Bioavailability of natural (plant) food colorants

Today the challenge of food industry is to provide foods as natural as possible and thus the use of natural colorants is likely to expand. The four main classes of natural pigments from plants used in food industry are: carotenoids, anthocyanins, betalains and chlorophylls. In addition to provide colours, these compounds exhibit potential benefits for human health, making them even more attractive. In view of their extensive use, it is important to investigate the fate of natural pigments in the human body for safety reasons and for optimizing their health-promoting effects. Carotenoids have been the most studied so for, probably because their high consumption was linked to a lower incidence of certain diseases and because some of them exhibit a provitamin A activity. Clearly, more investigations ore needed for a better understanding of natural pigment bioavoilability

The O-methylation of chrysin markedly improves its intestinal anti-inflammatory properties: Structure-activity relationships of flavones

The aim of this study was to investigate whether methoxylated flavones versus their unmethylated analogs can modulate the intestinal inflammatory response. Flavone effects were assessed on soluble pro-inflammatory mediator (IL-8, IL-6, macrophage chemoattractant protein-1 (MCP-1), and cyclooxygenase-2 (COX-2)-derived PGE2) production and on nuclear factor (NF)-κB activation in 3d-confluent and 21d-differentiated Caco-2 cells stimulated with interleukin (IL)-1β. Chrysin (CHRY) showed anti-inflammatory properties by decreasing COX-2-derived PGE2 and reducing NF-κB activation. Compared to CHRY, the dimethoxylated form (CHRY-DM) significantly reduced the secretion of all pro-inflammatory mediators, except IL-8, at both cellular stages (P < 0.05); these effects being dose-dependent in 3d-cells. The reduction of NF-κB activation was significantly more pronounced with CHRY-DM. By evaluating other flavones, it was established that several structural dispositions of flavones seemed to be determinant in order to attenuate the intestinal inflammatory response, such as methoxylation of the 5- and 7-hydroxyl groups on the A-ring, non-methoxylation of the 3′-hydroxyl groups on the B-ring, and methoxylation of the 3-hydroxyl group on the C-ring. Of all flavones examined, CHRY-DM exhibited the strongest anti-inflammatory activity. These data indicate that, in the Caco-2 cell model, methoxylation of CHRY greatly improves its anti-inflammatory properties, probably through a more pronounced inhibition of the NF-κB signaling pathway. Nevertheless, methoxylation of other flavones was not systematically beneficial. Chemical compounds studied in this article*Chrysin (PubChem CID 5281607)*5,7-dimethoxyflavone (PubChem CID 88881)*3′,4′- dihydroxyflavone (PubChem CID 145726)*3′,4′-dimethoxyflavone (PubChem CID 688674)*apigenin (PubChem CID 5280443)*4′,5,7- trimethoxyflavone (PubChem CID 79730)*luteolin (PubChem CID 5280445)*3′,4′,5,7-tetramethoxyflavone (PubChem CID 631170)*quercetin (PubChem CID 5280343)*3′,4′,3,5,7- pentamethoxyflavone (PubChem CID 97332) Abbreviations*API*apigenin or 4′,5,7-trihydroxyflavone*API-TM*4′,5,7- trimethoxyflavone*CHRY*chrysin or 5,7-dihydroxyflavone*CHRY- DM*dimethylated chrysin or 5,7-dimethoxyflavone*COMT*catechol- O-methyltransferase*COX*cyclooxygenase*CTL* control*3′,4′-DHF*3′,4′- dihydroxyflavone*3′,4′-DMF*3′,4′- dimethoxyflavone*DSS*dextran sodium sulfate*FBS*fetal bovine serum*IBDs*intestinal bowel diseases*IL* interleukin*LDH*lactate dehydrogenase*IECs*intestinal epithelial cells*iNOS*inducible nitric oxide synthase* LPS*lipopolysaccharide*LUT*luteolin or 3′,4′,5,7- tetrahydroxyflavone*LUT-QM*3′,4′,5,7- tetramethoxyflavone*MCP-1*monocyte chemotactic protein- 1*NEAA*nonessential amino acids*NF-κB*nuclear factor κB*QUER*quercetin or 3′,4′,3,5,7- pentahydroxyflavone*QUER-PM*3′,4′,3,5, 7-pentamethoxyflavone. © 2013 Elsevier Inc. All rights reserved

Citrus flavanones enhance carotenoid uptake by intestinal Caco-2 cells

International audienceThe health benefit of a diet rich in fruits and vegetables could be attributed to the presence of a large diversity of phytochemicals, including carotenoids. Bioactivities of carotenoids greatly depend on their bioavailability that could be modulated by the presence of other dietary constituents. Because citrus juices contain diverse antioxidant phytochemicals, the effects of flavonoids and ascorbic acid on intestinal carotenoid uptake were investigated. Experiments were conducted by using a Caco-2 cell monolayer exposed to micelles enriched in beta-cryptoxanthin (b-CX, 5 mu M) and beta-carotene (b-C, 5 mu M) in the presence of hesperetin (HES, 250 mu M), hesperidin (HES-G, 250 mu M), naringenin (NGN, 250 mu M), acid ascorbic (AA, 50 mu M) and iron. At 5 h or 24 h incubation, HES-G and HES significantly increased b-CX and b-C uptake by 1.7- and 1.6-fold, respectively (p < 0.05). Interestingly, AA was shown to eliminate the enhancing effect of HES-G by decreasing significantly the cellular uptake of carotenoids from 48.2 to 39.8% after 5 h incubation (p < 0.05). Iron decreased the carotenoid uptake, while HES-G in the presence of iron restored it, suggesting that the enhancing effect of HES-G on carotenoid uptake could be attributed to its iron-chelating activity