lactones with the (9R)-eudesman-9,12-olide framework, wedelolides I and J, have been isolated together with five eudesmanolide sesquiterpenes and twelve ent-kaurene diterpenes from the aerial parts of Indonesian Wedelia prostrata. The absolute configurations of wedelolides I and J, proposed in the previous communication, were proven by comparing their experimental Electronic Circular Dichroism (ECD) spectra with the calculated ECD spectrum of wedelolide I. The phytochemical study on the aerial parts of Okinawan Wedelia chinensis led to the isolation of three other eudesmanolide sesquiterpenes in addition to the three sesquiterpenes and eleven diterpenes isolated from the Indonesian W. prostrata as above. However, the wedelolide derivatives found in the Indonesian plant were not detected. Among these compounds, most of the diterpenes inhibited protein tyrosine phosphatase (PTP) 1B activity, and a structure-activity relationship study revealed that the cinnamoyl group enhanced inhibitory activity. Therefore, two ent-kaurene derivatives with and without a cinnamoyl group were examined for the ability to accumulate phosphorylated-Akt (p-Akt) because PTP1B dephosphorylates signal transduction from the insulin receptor such as phosphorylated Akt, a key downstream effector. However, neither compound enhanced insulin-stimulated p-Akt levels in two human hepatoma cell lines (Huh-7 and HepG2) at non-cytotoxic doses.

New geranyl flavonoids from the leaves of Artocarpus communis.

Four new geranyl flavonoids 1-4 and four known flavonoids 5-8 were obtained from the leaves of Artocarpus communis collected in Indonesia. The planar structures of flavonoids were elucidated by analyses of MS and NMR spectroscopic data. Absolute configurations of 1 and 2 were determined by ECD spectroscopy. Analyses by HPLC with a chiral-phase column and ECD spectra confirmed that 3 and 4 were stereoisomeric mixtures and 7 and 8 were racemic mixtures. The compounds obtained in this study inhibited the enzymatic activities of ubiquitin-specific protease 7 (USP7) and the chymotrypsin-like activity of the proteasome. Among the geranyl flavonoids tested in this experiment, the USP7 inhibitory activity of 6 (IC50 value, 0.094 µM) was 55 times more potent than the commercially available positive control, P5091 (IC50 value, 5.2 µM).

Oleanane triterpenes with protein tyrosine phosphatase 1B inhibitory activity from aerial parts of Lantana camara collected in Indonesia and Japan.

During the search for new protein tyrosine phosphatase (PTP) 1B inhibitors, EtOH extracts from the aerial parts of Lantana camara L. (lantana) collected at Manado (Indonesia) and two subtropical islands in Japan (Ishigaki and Iriomote Islands, Okinawa) exhibited potent inhibitory activities against PTP1B in an enzyme assay. Four previously undescribed oleanane triterpenes were isolated together with known triterpenes and flavones from the Indonesian lantana. The EtOH extracts of lantana collected in Ishigaki and Iriomote Islands exhibited different phytochemical profiles from each other and the Indonesian lantana. Triterpenes with a 24-OH group were isolated from the Indonesian lantana only. Five known triterpene compounds were detected in the Ishigaki lantana, and two oleanane triterpenes with an ether linkage between 3ß and 25 were the main components together with five known triterpenes as minor components in the Iriomote lantana. The structures of previously undescribed compounds were assigned on the basis of their spectroscopic data. Among the compounds obtained in this study, oleanolic acid exhibited the most potent activity against PTP1B, and is used as a positive control in studies on PTP1B.

Ceylonins A-F, Spongian Diterpene Derivatives That Inhibit RANKL-Induced Formation of Multinuclear Osteoclasts, from the Marine Sponge Spongia ceylonensis.

Six new spongian diterpene derivatives, ceylonins A-F (1-6), were isolated from the Indonesian marine sponge Spongia ceylonensis along with spongia-13(16),14-dien-19-oic acid (7). They contained three additional carbons in ring D to supply an ether-bridged bicyclic ring system. Their structures were elucidated by analyzing NMR spectroscopic data and calculated ECD spectra in comparison to experimental ECD spectra. The bicyclic ring system may be derived from the major metabolite 7 and a C3 unit (an acrylic acid equivalent) through an intermolecular Diels-Alder reaction, which was experimentally supported by the formation of 1-6 from 7 and acrylic acid. The inhibitory effects of the isolated compounds on the RANKL-induced formation of multinuclear osteoclasts in RAW264 macrophages were examined.

Bastadins, brominated-tyrosine derivatives, suppress accumulation of cholesterol ester in macrophages.

The formation of foam cells in macrophages has been suggested to play an essential role in the progression of early atherosclerotic lesions in vivo and, thus, its suppression is considered to be one of the major approaches for the treatment of atherosclerosis. We isolated eight brominated-tyrosine derivatives, bastadins, from the EtOH extract of the marine sponge Ianthella vasta as inhibitors of the formation of foam cells induced by acetylated low-density lipoproteins in human monocyte-derived macrophages. Bastadin 6 was the strongest inhibitor of foam cell formation due to its suppression of acyl-coenzyme A:cholesterol acyltransferase.

Strongylophorines, meroditerpenoids from the marine sponge Petrosia corticata, function as proteasome inhibitors.

Two new strongylophorine derivatives, along with six known strongylophorines, were isolated from the marine sponge Petrosia corticata as proteasome inhibitors. Of these, a hemiacetal mixture of strongylophorines-13/-14 was the strongest inhibitor of the proteasome with an IC50 of 2.1µM.

Manadodioxans A-E: polyketide endoperoxides from the marine sponge Plakortis bergquistae.

Five new polyketide endoperoxides, manadodioxans A-E, were isolated from the marine sponge Plakortis bergquistae. Manadodioxan E showed antimicrobial activity against Escherichia coli at 10 µg/disk, while its oxo congener, manadodioxan D, was inactive.

Halenaquinone inhibits RANKL-induced osteoclastogenesis.

Halenaquinone was isolated from the marine sponge Petrosia alfiani as an inhibitor of osteoclastogenic differentiation of murine RAW264 cells. It inhibited the RANKL (receptor activator of nuclear factor-κB ligand)-induced upregulation of TRAP (tartrate-resistant acid phosphatase) activity as well as the formation of multinuclear osteoclasts. In addition, halenaquinone substantially suppressed RANKL-induced IκB degradation and Akt phosphorylation. Thus, these results suggest that halenaquinone inhibits RANKL-induced osteoclastogenesis at least by suppressing the NF-κB and Akt signaling pathways.

Acantholactam and pre-neo-kauluamine, manzamine-related alkaloids from the Indonesian marine sponge Acanthostrongylophora ingens.

Two new manzamine alkaloids, acantholactam (3) and pre-neo-kauluamine (4), were isolated from the marine sponge Acanthostrongylophora ingens along with manzamine A (1) and neo-kauluamine (2). Acantholactam contains a γ-lactam ring N-substituted with a (Z)-2-hexenoic acid moiety and is proposed to be biosynthetically derived from manzamine A by oxidative cleavage of the eight-membered ring. Compound 4 was converted to the dimer 2 during storage, suggesting nonenzymatic dimer formation. Among the four isolated compounds, 1, 2, and 4 showed proteasome inhibitory activity.

Acanthomanzamines A-E with new manzamine frameworks from the marine sponge Acanthostrongylophora ingens.

Five new manzamine alkaloids, acanthomanzamines A-E, were isolated from the marine sponge Acanthostrongylophora ingens. Acanthomanzamines A and B are the first examples, containing a tetrahydroisoquinoline instead of a ß-carboline in manzamine-related alkaloids. Acanthomanzamine C contains a hexahydrocyclopenta[b]pyrrol-4(2H)-one ring that may be converted from an eight-membered ring in manzamine A. Acanthomanzamines D and E have an additional oxazolidine and 2-methyloxazolidine rings, respectively, which fuse to the manzamine skeleton.

Variabines A and B: new ß-carboline alkaloids from the marine sponge Luffariella variabilis.

Two new ß-carboline alkaloids, variabines A (1) and B (2), were isolated from the Indonesian marine sponge Luffariella variabilis. Their structures were elucidated from spectral data, and 1 was found to be a sulfonated derivative of 2. Although numerous ß-carboline alkaloids have been isolated from natural sources to date, 1 is the first ß-carboline derivative containing a sulfate group. Compound 2 inhibited chymotrypsin-like activity of the proteasome and Ubc13 (E2)-Uev1A interaction with IC50 values of 4 and 5 µg/mL, respectively, whereas 1 had little effect on the activity or interaction.

Spongiacidin C, a pyrrole alkaloid from the marine sponge Stylissa massa, functions as a USP7 inhibitor.

USP7, a deubiquitylating enzyme hydrolyzing the isopeptide bond at the C-terminus of ubiquitin, is an emerging cancer target. We isolated spongiacidin C from the marine sponge Stylissa massa as the first USP7 inhibitor from a natural source. This compound inhibited USP7 most strongly with an IC50 of 3.8 µM among several USP family members tested.

Manzamine A, a marine-derived alkaloid, inhibits accumulation of cholesterol ester in macrophages and suppresses hyperlipidemia and atherosclerosis in vivo.

The formation of foam cells in macrophages plays an essential role in the progression of early atherosclerotic lesions and therefore its prevention is considered to be a promising target for the treatment of atherosclerosis. We found that an extract of the marine sponge Acanthostrongylophora ingens inhibited the foam cell formation induced by acetylated low-density lipoprotein (AcLDL) in human monocyte-derived macrophages, as measured based on the accumulation of cholesterol ester (CE). Bioassay-guided purification of inhibitors from the extract afforded manzamines. Manzamine A was the most potent inhibitor of foam cell formation, and also suppressed CE formation in Chinese hamster ovary cells overexpressing acyl-CoA:cholesterol acyl-transferase (ACAT)-1 or ACAT-2. In addition, manzamine A inhibited ACAT activity. Next, we orally administered manzamine A to apolipoprotein E (apoE)-deficient mice for 80 days, and found that total cholesterol, free cholesterol, LDL-cholesterol, and triglyceride levels in serum were significantly reduced and the area of atherosclerotic lesions in the aortic sinus was also substantially diminished. These findings clearly suggest that manzamine A suppresses hyperlipidemia and atherosclerosis in apoE-deficient mice by inhibiting ACAT and is therefore a promising lead compound in the prevention or treatment of atherosclerosis. Although manzamine A has been reported to show several biological activities, this is the first report of a suppressive effect of manzamine A on atherosclerosis in vivo.

Manadosterols A and B, sulfonated sterol dimers inhibiting the Ubc13-Uev1A interaction, isolated from the marine sponge Lissodendryx fibrosa.

Two new dimeric sterols, manadosterols A (1) and B (2), were isolated from the marine sponge Lissodendryx fibrosa collected in Indonesia. The two compounds are comprised of two sulfonated sterol cores connected through the respective side chains. Manadosterols A (1) and B (2) inhibited the Ubc13-Uev1A interaction with IC(50) values of 0.09 and 0.13 µM, respectively. They are the second and third natural compounds showing inhibitory activities against the Ubc13-Uev1A interaction and are more potent than leucettamol A (IC(50), 106 µM), the first such inhibitor, isolated from another marine sponge.

Hyrtioreticulins A-E, indole alkaloids inhibiting the ubiquitin-activating enzyme, from the marine sponge Hyrtios reticulatus.

Hyrtioreticulins A-E (1-5) were isolated from the marine sponge Hyrtios reticulatus, along with a known alkaloid, hyrtioerectine B (6). Structural elucidation on the basis of spectral data showed that 1, 2, and 5 are new tetrahydro-ß-carboline alkaloids, while 3 and 4 are new azepinoindole-type alkaloids. Hyrtioreticulins A and B (1 and 2) inhibited ubiquitin-activating enzyme (E1) with IC(50) values of 0.75 and 11µg/mL, respectively, measured by their inhibitory abilities against the formation of an E1-ubiquitin intermediate. So far, only five E1 inhibitors, panapophenanthrine, himeic acid A, largazole, and hyrtioreticulins A and B (1 and 2), have been isolated from natural sources and, among them, 1 is the most potent E1 inhibitor.