The aim of the present study was to assess the renal excretion of red beet juice (RBJ) antioxidants in six healthy humans. After a single oral dose of RBJ. The pharmacokinetic parameters obtained from urine were compared to those obtained after ingestion of water on an intra-individual basis. Urine was collected in intervals up to 24h post-intake. After RBJ ingestion, the betacyanins betanin and isobetanin were excreted in the volunteers’ urine (0.28% of the administered dose) and unambiguously identified by HPLC–ESI-MS/MS. Compared to the ingestion of water, RBJ consumption resulted in a significantly increased urinary excretion of total phenolics (51.1% of the administered phenolics) and other antioxidant compounds (43.9% of the administered compounds) within 24h.

We investigated the urinary pharmacokinetics of monomeric anthocyanins in seven healthy volunteers. The volunteers were administered a single oral dose of 3.57 g total anthocyanins contained in 150 ml of a concentrated elderberry juice under fasting conditions. Within 24 h the urinary excretion of unchanged cyanidin-3,5-diglucoside (cyanidin-3-sambubioside-5-glucoside and cyanidin-3,5-diglucoside were calculated as cyanidin-3,5-diglucoside equivalents), cyanidin-3-glucoside, cyanidin-3-sambubioside and total anthocyanins (i.e., the sum of all quantifiable anthocyanidin glycosides) was 0.16, 0.06, 0.05 and 0.06% of the administered doses, respectively. Maximum excretion rates were determined within 1.0 h after intake. The estimates (arithmetic mean +/- SD) of t(1/2) were 1.25 +/- 0.25, 1.53 +/- 0.36, 1.38 +/- 0.20 and 1.35 +/- 0.18 h for cyanidin-3,5-diglucoside, cyanidin-3-glucoside, cyanidin-3-sambubioside and total anthocyanins, respectively. The urinary excretion of intact anthocyanins was fast and the decline of excretion rates appeared to be monophasic, suggesting a one-compartment pharmacokinetic model, The low urinary excretion of dietary anthocyanidin glycosides with values below 1% indicates that a large proportion of these plant pigments consumed are metabolized before entry into the circulation.

The aim of the present pilot study was to characterise the renal elimination of betalains after consumption of red beet juice (RBJ). Six healthy, non-smoking female volunteers were given a single oral dose of either 500 mL of a commercial RBJ containing 362.7 mg of betalains and 500 mL of tap water, respectively, in a sequential manner. Urine was collected in intervals up to 24 h post-dose. Renal excretion of betalains was determined spectrophotometrically and quantified as betanin-equivalents. In addition, the identity of individual compounds was confirmed by HPLC coupled with diode-array detection and positive ion electrospray mass spectrometry, respectively. The amount (mean+/-S.D.) of intact betalains (betanin and isobetanin) recovered in urine was 1001+/-273 microg corresponding to 0.28+/-0.08% of the administered dose. Maximum excretion rates were observed after a median tmax,R of 3.0 h (range 2.5-8.0 h) amounting to 91.7+/-30.1 microg/h. The terminal elimination rate constant (lambdaz) and the corresponding half-life were 0.097+/-0.021 h(-1) and 7.43+/-1.47 h, respectively. Using the lambdaz estimates obtained the expected total betalain amount excreted in urine was 1228+/-291 microg. Based on the results obtained it is assumed that either the bioavailability of the betalains is low or that renal clearance is a minor route of systemic elimination for these compounds. The urinary excretion rates of unmetabolised betalains were fast and appeared to be monoexponential suggesting a one-compartment model. In order to get a more complete picture of the pharmacokinetics and health-promoting properties of red beet betalains, quantitative data on betalain bioavailability should include measurements of unchanged compounds and their corresponding metabolites in plasma, urine and bile.

The aims of the present study were to asses the renal excretion characteristics of elderberry anthocyanins, and to determine whether the consumption of elderberry juice would enhance postprandial plasma antioxidant status in healthy humans. In eight healthy subjects receiving a single oral dose of elderberry juice, the pharmacokinetic parameters were obtained from 7 h urine excretion. The mean fraction of orally ingested total anthocyanins (sum of cyanidin-3-sambubioside and cyanidin-3-glucoside) excreted unchanged with values of 0.033%, 0.038% and 0.040% after ingestion of 361, 541 and 722 mg, respectively, did not differ significantly (p>0.05). This is suggestive of a dose-independent urinary excretion of elderberry anthocyanins. Furthermore, plasma antioxidant capacity and total phenolics were significantly increased 1 h after ingestion of 400 ml of elderberry juice. Anthocyanins as the characteristic phenolic compounds in elderberries and elderberry juice were detected as unchanged glycosides in the volunteers’ plasma post-intake.

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.

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.