Dictyoneolone,a B/C ring juncture-defused steroid from a Dictyonella sp. sponge

Dictyoneolone (1), a new secosteroid was isolated from a Dictyonella sp. sponge collected from Gageo-do, Korea. Based upon the results of combined spectroscopic analyses, the structure of this compound was determined to possess a highly unusual B/C ring juncture-defused moiety. The configurations of 1 were determined by a combination of proton-proton couplings and NOESY analyses. Dictyoneolone exhibited weak cytotoxicity against the K562 and A549 cancer cell lines.     

Dictyotadimer A, a new dissymmetric bis-diterpene from a brown alga of the genus Dictyota

A phytochemical investigation of a Mediterranean brown alga (Dictyota sp.) led to the isolation of a novel C₄₀bis-diterpene, named dictyotadimer A. The chemical structure of this unusual dissymmetric dimer, characterized by a C-C linkage between two different xenicane units, was elucidated by 1D and 2D NMR analyses together with HR-ESI mass spectrometry. The relative configuration of the two diterpenoid components was determined by NOESY NMR correlations and molecular modeling. A plausible biogenetic pathway of dictyotadimer A was also proposed.     

Suffruticosine, a novel octacyclic alkaloid with an unprecedented skeleton from Securinegasuffruticosa (Pall.) Rehd.

A novel securinega alkaloid, suffruticosine (1), was isolated from the leaves and barks of Securinegasuffruticosa. The structure of 1, characterized by a fused complex octacyclic system, was elucidated by combined spectroscopic techniques, especially 2D NMR and CD spectral analyses.     

Rhamnosylation of lignans by a Streptomyces strain

Screening of 400 Streptomyces strains for biotransformation of the natural lignan matairesinol led to the identification of Streptomyces sp. LS136, capable of producing a single metabolite in moderate yields. Isolation and purification by preparative HPLC, followed by structural analyses by LC-MS and NMR, established the structure as matairesinol-4-O-rhamnoside. This bacterial strain was also used for rhamnosylation of the abundant natural lignans, hydroxymatairesinol and secoisolariciresinol.     

Synthesis of silicated hydroxyapatite Ca10(PO4)6−x(SiO4)x(OH)2−x

The preparation of silicated hydroxyapatite Ca₁₀(PO₄)_6−x(SiO₄)_x(OH)_2−x (SiHA) with 0?x?2 was investigated using a wet precipitation method followed by a heat treatment. X-ray diffraction and Rietveld refinement, Fourier transformed IR (FTIR) spectroscopy, elemental analyses, transmission electron microscopy and thermal analyses were used to characterize the samples. The raw materials were composed of a partially silicated and carbonated apatite and a secondary minor phase containing the excess silicon. Single phase silicated hydroxyapatites, with 0?x?1, could be synthesized after a thermal treatment of the raw powders above 700 °C. The presence of carbonate groups in the raw apatite played an important role in the incorporation of silicates during heating. From the different results, the mechanisms of formation of SiHA are discussed.     

Synthesis and CO2 capture evaluation of Li2−xKxZrO3 solid solutions and crystal structure of a new lithium-potassium zirconate phase

Solid solutions of lithium and potassium metazirconates Li_2−xK_xZrO₃ (where, 0?x?2) were prepared by coprecipitation. Samples were characterized by powder X-ray diffraction, scanning electron microscopy, and thermogravimetric analyses. Results showed that the solubility limits of potassium into Li₂ZrO₃ is x=0.2. Furthermore, at higher potassium concentrations, a new phase was synthesized, Li_2.27K_1.19Zr_2.16O_6.05. For structural studies of this new phase, XRD data were analyzed by Rietveld refinements. Additionally, at high potassium concentrations different phases of ZrO₂ were found, as potassium tends to sublimate. On the other hand, lithium-potassium metazirconate solid solutions, Li_2−xK_xZrO₃, were tested as CO₂ captors. Thermal analyses into a CO₂ flux showed that Li_2−xK_xZr₂O₃ solid solutions present a better CO₂ absorption than Li₂ZrO₃ pure. The differences observed in the CO₂ sorption processes were explained with thermodynamic data.     

Carteraol E, a potent polyhydroxyl ichthyotoxin from the dinoflagellate Amphidinium carterae

Carteraol E (1), C₇₄H₁₂₆O₂₄, a polyhydroxyl ichthyotoxin, was isolated from the lab-cultured marine dinoflagellate Amphidinium carterae. Carteraol E possessed three tetrahydropyrans, and 19 hydroxyl groups on a C69-linear aliphatic chain with a ketone moiety, an exo-methylene, and three methyl branches. The structure was elucidated by extensive analyses of 2D NMR spectra. Cateraol E exhibited potent ichthyotoxicity with LD₅₀ value of 0.28 μM, and antifungal activity against Aspergillus niger.     

Maedamide,a novel chymotrypsin inhibitor from a marine cyanobacterial assemblage of Lyngbya sp.

Maedamide, a novel chymotrypsin-inhibiting depsipeptide, was isolated from a cyanobacterial assemblage that mostly consisted of Lyngbya sp. Its structure was elucidated by spectroscopic analyses and chiral HPLC analyses of hydrolysis products. Maedamide selectively inhibited chymotrypsin but not elastase and trypsin. In addition, Maedamide strongly inhibited the growth of HeLa cells and HL60 cells.     

Tandyukisin,a novel ketoaldehyde decalin derivative,produced by a marine sponge-derived Trichoderma harzianum

Tandyukisin (1), a novel decalin derivative with an enolic β-ketoaldehyde, has been isolated from a strain of Trichoderma harzianum OUPS-111D-4 originally derived from the marine sponge Halichondria okadai, and its structure has been elucidated on the basis of spectroscopic analyses using 1D and 2D NMR techniques. In addition, the absolute configuration for 1 was established by the application of CD spectrum to the tribenzoate derivative. This compounds exhibited moderate cytotoxicity against human cancer cell lines.     

Structural, microstructural and surface properties of a specific CeO2-Bi2O3 multiphase system obtained at 600 °C

Polycrystalline samples of (1−x) CeO₂−x/2 Bi₂O₃ phases, where x is the atom fraction of bismuth have been synthesized by the precipitation process and after the thermal treatment at 600 °C, under air. Samples are first characterized by the X-ray diffraction and scanning electron microscopy. To determine the samples specific surface areas, Brunauer-Emmett-Teller (BET) analyses have been performed. In the composition range 0≤x≤0.20, a cubic solid solution with fluorite structure is obtained. For compositions x comprised between 0.30 and 0.90, two types of T′ (or β′) and T (or β) tetragonal phases, similar to the well-known β′ or β Bi₂O₃ metastable structural varieties, are observed. However, the crystal cell volumes of these β′ or β Bi₂O₃ phases increase with the composition x in bismuth: this might be due to the presence of defects or substitution by cerium atoms, in the tetragonal lattices. Using X-ray diffraction profile analyses, correlations between bismuth composition x and crystal sizes or lattice distortions have been established. The solid-gas interactions between these polycrystalline materials and air-CH₄ and air-CO flows have been studied as a function of temperature and composition x, using Fourier transform infrared (FTIR) analyses of the conversions of CH₄ and CO gases into the CO₂ gas. The transformations of CH₄ and CO molecules as a function of time and temperature are determined through the intensities of FTIR CO₂ absorption bands. Using the specific surface areas determined from BET analyses, these FTIR intensities have been normalized and compared. For all bismuth compositions, a low catalytic reactivity is observed with air-CH₄ gas flows, while, for the highest bismuth compositions, a high catalytic reactivity is observed with air-CO gas flows.     

Aspergiolide A, a novel anthraquinone derivative with naphtho[1,2,3-de]chromene-2,7-dione skeleton isolated from a marine-derived fungus Aspergillus glaucus

Aspergiolide A (1), an anthraquinone derivative with naphtho[1,2,3-de]chromene-2,7-dione skeleton, has been isolated from cultures of a marine-derived fungus Aspergillus glaucus. The structure and stereochemistry of 1 was determined by NMR and X-ray diffraction analyses. Compound 1 showed selective cytotoxicities against A-549, HL-60, BEL-7402, and P388 cell lines.     

Coibanoles, a new class of meroterpenoids produced by Pycnoporus sanguineus

Three new terpenoids of mixed biosynthetic origin were isolated from the culture filtrate of the endophytic fungus Pycnoporus sanguineus. Their structures were determined by extensive spectroscopic analyses. We have named these tricyclic and tetracyclic metabolites ‘coibanoles A-C’ in reference to Coiba Island and Coiba National Park, Panamá, from which the plant and endophyte were collected. The extract was inactive to the human parasites Trypanosoma cruzi, Leishmania donovani, and Plasmodium falciparum at a test concentration of 10 μg/mL.     

Caldorin,a new polyketide from the marine cyanobacterium Caldora penicillata

A new polyketide with a cis-fused decalin ring scaffold, caldorin, was isolated from the marine cyanobacterium Caldora penicillata. The gross structure and relative configuration were elucidated by spectroscopic analyses. We also clarified that caldorin is a weak SOAT inhibitor and moderate osteoblast differentiation inhibitor. On the other hand, caldorin did not exhibit cytotoxicity against either HeLa or HL60 cells.     

Ce10[Si10O9N17]Br, Nd10[Si10O9N17]Br and Nd10[Si10O9N17]Cl oxonitridosilicate halides with a new layered structure type

The isotypic oxonitridosilicate halides Ce₁₀[Si₁₀O₉N₁₇]Br, Nd₁₀[Si₁₀O₉N₁₇]Br and Nd₁₀[Si₁₀O₉N₁₇]Cl were obtained by the reaction of the respective lanthanide metals, their oxides and halides with “Si(NH)₂” in a radiofrequency furnace at temperatures around 1800 °C, using CsBr, resp. CsCl, as a flux. The crystal structures were determined by single-crystal X-ray diffraction (Pbam, no. 55, Z=2; Ce/Br: a=10.6117(9) Å, b=11.2319(10) Å, c=11.688(8) Å, R1=0.0356; Nd/Br: a=10.523(2) Å, b=11.101(2) Å, c=11.546(2) Å, R1=0.0239; Nd/Cl: a=10.534(2) Å, b=11.109(2) Å, c=11.543(2) Å, R1=0.0253) and represent a new layered structure type. The structure refinements were performed utilizing an O/N-distribution model according to Paulings rules, i.e. nitrogen was positioned on all bridging sites and mixed O/N-occupation was assumed on the terminal sites resulting in charge neutrality of the compounds. The layers consist of condensed [SiN₂(O/N)₂] and [SiN₃(O/N)] tetrahedra of Q² and Q³ type. The chemical composition of the compounds was derived from chemical analyses for Nd₁₀[Si₁₀O₉N₁₇]Br and electron probe micro analyses (EPMA) for all three compounds. The results of IR spectroscopic investigations are reported.     

Sinutriangulin A, a novel diterpenoid from the soft coral Sinularia triangula

A novel compound, named sinutriangulin A (1), was isolated from the soft coral Sinularia triangula. The compound possesses a new carbon skeleton that is derived from the cubitane skeleton. The structure was determined by extensive spectroscopic analyses. In addition, compound 1 exhibited weak cytotoxicity toward human tumor cell lines CCRF-CEM and DLD-1.     

(−)-epi-Presilphiperfolan-1-ol, a new triquinane sesquiterpene from the essential oil of Anemia tomentosa var. anthriscifolia (Pteridophyta)

(−)-epi-Presilphiperfolan-1-ol, (1), a new triquinane sesquiterpene, was isolated from the essential oil of Anemia tomentosa var. anthriscifolia by column chromatography. Its structure elucidation was accomplished by extensive 1D- and 2D-NMR analyses, as well as by GC-MS, chiral bidimensional GC, dehydration reactions, and a comparative (GIAO/DFT) theoretical study of the ¹³C NMR chemical shifts of 1 and its known isomers (presilphiperfolan-1-ol (1a), presilphiperfolan-8-ol (3), and presilphiperfolan-9-ol (4)).     

Conformational analysis of bridgehead-substituted bicyclo[m.m.m]alkanes and bicyclo[8.8.n]alkanes

Conformational analyses of bicyclo[m.m.m]alkanes where m=1-10 and of bicyclo[8.8.n]alkanes where n=1-7 bearing methyl groups on the bridgeheads were carried out using a Monte Carlo search strategy. In the bicyclo[m.m.m]alkane series, greater variability was observed for the inter-bridgehead distance for larger values of m. This suggests that properly substituted bicyclo[8.8.8]hexacosanes or larger ring systems might serve as molecular springs.     

Symbiodinolactone A,a new 12-membered macrolide from symbiotic marine dinoflagellate Symbiodinium sp.

A new 12-membered macrolide, symbiodinolactone A, was isolated from the culture broth of symbiotic marine dinoflagellate Symbiodinium sp. The gross structure of symbiodinolactone A was elucidated by spectroscopic analyses, and the relative configuration was elucidated by the J-based configuration analysis and density-functional theory calculations. Symbiodinolactone A is the new 12-membered macrolide possessing an E double bond between C-4 and C-5, a branched methyl group at C-7, and a 1,2,3-trihydroxybutyl group at C-11. Symbiodinolactone A is the first usual size macrolide and the first non-nitrogen-containing macrolide from dinoflagellate Symbiodinium sp. Symbiodinolactone A might be generated by the unexplained dinoflagellate polyketide biosynthetic machinery.     

Identification of the biosynthetic units of Cypridina luciferin in Cypridina (Vargula) hilgendorfii by LC/ESI-TOF-MS

In a luminous ostracod Cypridina (Vargula) hilgendorfii, Cypridina luciferin with an imidazopyrazinone structure (3,7-dihydroimidazopyrazin-3-one) is utilized for the luminescence reaction. To identify the biosynthetic units of Cypridina luciferin, the stable isotope labeled compounds were examined by feeding experiments with living Cypridina specimens. The incorporation of the labeled compounds into Cypridina luciferin was identified by the method of LC/ESI-TOF-MS analyses and these results suggested that l-tryptophan, l-arginine and l-isoleucine are structural units of Cypridina luciferin.     

Amphezonol A, a novel polyhydroxyl metabolite from marine dinoflagellate Amphidinium sp.

Amphezonol A (1), a novel polyhydroxyl linear carbon-chain metabolite, has been isolated from the cultured marine dinoflagellate Amphidinium sp., which was isolated from an Okinawan marine acoel flatworm Amphiscolops sp. The structure of 1 was elucidated by detailed analyses of 2D NMR spectra. Amphezonol A (1) possesses one tetrahydrofuran ring, two tetrahydropyran rings, and twenty-one hydroxyl groups on C₆₀-linear aliphatic chain with one exo-methylene and one methyl branch. Amphezonol A (1) exhibited a modest inhibitory activity against DNA polymerase α.