Andrew L. Waterhouse

Inhibition of in vitro human LDL oxidation by phenolic antioxidants from grapes and wines

Current research suggests that wine contains substances that may reduce the mortality rate from coronary diseases. The oxidation of low-density lipoprotein (LDL) is thought to be a key step in the development of atherosclerosis. Phenolic fractions of a Petite Syrah wine were evaluated for their antioxidant activity in inhibiting LDL oxidation in vitro. The more active fractions contained components of the catechin family. The catechin oligomers and the procyanidin dimers (B 2 , B 3 , B 4 , B 6 , B 8 ) and trimers (C 1 , C 2 ) were extracted, isolated and purified from grapes seeds. These compounds were tested for their inhibition of LDL oxidation, along with other monomeric wine phenolics. The procyanidin dimers B 2 and B 8 , and trimer C 1 , and the monomers catechin, epicatechin and myricetin had the highest antioxidant activity. The procyanidin dimers B 3 , B 4 and C 2 and the monomers gallic acid, quercetin, caffeic acid, and rutin, and a group of compounds that included the dimer B 6 , ellagic acid, sinapic acid, cyanidin had lower antioxidant activity and α-tocopherol had the least activity. Thus, the numerous phenolic compounds found in wine are potent antioxidants in inhibiting LDL oxidation in vitro.

Changes in grape seed polyphenols during fruit ripening

The quantity and characterization of extracted flavan-3-ol monomers and procyanidins was determined in seeds from Vitis vinifera cv. Cabernet Sauvignon berries, over the course of ripening and at different levels of vine water status. The per berry extractive yield of all polyphenols decreased with maturity, and followed second-order kinetics. The flavan-3-ol monomers decreased most rapidly, followed by the procyanidin extension units and finally, the terminal units. The relative proportion of procyanidin extension units did not vary with maturity. During fruit ripening, the mean degree of polymerization of extracted procyanidins is unchanged when analyzed intact by HPLC, but decreases by thiolytic degradation. The proportion of extracted procyanidins resistant to acid catalyzed thiolysis increased with maturity. Changes in vine water status affected polyphenol amounts, indicating that cultural practices can be used to influence composition. Oxidation of the seed polyphenols during fruit ripening, could explain these observations.

Cocoa and health: a decade of research

It has been over 10 years since the first mention in a medical journal about cocoa and chocolate as potential sources of antioxidants for health. During this time, cocoa has been found to improve antioxidant status, reduce inflammation and correlate with reduced heart disease risk; with these results, and its popularity, it has received wide coverage in the press. However, after 10 years of research, what is known about the potential health benefits of cocoa and what are the important next steps in understanding this decadent source of antioxidants?

The calcium-ryanodine receptor complex of skeletal and cardiac muscle

[3H]Ryanodine binds with high affinity to saturable and Ca2+-dependent sites in heavy sarcoplasmic reticulum (SR) preparations from rabbit skeletal and cardiac muscle. Ruthenium red, known to interfere with Ca2+-induced Ca2+ release from SR vesicles, inhibits [3H]ryanodine specific binding in both skeletal and cardiac preparations whereas Mg2+, Ba2+, Cd2+ and La3+ selectively inhibit the skeletal preparation. The toxicological relevance of the [3H]ryanodine binding site is established by the correlation of binding inhibition with toxicity for seven ryanoids including two botanical insecticides. These findings provide direct evidence for Ca2+-ryanodine receptor complexes that may play a role in excitation-contraction coupling.

The present and future of the international wine industry

Wine production is both art and science, a blend of individual creativity and innovative technology. But wine production is also business, with economic factors driving manufacturing practices. To be successful in the modern marketplace, a winemaker must integrate the artistic and economic aspects of wine production, and possess a solid understanding of the intrinsic and extrinsic factors that underlie purchase motivation.

The occurrence of piceid, a stilbene glucoside, in grape berries

Abstract Piceid, the 3-β-glucoside of resveratrol, was observed in berries of two of the three varieties tested. These results suggest that the source and fate of this glucoside could be related to the biosynthesis of resveratrol and its production or loss in response to plant stress. Also, the levels of piceid in wine could affect the physiologically available amounts of resveratrol to consumers of wine.

Metabolites Are Key to Understanding Health Effects of Wine Polyphenolics

Phenolic compounds in grapes and wine are grouped within the following major classes: stilbenes, phenolic acids, ellagitannins, flavan-3-ols, anthocyanins, flavonols, and proanthocyanidins. Consumption of foods containing phenolic substances has been linked to beneficial effects toward chronic diseases such as coronary heart disease and colorectal cancer. However, such correlations need to be supported by in vivo testing and bioavailability studies are the first step in establishing cause and effect. Class members from all phenolic groups can be glucuronidated, sulfated, and/or methylated and detected at low concentrations in the bloodstream and in urine. But the majority of phenolic compounds from grapes and wine are metabolized in the gastrointestinal tract, where they are broken down by gut microflora. This typically involves deglycosylation, followed by breakdown of ring structures to produce phenolic acids and aldehydes. These metabolites can be detected in bloodstream, urine, and fecal samples by using sophisticated instrumentation methods for quantitation and identification at low concentrations. The health effects related to grape and wine consumption may well be due to these poorly understood phenolic acid metabolites. This review discusses the known metabolism of each major class of wine and grape phenolics, the means to measure them, and ideas for future investigations.

Identification of Cabernet Sauvignon Anthocyanin Gut Microflora Metabolites

Anthocyanins are polyphenol antioxidants that have been shown to prevent many chronic diseases, including colon cancer. The compounds are largely metabolized by various enzymes and bacteria in the large intestine, and the health benefits of consuming foods rich in anthocyanins could be due mostly to the effects of these metabolites. In this study, the contents of the large intestine of pigs were used to model anthocyanin metabolism because pig and human intestinal microflora are similar. An anthocyanin extract from Cabernet Sauvignon grapes that contained delphinidin-3-glucoside, petunidin-3-glucoside, peonidin-3-glucoside, and malvidin-3-glucoside was employed. The extract was incubated anaerobically in the contents of the large intestine of freshly slaughtered pigs for 0, 0.5, and 6 h (final concentrations of 20.9, 28.2, 61.4, and 298.0 microM of the above anthocyanin compounds, respectively, at t = 0 h). Anthocyanins and their metabolites were measured by LC-ESI-MS. After 6 h, anthocyanins were no longer detected, and three metabolites were identified as 3-O-methylgallic acid, syringic acid, and 2,4,6-trihydroxybenzaldehyde. Results from this study suggest that consumption of Cabernet Sauvignon grape anthocyanins could lead to the formation of specific metabolites in the human gut, and it is possible that these metabolites offer the protective effect against colon cancer attributed to anthocyanin consumption.

Milk Does Not Affect the Bioavailability of Cocoa Powder Flavonoid in Healthy Human

Background: The beneficial effects of cocoa polyphenols depend on the amount consumed, their bioavailability and the biological activities of the formed conjugates. The food matrix is one the factors than can affect their bioavailability, but previous studies have concluded rather contradictory results about the effect of milk on the bioavailability of polyphenols. Aim: The objective was to evaluate the possible interaction of milk on the absorption of (–)-epicatechin ((–)-Ec) from cocoa powder in healthy humans. Methods: 21 volunteers received three interventions in a randomized crossover design with a 1-week interval (250 ml of whole milk (M-c) (control), 40 g of cocoa powder dissolved in 250 ml of whole milk (CC-M), and 40 g of cocoa powder dissolved with 250 ml of water (CC-W)). Quantification of (–)-Ec in plasma was determined by LC-MS/MS analysis prior to a solid-phase extraction procedure. Results: 2 h after the intake of the two cocoa beverages, (–)-Ec-glucuronide was the only (–)-Ec metabolite detected, showing a mean (SD) plasma concentration of 330.44 nmol/l (156.1) and 273.7 nmol/l (138.42) for CC-W and CC-M, respectively (p = 0.076). Conclusion: Cocoa powder dissolved in milk as one of the most common ways of cocoa powder consumption seems to have a negative effect on the absorption of polyphenols; however, statistical analyses have shown that milk does not impair the bioavailability of polyphenols and thus their potential beneficial effect in chronic and degenerative disease prevention.

A method to quantify quinone reaction rates with wine relevant nucleophiles: a key to the understanding of oxidative loss of varietal thiols.

Quinones are key reactive electrophilic oxidation intermediates in wine. To address this question, the model 4-methyl-1,2-benzoquinone was prepared to study how it reacts with wine nucleophiles. Those investigated included the varietal volatile thiols 4-methyl-4-sulfanylpentan-2-one (4MSP), 3-sulfanylhexan-1-ol (3SH), and 2-furanmethanethiol (2FMT); hydrogen sulfide (H2S); glutathione (GSH); sulfur dioxide; ascorbic acid (AA); and the amino acids methionine (Met) and phenylalanine (Phe) in the first kinetic study of these reactions. Products were observed in fair to quantitative yields, but yields were negligible for the amino acids. The reaction rates of 4-methyl-1,2-benzoquinone toward the nucleophiles were quantified by UV-vis spectrometry monitoring the loss of the quinone chromophore. The observed reaction rates spanned three orders of magnitude, from the unreactive amino acids (Met and Phe) (KNu = 0.0002 s(-1)) to the most reactive nucleophile, hydrogen sulfide (KH2S = 0.4188 s(-1)). Analysis of the kinetic data showed three categories. The first group consisted of the amino acids (Met and Phe) having rates of essentially zero. Next, phloroglucinol has a low rate (KPhl = 0.0064 s(-1)). The next group of compounds includes the volatile thiols having increasing reactions rates K as steric inhibition declined (K4MSP = 0.0060 s(-1), K3SH = 0.0578 s(-1), and K2FMT = 0.0837 s(-1)). These volatile thiols (4MSP, 3SH, 2FMT), important for varietal aromas, showed lower K values than those of the third group, the wine antioxidant compounds (SO2, GSH, AA) and H2S (KNu = 0.3343-0.4188 s(-1)). The characterization of the reaction products between the nucleophiles and 4-methyl-1,2-benzoquinone was performed by using HPLC with high-resolution MS analysis. This study presents the first evidence that the antioxidant compounds, H2S, and wine flavanols could react preferentially with oxidation-induced quinones under specific conditions, providing insight into a mechanism for their protective effect.