Anthocyanins in purple-orange carrots (Daucus carota L.) do not influence the bioavailability of beta-carotene in young women

Anthocyanin and Lycopene Contents Do Not Affect β-Carotene Bioefficacy from Multicolored Carrots (Daucus carota L.) in Male Mongolian Gerbils

BACKGROUND

Anthocyanins and carotenoids are phytochemicals that may benefit health through provitamin A carotenoid (PAC), antioxidant, and anti-inflammatory activities. These bioactives may mitigate chronic diseases. Consumption of multiple phytochemicals may impact bioactivity in synergistic or antagonistic manners.

OBJECTIVES

Two studies in weanling male Mongolian gerbils assessed the relative bioefficacy of β-carotene equivalents (BCEs) to vitamin A (VA) with simultaneous consumption of the non-PAC lycopene or anthocyanins from multicolored carrots.

METHODS

After 3-wk VA depletion, 5-6 gerbils were killed as baseline groups. The remaining gerbils were divided into 4 carrot treatment groups; the positive control group received retinyl acetate and the negative control group was given vehicle soybean oil (n = 10/group; n = 60/study). In the lycopene study, gerbils consumed feed varying in lycopene sourced from red carrots. In the anthocyanin study, gerbils consumed feed varying in anthocyanin content sourced from purple-red carrots, and positive controls received lycopene. Treatment feeds had equalized BCEs: 5.59 ± 0.96 μg/g (lycopene study) and 7.02 ± 0.39 μg/g (anthocyanin study). Controls consumed feeds without pigments. Serum, liver, and lung samples were analyzed for retinol and carotenoid concentrations using HPLC. Data were analyzed by ANOVA and Tukey's studentized range test.

RESULTS

In the lycopene study, liver VA did not differ between groups (0.11 ± 0.07 μmol/g) indicating no effect of varying lycopene content. In the anthocyanin study, liver VA concentrations in the medium-to-high (0.22 ± 0.14 μmol/g) and medium-to-low anthocyanin (0.25 ± 0.07 μmol/g) groups were higher than the negative control (0.11 ± 0.07 μmol/g) (P < 0.05). All treatment groups maintained baseline VA concentrations (0.23 ± 0.06 μmol/g). Combining studies, serum retinol had 12% sensitivity to predict VA deficiency, defined as 0.7 μmol/L.

CONCLUSIONS

These gerbil studies suggested that simultaneous consumption of carotenoids and anthocyanins does not impact relative BCE bioefficacy. Breeding carrots for enhanced pigments to improve dietary intake should continue.

Identification of a wild carrot as carrot psylla (Bactericera trigonica) attractant and host plant chemistry

Carrot psylla is one of the devastating pests of carrot throughout northern Europe and the Mediterranean basin. Here we characterized the behavioral response of psylla females towards different carrot germplasm and identified the chemical cues involved in the host selection of psylla females by oviposition choice experiments and metabolic profiling of leaf volatiles. In choice assays, carrot psylla displayed differential responses to tested 14 germplasm. Among germplasm, wild accessions 21793 and 20465 were highly preferred by carrot psylla, while wild accessions 20465 and the orange cultivar Nairobi were less. In non-choice experiments conducted only with this four-germplasm revealed that the carrot psylla females gave higher preference to the Nairobi and wild accession 20465, indicating the vicinity to other host plants in the same area might affect female preference. Moreover, the nymph development and survival experiments showed the lowest nymphs survival rate on the wild accessions 21793 and 20497. Furthermore, the volatile emissions among different carrot cultivars infested with psylla showed qualitative and quantitative differences versus intact plants. Among these volatiles, apiol, β-asarone, myristicin, and sabinene showed a relationship with psyllas growth and survival. We also showed that myristicin and sabinene exogenous applications caused a dramatic reduction in the number of eggs laid by psylla and subsequent nymph survival. This is an initial study of the volatiles that mediate attraction and oviposition preference of carrot psylla in response to its host plant. The results from this study provide baseline information for the development of new control strategies against carrot psylla.

Biosynthesis of methyleugenol and methylisoeugenol in Daucus carota leaves: Characterization of eugenol/isoeugenol synthase and O-Methyltransferase

Carrot (Daucus carota subsp. sativus) is a widely cultivated root vegetable of high economic importance. The aroma of carrot roots and aboveground organs is mainly defined by terpenes. We found that leaves of orange carrot cultivar also produce considerable amounts of the phenylpropenes methyleugenol and methylisoeugenol. Notably, methyleugenol is most abundant in young leaves, while methylisoeugenol is the dominant phenylpropene in mature leaf tissue. The goal of the present study was to shed light on the biochemistry and molecular biology of these compounds' biosynthesis and accumulation. Using the available genomic and transcriptomic data, we isolated a cDNA encoding eugenol/isoeugenol synthase (DcE(I)GS1), an NADPH-dependent enzyme that converts coniferyl acetate to eugenol. This enzyme exhibits dual product specificity and yields propenylphenol isoeugenol alongside allylphenol eugenol. Furthermore, we identified a cDNA encoding S-adenosyl-L-methionine:eugenol/isoeugenol O-methyltransferase 1 (DcE(I)OMT1) that produces methyleugenol and methylisoeugenol via methylation of the para-OH-group of their respective precursors. Both DcE(I)GS1 and DcE(I)OMT1 were expressed in seeds, roots, young and mature leaves, and the DcE(I)OMT1 transcript levels were the highest in leaves. The DcE(I)GS1 protein is 67% identical to anise t-anol/isoeugenol synthase and displays an apparent K_m of 247 μM for coniferyl acetate. The catalytic efficiency of DcEOMT1 with eugenol is more than five-fold higher than that with isoeugenol, with K_m values of 40 μM for eugenol, and of 115 μM for isoeugenol. This work expands the current knowledge of the enzymes involved in phenylpropene biosynthesis and would enable studies into structural elements defining the regioselectivity of phenylpropene synthases.

Anti-Colitic Effect of Purple Carrot on Dextran Sulfate Sodium (DSS)-Induced Colitis in C57BL/6J Mice

The anti-colitic effect of purple carrot (PC) on 2% dextran sulfate sodium (DSS)-induced colitis in C57BL6/J mice was compared with those of yellow carrot (YC), beet (BT), and red cabbage (RC). Component analysis showed that PC contained cyanidin-3-xyloglucoside, cyanidin-3-xylosyl(sinapoly-glucosyl)galactoside, cyanidin-3-xylosyl(feruloylglucosyl) galactoside, and cyanidin-3-O-(6-O-glycosyl-2-O-xylosylgalactoside). PC diet (5% in AIN 93G diet) strongly reduced DSS-induced colon shortening and inflammatory cell infiltration in mice, followed by RC, BT, and YC diets. Treatment with PC reduced serum levels of pro-inflammatory cytokines such as tumor necrosis factor-α and interleukin-6 as well as reduced mRNA expression in colon tissue of colitis mice in comparison with other treatments. In addition, PC treatment inhibited colonic mRNA expression of inflammatory factors such as inducible nitric oxide synthase and cyclooxygenase-2 in mice. These results suggest that PC can attenuate the inflammatory reaction in mice with DSS-induced colitis, probably due to the anthocyanins in PC.

Carotenoid Biosynthesis in Daucus carota

Carrot (Daucus carota) is one of the most important vegetable cultivated worldwide and the main source of dietary provitamin A. Contrary to other plants, almost all carrot varieties accumulate massive amounts of carotenoids in the root, resulting in a wide variety of colors, including those with purple, yellow, white, red and orange roots. During the first weeks of development the root, grown in darkness, is thin and pale and devoid of carotenoids. At the second month, the thickening of the root and the accumulation of carotenoids begins, and it reaches its highest level at 3 months of development. This normal root thickening and carotenoid accumulation can be completely altered when roots are grown in light, in which chromoplasts differentiation is redirected to chloroplasts development in accordance with an altered carotenoid profile. Here we discuss the current evidence on the biosynthesis of carotenoid in carrot roots in response to environmental cues that has contributed to our understanding of the mechanism that regulates the accumulation of carotenoids, as well as the carotenogenic gene expression and root development in D. carota.

Formation of norisoprenoid flavor compounds in carrot (Daucus carota L.) roots: characterization of a cyclic-specific carotenoid cleavage dioxygenase 1 gene

Carotenoids are isoprenoid pigments that upon oxidative cleavage lead to the production of norisoprenoids that have profound effect on flavor and aromas of agricultural products. The biosynthetic pathway to norisoprenoids in carrots (Daucus carota L.) is still largely unknown. We found the volatile norisoprenoids farnesylacetone, α-ionone, and β-ionone accumulated in Nairobi, Rothild, and Purple Haze cultivars but not in Yellowstone and Creme de Lite in a pattern reflecting their carotenoid content. A cDNA encoding a protein with carotenoid cleavage dioxygenase activity, DcCCD1, was identified in carrot and was overexpressed in Escherichia coli strains previously engineered to produce different carotenoids. The recombinant DcCCD1 enzyme cleaves cyclic carotenes to generate α- and β-ionone. No cleavage products were found when DcCCD1 was co-expressed in E. coli strains accumulating non-cyclic carotenoids, such as phytoene or lycopene. Our results suggest a role for DcCCD1 in carrot flavor biosynthesis.

A randomized, double-blind, placebo-controlled trial of the effect of dried purple carrot on body mass, lipids, blood pressure, body composition, and inflammatory markers in overweight and obese adults: The QUENCH Trial

Obesity is a significant health issue worldwide and is associated with chronic, low-grade inflammation predisposing the individual to cardiovascular disease and impaired blood glucose homeostasis. Anthocyanins and phenolic acids from purple carrots are effective at reversing inflammation and metabolic alterations in animal models, potentially through inhibition of inflammatory pathways. The effects of dried purple carrot on body mass, body composition, blood pressure, lipids, inflammatory markers, liver function tests, and appetite were investigated in 16 males (aged 53.1 ± 7.6 years and with a mean BMI of 32.8 ± 4.6 kg/m2) with normal lipid and inflammatory markers. There was no evidence that 118.5 mg/day of anthocyanins and 259.2 mg/day of phenolic acids for 4 weeks resulted in statistically significant changes in body mass, body composition, appetite, dietary intake, low density lipoprotein, total cholesterol, blood pressure, or C-reactive protein in these obese participants at the dose and length of intervention used in this trial. High density lipoprotein cholesterol was lower in the intervention group (p < 0.05). Aspartate amino transferase and alanine amino transferase did not change, indicating that the intervention was safe. More studies are required to establish the bioavailability and pharmacokinetic effects of purple carrot anthocyanins and phenolic acids prior to further trials of efficacy with respect to treating inflammation and metabolic alterations.

Sun-dried cowpeas and amaranth leaves recipe improves β-carotene and retinol levels in serum and hemoglobin concentration among preschool children

PURPOSE

Vitamin A deficiency (VAD) and anemia are major challenges among children and expecting and lactating mothers in developing countries. Intervention with locally available dark green leafy vegetables (DGLV) is more sustainable to eradicate VAD, being cost-effective and readily adaptable to local communities. DGLV contain high levels of iron and β-carotene (BC) and therefore useful in fighting VAD and anemia. Since DGLVs are season-dependent sun-drying enables their availability during low seasons. However, their contribution to the bioavailability of BC and the improvement of hemoglobin are not well understood. The study therefore investigated the effect of consuming cooked recipe consisting of sun-dried amaranth and cowpea leaves on the levels of BC, retinol, and hemoglobin in preschool children from Machakos District, a semiarid region in Kenya.

METHODS

Vegetables were purchased from local vegetable market, with some sun-dried in an open shade. Levels of BC and retinol in serum and BC in fresh and processed vegetables were determined by a HPLC method and hemoglobin using a portable Hemocue Analyzer.

RESULTS

All-trans-BC levels in uncooked fresh cowpea and amaranth leaves were 806.0 μg/g and 599.0 μg/g dry matter, respectively, while the dehydration and cooking processes retained the β-carotene levels at over 60 %. Consumption of the dehydrated vegetables significantly improved both serum BC and retinol levels (p < 0.05), while the baseline hemoglobin levels improved by 4.6 %.

CONCLUSION

The study has shown that intervention with locally available sun-dried vegetables improves the bioavailability of BC, retinol, and hemoglobin levels among preschool children.