Direct determination of tocopherols in paprika and paprika oleoresin by liquid chromatography

A method for the determination of tocopherols and tocopherol esters, quantified as tocopherol acetate, in paprika and paprika oleoresin is reported. Paprika samples were extracted with ethyl acetate and aliquots of the extracts were directly injected into a liquid chromatograph. Reverse phase high-performance liquid chromatography with spectrophotometric detection at 280 nm was used. Gradient elution was applied, allowing the determination of tocopherols and tocopherol esters in the presence of carotenoids. The method does not need previous separation steps, so is useful for the routine determination of vitamin E in commercial samples.     

Cork biomass as biosorbent for Cu(II), Zn(II) and Ni(II)

The removal of Cu(II), Zn(II) and Ni(II) from solutions using biosorption in cork powder is described. The adsorption isotherms were determined, along with the effect of different variables, such as the solid–liquid ratio, temperature and pH on the removal efficiency of the metals. The potentiometric titration curve of the cork biomass was determined and some zeta-potential studies were carried out. The effect of the pre-treatment by Fisher esterification on the biosorption properties of cork is also presented. It was concluded that the adsorption of the heavy metals was favoured by an increase in pH. The degree of heavy metal removal is directly related to the concentration of cork biomass, and the maximum sorption capacity of cork biomass for Cu(II), Zn(II) and Ni(II) was 0.63, 0.76 and 0.34 meq./g, respectively. It is shown that ion exchange plays a more important role in the sorption of Cu(II) and Ni(II) on cork biomass than in the sorption of Zn(II). The pre-treatment by Fisher esterification confirmed the important role of the carboxylic groups in binding of Cu(II) and Ni(II) and showed that they are the only binding sites for Zn(II).     

ACMA (9-amino-6-chloro-2-methoxy acridine) forms three complexes in the presence of DNA

The interaction of ACMA (9-amino-6-chloro-2-methoxy acridine) (D) with DNA (P) has been studied by absorbance, fluorescence, circular dichroism, spectrophotometry, viscometry and unwinding electrophoresis. A T-jump kinetic study has also been undertaken. The experimental data show that, totally unlike other drugs, ACMA is able to form with DNA three complexes (PD(I), PD(II), PD(III)) that differ from each other by the characteristics and extent of the binding process. The main features of PD(I) fulfil the classical intercalation pattern and the formation/dissociation kinetics have been elucidated by T-jump techniques. PD(II) and PD(III) are also intercalated species but, in addition to the dye units lodged between base pairs, they also bear dye molecules externally bound, more in PD(III) relative to PD(II). A reaction mechanism is put forward here. Comparison between absorbance, fluorescence and kinetic experiments has enabled us to determine the binding constants of the three complexes, namely (6.5 ± 1.1) × 10(4) M(-1) (PD(I)), (5.5 ± 1.5) × 10(4) M(-1) (PD(II)) and (5.7 ± 0.03) × 10(4) M(-1) (PD(III)). The Comet assay reveals that the ACMA binding to DNA brings about genotoxic properties. The mutagenic potential studied by the Ames test reveals that ACMA can produce frameshift and transversion/transition mutations. ACMA also is able to produce base-pair substitution in the presence of S9 mix. Moreover, the MTT assays have revealed cytotoxicity. The biological effects observed have been rationalized in light of these features.     

Plasmon-mediated photopolymerization maps plasmon fields for silver nanoparticles

Visible light exposure of films containing silver nanoparticles (AgNPs) shows that the enhanced field around AgNPs in a thin film containing an azo free radical initiator (AIBN) and a triacrylate selectively cross-links the triacrylate within the plasmonic region around the particles. The cross-linked polymer is less soluble than its precursor and behaves as a solubility switch. After the film is developed with ethanol, polymer-encapsulated nanoparticles are preserved on the surface. The 8-10 nm polymer structure that encapsulates the particles effectively maps and preserves the morphology of the plasmon field in AgNP-controlled nanostructures.     

Diplopuupehenone, a new unsymmetrical puupehenone-related dimer from the marine sponge Dysidea sp.

A new unsymmetrical puupehenone-related dimer, diplopuupehenone, comprising puupehenone and puupehenol segments, was isolated from the marine sponge Dysidea sp., along with the known metabolites, puupehenone and bispuupehenone. The structure of diplopuupehenone was established from spectroscopic data and by spectroscopic analysis of an acetoxy derivative. Diplopuupehenone showed 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity with an IC₅₀ value of 8 μM.     

The Universal Multiplicative Envelope of the Free Malcev Superalgebra on One Odd Generator

A base of the universal multiplicative envelope for the free Malcev superalgebra on one odd generator is constructed. Some corollaries for central skew-symmetric elements in free Malcev and free alternative algebras are obtained. In particular, the Malcev Grassmann algebra is constructed.