13-Chloro-3-O-β-d-glucopyranosylsolstitialin from Leontodon palisae: the first genuine chlorinated sesquiterpene lactone glucoside

Apart from a number of known sesquiterpenoids, a novel chlorinated sesquiterpene lactone glucoside--13-chloro-3-O-β-d-glucopyranosylsolstitialin--has been isolated from the Southwestern European plant Leontodon palisae (Asteraceae, tribe Lactuceae). The structure has been established by high resolution mass spectrometry and 1D as well as 2D NMR spectroscopy. The compound represents the first naturally occurring chlorinated sesquiterpene lactone glucoside. The cytotoxicity of the new compound and related ones was evaluated using the MTT assay.     

Additional cytotoxic substances isolated from the sponge-derived Gymnascella dankaliensis

A continuous investigation of secondary metabolites produced by the sponge-derived fungus, Gymnascella dankaliensis, has yielded a new polyketide tyrosine derivative, dankastatin C (3) and the known steroid, demethylincisterol A₃ (4), which was originally found from a Homaxinella marine sponge. The stereostructure of the new compound has been determined based on the analysis of 1D and 2D NMR data. Dankastatin C (3) showed potent cell growth inhibitory activity against the murine P388 cell line.     

Novel pyridino-α-pyrone sesquiterpene type pileotin produced by a sea urchin-derived Aspergillus sp.

A new metabolite, pileotin A, was isolated from a strain of Aspergillus fumigatus originally obtained from the sea urchin Toxopneustes pileolus together with the known compound oxalicine B. The relative stereostructure of pileotin A was elucidated based on spectroscopic analyses, including 1D and 2D NMR techniques. This unique pyridino-α-pyrone sesquiterpene type metabolite has spiro-δ-lactone at C-4.     

A novel polyprenylated phloroglucinol, garcinialone, from the roots of Garcinia multiflora

A novel polyprenylated phloroglucinol garcinialone (1) along with a known compound isoxanthochymol (2) have been isolated from the roots of Garcinia multiflora. The structures of 1 and 2 were elucidated spectroscopically, by 1D and 2D NMR and mass spectrometry.     

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.     

Isolation and structure of five lyngbyabellin derivatives from a Papua New Guinea collection of the marine cyanobacterium Lyngbya majuscula

Five new lyngbyabellin analogs along with a known compound, dolabellin, have been isolated from the marine cyanobacterium Lyngbya majuscula collected from Papua New Guinea. The structures of lyngbyabellins E-I were elucidated through extensive spectroscopic analysis, including HR-FABMS and 1D and 2D NMR experiments. The absolute configurations of lyngbyabellin E and H were ascertained by chiral HPLC and GC/MS analysis of degradation products, in combination with NMR experiments. All five lyngbyabellins showed cytotoxicity to NCI-H460 human lung tumor and neuro-2a mouse neuroblastoma cell lines with LC₅₀ values between 0.2 and 4.8 μM.     

A twofold interpenetrating framework based on the α-metatungstates

A new compound based on polyoxometalates, [Cu(bbi)]₅H[H₂W₁₂O₄₀] (1) (bbi=1,1′-(1,4-butanediyl)bis(imidazole)), has been hydrothermally synthesized and characterized by elemental analyses, IR spectroscopy, thermogravimetric analyses, and single X-ray diffraction. Compound 1 shows a twofold 3D+3D topology, and it represents the first interpenetrating network based on the isopolytungstate. The electrochemical property of compound 1 modified carbon paste electrode (1−CPE) was investigated in 1 M H₂SO₄ solution, and the results indicate that 1−CPE exhibits the electrocatalytic activity toward the reduction of bromate and nitrite. Further, the non-isothermal kinetics of the thermal decomposition of compound 1 provides the dynamic parameters E (activation energy) and A (pre-exponential factor) for the pyrolytic reaction of the organic ligands.     

The first A-nor-hippuristanol and two novel 4,5-secosuberosanoids from the Gorgonian Isis hippuris

The first A-nor-hippuristanol, A-nor-22-epi-hippurin-2α-carboxylic acid (1), and two 4,5-secosuberosane sesquiterpenoids, isishippuric acids A and B (2 and 3), have been isolated from the gorgonian coral Isis hippuris. Those structures were deduced by extensive 1D and 2D NMR studies. The structure of 1 was further supported by a single crystal X-ray diffraction analysis. Isishippuric acid B has been shown to exhibit potent cytotoxicity toward a limited panel of cancer cells.     

A xanthone and a polyketide derivative from the leaves of Cassia obtusifolia (Leguminosae)

A new xanthone, 1,8-dihydroxy-3-methoxy-6-methylxantone and a new polyketide derivative, (4R^∗,5S^∗,6E,8Z)-ethyl-4-((E)-but-1-enyl)-5-hydroxypentdeca-6,8-dienoate, together with 20 known secondary metabolites, including 2 steroids, 4 xanthones, 10 anthraquinones, 2 triterpenoids, 1 fatty ester, and (E)-eicos-14-enoic acid, were isolated from the leaves of Cassia obtusifolia. To the best of our knowledge, the last compound was isolated from a natural source for the first time. The structures of all the compounds were elucidated on the basis of 1D and 2D NMR experiments. Some of the compounds were tested against Salmonella typhi, Staphylococcus aureus, Candida albicans ATCC 9002, and Candida tropicalis, they did not show any activity.     

Novel method for the synthesis of functionalized tetrathiafulvalenes, an acceptor-donor-acceptor molecule comprising of two o-quinone moieties linked by a TTF bridge

In search of a synthesis of o-quinone-tetrathiafulvalene-o-quinone triads a novel facile route was developed. Sodium tetrathiooxalate was for the first time used as a synthon in functionalized TTF preparation. The main purpose of this work was to construct an organic compound, which on the one hand possesses a redox-amphotericity, and on the other hand can act as a bridging ligand in construction of linear, 2D and 3D assemblies. Properties of new acceptor-donor-acceptor ligand in respect to application as a building block for the molecular devices have been investigated.     

Polyhydroxylated macrolide isolated from the endophytic fungus Pestalotiopsis mangiferae

A new polyhydroxylated macrolide, named mangiferaelactone (1) was isolated from a solid culture of the endophytic fungus Pestalotiopsis manguiferae, together with ten known compounds [(6S,1′S)-LL-P880α; (6S,1′S,2′R)-LL-P880β; (1′S,2′R)-LL-880γ; (1′R)-dehydropestalotin; (−)-5-carboxylmellein; (−)-5-methylmellein; (−)-5-hydroxylmethylmellein; arabenoic acid; 5,6-dihydro-4-methoxy-2H-pyran-2-one; and the (−)-2-hexylidene-3-methylsuccinic acid]. P. manguiferae was isolated from Hyptis dilatata, a small shrub common in the central region of Panama. The structure of compound 1 was elucidated by a combination of spectroscopic methods (IR, MS, optical rotation, 1D and 2D NMR spectroscopy). The absolute configuration of 1 was established as 4R,7R,8R,9S by application of vibrational circular dichroism (VCD). Compound 1 showed a minimum inhibitory concentration (MIC) of 1.6863 mg/mL against Listeria monocytogenes, and 0.5529 mg/mL against Bacillus cereus. No activity was observed for compound 1 against Plasmodium falciparum or Trypanosoma cruzi; likewise, no cytotoxic activity was observed against A2058 and H522-T1 cells.     

Tragoponol, a dimeric dihydroisocoumarin from Tragopogon porrifolius L.

A phytochemical re-investigation of Tragopogon porrifolius L. (Asteraceae) yielded (7S,15S)-2,4,12-trihydroxy-7-(4-hydroxyphenyl)-10-methoxy-15-(4-methoxyphenyl)-7,8,15,16-tetrahydrodibenzo[c,i][1,7]dioxacyclododecine-5,13-dione, named tragoponol, a dimeric dihydroisocoumarin.The compound, which represents the first of its kind, is comprised of the open-chained forms of two different mono-methoxylated dihydroisocoumarin moieties, scorzocreticin and hongkongenin, which are connected via two ester bonds to form a macrolide with two lactone moieties featuring a 12-membered ring. The structure of the nearly symmetrical compound was established by HR mass spectrometry, CD measurements, and extensive 1D and 2D NMR experiments.     

Toxicity evaluation of single and mixed antifouling biocides measured with acute toxicity bioassays

Antifouling biocides used in boat paints were analyzed with a battery of toxicity bioassays to evaluate the toxic effects of these compounds on Vibrio fischeri, Daphnia magna and Selenastrum capricornotum. The antifoulants tested were Irgarol 1051, Kathon 5287, chlorothalonil, diuron, dichlofluanid, 2-thiocyanomethylthiobenzothiazole (TCMTB) and tributyltin (TBT). In most cases, the sensitivity of the organisms towards the toxicants followed the order: S. capricornotum > D. magna > V. fischeri. Toxicity by concentration level had the following order: TBT=Kathon 5287>chlorothalonil>Irgarol 1051>diuron>dichlofluanid>TCMTB for S. capricornotum. For D. magna (48 h test), the toxicity order of compounds was TBT>Kathon 5287>chlorothalonil>TCMTB>dichlofluanid>Irgarol 1051>diuron. For V. fischeri (30 min test), the compound toxicity had the following order: Kathon 5287>TBT>TCMTB>dichlofluanid>Irgarol 1051>chlorothalonil.Degradation products of Irgarol 1051 and diuron were also tested. Degradation product of Irgarol 1051 was found to be less toxic to the crustacean and the microalga but more toxic to the bacterium. Degradation products of diuron were less toxic to the microalga in comparison with the bacterium. For mixtures of compound, toxicities were additive in only 33% of the cases and 21% of mixtures were less toxic than expected based on the sum of concentrations of toxicants (antagonistic effect). Synergistic enhancements of toxicity were observed for a majority (46%) of the mixtures.The average reproducibility of the EC₅₀ and LOEC measurements was 27, 24 and 28%, respectively, in the V. fischeri, S. capricornotum and D. magna bioassays. For single compound, the reproducibility of EC₅₀ was better than ±20% for a vast majority of the measurements with the V. fischeri system, thus agreeing closely with the reported reproducibility values for this relatively well-known assay.     

Hydrogen cycling induced diffraction peak broadening in C14 and C15 Laves phases

The diffraction peak broadening induced by hydrogen absorption-desorption cycling has been analyzed in four different Laves phase compounds with the C14 and C15 structures. The broadening is due to strain most probably originating from dislocations generated at the interface between the α and β hydride phases in connection with the cell volume difference between the two phases. It has been shown that it is strongly compound dependent. In the case of the C14 structure, the broadening is large and isotropic, and the latter can be related to the isotropy of the elastic constants of the metallic phase. The broadening is less for the compounds with the C15 structure, which can be related to a possibly softer lattice. Better ageing properties after long-term cycling are predicted for this crystal structure.     

Isolation, characterisation and synthesis of an insecticidal tetramethyltetrahydrochromenedione-spiro-bicyclo[3.1.1]cycloheptane from two species of Myrtaceae

A new moderately insecticidal compound, named ficifolidione, has been isolated from the hexane extract of the aerial parts of two species of Myrtaceae, Eucalyptus ficifolia and Kunzea ericoides. Its structure, (1′R,2′R,4R)-4-isobutyl- 6,6,8,8-tetramethyl-2,3,4,8-tetrahydrochromene-5,7-dione-2-spiro-2′-6,6-dimethyl-bicyclo[3.1.1]heptane (1), was confirmed by synthesis from syncarpic acid, isovaleraldehyde and (1S)-β-pinene.     

Microwave and vibrational spectra, ab initio calculations, conformational stabilities and assignments of the fundamentals of the Cs conformer of n-butylgermane

The FT-microwave spectrum of n-butylgermane, CH₃CH₂CH₂CH₂GeH₃ has been investigated from 4000 to 18,000 MHz and the microwave spectra have been observed for all of the five naturally occurring germanium isotopologues for the anti-anti (aa) conformer. The dipole moment for the ⁷⁴Ge containing species has been measured, giving a total dipole moment of 0.881 (26) D. In addition, the vibrational spectrum of n-butylgermane is described. Modestly complete assignments are made for the aa conformer. The relative stabilities of the five conformers are calculated, and the anti-anti (aa) conformer is found to be the most stable in all calculations done. This conclusion is confirmed by the infrared and Raman spectrum of the annealed crystal. The dipole moments of all conformers are calculated to be approximately equal and less than 1 D, ranging from approximately 0.8 to 0.9 D.     

Enantioselective, chemoenzymatic synthesis, and absolute configuration of the antioxidant (−)-gloeosporiol

The natural antioxidant (−)-gloeosporiol, isolated as a peracetylated derivative from a culture of the fungus Colletotrichum gloeosporioides, has been enantioselectively prepared from 3,4-dihydroxybenzaldehyde by means of a chemoenzymatic synthesis. The key intermediate was obtained by resolution with a lipase from Pseudomonas cepacia. Its stereochemistry, initially assigned as R, according to the Kazlaukas empirical rule for secondary alcohols, was independently confirmed by NMR and chirooptic methods. This, in turn, allowed the assignment of compound (−)-1 as (−)-(2S,3R,4R)-2-(3′,4′dihydroxyphenyl)tetrahydrofuran-3,4-diol.     

Infectopyrone, a potential mycotoxin from Alternaria infectoria

A new metabolite, infectopyrone (1), has been isolated from the filamentous fungus Alternaria infectoria. The structure of 1 was elucidated by analysis of 2D NMR spectroscopic data. Compound 1 is an α-pyrone resembling known toxins, and is a useful phenotaxonomic marker for the A. infectoria species-group. Infectopyrone (1) was also produced by species within Stemphyllium and Ulocladium, and found in mouldy food.     

Novel cleavage of (E)-allyl vic-diols to aldehydes using the 2nd-generation Grubbs catalyst

Secondary (E)-allyl vic-diol cleavage in the presence of the 2nd-generation Grubbs catalyst has been developed. The position of a vic-diol adjacent to CC plays a crucial role in the cleavage reaction compared to an alkyl vic-diol based on a model compound.     

Agariblazeispirol C from the cultured mycelia of the fungus, Agaricus blazei, and the chemical conversion of blazeispirol A

Agariblazeispirol C, which has a unique steroidal skeleton, has been isolated from the cultured mycelia of Agaricus blazei (Agaricaceae). The structure of agariblazeispirol C was established to be (23S,24S)-13,23-cyclo-25-hydroxy-14β-methyl-18-nor-des-A-ergosta-5,7,9,11,17(20)-pentaen-22-one by comparison of extensive 1D and 2D NMR spectral data with those of agariblazeispirols A and B. At the same time, agariblazeispirol C was synthesized by the reaction of blazeispirol A with BF₃·OEt₂ along with some interesting compounds.