Sponge-Derived Polyunsaturated C16 Di- and Tribromocarboxylic Acids

One previously described and two new bromo-substituted polyunsaturated C₁₆ fatty acids were isolated from an Indonesian sponge, Oceanapia sp. Their common structural feature is an (13E, 15Z)-14,16-dibromodiene terminus. They differ in their C(5) to C(10) portions in unsaturation and halogenation. All three compounds are unstable oils. The mixture exhibits mild cytotoxicity against KB cells.     

Determination of the antiretroviral drug tenofovir in plasma from HIV-infected adults by ultrafast isotope dilution MALDI-triple quadrupole tandem mass spectrometry

A new and reliable mass spectrometric method using an isotope dilution method in combination with matrix-assisted laser desorption/ionization-triple quadrupole tandem mass spectrometry (ID-MALDI-QqQ-MS/MS) has been developed and validated for the determination of concentrations of the antiretroviral drug tenofovir (TNV) in plasma from HIV-infected adults. The advantage of this new method is that (1) the method is ultrafast and (2) can be applied for high-throughput measurement of TNV in plasma. The method is based on a simple plasma deproteinization step in combination with the use of [adenine-(13) C(5) ]-TNV as the internal standard. TNV and [adenine-(13) C(5) ]-TNV were monitored by multiple reaction monitoring using the transition m/z 288.0 → 176.2 and m/z 293.2 → 181.2 for TNV and [adenine-(13) C(5) ]-TNV, respectively. The method was validated according to the most recent FDA guidelines for the development and validation of (new) bio-analytical assays. Validated method parameters were: linearity, accuracy, precision and stability of the method. The lowest limit of quantification was 0.10 μmol/l, whereas the limit of detection determined at a signal-to-noise ratio (S/N = 3:1) in pooled drug free human control plasma was 0.04 μmol/l. The validated method was successfully applied and tested for its clinical feasibility by the analysis of plasma samples from selected HIV-infected adults receiving the prodrug tenofovir disoproxil fumarate. Observed plasma TNV concentrations ranged between 0.11 and 0.76 μmol/l and measured plasma TNV concentrations were within the therapeutically relevant concentration range.     

Application of total-reflection X-ray fluorescence spectrometry in material analysis

X-ray fluorescence spectrometry with total reflection conditions is applied in the qualitative and quantitative determination of impurities in thin layers of Ti, TiO₂, and HfO₂ prepared by evaporation and of SiO₂, TiO₂, and Ta₂O₅ prepared by ion beam sputtering. The same method is used to examine stainless steel discs, which have to be used as reference materials,Dedicated to Professor Günther Tölg on the occasion of his 60th birthday     

The coraxeniolides,constituents of pink coral, corallium sp

From a deep-sea (?350m) gorgonian, Corallium sp., we have isolated five diterpenes, which are structurally related to the xenicins, previously known from soft corals and brown algae. The structure of the principal constituent, coraxeniolide-A (1) was determined by X-ray diffraction studies. Spectral analysis and chemical correlations elucidated the structures of coraxeniolides B(3), C(7), C'(10), and of corabohcin (13).     

Ilimaquinone,a sesquiterpenoid quinone from a marine sponge

Ilimaquinone (1) is a new sponge metabolite of composition C₂₂H₃₀O₄. Its structure, which was determined by spectral correlations and X-ray crystallography, comprises a rearranged drimane sesquiterpene moiety linked to a 2-hydroxy-5-methoxybenzoquinone at C-3.     

Semiconductor saturable-absorber mirror assisted Kerr-lens mode-locked Ti:sapphire laser producing pulses in the two-cycle regime

Pulses of sub-6-fs duration have been obtained from a Kerr-lens mode-locked Ti:sapphire laser at a repetition rate of 100 MHz and an average power of 300 mW. Fitting an ideal sech(2) to the autocorrelation data yields a 4.8-fs pulse duration, whereas reconstruction of the pulse amplitude profile gives 5.8 fs. The pulse spectrum covers wavelengths from above 950 nm to below 630 nm, extending into the yellow beyond the gain bandwidth of Ti:sapphire. This improvement in bandwidth has been made possible by three key ingredients: carefully designed spectral shaping of the output coupling, better suppression of the dispersion oscillation of the double-chirped mirrors, and a novel broadband semiconductor saturable-absorber mirror.     

Defense allomones of some marine mollusks

Certain marine mollusks that lack obvious physical protection have evolved various biological and chemical defense strategies. One type of chemical defense involves accumulation of small organic molecules, largely from the diet, which afford protection from common predators. Our work and research by others has shown that the animals can utilize different structural types. Interestingly several of the defense allomones which have been defined are structurally related to the drimane sesquiterpenoids which have been shown to be antifeedants against terrestrial insects.