Mónica Schwarz

Development and validation of UPLC for the determination of phenolic compounds and furanic derivatives in Brandy de Jerez.

Brandy and other aged distillates are a rich source of polyphenols. For brandies, contact with wood during ageing makes an important contribution to their polyphenols content. This paper describes the use of a previously devised ultra performance LC (UPLC) method to study the polyphenols content of Brandy de Jerez. UPLC is a new technique in LC offering several potential advantages, especially the reduction of time. Analyses of brandy performed by HPLC were repeated by UPLC. A special UPLC analytical column (Acquity UPLC BEH C18 column, 100 x 2.1 mm), with a particle size of 1.7 microm, forms part of this system. Using the UPLC system enabled the time needed for analysis to be reduced to one tenth of the time needed in the conventional HPLC system. In conclusion, the separation factor results of the UPLC were compared to those obtained using HPLC methods; this demonstrated that simple, high efficiency UPLC gradients are viable and advantageous substitutes for traditional analysis of polyphenols in brandy by HPLC. The method enabled 14 phenolic compounds to be identified and determined in 33 different commercial brandies, and this allowed them to be differentiated in function of quality.

Evolution of the colour, antioxidant activity and polyphenols in unusually aged Sherry wines.

The present paper reports the results of a study monitoring several key analytical parameters in a set of aged samples of vintages from 1999 back to 1935. The analysed parameters were: colour, antioxidant activity, low molecular weight phenolics, index of total polyphenols and SO2 content. It can be concluded that the antioxidant activity of the old wines studied is clearly related to the ageing time and to the polyphenols extracted from the wood during this period. The wines also showed differences in their chromatic characteristics according to the duration of their ageing in years. A principal component analysis confirmed that most of the studied variables (except hydroximethylfurfural and SO2) are strictly linked to ageing, which allowed a discrimination of 100% of the wines belonging to different decades, according to the results obtained by means of the application of linear discriminant analysis.

An Overview on the Importance of Combining Complementary Analytical Platforms in Metabolomic Research

The analytical bias introduced by most of the commonly used techniques in metabolomics considerably hinders the simultaneous detection of all metabolites present in complex biological samples. In order to solve this limitation, the combination of complementary approaches is emerging in recent years as the most suitable strategy in order to maximize metabolite coverage. This review article presents a general overview of the most important analytical techniques usually employed in metabolomics: nuclear magnetic resonance, mass spectrometry and hybrid approaches. Furthermore, we emphasize the potential of integrating various tools in the form of metabolomic multi-platforms in order to get a deeper metabolome characterization, for which a revision of the existing literature in this field is provided. This review is not intended to be exhaustive but, rather, to give a practical and concise guide to readers not familiar with analytical chemistry on the considerations to account for the proper selection of the technique to be used in a metabolomic experiment in biomedical research.

Synergic effects of sugar and caffeine on insulin-mediated metabolomic alterations after an acute consumption of soft drinks

High sugar consumption elicits numerous deleterious effects on health by inducing insulin resistance, which is closely associated with the development of metabolic disorders such as obesity or type‐2 diabetes. Furthermore, there is also growing evidence that caffeine may play an important role in the regulation of insulin release and the appearance of related metabolic impairments. Thus, the aim of this work was to investigate the impact of acute sugar and caffeine intake on the metabolic health status by using a metabolomic multi‐platform based on the combination of flow injection mass spectrometry and ultra‐high performance liquid chromatography mass spectrometry. To this end, we performed a randomized, crossover and double‐blind intervention study with different soft drinks from the same brand. Numerous metabolomic changes were detected in serum samples over time after the intake of sugar‐sweetened beverages, including energy‐related metabolites, amino acids and lipids, thus demonstrating the intense effects provoked by acute sugar consumption on the organism during 3 h of follow‐up. However, the most significant findings were observed after the co‐ingestion of caffeine, which could be indicative of a synergic effect of this psychostimulant on insulin‐mediated perturbations.

Obesity induced alterations in redox homeostasis and oxidative stress are present from an early age

Objectives Oxidative stress and inflammation have been postulated as underlying mechanisms for the development of obesity-related insulin resistance. This association however, remains elusive especially in childhood. We sought to investigate this relation by measuring oxidative stress and antioxidant response biomarkers, before and during an oral glucose tolerance test (OGTT), in different biological samples from obese children. Subjects 24 children were recruited for the study, (18 obese and 6 controls). After OGTT, the obese group was subdivided in two, according to whether or not carbohydrate metabolic impairment (Ob.IR+, Ob.IR-; respectively) was found. Different biomarkers were analyzed after fasting (T = 0) and during an OGTT (T = 60 and 120 min). Lipoperoxides were measured in plasma, erythrocytes, and urine; while advanced glycation end products were determined in plasma, and redox status (GSH/GSSG ratio) in erythrocytes. Results We found marked differences in the characterization of the oxidative status in urine and erythrocytes, and in the dynamics of the antioxidant response during OGTT. Specifically, Ob.IR+ children show increased oxidative stress, deficient antioxidant response and a significant imbalance in redox status, in comparison to controls and Ob.IR- children. Conclusion Obese children with insulin resistance show increased levels of oxidative stress biomarkers, and a stunted antioxidant response to an OGTT leading to increased oxidative stress after a single glucose load, as detected in erythrocytes, but not in plasma. We propose erythrocytes as sensors of early and acute changes in oxidative stress associated with insulin resistance in childhood obesity. This is a pilot study, performed with a limited sample size, so data should be interpreted with caution until reproduced.