Lipozyme 435-Mediated Synthesis of Xylose Oleate in Methyl Ethyl Ketone.

In this paper, we have performed the Lipozyme 435-catalyzed synthesis of xylose oleate in methyl ethyl ketone (MEK) from xylose and oleic acid. The effects of substrates' molar ratios, reaction temperature, reaction time on esterification rates, and Lipozyme 435 reuse were studied. Results showed that an excess of oleic acid (xylose: oleic acid molar ratio of 1:5) significantly favored the reaction, yielding 98% of xylose conversion and 31% oleic acid conversion after 24 h-reaction (mainly to xylose mono- and dioleate, as confirmed by mass spectrometry). The highest Lipozyme 435 activities occurred between 55 and 70 °C. The predicted Ping Pong Bi Bi kinetic model fitted very well to the experimental data and there was no evidence of inhibitions in the range assessed. The reaction product was purified and presented an emulsion capacity close to that of a commercial sugar ester detergent. Finally, the repeated use of Lipozyme 435 showed a reduction in the reaction yields (by 48 and 19% in the xylose and oleic acid conversions, respectively), after ten 12 h-cycles.

C-cinnamoyl Glycosides: An Emerging "Tail" for the Development of Selective Carbonic Anhydrase Inhibitors.

Attachment of different tails to the well-known carbonic anhydrase (CA) pharmacophores has led to the development of several new CA inhibitors (CAIs). A very good example of such "tails" is constituted by carbohydrates, which represent a wide range of chemotypes, leading thus to a high number of new CAIs. In the last years, several C-cinnamoyl glycosides containing different scaffolds have been prepared and investigated as carbonic anhydrase inhibitors, showing that some of them are very potent and selective CAIs. This article will review the latest developments in the synthesis and biological activity of these Cglycosides.

Detection of polymolecular associations in hydrophobized chitosan derivatives using fluorescent probes.

The microenvironment formed by lauroyl and stearoyl derivatives of chitosan in solution has been studied using two fluorescent probes, pyrene and nabumetone. Existence or not of microdomains formed by polymolecular associations, the inherent hydrophobicity of them in aqueous solution, and the influence of degree of substitution (DS) of derivatives were investigated by emission properties of pyrene and strengthened by the photophysical behavior of nabumetone. Additionally, the ratio between the fluorescence intensities of first (approximately 372 nm) to the third (approximately 384 nm) bands of the emission spectrum of pyrene was used to determine the critical aggregation concentration (CAC). In a previous work, it was already reported the characterization of chitosan derivatives by three spectroscopic techniques ((13)C-NMR, (1)H-NMR and infrared), as well as data on the solubility and swelling-index of them. In addition of that, the new results show that the investigated lauroyl and stearoyl derivatives of chitosan are expected to be potential models for applications in the medical field.

New progresses in the enantioselective synthesis and biological properties of carbocyclic nucleosides.

The recent advances in the chemistry of carbocyclic nucleosides focused on different synthetic approaches that lead to optically pure products as well as a comprehensive overview of their biological properties are discussed. In the latter aspect, molecular recognition of enzymes of pharmacological importance such as: reverse transcriptase, adenosine deaminase, thymidine kinase, DNA cytosine-C5 methyl transferase, S-adenosylhomocysteine hydrolase, etc are considered. The role of conformation and puckering of the glycon moiety in modulating the biological activity and also the use of carbanucleosides as building blocks to prepare oligonucleotides are carefully illustrated.

Photobiological properties of nabumetone (4-[6-methoxy-2-naphthalenyl]-2-butanone), a novel non-steroidal anti-inflammatory and analgesic agent.

The photolability of nabumetone (NB, 1, 4-[6-methoxy-2-naphthalenyl]-2-butanone) and its photobiological properties were studied under aerobic and anaerobic conditions using a variety of in vitro phototoxicity assays: photohemolysis, photoperoxidation of linoleic acid, and photosensitized degradation of histidine and thymine. The photodegradation rate of NB in methanol and phosphate buffered saline (PBS) was enhanced under oxygenated media. NB was phototoxic in vitro. The photohemolysis rate was enhanced by deuterium oxide and inhibited by the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO), butylated hydroxyanisole (BHA), sodium azide (NaN3) and reduced gluthathione (GSH). The induced photoperoxidation of linoleic acid was inhibited significantly by sodium azide and reduced gluthathione. Histidine and thymine were photodegraded by a photosensitized reaction induced by NB. A mechanism involving singlet oxygen, radicals and photoproducts is suggested for the observed photoxicity.