Meroantarctines A-C, Meroterpenoids with Rearranged Skeletons from the Alga-Derived Fungus Penicillium antarcticum KMM 4685 with Potent p-Glycoprotein Inhibitory Activity.

New meroterpenoids, meroantarctines A-C (1-3), with unique 6/5/6/6, 6/5/6/5/6, and 6/5/6/5 polycyclic systems were isolated from the alga-derived fungus Penicillium antarcticum KMM 4685. Their structures were elucidated by spectroscopic methods, X-ray diffraction, and quantum chemical calculations. A biogenetic pathway for 1-3 was proposed. Meroantarctines A-C (1-3) inhibited p-glycoprotein activity and could resensitize drug-resistant cancer cells to docetaxel.

New Deoxyisoaustamide Derivatives from the Coral-Derived Fungus Penicillium dimorphosporum KMM 4689.

Seven new deoxyisoaustamide derivatives (1-7) together with known compounds (8-10) were isolated from the coral-derived fungus Penicillium dimorphosporum KMM 4689. Their structures were established using spectroscopic methods, X-ray diffraction analysis and by comparison with related known compounds. The absolute configurations of some alkaloids were determined based on CD and NOESY data as well as biogenetic considerations. The cytotoxic and neuroprotective activities of some of the isolated compounds were examined and structure-activity relationships were pointed out. New deoxyisoaustamides 4-6 at concentration of 1 µM revealed a statistical increase of PQ(paraquat)-treated Neuro-2a cell viability by 30-39%.

Guitarrins A-E and Aluminumguitarrin A: 5-Azaindoles from the Northwestern Pacific Marine Sponge Guitarra fimbriata.

Guitarrins A-E (1-5), the first natural 5-azaindoles, and aluminumguitarrin A (1a), the first aluminum-containing compound from marine invertebrates, were isolated from the sponge Guitarra fimbriata. The structures of these compounds were established using detailed analysis of 1D and 2D NMR data, mass spectra, and X-ray analysis of 1 and 1a. Compound 3 was proved to be a natural inhibitor of alkaline phosphatase.

Zosteropenillines: Polyketides from the MarineDerived Fungus Penicillium thomii.

Twelve new polyketides, zosteropenillines A-L (1-12), together with known polyketide pallidopenilline A (13), were isolated from the ethylacetate extract of the fungus Penicillium thomii associated with the seagrass Zostera marina. Their structures were established based on spectroscopic methods. The absolute configuration of zosteropenilline A (1) as 4R, 5S, 8S, 9R, 10R, and 13S was determined by a combination of the modified Mosher's method, X-ray analysis, and NOESY data. Absolute configurations of zosteropenillines B-D (2-4) were determined by timedependent density functional theory (TD-DFT) calculations of ECD spectra. The effect of compounds 1-3, 7, 8, 10, and 11 on the viability of human drug-resistant prostate cancer cells PC3 as well as on autophagy in these cancer cells and inhibitory effects of compounds 1, 2, and 8-10 on NO production in LPS-induced RAW 264.7 murine macrophages were examined.

Dinuclear oxofluorometallates as a new structural type of d(0) transition metal oxofluoride compound.

Five isomorphous d(0) transition metal oxofluoride compounds A(3)[M(2)O(x)F(11-x)]·(AF)(0.333) (A = K, Rb, NH(4); M = Nb, Mo, W; x = 2, 4) have been synthesized from acid fluoride solutions, and their crystal structures have been determined by single-crystal X-ray diffraction. The basic structural building units are dinuclear M(2)X(11) (dimers) formed from NbOF(5) or Mo(W)O(2)F(4) octahedra connected by the fluorine bridging atom. In the Nb(2)O(2)F(9) dimer, the O atoms occupy apical corners. In the M(2)O(4)F(7) (M = Mo, W) dimers two O atoms are also apically placed, whereas the other two O atoms are statistically disordered in equatorial planes. The arrangement of dimers is so that the hexagonal tunnels containing `free' fluoride ions are formed. During the irradiation process the orthorhombic structure of K(3)Nb(2)O(2)F(9)·(KF)(0.333) transforms into a pseudo-trigonal one with a = 23.15 Å, which is the [101] diagonal of the orthorhombic unit cell. The other four trigonal crystals are merohedral twins.

Dynamic orientational disorder in crystals of fluoroelpasolites, structural refinement of (NH4)3AlF6, (NH4)3TiOF5 and Rb2KTiOF5.

Room-temperature crystal structures of triammonium hexafluoroaluminate, (NH(4))(3)AlF(6) (I), and triammonium oxopentafluorotitanate, (NH(4))(3)TiOF(5) (II), were refined, and the crystal structures of dirubidium potassium oxopentaflourotitanate, Rb(2)KTiOF(5), at 297 K (III) and 218 K (IV) were determined using single-crystal X-ray diffraction techniques. In ammonium fluoroelpasolites [(I) and (II)], the ligand (O, F) atoms are located in the mixed 24e + 96j position of the Fm3m unit cell. The 24e position is occupied by the ligand atoms predominantly in (III) and fully in (IV). 'Ordered' N1 and Rb atoms are tetrahedrally displaced from the 8c position into the 32f site, and the H atoms of the disordered ammonium group N2 are statistically distributed in the 96k and 32f positions. The Ti atoms in (II) and (IV) are shifted from the 4a position to 24e thus allowing identification of the O and F atoms in the octahedron on a local scale. The disorder in the crystals is of a dynamic nature. Unique Raman spectra of Rb(2)KTiOF(5) under the laser beam of 1064 nm indicate fast octahedral reorientations resulting in physical equalizations of the Ti-O and Ti-F distances as well as in the appearance of totally synchronous Ti-O and Ti-F stretching vibrations at 750 cm(-1). This phenomenon is assumed to also take place under X-rays.

Orientational disorder and phase transitions in crystals of dioxofluoromolybdate, (NH4)2MoO2F4.

Dioxotetrafluoromolybdate, (NH(4))(2)MoO(2)F(4), was synthesized in a single-crystal form and its structures [(I) at 297 K and (II) at 223 K] were determined by X-ray diffraction. Two independent states of a cis-MoO(2)F(4) octahedron are characteristic of static and dynamic disorder in structure (I). The dynamically disordered Mo atom is displaced from the symmetry axis producing four possible orientations of an anion that allow O and F atoms to be identified in separate orientations owing to the inherent differences between the Mo-O and Mo-F bonding. After the phase transition at lower temperature, (I) transforms into the statically disordered structure (II) with three possible orientations of the cis-MoO(2)F(4) octahedron. In this case, it also seemed possible to distinguish between O and F atoms on a local scale. H atoms of two independent NH(4) groups in (II) which form bifurcated N-H...F(O) hydrogen bonds were localized.

Ammonium tantalum oxide fluorides: new features of dynamic disorder.

Ammonium fluoride salts of seven- and eight-coordinated tantalum were grown in the form of well shaped single crystals at different pH of solutions, and their crystal structures were determined by X-ray diffraction. The first one, (NH4)3TaOF6, belongs to elpasolite-type structure (Fm{\overline 3}m, Z = 4) and is characterized by strong dynamic disorder. The ligand atoms (O and F) are each distributed in three positions (one 24e and two 96j). The tantalum atom is seven-coordinated in the form of a pentagonal bipyramid (PB) and occupies the 4a position without leaving the symmetry center of the polyhedron during its fast reorientation. One of the ammonium groups is tetrahedrally disordered (the nitrogen atom is shifted from the 8c into the 32f site), while the other group in the 4b site forms eight spatial orientations due to disordering of hydrogen atoms in the 96k and 32f positions. Strong dynamic disorder of [TaOF6]3- as a flexible unit is reflected in the IR spectrum at 736 cm-1 and in the 19F MAS NMR spectrum at -51 ppm, indicating a state with synchronous stretching vibrations of Ta-O and Ta-F bonds. Two double ammonium fluoride salts of tantalum, which are formed concomitantly, differ slightly in composition but their crystal structures contain the same polyhedra in the form of a mono-capped trigonal prism (CTP or TPRS-7) and a distorted cube (CU or CU-8) with one vacant vertex. The latter tantalum polyhedron is detected for the first time. The CU polyhedron in one of the modifications of the tantalum double salt splits into two CTPs during a phase transition with decreasing temperature. The presence of oxygen in the compounds is confirmed by vibrational spectroscopy.

Fluxional seven-coordinated fluorido- and oxofluoridotantalates.

Seven-coordinated (NH4)2TaF7, Rb2TaF7 and Rb3TaOF6 were synthesized in single-crystal form and their structures were determined. A monocapped trigonal prism (CTP) or a pentagonal bipyramid (PB) of the TaF72- anion are stereochemically nonrigid and coexist in the first two compounds as a result of strong intraspheric dynamics. Upon cooling, tetragonal Rb2TaF7 undergoes a first-order phase transition at 145 K and the seven-coordinated polyhedron transforms into a regular CTP. The seven-coordinated polyhedron in (NH4)2TaF7 approaches the PB configuration as the temperature decreases. Cubic elpasolite-like Rb3TaOF6 is characterized by the simultaneous two-state coexistence of TaOF63- of the PB shape as rigidly reoriented and as fluxional. In the former case, the central atom is disordered over the octahedron in the unit cell, allowing the determination of the short Ta-O distance, whereas in the latter case, tantalum remains in the polyhedron center, resulting in synchronous Ta-O and Ta-F stretching vibrations appearing as the infrared band at 723 cm-1.

Orientational disorder and phase transitions in crystals of (NH4)2NbOF5.

Ammonium oxopentafluoroniobate, (NH(4))(2)NbOF(5), was synthesized in a single-crystal form and the structures of its different phases were determined by X-ray diffraction at three temperatures: phase (I) at 297 K, phase (II) at 233 K and phase (III) at 198 K. The distorted [NbOF(5)](2-) octahedra are of similar geometry in all three structures, with the central atom shifted towards the O atom. The structure of (I) is disordered, with three spatial orientations of the [NbOF(5)](2-) octahedron related by a jump rotation around the pseudo-threefold local axis such that the disorder observed is of a dynamic nature. As the temperature decreases, the compound undergoes two phase transitions. The first is accompanied by full anionic ordering and partial ordering of the ammonium groups (phase II). The structure of (III) is completely ordered. The F and O atoms in the structures investigated were identified via the Nb-X (X = O and F) distances. The crystals of all three phases are twinned.

Disorder in crystals of dioxofluorotungstates, (NH4)2WO2F4 and Rb2WO2F4.

Dioxotetrafluorotungstates (NH4)2WO2F4 and Rb2WO2F4 [(I) at 297 K and (II) at 133 K] and Rb2WO2F4 (III) were synthesized in a single-crystal form and their structures were determined by X-ray diffraction. Two independent states of the cis-WO2F4 octahedron are characteristic of static and dynamic disorder in structure (I). Dynamically disordered W2 is displaced from the symmetry axis producing four possible orientations of anion that permits O and F atoms to be identified in separate orientations owing to the inherent differences between W-O and W-F bonding. After the phase transition at lower temperature (201 K), (I) transforms into the twin structure (II) with complete O/F ordering. Structure (III) is characterized by full O/F static disorder without any phase transitions at lower temperature.