Vitamin K absorption and kinetics in human subjects after consumption of 13C-labelled phylloquinone from kale.

The absorption and plasma disappearance of vitamin K were investigated by uniformly labelling phylloquinone in kale with carbon-13, and by feeding the kale to study subjects. Seven healthy volunteers ingested a single 400 g serving of kale with 30 g vegetable oil. The kale provided 156 nmol of phylloquinone. Serial plasma samples were collected and analysed for the appearance of 13C-phylloquinone by HPLC-MS. Six of the subjects showed significant amounts of labelled phylloquinone in plasma, though one subject's plasma was not consistently enriched above the detection limit, and this subject's baseline plasma phylloquinone level was the lowest in the group. After ingestion of the labelled kale, plasma 13C-phylloquinone concentration increased rapidly to a peak between 6 and 10 h, and then rapidly decreased. Average peak plasma concentration for the six subjects with detectable 13C-phylloquinone was 2.1 nmol/l. Plasma concentration-time data were analysed by compartmental modelling. Modelling results demonstrated a mean (n 6) bioavailability of phylloquinone from kale to be 4.7%. Plasma and tissue half-times for phylloquinone were found to be 8.8 and 215 h, respectively.

Bioavailability of anthocyanins from purple carrot juice: effects of acylation and plant matrix.

Absorption of cyanidin-based anthocyanins is not fully understood with respect to dose or anthocyanin structure. In feeding studies using whole foods, nonacylated anthocyanins are more bioavailable than their acylated counterparts, but the extent to which plant matrix determines relative bioavailability of anthocyanins is unknown. Using juice of purple carrots to circumvent matrix effects, a feeding trial was conducted to determine relative bioavailability of acylated and nonacylated anthocyanins and to assess dose-response effects. Appearance of anthocyanins in plasma was measured in 10 healthy adults for 8 h following consumption of purple carrot juice. Each subject consumed 50, 150, and 250 mL of juice containing 76 micromol (65 mg), 228 micromol (194 mg), and 380 micromol (323 mg) of total anthocyanins, respectively. Acylated anthocyanins comprised 76% of total anthocyanins in the juice, yet their bioavailability was found to be significantly less than that of nonacylated anthocyanins. Peak plasma concentrations of nonacylated anthocyanins were 4-fold higher than that for acylated anthocyanins. Absorption efficiency declined across the doses administered. Because the treatments were consumed as juice, it could be discerned that the difference in bioavailability of acylated versus nonacylated anthocyanins was not primarily caused by interactions with the plant matrix.

Influence of growth temperature on the amounts of tocopherols, tocotrienols, and gamma-oryzanol in brown rice.

Brown rice is a valuable source of lipid-soluble antioxidants including ferulated phytosterols (i.e., gamma-oryzanol), tocopherols, and tocotrienols. To evaluate the impact of temperature on the accumulation of these compounds, seeds from six different rice lines grown to maturity in replicate greenhouses in Gainesville, FL, were analyzed. The lines represented Oryza sativa indica, O. sativa japonica, and Oryza glaberrima of different origins. Temperatures were maintained near ambient at one end of each greenhouse and at approximately 4.5 degrees C above ambient at the other end. gamma-Oryzanols, tocopherols, and tocotrienols were extracted from whole seed (i.e., brown rice) and analyzed by HPLC. Tocotrienols and tocopherols varied widely between lines but changed only slightly with respect to temperature. In general, the proportions of alpha-tocotrienol and/or alpha-tocopherol increased at elevated temperature, whereas gamma-tocopherol and gamma-tocotrienol decreased. Six gamma-oryzanol peaks, identified on the basis of absorbance maxima at 330 nm and HPLC-mass spectrometry, were quantified. The most abundant component was 24-methylenecycloartanyl ferulate, present at 40-62% of total. Its levels increased 35-57% at elevated temperature in five of six lines, accounting for most of the change in total gamma-oryzanol. The results suggest that the physiological action of individual ferulated phytosterols should be investigated because their relative proportions in gamma-oryzanol can change.

effect of dose size on bioavailability of acylated and nonacylated anthocyanins from red cabbage (Brassica oleracea L. Var. capitata).

Recent studies indicate that anthocyanin intake conveys a variety of health benefits, which depend on absorption and metabolic mechanisms that deliver anthocyanins and their bioactive metabolites to responsive tissues. The anthocyanin bioavailability of red cabbage (Brassica oleracea L. var. capitata) was evaluated as reflected by urinary excretion of anthocyanins and anthocyanin metabolites. Twelve volunteers consumed 100, 200, and 300 g of steamed red cabbage (containing 1.38 micromol of anthocyanins/g of cabbage) in a crossover design. Anthocyanin concentration in cabbage extract and urine was measured by HPLC-MS/MS. Six nonacylated and 30 acylated anthocyanins were detected in red cabbage, and 3 nonacylated anthocyanins, 8 acylated anthocyanins, and 4 metabolites were present in urine. Mean 24 h excretion of intact anthocyanins increased linearly from 45 (100 g dose) to 65 nmol (300 g dose) for acylated anthocyanins and from 52 (100 g dose) to 79 nmol (300 g dose) for nonacylated anthocyanins. Urinary recovery of intact anthocyanins (percent of anthocyanin intake) decreased linearly from 0.041% (100 g dose) to 0.020% (300 g dose) for acylated anthocyanins and from 0.18% (100 g dose) to 0.09% (300 g dose) for nonacylated anthocyanins. Anthocyanin metabolites consisted of glucuronidated and methylated anthocyanins. The results show that red cabbage anthocyanins were excreted in both intact and metabolized forms and that recovery of nonacylated anthocyanins in urine was >4-fold that of acylated anthocyanins.

Plasma and urine responses are lower for acylated vs nonacylated anthocyanins from raw and cooked purple carrots.

The bioavailability of acylated vs nonacylated anthocyanins and the effect of cooking and dose on the comparative bioavailability were investigated in a clinical feeding study using purple carrots as the anthocyanin source. Treatments were purple carrots as follows: 250 g raw (463 micromol of anthocyanins: 400 micromol acylated, 63 micromol nonacylated), 250 g cooked (357 micromol of anthocyanins: 308.5 micromol acylated, 48.5 micromol nonacylated), and 500 g cooked (714 micromol of anthocyanins: 617 micromol acylated, 97 micromol nonacylated). Four of the five carrot anthocyanins were found intact in plasma by 30 min after carrot consumption and peaked between 1.5 and 2.5 h. Acylation of anthocyanins resulted in an 11-14-fold decrease in anthocyanin recovery in urine and an 8-10-fold decrease in anthocyanin recovery in plasma. Cooking increased the recovery of nonacylated anthocyanins but not acylated anthocyanins. Large dose size significantly reduced recovery of both acylated and nonacylated anthocyanins, suggesting saturation of absorption mechanisms.

Plasma appearance of labeled beta-carotene, lutein, and retinol in humans after consumption of isotopically labeled kale.

The bioavailability of carotenoids from kale was investigated by labeling nutrients in kale with 13C, feeding the kale to seven adult volunteers, and analyzing serial plasma samples for labeled lutein, beta-carotene, and retinol. Ingested doses of labeled carotenoids were 34 micromol for beta-carotene and 33 micromol for lutein. Peak plasma concentrations, areas under the plasma concentration-time curves (AUCs), and percentages of dose recovered at peak plasma concentrations were calculated. Average peak plasma concentrations were 0.38, 0.068, and 0.079 microM for [13C]lutein, [13C]beta-carotene, and [13C]retinol, respectively. Average AUC values (over 28 days) were 42.8, 13.6, 13.2 microM h for [13C]lutein, [13C]beta-carotene, and [13C]retinol, respectively. Percentages of dose recovered at peak plasma concentrations were 3.6, 0.7, and 0.7% for [13C]lutein, [13C]beta-carotene, and [13C]retinol, respectively. A positive relationship was observed between baseline plasma retinol levels and [13C]retinol plasma response. It is possible that this relationship was mediated either through some aspect of beta-carotene absorption or via the common pathways of metabolism for postdose and endogenous retinoid.

Effect of temperature, elevated carbon dioxide, and drought during seed development on the isoflavone content of dwarf soybean [Glycine max (L.) Merrill] grown in controlled environments.

The effects of elevated temperature, carbon dioxide, and water stress on the isoflavone content of seed from a dwarf soybean line [Glycine max (L.) Merrill] were determined, using controlled environment chambers. Increasing the temperature from 18 degrees C during seed development to 23 degrees C decreased total isoflavone content by about 65%. A further 5 degrees C increase to 28 degrees C decreased the total isoflavone content by about 90%. Combining treatments at elevated temperature with elevated CO(2) (700 ppm) and water stress to determine the possible consequences of global climate change on soybean seed isoflavone content indicated that elevated CO(2) at elevated temperatures could partially reverse the effects of temperature on soybean seed isoflavone content. The addition of drought stress to plants grown at 23 degrees C and elevated CO(2) returned the total isoflavone levels to the control values obtained at 18 degrees C and 400 ppm CO(2). The promotive effects of drought and elevated CO(2) at 23 degrees C on the 6' '-O-malonygenistin and genistin levels were additive. The individual isoflavones often had different responses to the various growth conditions during seed maturation, modifying the proportions of the principal isoflavones. Therefore, subtle changes in certain environmental factors may change the isoflavone content of commercially grown soybean, altering the nutritional values of soy products.

Structural characterization and detection of kale flavonoids by electrospray ionization mass spectrometry.

Sensitive and precise analytical methods are needed for flavonols, a subclass of flavonoids that has strong antioxidant activity. We report an improved method for identifying the predominant flavonols, quercetin and kaempferol, by collisionally activated dissociation (CAD) and quantifying them by high-performance liquid chromatography electrospray ionization mass spectrometry (HPLC-ESI-MS) in the selected ion monitoring mode. Practical applications of the method were demonstrated using several kale and biological samples. Two commercial kale samples were found to have 77 or 244 ppm quercetin and 235 or 347 ppm kaempferol (ppm = microg of quercetin/g of kale or microg of kaempferol/g of kale by fresh weight, 5-15% relative standard deviation). Blanching was found to reduce the flavonols to approximately 60% of the levels found in the unblanched kale. Isotopically labeled kale (cultivar Vates) grown in a greenhouse under an atmosphere of (13)CO(2) was found to have much lower flavonol levels. UV-A and UV-B supplementation during kale growth in the greenhouse was found to enhance both quercetin and kaempferol levels in Vates kale. The UV-B-supplemented kale not only produced more flavonols but the quercetin-to-kaempferol ratio was also higher than the UV-A-supplemented or the nonsupplemented kale. Recovery of flavonols from kale was approximately 60% based on spike and recovery trials with rutin, a glycoside of quercetin. Recovery of flavonols from biological samples spiked with rutin ranged from 96% for urine to 70% for plasma. Compared to UV detection, ESI-MS in the deprotonation mode provided lower detection limits, and both higher sensitivity and selectivity, in addition to structural characterization of the kale flavonols by CAD.

Isotopic labeling and LC-APCI-MS quantification for investigating absorption of carotenoids and phylloquinone from kale (Brassica oleracea).

The ability to study bioavailability of nutrients from foods is an important step in determining the health impact of those nutrients. This work describes a method for studying the bioavailability of nutrients from kale (Brassica oleracea var. Acephala) by labeling the nutrients with carbon-13, feeding the kale to an adult volunteer, and analyzing plasma samples for labeled nutrients. Results showed that conditions for producing atmospheric intrinsically labeled kale had no detrimental effect on plant growth. Lutein, beta-carotene, retinol, and phylloquinone were analyzed using liquid chromatography-atmospheric pressure chemical ionization mass spectrometry. Analysis of plasma samples showed that labeled lutein peaked in plasma at 11 h (0.23 microM), beta-carotene peaked at 8 (0.058 microM) and 24 h (0.062 microM), retinol peaked at 24 h (0.10 microM), and phylloquinone peaked at 7 h (3.0 nM). This method of labeling kale with (13)C was successful for producing clearly defined kinetic curves for (13)C-lutein,(13)C-beta-carotene, (13)C-retinol, and (13)C-phylloquinone.

Warm temperatures or drought during seed maturation increase free alpha-tocopherol in seeds of soybean (Glycine max [L.] Merr.).

Soybean seeds are an important source of dietary tocopherols, but like seeds of other dicotyledonous plants, they contain relatively little alpha-tocopherol, the form with the greatest vitamin E activity. To evaluate potential effects of environmental stress during seed maturation on tocopherols, soybeans were raised in greenhouses at nominal average temperatures of 23 degrees C or 28 degrees C during seed fill, with or without simultaneous drought (soil moisture at 10-25% of capacity), during normal growing seasons in 1999 (cvs. Essex and Forrest) and 2000 (cvs. Essex, Forrest, and Williams). Total free (nonesterified) tocopherols increased slightly in response to drought in Essex and Forrest. All three lines responded to elevated temperature and, to a lesser extent, drought with large (2-3-fold) increases in alpha-tocopherol and corresponding decreases in delta-tocopherol and gamma-tocopherol. The results suggest that weather or climate can significantly affect seed tocopherols. It may be possible to breed for elevated alpha-tocopherols by selecting for altered plant response to temperature.

ENDOGENOUS AND PHOTOPERIODIC DIURNAL RHYTHMS OF IN VIVO LIGHT ABSORPTION AND SCATTERING IN THE GREEN ALGA ULVA LACTUCA L.

Techniques of in vivo spectroscopy were employed to demonstrate the presence of rhythms of light absorption and scattering in the green thalloid alga Ulva lactuca L. maintained in artificial nutrient medium under constant photoperiod. The absorbance during photophase at 682 nm, the chlorophyll a in vivo absorption maximum, was typically two to three times that during scotophase. Prephased endogenous rhythms (in continued darkness) were observed for a time period equal to three photoperiods. The absorbance rhythm did not correlate with changes in extractable chlorophyll a or b concentration. No changes in linear dichroism were observed, indicating the rhythm of light absorption could not be explained on the basis of orientation of individual absorber molecules. In vivo light microscopy did not reveal differences in chloroplast orientation. Alternative mechanisms are discussed.