Biomedical subjects

V Felipe Laurie

Publications and source records attributed to V Felipe Laurie.

3 recordsLinked to original sources

PubMed2006

Glyceraldehyde bridging between flavanols and malvidin-3-glucoside in model solutions.

Hydroxyl radicals (.OH) seem to have an important role in the oxidation of wine constituents and the production of important electrophilic aldehydes and ketones. In this experiment, glyceraldehyde, a .OH oxidation product of glycerol, recently described in wine, reacts with (+)-catechin, (-)-epicatechin, and malvidin-3-glucoside (Mv3gl), in model solutions, yielding new condensed phenolic compounds. The adduct compounds formed were separated by means of reversed phase liquid chromatography and detected and characterized using UV-vis and electrospray ionization mass spectrometry. Flavanol-flavanol and anthocyanin-flavanol adducts linked with glyceraldehyde yielded compounds with m/z ratios for their main ions, in positive ion mode, of 653.2 for the (+)-catechin dimer or the (-)-epicatechin dimer and 855.5 for Mv3gl/(+)-catechin or Mv3gl/(-)-epicatechin dimers. The possible occurrence of these compounds in wine is suggested, and the potential role of these and related reactions in wine aging is discussed.

Anthocyanins↗

PubMed2006

Oxidation of glycerol in the presence of hydrogen peroxide and iron in model solutions and wine. Potential effects on wine color.

Wine oxidation appears to include the formation of hydroxyl radical (*OH), an exceptionally reactive and thus nonselective compound that might be involved in the production of important aldehydes and ketones. This experiment examined the *OH oxidation of glycerol, a major wine constituent, and thus a likely target of such oxidation, in model wine, generated by hydrogen peroxide and iron catalysis. The oxidation products generated were analyzed as their hydrazones using LC-DAD/MS. Glyceraldehyde and dihydroxyacetone were the main compounds identified, both of which were also observed in naturally aged and *OH-oxidized wines. As anticipated, the presence of ethanol in the model wine did not preclude the formation of these compounds. Additionally, when a young red wine was treated with these oxidation derivatives, a noteworthy increase in color was observed, most likely due to the formation of novel anthocyanin-based structures.

Chromatography, Liquid↗

PubMed2006

A simple method to separate red wine nonpolymeric and polymeric phenols by solid-phase extraction.

Simple polyphenols and tannins differ in the way that they contribute to the organoleptic profile of wine and their effects on human health. Very few straightforward techniques to separate red wine nonpolymeric phenols from the polymeric fraction are available in the literature. In general, they are complex, time-consuming, and generate large amounts of waste. In this procedure, the separation of these compounds was achieved using C18 cartridges, three solvents with different elution strengths, and pH adjustments of the experimental matrices. Two full factorial 2(3) experimental designs were performed to find the optimal critical variables and their values, allowing for the maximization of tannin recovery and separation efficiency (SE). Nonpolymeric phenols such as phenolic acids, monomers, and oligomers of flavonol and flavan-3-ols and anthocyanins were removed from the column by means of an aqueous solvent followed by ethyl acetate. The polymeric fraction was then eluted with a combination of methanol/acetone/water. The best results were attained with 1 mL of wine sample, a 10% methanol/water solution (first eluant), ethyl acetate (second eluant), and 66% acetone/water as the polymeric phenols-eluting solution (third eluant), obtaining a SE of ca. 90%. Trials with this method on fruit juices also showed high separation efficiency. Hence, this solid-phase extraction method has been shown to be a simple and efficient alternative for the separation of nonpolymeric phenolic fractions and the polymeric ones, and this method could have important applications to sample purification prior to biological testing due to the nonspecific binding of polymeric phenolics to nearly all enzymes and receptor sites.

Acetone↗