G. Strass

Bioavailability and Biokinetics of Anthocyanins From Red Grape Juice and Red Wine

In a comparative study, 9 healthy volunteers ingested a single oral dose of 400 mL red grape juice or red wine with dose-adjusted anthocyanin content (283.5 mg or 279.6 mg, resp) in crossover. The content of anthocyanin glucosides was detected in plasma and urinary excretion. Additionally, the plasmatic antioxidant activity was assessed after intake. Based on the plasma content, biokinetic criteria of the single anthocyanins were calculated, such as AUC, cmax, tmax, and the elimination rate t1/2. The urinary excretion of total anthocyanins differed significantly and amounted to 0.18% (red wine) and 0.23% (red grape juice) of the administered dose. Additionally, the plasmatic antioxidant activity increased to higher levels after juice ingestion compared to wine. The intestinal absorption of the anthocyanins of red grape juice seemed to be improved compared to red wine, suggesting a possible synergistic effect of the glucose content of the juice. The improved absorption resulted in an enhanced plasmatic bioactivity.

Effect of grape processing on selected antioxidant phenolics in red wine

Wine, particularly red wine, is an important source of polyphenols and several studies have shown that moderate wine consumption is associated with a reduced risk of coronary heart disease. It has been hypothesized that these antioxidant compounds may be responsible for the potential beneficial effects of wine. The influence of different vinification techniques (fermentation on skin [A], mash heating [B], and the combination of both [C]) on the antioxidant capacity and the phenolic composition of red wines (Spatburgunder [Pinot Noir], Lemberger, and Cabernet Franc) were tested in the present study. The highest concentrations of anthocyanins, flavan-3-ols, flavonols, stilbenes, and antioxidant capacity were found in the red wines which were produced under the conditions of C, followed by B and A.

In vivo antioxidative capacity of a composite berry juice

In order to test the health protective potential of a special antioxidant-rich juice (containing 30% white grape-, 25% black-currant-, 15% elderberry-, 10% sour cherry-, 10% blackberry- and 10% aronia-juice), the bioavailability of its most important bioactive compounds (anthocyanins and ascorbic acid) and the influence of juice consumption on plasma antioxidant capacity and plasma malondialdehyde (MDA) was assessed by six healthy volunteers. The juice ingestion (400 ml) resulted in a significantly increased plasmatic antioxidant capacity after 2 h (30%) and significantly decreased plasma MDA after 4 h (18%). The cumulative urinary excretion of ascorbic acid and anthocyanins was 79 and 0.06% of the ingested amount. From the present findings it can be concluded that various juice antioxidants are variably absorbed and are active as antioxidants in vivo.

Pharmacokinetics of Anthocyanidin-3-Glycosides Following Consumption of Hibiscus sabdariffa L. Extract

Pharmacokinetic parameters of several dietary anthocyanins following consumption of Hibiscus sabdariffa L. extract were determined in 6 healthy volunteers. Subjects were given a single oral dose of 150 mL of Hibiscus sabdariffa L. extract yielding 62.6 mg of cyanidin‐3‐sambubioside, 81.6 mg of delphindin‐3‐sambubioside, and 147.4 mg of total anthocyanins (calculated as cyanidin equivalents). Within 7 hours, the urinary excretion of cyanidin‐3‐sambubioside, delphinidin‐3‐sambubioside, and total anthocyanins (ie, the sum of all quantifiable anthocyanidin glycosides) was 0.016%, 0.021%, and 0.018% of the administered doses, respectively. Maximum excretion rates were determined at 1.5 to 2.0 hours after intake. The dose‐normalized plasma area under the curve estimates were 0.076, 0.032, and 0.050 ng•h/mL/mg for cyanidin‐3‐sambubioside, delphinidin‐3‐sambubioside, and total anthocyanins, respectively. The dose‐normalized Cmax estimates were 0.036, 0.015, and 0.023 ng/mL/mg in the same sequence. They were reached each at 1.5 hours (median) after intake. The geometric means of t1/2 were 2.18, 3.34, and 2.63 hours for cyanidin‐3‐sambubioside, delphinidin‐3‐sambubioside, and total anthocyanins, respectively. The urinary excretion of intact anthocyanins was fast and appeared to be monoexponential. To evaluate the contribution of anthocyanins to the health‐protecting effects of Hibiscus sabdariffa L. extract, it will be necessary to perform further studies on both the intact glycosides and their in vivo metabolites or conjugates in human plasma and urine.

Urinary Excretion of Cyanidin Glucosides and Glucuronides in Healthy Humans After Elderberry Juice Ingestion

In a pilot study with 6 females and 1 male, the metabolism of various cyanidin glucosides after oral administration of elderberry juice was investigated. The anthocyanin metabolites were detected in urinary excretion. After ingestion of a bolus quantity of 3.57 g total anthocyanins in a 150 mL elderberry juice concentrate, 0.053% of the administered dose was excreted in urine as glucosidically bound cyanidins within the first 5 hours. Only 0.003% of the ingested anthocyanin glucosides was excreted as cyanidin glucuronide, suggesting that this conversion step might be of minor importance in urinary excretion.

Bioavailability of antioxidative compounds from Brettacher apple juice in humans

The human bioavailability of ascorbic acid and polyphenolics such as chlorogenic acid and caffeic acid resp. from apple juice produced from the polyphenolic rich variety Brettacher was tested. After intake of 700 ml juice the antioxidant capacity in the plasma of human volunteers assessed by the TRAP-test increased significantly by 52% during the following 2 h. The cumulative urinary excretion of ascorbic acid within 7 h after intake was measured to 104% the ingested dose of the juice. Caffeic acid as the intestinal cleavage product of chlorogenic acid was excreted to only 0.56% of the dose in the juice. The results demonstrate in view of the favourable absorptive attributes and the influence on the plasmatic antioxidative capacity of these juice components that Brettacher apple juice may be suitable as a functional food.