From grape to wine: Changes in phenolic composition and its influence on antioxidant activity.

The evolution of phenolic compounds and their relationship with the antioxidant capacity (AC) of samples taken along the winemaking process of three Vitis vinifera L. cv., Syrah, Merlot and Cabernet Sauvignon grown in Argentina were studied. Forty-five compounds were identified by HPLC-PDA-MS/MS, while the AC was determined by FRAP, ABTS and DPPH assays. Results show that phenolic composition and AC vary along the winemaking process and between varieties. Multiple regression analysis showed a high correlation between phenolic composition and AC of samples, being anthocyanins the main family with significant contribution to AC. In addition, quantitative differences in specific phenolic compounds help to explain differences in AC observed between varieties. A high phenolic content and bioactivity still remain in pomaces which support its use as an inexpensive source of antioxidants.

Antioxidant neolignans from Cordia americana.

Five new neolignans with a bicyclo[2.2.2]octene framework were isolated from an ethanolic extract of the bark of Cordia americana. The structures and relative configurations of the compounds were elucidated by a combination of spectroscopic methods. All the isolated compounds showed good antioxidant activities in the DPPH radical scavenging (0.5-100 µg/mL) and Ferric-reducing antioxidant power (FRAP, 1-100 µg/mL) assays. One of the compounds displayed mild fungistatic activity at 0.1 µmol/spot against Fusarium virguliforme while, at the same time, all compounds were inactive against several strains of Gram (+) and Gram (-) bacteria at all assayed concentrations (10-1,000 µg/mL).

Markers of typical red wine varieties from the Valley of Tulum (San Juan-Argentina) based on VOCs profile and chemometrics.

We studied the VOCs profile of three red wine varieties, produced in the Valley of Tulum (San Juan-Argentina), over 4 consecutive years. Our main goal was to verify if different wine varieties could be differentiated from their VOCs profile, considering changes induced by their age, the yeast inoculated and the type of alcoholic fermentation, establishing those compounds that could be used as chemical markers of a particular variety. Stepwise LDA of selected VOCs allowed 100% differentiation between studied wines, showing that high levels of 1-hexanol were characteristic for Malbec, while low level of ethyl caproate was characteristic for Bonarda. Using controlled fermentations, 1-hexanol, a pre-fermentative VOC, presented a similar trend in wines produced from different yeast; while other fermentative VOCs, like ethyl caproate and ethyl caprilate, presented lower levels for Bonarda but also for Syrah. To our knowledge, this is the first report on characterization of VOCs from Bonarda. Additionally, the quantitative analysis of VOCs profile, coupled to chemometrics, present a good alternative to differentiate wines from different varieties and also for studying wine fermentation.

Fingerprints for main varieties of argentinean wines: terroir differentiation by inorganic, organic, and stable isotopic analyses coupled to chemometrics.

Our main goal was to investigate if robust chemical fingerprints could be developed for three Argentinean red wines based on organic, inorganic, and isotopic patterns, in relation to the regional soil composition. Soils and wines from three regions (Mendoza, San Juan, and Córdoba) and three varieties (Cabernet Sauvignon, Malbec, and Syrah) were collected. The phenolic profile was determined by HPLC-MS/MS and multielemental composition by ICP-MS; (87)Sr/(86)Sr and δ(13)C were determined by TIMS and IRMS, respectively. Chemometrics allowed robust differentiation between regions, wine varieties, and the same variety from different regions. Among phenolic compounds, resveratrol concentration was the most useful marker for wine differentiation, whereas Mg, K/Rb, Ca/Sr, and (87)Sr/(86)Sr were the main inorganic and isotopic parameters selected. Generalized Procrustes analysis (GPA) using two studied matrices (wine and soil) shows consensus between them and clear differences between studied areas. Finally, we applied a canonical correlation analysis, demonstrating significant correlation (r = 0.99; p < 0.001) between soil and wine composition. To our knowledge this is the first report combining independent variables, constructing a fingerprint including elemental composition, isotopic, and polyphenol patterns to differentiate wines, matching part of this fingerprint with the soil provenance.

Differential absorption of metals from soil to diverse vine varieties from the Valley of Tulum (Argentina): consequences to evaluate wine provenance.

We report the effect of vine variety on the absorption of metals from soil and follow the variety from wine through juice, verifying which metals could be used to assess wine provenance. Eleven metals were determined by atomic absorption spectroscopy in 32 soils, 16 grapes juices, and 18 wines sampled from a single vineyard having four red grape varieties (Cabernet Sauvignon, Bonarda, Malbec, and Syrah). The K nearest neighbor method allows us to distinguish among different soils, juices, and wines. Linear discriminant analysis affords descriptors to point out differences, mainly Mg, Mn, Ca, K, and Na. Data analysis evidenced that some elements have equivalent concentrations in soil, juice, and wine, while others did not. Canonical analysis shows good correlation between grape juice and wine with their provenance soil. We suggest using Mg as a marker of wine provenance, while Mn could be used to evaluate differences between wine varieties associated with plant physiology.

Main flavonoids, DPPH activity, and metal content allow determination of the geographical origin of propolis from the Province of San Juan (Argentina).

The chemical characterization as well as the assessment of geographical origin of propolis from several areas of the Provincia de San Juan (Argentina) is reported. Chemical characterization of propolis was performed by measuring total phenolic (TP), total flavonoids (FL), free radical scavenging capacity (DPPH bleaching), and metal content in samples of six different districts. Methanolic propolis extracts (MEP) showed TP ranging from 25.7 to 39.3 g of gallic acid equivalents per 100 g of MEP, whereas flavonoids ranged from 6.6 to 13.3 g of quercetin equivalents per 100 g of MEP. Six main flavonoids were isolated and identified from the propolis samples, comprising the flavanones 7-hydroxy-8-methoxyflavanone (1), pinocembrin (2), and pinobanksin (3), the flavones chrysin (4) and tectochrysin (5), and the flavonol galangin (6). Compounds 1-6 were quantified by HPLC-PDA. Free radical scavenging activity, measured as percent DPPH bleaching, ranged from 46.6 to 89.5 at 10 mug/mL. Moreover, propolis samples presented high contents of Ca, K, Fe, Na, and Mg, but low amounts of Mn and Zn. Linear discriminant analysis affords eight descriptors, galangin, pinocembrin, pinobanksin, chrysin, tectochrysin, DPPH, K, and Na, allowing a clear distinction with 100% accuracy among different origins within the Provincia de San Juan. A direct relationship of DPPH free radical scavenging activity with TP or with compounds 1-6 was not found, showing the need of further evaluation on the origin of free radical activity in propolis samples.