Bioverfügbarkeit und Biokinetik von Polyphenolen aus Rotwein (Lemberger) gegenüber rotem Traubensaft wurden in einem gemischten Kollektiv mit 9 gesunden Probanden im crossover Vergleich untersucht. Nach Verabreichung einer Einzeldosis entweder von 400 ml Rotwein oder 400 ml rotem Traubensaft mit abgestimmtem Gesamtanthozyangehalt (27,6 mg bzw. 283,5 mg) wurde der Plasmaspiegel von Anthozyaninglukosiden ebenso wie deren Harnausscheidungsrate in regelmässigen Intervallen HPLC analytisch ermittelt. Aus den Plasmawerten wurden biokinetische Parameter wie AUC, Maximalkonzentration cmax, deren Zeitpunkt tmax und die Halbwertszeit t1/2 abgeleitet. In der Harnausscheidung konnten Rmax (max. gemessene Ausscheidungsrate).deren Zeitpunkt tmax,R, Ae (Gesamtmenge ausgeschiedener Anthozyane) sowie der prozentuale Anteil der Aufnahmedosis Xe erfasst werden. In der Biokinetik der plasmatischen Anthozyane waren keine Unterschiede zwischen Rotwein und rotem Traubensaft zu erkennen, dagegen übertraf die Anthozyanausscheidungsrate nach Traubensaftzufuhr mit 0,23% der Aufnahmedosis signifikant diejenige nach Rotweinzufuhr mit 0,18% der Aufnahmedosis. Signifikant erhöht war auch das antioxidative Potential im Plasma (TRAP-test) nach Traubensafteinnahme gegenüber Rotwein. Es zeigte sich, dass Anthozyane aus roten Trauben zu geringem Anteil als intakte Glukoside resorbiert und als solche im Harn ausgeschieden werden. Roter Traubensaft scheint wenigstens gleich- oder sogar höherwertig gegenüber dem getesteten Rotwein zu sein im Vergleich der nachweisbaren, bioaktiven Inhaltsbestandteile.

BACKGROUND:To evaluate health benefits attributed to Hibiscus sabdariffa L. a randomized, open-label, two-way crossover study was undertaken to compare the impact of an aqueous H. sabdariffa L. extract (HSE) on the systemic antioxidant potential (AOP; assayed by ferric reducing antioxidant power (FRAP)) with a reference treatment (water) in eight healthy volunteers. The biokinetic variables were the areas under the curve (AUC) of plasma FRAP, ascorbic acid and urate that are above the pre-dose concentration, and the amounts excreted into urine within 24 h (Ae(0-24) ) of antioxidants as assayed by FRAP, ascorbic acid, uric acid, malondialdehyde (biomarker for oxidative stress), and hippuric acid (metabolite and potential biomarker for total polyphenol intake).RESULTS:HSE caused significantly higher plasma AUC of FRAP, an increase in Ae(0-24) of FRAP, ascorbic acid and hippuric acid, whereas malondialdehyde excretion was reduced. Furthermore, the main hibiscus anthocyanins as well as one glucuronide conjugate could be quantified in the volunteers' urine (0.02% of the administered dose).CONCLUSION:The aqueous HSE investigated in this study enhanced the systemic AOP and reduced the oxidative stress in humans. Furthermore, the increased urinary hippuric acid excretion after HSE consumption indicates a high biotransformation of the ingested HSE polyphenols, most likely caused by the colonic microbiota.

Seit etlichen Jahren sind Grundlagen und Teilbereiche des Faches „Ernährungswissenschaften“ in die Studienordnungen für Lebensmittelchemiker und -technologen aufgenommen worden. Hierzu hat man sich unter anderem deshalb entschlossen, weil ernährungsbezogene Aussagen im Verkehr mit Lebensmitteln und bei deren Beurteilung eine immer größere Bedeutung für die genannten Berufsgruppen gewinnen. Darüber hinaus liegen inzwischen immer mehr Erkenntnisse vor, wonach die Ernährungsweise einen wichtigen und gleichzeitig weitgehend vermeidbaren Risikofaktor für die Mortalität an chronischen Erkrankungen darstellt. Dies gilt z. B. für die häufigsten Todesursachen in Deutschland, die Herz-Kreislauferkrankungen und die bösartigen Tumore (Ernährungsbericht 2004). Im Folgenden wird daher ein kurzer Überblick über einige zentrale Aspekte dieser komplexen und zukunftsträchtigen Disziplin gegeben. Ziel dieser Fachrichtung, deren Wurzeln in Medizin, Natur- und Agrarwissenschaften liegen, ist die Erforschung von Nutzen und Risiken, die sich für den Menschen durch die von ihm praktizierte Ernährungsweise ergeben.

The concentration and the composition of secondary plant metabolites are strictly dependent on the apple varieties. In this study, twelve cloudy apple juices made from nine different cider apple cultivars of the harvests from 2001 to 2003 were produced and characterized analytically. The average values for total polyphenols (Folin and HPLC) were 1237 mg/l (822-2161 mg/l), and 520 mg/l (197-1229 mg/l), respectively. With antioxidant capacities up to 20 mmol Trolox/l (Mean 10 mmol/l, range 6-20 mmol/l), some of them matched or exceeded the values of red wine. The cultivars Bittenfelder and Bohnapfel showed the highest polyphenol concentrations. In comparison with commercial apple juices, the analyses of other chemical parameters revealed some peculiarities of apple juices made from special cider cultivars. For the sake of comparison, also apple juices of four dessert apples cultivars were investigated (Golden Delicious, Cox Orange, Granny Smith and Topaz). The polyphenol concentrations of 316-736 mg/l (Folin) and 22-221 mg/l (HPLC), respectively, as well as the antioxidative capacities (1-4 mmol/l Trolox) were far below that of cider apple varieties. The average value for the polyphenols (HPLC) of 102 mg/l in dessert apple juices was lower by a factor of five, compared to cider apple juice (average value 520 mg/l, HPLC). Boskoop had an antioxidative capacity of 6 mmol/l Trolox which is between dessert apple juices and cider apple juices. Four versions of juice were made from each table apple cultivar: cloudy direct juice, cloudy juice from concentrate, clear direct juice and clear juice from concentrate. The juices from concentrate did not differ from the direct juices in polyphenols and antioxidant capacity. On the other hand, the clarification of the apple juices had a pronounced effect on polyphenol contents and antioxidant capacities. The latter were up to 70% lower than the contents in the corresponding cloudy juices of the same cultivar. The quality of apple juice may generally be improved by using varieties with high concentrations of secondary plant metabolites. Cider apple cultivars had better antioxidant capacity than most of the commercial juices and can be used in apple juice blends. In consideration of functional fruit juices or fruit based beverages the genetic pool of classical apple varieties has to be preserved.

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 C max 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 t 1/2 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.

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, c(max), t(max), and the elimination rate t(1/2). 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.

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 (Spätburgunder [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.

The influence of classical and modern processing technologies on the antioxidant compounds of apple juices, predominantly polyphenols, has been studied. The change of antioxidant capacity (TEAC assay based on ABTS radical cation/Trolox) and the polyphenolic composition (HPLC) inflicted by enzymatic oxidation during mash and juice period. dejuicing, ascorbic acid dosage, separation, pasteurisation, fining with gelatin and silica sol, ultrafiltration. stabilisation of ultrafiltered apple juice using PVPP or adsorber resin as well as storage under forced conditions was investigated. The production of cloudy apple juice resulted in a loss of antioxidant capacity ranging from 20-40 % relative to freshly pressed juice (100 %), which was due to oxidation and the separation of juice solids. Juice clarification reduced the antioxidant capacity due to a complete removal of antioxidants bound to the cloud particles of the press juice and represented a major factor influencing the antioxidant capacity of the apple juice. Combination of ultrafiltration and adsorbents resulted in a great loss of polyphenols and antioxidant capacity (over 50%) whereas the classical gelatin and silica sol fining was significantly more gentle, Based on the results, recommendations for the conservation of juice polyphenols and the achievement of a high antioxidant capacity during production of apple juice can be given.

A pilot study was performed to prove the suitability of stable isotope dilution assays for assessing the bioavailability of endogenous folates in foods. By using [2H4]folic acid, [2H4]tetrahydrofolate, [2H4]5-methyltetrahydrofolate, [2H4]5-formyltetrahydrofolate and [2H4]10-formylfolic acid as internal standards, folates in spinach, apple juice and blood plasma were quantified by liquid chromatography coupled to tandem mass spectrometry. To liberate the pteroyl monoglutamates, sample extracts of foods were treated by rat plasma. Sample clean-up was achieved by solid-phase extraction on anion-exchange cartridges, which proved to be sufficient to obtain mass chromatograms devoid of matrix interferences. The bioavailability study was designed as a short-time protocol with three meals, the first consisting of 600 g spinach (meal A), the second consisting of 600 g apple sauce with additionally 400 μg synthetic folic acid (meal B) and the third consisting solely of 600 g apple sauce (meal C). Prior to the meals, the participating volunteer’s tissue was saturated with folates to achieve a significant response of plasma folate to the meals. After consumption of meals A and B a significant rise in folate plasma level compared to meal C (mean level at 28 μg/ml) was observed. The relative bioavailability of folate following meal A exceeded significantly the suggested value of 50% for food folates by taking the dose-normalized area under the curve (AUC) following ingestion of meal B as reference.

Pharmacokinetic parameters and the bioavailability of several dietary anthocyanins following consumption of red wine and red grape juice were compared in nine healthy volunteers. They were given a single oral dose of either 400 mL of red wine (279.6 mg total anthocyanins) or 400 mL of red grape juice (283.5 mg total anthocyanins). Within 7 h, the urinary excretion of total anthocyanins was 0.23 and 0.18% of the administered dose following red grape juice and red wine ingestion, respectively. Pharmacokinetic parameters derived from plasma and urine concentrations exhibited higher variability after ingestion of red grape juice. Compared to red grape juice anthocyanins, the relative bioavailability of red wine anthocyanins was calculated to be 65.7, 61.3, 61.9, 291.5, 57.1, and 76.3% for the glucosides of cyanidin, delphinidin, malvidin, peonidin, petunidin, and its sum (referred to as total anthocyanins), respectively. Bioequivalence was established for none of the anthocyanins. On a low level, urinary excretion of anthocyanins was fast, and the excretion rates seem to exhibit monoexponential characteristics over time after ingestion of both red grape juice and red wine. Due to low bioavailability, any significant contribution of anthocyanins to health protecting properties of red wine or red grape juice seems questionable, but the clinical relevance of these findings awaits further investigation.

In order to test the health protective potential of a special antioxidant-rich juice (containing 30% white grape-, 25% blackcurrant-, 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.

Gallic acid occurs naturally in plants and has been found to be pharmacologically active as antioxidant, antimutagenic and anticarcinogenic agent. In this work, the metabolism of gallic acid in the human body was investigated. Two methods were developed for the identification and determination of gallic acid and its phenolic metabolites in human plasma and urine by reversed-phase high-performance liquid chromatography using UV detection and involving isocratic elution. One of these methods enables the simultaneous separation and determination of gallic acid (GA), 4-O-methylgallic acid (4OMGA), pyrogallol (PY), 2-O-methylpyrogallol (2OMPY) and resorcinol (RE) in biological fluids. This method is of interest because it allows the separation of a large number of phenolic compounds by isocratic elution using a solution of 4.4·10−3 M phosphoric acid in water as mobile phase. The analysis time for this method, however, is not optimal (57 min). After oral administration of 50 mg GA, 4OMGA rapidly appeared in the plasma and urine besides unchanged GA. Other phenolic compounds, PY, 2OMPY and RE, were not detected. The second method was developed to determine GA and 4OMGA with a short analysis time (25 min).