The Colors of Health: Chemistry, Bioactivity, and Market Demand for Colorful Foods and Natural Food Sources of Colorants

Recent Findings in Azaphilone Pigments

Filamentous fungi are known to biosynthesize an extraordinary range of azaphilones pigments with structural diversity and advantages over vegetal-derived colored natural products such agile and simple cultivation in the lab, acceptance of low-cost substrates, speed yield improvement, and ease of downstream processing. Modern genetic engineering allows industrial production, providing pigments with higher thermostability, water-solubility, and promising bioactivities combined with ecological functions. This review, covering the literature from 2020 onwards, focuses on the state-of-the-art of azaphilone dyes, the global market scenario, new compounds isolated in the period with respective biological activities, and biosynthetic pathways. Furthermore, we discussed the innovations of azaphilone cultivation and extraction techniques, as well as in yield improvement and scale-up. Potential applications in the food, cosmetic, pharmaceutical, and textile industries were also explored.

MMP-9 and IL-1β as Targets for Diatoxanthin and Related Microalgal Pigments: Potential Chemopreventive and Photoprotective Agents

Photochemoprevention can be a valuable approach to counteract the damaging effects of environmental stressors (e.g., UV radiations) on the skin. Pigments are bioactive molecules, greatly attractive for biotechnological purposes, and with promising applications for human health. In this context, marine microalgae are a valuable alternative and eco-sustainable source of pigments that still need to be taken advantage of. In this study, a comparative in vitro photochemopreventive effects of twenty marine pigments on carcinogenic melanoma model cell B16F0 from UV-induced injury was setup. Pigment modulation of the intracellular reactive oxygen species (ROS) concentration and extracellular release of nitric oxide (NO) was investigated. At the cell signaling level, interleukin 1-β (IL-1β) and matrix metallopeptidase 9 protein (MMP-9) protein expression was examined. These processes are known to be involved in the signaling pathway, from UV stress to cancer induction. Diatoxanthin resulted the best performing pigment in lowering MMP-9 levels and was able to strongly lower IL-1β. This study highlights the pronounced bioactivity of the exclusively aquatic carotenoid diatoxanthin, among the others. It is suggested increasing research efforts on this molecule, emphasizing that a deeper integration of plant ecophysiological studies into a biotechnological context could improve the exploration and exploitation of bioactive natural products.

Mechanistic aspects of carotenoid health benefits - where are we now?

Dietary intake and tissue levels of carotenoids have been associated with a reduced risk of several chronic diseases, including cardiovascular diseases, type 2 diabetes, obesity, brain-related diseases and some types of cancer. However, intervention trials with isolated carotenoid supplements have mostly failed to confirm the postulated health benefits. It has thereby been speculated that dosing, matrix and synergistic effects, as well as underlying health and the individual nutritional status plus genetic background do play a role. It appears that our knowledge on carotenoid-mediated health benefits may still be incomplete, as the underlying mechanisms of action are poorly understood in relation to human relevance. Antioxidant mechanisms - direct or via transcription factors such as NRF2 and NF-κB - and activation of nuclear hormone receptor pathways such as of RAR, RXR or also PPARs, via carotenoid metabolites, are the basic principles which we try to connect with carotenoid-transmitted health benefits as exemplified with described common diseases including obesity/diabetes and cancer. Depending on the targeted diseases, single or multiple mechanisms of actions may play a role. In this review and position paper, we try to highlight our present knowledge on carotenoid metabolism and mechanisms translatable into health benefits related to several chronic diseases.

Technological Applications of Natural Colorants in Food Systems: A Review

Natural colorants have emerged as an alternative to their synthetic counterparts due to an existing health concern of these later. Moreover, natural-food colorants are a renewable option providing health benefits and interesting technological and sensory attributes to the food systems containing them. Several sources of natural colorants have been explored aiming to deliver the required wide color range demanded by consumers. This review aimed to compare and discuss the technological applications of the main natural-food colorants into food system in the last six years, giving additional information about their extraction process. Although natural colorants are promising choices to replace synthetic ones, optimization of processing conditions, research on new sources, and new formulations to ensure stability are required to equate their properties to their synthetic counterparts.

Red beet (Beta vulgaris) betalains and grape (Vitis vinifera) anthocyanins as colorants in white currant juice - Effect of storage on degradation kinetics, color stability and sensory properties

Red beet betalains, grape anthocyanins, and their mixtures were used as colorants in white currant juice. Storage stability of the compounds was evaluated using liquid chromatography and the degradation kinetic order and parameters were calculated. Degradation of betalains followed first-order kinetics, while the degradation of anthocyanins did not have any trend toward any order kinetics. The coexisting anthocyanins and their concentration affected the rate constant of betalains. Betalains degraded faster than anthocyanins, their mixtures promoted respective degradation. Pyruvate derivatives of anthocyanins showed better stability. During storage, all samples became more yellowish with CIELab method and lighter in color. In the projective mapping sensory test, samples were distinguished by the colorant type as the main criteria and the storage time as the second criteria. Anthocyanin (described as 'dark' and 'natural') was preferred by sensory panelists over betalain (described as 'pink' and 'unnatural'), as were the fresh samples over stored samples.

Enhancement of Biological Properties of Blackcurrants by Lactic Acid Fermentation and Incorporation into Yogurt: A Review

Blackcurrants (BC) and yogurt are known to possess several health benefits. The objective of this review was to compile the latest information on the effect of lactic acid fermentation on BC and their incorporation into yogurt, including the impact of this combination on chemical composition, sensory aspects, and health attributes of the blend. Google Scholar, Scopus, and PubMed were used to research the most recent literature on BC juice, the whole BC berry, and yogurt. Health benefits were assessed from human and animal studies within the last 5 years. The results suggest that BC have several health promoting compounds that ameliorate some neurological disorders and improve exercise recovery. Yogurt contains compounds that can be used to manage diseases such as type 2 diabetes (T2D) and irritable bowel disease (IBD). Fermenting BC with lactic acid bacteria (LAB) and its incorporation into yogurt products increases the polyphenol and antioxidant capacity of BC, creating a blend of prebiotics and probiotics compounds with enhanced benefits. More research is needed in the area of lactic acid fermentation of berries in general, especially BC.

Elevated temperature and drought stress significantly affect fruit quality and activity of anthocyanin-related enzymes in jujube (Ziziphus jujuba Mill. cv. 'Lingwuchangzao')

The quality attributes of jujube fruit can be directly and indirectly affected by abiotic stresses associated with climate change. Increased temperature and drought are among the most important factors challenging sustainable jujube production in the temperate semi-arid region in northwest China. The main objective of the present study was to understand the effects of elevated air temperature and drought stress on sugar and acid accumulation and coloration of jujube fruits. The content of soluble sugar, organic acid and pigments of traditional jujube "Linwuchangzao" under different atmospheric temperatures and drought stresses were analyzed during three different fruit ripening stages. The elevated temperature (1.5-2.5° C than normal temperature) significantly increased the fruit sugar content, sugar-acid ratio, anthocyanins, flavonoids and carotenoids content. Under the drought stress where the soil moisture was 30% -50% of the field capacity, sugar content, anthocyanin, flavonoid and carotenoid content of the fruit were significantly reduced at the same temperature, but the chlorophyll and organic acid content increased. No significant interaction of Temperature x Drought was observed for all the analyzed quality parameters. The current results showed that the fruit quality of jujube variety "Lingwuchangzao" could be improved when the atmospheric temperature increases by 2° C in this region. However, drought stress had a negative impact on the fruit's sugar-acid ratio and pigment content. The present results also showed that the synthesis and accumulation of anthocyanins in jujube fruit were positively correlated with sugar content and related enzyme activities, especially Phenylalanine Ammonia-lyase (PAL) activity. This study, therefore, provides novel information for understanding the influence of growth environment on the quality properties of jujube fruits. This knowledge will help develop appropriate crop management practices for jujube production in arid and semi-arid areas in northwest China.

Co-Ingestion of Black Carrot and Strawberry. Effects on Anthocyanin Stability, Bioaccessibility and Uptake

Although the fate of anthocyanins along digestion has been a matter of research over the last decade, their bioaccessibility so far has been mainly assessed for single administered fruits or vegetables, which is far from the real scenario where they are co-ingested in a meal. Accordingly, the aim of this study was to evaluate the effect of simultaneous intake of fruit and vegetable on in vitro stability, bioaccessibility and uptake of anthocyanins. Black carrot and strawberry were used as food sources of anthocyanins. Anthocyanin identification and quantification were performed using HPLC-Qtof/HPLC-UV. Single matrices and mixtures thereof, were submitted to a standardized in vitro digestion procedure. Anthocyanin uptake was evaluated through an intestinal Caco-2 cell model. Our results showed an increased intestinal stability for specific anthocyanins as a consequence of co-digestion. The presence of the strawberry food matrix positively affected the bioaccessibility of the carrot associated cyanidin-based anthocyanins, whereas no reciprocal effect was observed for pelargonidin-based derivatives in the presence of the black carrot food matrix. Anthocyanin transport was maintained after co-administration. Overall, co-ingestion of black carrot and strawberry did not negatively affect the stability, bioaccessibility or uptake of cyanidin-based anthocyanins, although the effect on pelargonidin-based anthocyanins depended on the type of pelargonidin derivative.

Beetroot, a Remarkable Vegetable: Its Nitrate and Phytochemical Contents Can be Adjusted in Novel Formulations to Benefit Health and Support Cardiovascular Disease Therapies

The cardioprotective effects of dietary nitrate from beetroot in healthy and hypertensive individuals are undeniable and irrefutable. Nitrate and nitrate-derived nitrite are precursors for nitric oxide synthesis exhibiting an effect on cardiomyocytes and myocardial ischemia/reperfusion, improving endothelial function, reducing arterial stiffness and stimulating smooth muscle relaxation, decreasing systolic and diastolic blood pressures. Beetroot phytochemicals like betanin, saponins, polyphenols, and organic acids can resist simulated gastrointestinal digestion, raising the hypothesis that the cardioprotective effects of beetroots result from the combination of nitrate/nitrite and bioactive compounds that limit the generation of reactive oxygen species and modulate gene expression. Nitrate and phytochemical concentrations can be adjusted in beet formulations to fulfill requirements for acute or long-term supplementations, enhancing patient adherence to beet intervention. Based on in vitro, in vivo, and clinical trials, beet nitrate and its bioactive phytochemicals are promising as a novel supportive therapy to ameliorate cardiovascular diseases.

Protein-polyphenol functional ingredients: The foaming properties of lactoferrin are enhanced by forming complexes with procyanidin

The solution turbidity and intrinsic fluorescence quenching increased after procyanidin was mixed with lactoferrin. The addition of procyanidin also caused a reduction in the surface hydrophobicity of the lactoferrin, suggesting procyanidin bound to non-polar patches on lactoferrin's surfaces. Moreover, the binding interaction caused an appreciable alteration in the structure of both the polyphenol and protein. Thermodynamic analysis indicated the interaction was spontaneous and mainly driven by entropy changes, suggesting that hydrophobic interactions dominated. A computational docking simulation provided insights into the location of the most-likely binding sites on the protein, as well as the nature of the interaction forces involved. In particular, both hydrophobic and hydrogen bonding were found to be important. The binding of the procyanidin to the lactoferrin enhanced its foaming properties. These results may lead to the development of a new class of natural functional ingredients that can be used in food products to improve their quality attributes.

Stability, kinetics, and application study of phycobiliprotein pigments extracted from red algae Gracilaria gracilis

Phycobiliprotein (PBP) pigments were extracted from red algae Gracilaria gracilis through maceration in phosphate buffer using previously optimized conditions. The stability of PBPs in the extracts was assessed by monitoring the extracts at different pHs and temperatures for 10 days. Since phycoerythrin (PE) is the main PBP present in G. gracilis, PE content was spectroscopically determined and used as a response factor. Kinetic modeling was used to describe PE degradation under different ranges of T and pH. The pigment extracts presented higher stability at pH 6.9 and -20 °C. PE was semipurified by precipitation with ammonium sulphate 65% followed by dialysis against water until a purity index of 0.7. The pigment was successfully applied as colorant in pancakes and yogurts with a pigment concentration of 0.15%. This study highlights the potential of PE pigments extracted from G. gracilis for applications in food products. PRACTICAL APPLICATION: Phycobiliprotein pigments were extracted from red algae Gracilaria gracilis through maceration in phosphate buffer. The stability of the pigment was evaluated at different pHs and temperatures, presenting higher stability at neutral pH and low temperatures. The pigment was successfully applied as colorant in pancakes and yogurts with a low pigment concentration. This study highlights the potential of phycobiliprotein pigments extracted from G. gracilis for applications in food products.

Lycopene Protects against Smoking-Induced Lung Cancer by Inducing Base Excision Repair

Background: Oxidative stress plays a critical role in lung cancer progression. Carotenoids are efficient antioxidants. The objective of this study was to explore the efficacy of all-trans retinoic acid (ATRA) and carotenoids in cigarette smoke-induced oxidative stress within A549 human lung cancer epithelial cells. Methods: A549 cells were pretreated with 1-nM, 10-nM, 100-nM, 1-μM and 10-μM ATRA, β-carotene (BC) and lycopene for 24 h, followed by exposure to cigarette smoke using a smoking chamber. Results: The OxyBlot analysis showed that smoking significantly increased oxidative stress, which was inhibited by lycopene at 1 nM and 10 nM (p < 0.05). In the cells exposed to smoke, lycopene increased 8-oxoguanine DNA glycosylase (OGG1) expression at 1 nM, 10 nM, 100 nM, and 1 μM (p < 0.05), but not at 10 μM. Lycopene at lower doses also improved Nei like DNA glycosylases (NEIL1, NEIL2, NEIL3), and connexin-43 (Cx43) protein levels (p < 0.05). Interestingly, lycopene at lower concentrations promoted OGG1 expression within the cells exposed to smoke to an even greater extent than the cells not exposed to smoke (p < 0.01). This may be attributed to the increased SR-B1 mRNA levels with cigarette smoke exposure (p < 0.05). Conclusions: Lycopene treatment at a lower dosage could inhibit smoke-induced oxidative stress and promote genome stability. These novel findings will shed light on the molecular mechanism of lycopene action against lung cancer.