Tithoniamarin and tithoniamide: a structurally unique isocoumarin dimer and a new ceramide from Tithonia diversifolia

Tithoniamarin (1), a new isocoumarin dimer and a new ceramide, named tithoniamide (2a), have been isolated from Tithonia diversifolia, in addition to the known beta-sitosterol and beta-sitosterol glucopyranoside. The structures were elucidated on the basis of spectroscopic and chemical evidence. Preliminary studies showed that 1 has antifungal and herbicidal activities against Microbotryum violaceum and Chlorella fusca.     

Phenylalanine and arginine adsorption in zeolites X, Y, and Beta

This paper documents a continuation of work published in Langmuir 2005, 21, 8743-8750. We report new aspects of this amino acid adsorption study, including the effect of changing zeolite framework type and results from adsorption of mixed amino acids. In single-amino-acid adsorption experiments, zeolite Y (Si/Al=2.5) was found to adsorb no phenylalanine while admitting arginine to a similar extent as observed with zeolite beta. Using this zeolite Y, we measured mixed-amino-acid separation selectivities for arginine/phenylalanine as large as 25,000 or 2 orders of magnitude larger than the corresponding selectivities measured with zeolite beta.     

Two new antimicrobial metabolites from the endophytic fungus, Seimatosporium sp

Two new acaranoic acids, named seimatoporic acid A and B (1, and 2), together with six known compounds, R-(-)-mellein (3), cis-4-hydroxymellein (4), trans-4-hydroxymellein (5), 4R-hydroxy-5-methylmellein (6), (-)-5-hydroxymethylmellein (7), and ergosterol (8) were isolated from an endophytic fungus, Seimatosporium sp, by a bioassay-guided procedure. The structures of the new compounds have been assigned from analysis of the 1H and 13C NMR spectra, DEPT, and by 2D COSY, HMQC, HMBC and NOESY experiments. A mixture of compounds 1 and 2 showed strong antifungal activity against Botrytis cinerea, Septoria tritici, and Pyricularia oryzae.     

Photo-assisted electron injection at a semiconductor—NH3 interface

Illumination of a p-type semiconductor—NH₃ interface (or heterojunction) with photons of energy greater than the semiconductor band gap causes electrons to be injected into the NH₃. There is no hole injection at a n-type electrode. Suggestions are made for the required energy levels in the liquid.     

Enantioselective synthesis of 3-demethoxyaranciamycinone via asymmetric epoxidation

The tetracyclic olefin 1 was enantioselectively epoxidized using a molybdenum(VI)- oxodiperoxo complex containing a chiral lactamide. Conversion to the glycosides 8 and 9 showed the epoxide 2 to be the predominant (3 : 1) enantiomer.     

Toward a New Test of the Relativistic Time Dilation Factor by Laser Spectroscopy of Fast Ions in a Storage Ring

Hyperfine Interactions - The frequency measurement of Doppler-shifted optical lines of ions circulating in a storage ring at high speed permits a sensitive test of the relativistic Doppler-formula...     

Synthese der citromycinone stereoselektive öffnung eines epoxids zum cis-diol

The citromycinone-derivatives $\text{14}$ and $\text{15}$ have been obtained by intramolecular Marschalk cyclisation of α-hydroxyaldehyde $\text{12}$. An unexpected opening of epoxide $\text{16}$ to $\text{cis}$-diol $\text{14}$ was observed. By exclusion of the alternative formula $\text{2}$ structure $\text{3}$ is proposed for α-citromycinone.     

Absolute configuration of 1β,10β-epoxydesacetoxymatricarin isolated from Carthamus oxycantha by means of TDDFT CD calculations

The absolute configuration of 1β,10β-epoxydesacetoxymatricarin 1, a sesquiterpenoid isolated from Carthamus oxycantha, was established by TDDFT CD calculations in combination with single crystal X-ray analysis. Since the solid-state CD spectrum shows contributions from intermolecular interactions in the crystal, 1 represents a test case for our solid-state CD/TDDFT approach.     

Prenylated anthraquinones and other constituents from the seeds of Vismia laurentii

Two new prenylated anthraquinones, laurenquinone A (1) and B (2) were isolated from the seeds of Vismia laurentii together with four known compounds; xanthone V(1) (3), physcion (4), 3-geranyloxyemodin anthrone (5) and friedelin (6). The structures of the new metabolites were determined with the help of spectroscopic data including extensive 2D-NMR spectroscopy. The known compounds were identified by comparison of their physical and spectroscopic data with those reported in the literature. Compounds 1, 4 and 5 exhibited moderate algicidal activity against Chlorella fusca and 3 showed moderate activity against the gram-positive bacterium Bacillus megaterium.