A Review of the Chemistry and Biological Activities of Natural Colorants, Dyes, and Pigments: Challenges, and Opportunities for Food, Cosmetics, and Pharmaceutical Application.

Natural pigments are important sources for the screening of bioactive lead compounds. This article reviewed the chemistry and therapeutic potentials of over 570 colored molecules from plants, fungi, bacteria, insects, algae, and marine sources. Moreover, related biological activities, advanced extraction, and identification approaches were reviewed. A variety of biological activities, including cytotoxicity against cancer cells, antioxidant, anti-inflammatory, wound healing, anti-microbial, antiviral, and anti-protozoal activities, have been reported for different pigments. Considering their structural backbone, they were classified as naphthoquinones, carotenoids, flavonoids, xanthones, anthocyanins, benzotropolones, alkaloids, terpenoids, isoprenoids, and non-isoprenoids. Alkaloid pigments were mostly isolated from bacteria and marine sources, while flavonoids were mostly found in plants and mushrooms. Colored quinones and xanthones were mostly extracted from plants and fungi, while colored polyketides and terpenoids are often found in marine sources and fungi. Carotenoids are mostly distributed among bacteria, followed by fungi and plants. The pigments isolated from insects have different structures, but among them, carotenoids and quinone/xanthone are the most important. Considering good manufacturing practices, the current permitted natural colorants are: Carotenoids (canthaxanthin, ß-carotene, ß-apo-8'-carotenal, annatto, astaxanthin) and their sources, lycopene, anthocyanins, betanin, chlorophyllins, spirulina extract, carmine and cochineal extract, henna, riboflavin, pyrogallol, logwood extract, guaiazulene, turmeric, and soy leghemoglobin.

The chromogenic mechanism of natural pigments and the methods and techniques to improve their stability: A systematic review.

Pigments have become a very important part of food research, not only adding sensory properties to food, but also providing functional properties to the food system. In this paper, we review the source, structure, modification, encapsulation and current status of the three main types of natural pigments that have been studied in recent years: polyphenolic flavonoids, tetraterpenoids and betaines. By examining the modification of pigment, the improvement of their stability and the impact of new food processing methods on the pigments, a deeper understanding of the properties and applications of the three pigments is gained, the paper reviews the research status of pigments in order to promote their further research and provide new innovations and ideas for future research in this field.

Azaphilones from the Endophyte Diaporthe sp. and Their Toxicity.

Chemotherapy and targeted therapies are increasingly used as conventional means to control tumor growth and prolong survival. Patient treated with anti-neoplastic agents experience severe side effects, especially those cytotoxic chemotherapies. Exploring chemo agents with less side effects is the hot spot of anticancer research. In this study, three azaphilone derivatives (chaetoviridin A (1), chaetoviridin E (2) and chaetomugilin D (3)) were isolated from the endophyte of the plant Anoectochilus roxburghii (Wall.) Lindl, their structures were elucidated by NMR. The toxicity of these compounds was evaluated by zebrafish model. The results show that these compounds had no toxicity against zebrafish. These compounds may act as safe anticancer drug leads according to this result. These three azaphilone derivatives were first time reported isolated from Diaporthe species which mainly used to isolate from Chaetomium species.

Bioprospecting of Microalgae Isolated from the Adriatic Sea: Characterization of Biomass, Pigment, Lipid and Fatty Acid Composition, and Antioxidant and Antimicrobial Activity.

Marine microalgae and cyanobacteria are sources of diverse bioactive compounds with potential biotechnological applications in food, feed, nutraceutical, pharmaceutical, cosmetic and biofuel industries. In this study, five microalgae, Nitzschia sp. S5, Nanofrustulum shiloi D1, Picochlorum sp. D3, Tetraselmis sp. Z3 and Tetraselmis sp. C6, and the cyanobacterium Euhalothece sp. C1 were isolated from the Adriatic Sea and characterized regarding their growth kinetics, biomass composition and specific products content (fatty acids, pigments, antioxidants, neutral and polar lipids). The strain Picochlorum sp. D3, showing the highest specific growth rate (0.009 h-1), had biomass productivity of 33.98 ± 0.02 mg L-1 day-1. Proteins were the most abundant macromolecule in the biomass (32.83-57.94%, g g-1). Nanofrustulum shiloi D1 contained significant amounts of neutral lipids (68.36%), while the biomass of Picochlorum sp. D3, Tetraselmis sp. Z3, Tetraselmis sp. C6 and Euhalothece sp. C1 was rich in glycolipids and phospholipids (75%). The lipids of all studied microalgae predominantly contained unsaturated fatty acids. Carotenoids were the most abundant pigments with the highest content of lutein and neoxanthin in representatives of Chlorophyta and fucoxanthin in strains belonging to the Bacillariophyta. All microalgal extracts showed antioxidant activity and antimicrobial activity against Gram-negative E. coli and S. typhimurium and Gram-positive S. aureus.

Novel Findings regarding the Bioactivity of the Natural Blue Pigment Genipin in Human Diseases.

Genipin is an important monoterpene iridoid compound isolated from Gardenia jasminoides J.Ellis fruits and from Genipa americana fruits, or genipap. It is a precursor of a blue pigment which may be attractive alternative to existing food dyes and it possesses various potential therapeutic properties such as anti-cancer, anti-diabetic and hepatoprotective activity. Biomedical studies also show that genipin may act as a neuroprotective drug. This review describes new aspects of the bioactivity of genipin against various diseases, as well as its toxicity and industrial applications, and presents its potential mechanism of action.

Azaphilones as Activation-Free Primary-Amine-Specific Bioconjugation Reagents for Peptides, Proteins and Lipids.

Residue-selective bioconjugation methods for biomolecules are highly sought to expand the scope of their biological and medical applications. Inspired by the mechanism of the generation of natural vinylogous γ-pyridones (vPDNs), we have developed a novel unique azaphilone-based, activation-free primary-amine-selective bioconjugation method for biomolecules. Our strategy allows facile functionalization of primary amine groups in peptides and proteins, including the clinically used therapeutic antibody trastuzumab, by generating a highly stable vPDN linkage. Excellent chemoselectivity toward primary amines also enables the azaphilone derivatives to specifically modify the lipid components of Gram-positive bacteria while bypassing Gram-negative bacteria and mammalian cells. The new method shows significant advantages including chemoselectivity, efficiency, flexibility and biocompatibility, and therefore provides a valuable addition to the current toolbox for biomolecule conjugation.

Optimized separation of anhydrosafflor yellow B from safflower by high-speed counter-current chromatography and evaluation of its cardio-protective effect.

Anhydrosafflor yellow B (AHSYB) is a major active water-soluble pigment in Safflower, but it has not received enough attention yet. In this study, high-speed counter-current chromatography (HSCCC) was used to prepare AHSYB from safflower. The parameters of the separation process were optimized by response surface methodology for the first time. The entropy weight method (EWM) was applied to calculate the information entropy and the weight of five indexes, and then figure out a comprehensive index of the HSCCC separation effect. Under the optimized separation conditions, a HSCCC apparatus speed of 850 rpm, a flow rate of 2 mL min-1 for the mobile phase and a separation temperature of 40 °C for AHSYB were achieved with a purity of 98%. Furthermore, AHSYB was found to have cardio-protective effects by inhibiting apoptosis via the mitochondrial-mediated pathway in oxygen-glucose deprivation/reoxygenation-induced H9c2 cells. This research provides good method guides for the rapid and efficient separation of active compounds from food-grade Chinese herb medicines.

Anti-Inflammatory Azaphilones from the Edible Alga-Derived Fungus Penicillium sclerotiorum.

To discover the new medical entity from edible marine algae, our continuously natural product investigation focused on endophytes from marine macroalgae Grateloupia sp. Two new azaphilones, 8a-epi-hypocrellone A (1), 8a-epi-eupenicilazaphilone C (2), together with five known azaphilones, hypocrellone A (3), eupenicilazaphilone C (4), ((1E,3E)-3,5-dimethylhepta-1,3-dien-1-yl)-2,4-dihydroxy-3-methylbenzaldehyde (5), sclerotiorin (6), and isochromophilone IV (7) were isolated from the alga-derived fungus Penicillium sclerotiorum. The structures of isolated azaphilones (1-7) were elucidated by spectrometric identification, especially HRESIMS, CD, and NMR data analyses. Concerning bioactivity, cytotoxic, anti-inflammatory, and anti-fibrosis activities of those isolates were evaluated. As a result, compound 1 showed selective toxicity toward neuroblastoma cell line SH-SY5Y among seven cancer and one fibroblast cell lines. 20 µM of compounds 1, 3, and 7 inhibited the TNF-α-induced NFκB phosphorylation but did not change the NFκB activity. Compounds 2 and 6 respectively promoted and inhibited SMAD-mediated transcriptional activities stimulated by TGF-ß.

Phlorotannin and Pigment Content of Native Canopy-Forming Sargassaceae Species Living in Intertidal Rockpools in Brittany (France): Any Relationship with Their Vertical Distribution and Phenology?

Five native Sargassaceae species from Brittany (France) living in rockpools were surveyed over time to investigate photoprotective strategies according to their tidal position. We gave evidences for the existence of a species distribution between pools along the shore, with the most dense and smallest individuals in the highest pools. Pigment contents were higher in lower pools, suggesting a photo-adaptive process by which the decreasing light irradiance toward the low shore was compensated by a high production of pigments to ensure efficient photosynthesis. Conversely, no xanthophyll cycle-related photoprotective mechanism was highlighted because high levels of zeaxanthin rarely occurred in the upper shore. Phlorotannins were not involved in photoprotection either; only some lower-shore species exhibited a seasonal trend in phlorotannin levels. The structural complexity of phlorotannins appears more to be a taxonomic than an ecological feature: Ericaria produced simple phloroglucinol while Cystoseira and Gongolaria species exhibited polymers. Consequently, tide pools could be considered as light-protected areas on the intertidal zone, in comparison with the exposed emerged substrata where photoprotective mechanisms are essential.

The Influence of Temperature, Storage Conditions, pH, and Ionic Strength on the Antioxidant Activity and Color Parameters of Rowan Berry Extracts.

Recent trends in the food industry combined with novel methods in agriculture could transform rowan into a valuable raw material with potential technological applications. Thus, the aim of this research was to investigate the content of bioactive compounds in its fruits and to assess the color and antioxidant stability of the extracts prepared from such fruits during various thermal treatments and at different pH and ionic strength values. Various spectrophotometric methods, HPLC, and capillary electrophoresis were used to quantify the concentrations of bioactive compounds-polyphenols, carotenoids, organic acids, and to assess antioxidant activity and color. The results show that rowan berries contain circa 1.34-1.47 g/100 g of polyphenols among which include catechin, epicatechin, ferulic acid methyl ester, procyanidin B1, etc.; ca 21.65 mg/100 g of carotenoids including zeaxanthin, ß-cryptoxanthin, all-trans-ß-carotene, and various organic acids such as malic, citric, and succinic, which result in a high antioxidant activity of 5.8 mmol TE/100 g. Results also showed that antioxidant activity exhibited high stability when the extract was subjected to various thermal treatments, pHs, and ionic strengths, while color was mainly impacted negatively when a temperature of 100 °C was employed. This data confirms the technological potential of this traditional, yet often overlooked species.

Tetrapyrrolic Pigments from Heme- and Chlorophyll Breakdown are Actin-Targeting Compounds.

Chlorophyll and heme are among the "pigments of life", tetrapyrrolic structures, without which life on Earth would not be possible. Their catabolites, the phyllobilins and the bilins, respectively, share not only structural features, but also a similar story: Long considered waste products of detoxification processes, important bioactivities for both classes have now been demonstrated. For phyllobilins, however, research on physiological roles is sparse. Here, we introduce actin, the major component of the cytoskeleton, as the first discovered target of phyllobilins and as a novel target of bilins. We demonstrate the inhibition of actin dynamics in vitro and effects on actin and related processes in cancer cells. A direct interaction with G-actin is shown by in silico studies and confirmed by affinity chromatography. Our findings open a new chapter in bioactivities of tetrapyrroles-especially phyllobilins-for which they form the basis for broad implications in plant science, ecology, and physiology.

Antioxidant Activity and Healthy Benefits of Natural Pigments in Fruits: A Review.

Natural pigments, including carotenoids, flavonoids and anthocyanidins, determine the attractive color of fruits. These natural pigments are essential secondary metabolites, which play multiple roles in the whole life cycle of plants and are characterized by powerful antioxidant activity. After decades of research and development, multiple benefits of these natural pigments to human health have been explored and recognized and have shown bright application prospects in food, medicine, cosmetics and other industries. In this paper, the research progress of natural fruit pigments in recent years was reviewed, including the structural characteristics and classification, distribution in fruits and analysis methods, biosynthetic process, antioxidant capacity and mechanism, bioaccessibility and bioavailability, and health benefits. Overall, this paper summarizes the recent advances in antioxidant activity and other biological functions of natural fruit pigments, which aims to provide guidance for future research.

Acylated Anthocyanins from Red Cabbage and Purple Sweet Potato Can Bind Metal Ions and Produce Stable Blue Colors.

Red cabbage (RC) and purple sweet potato (PSP) are naturally rich in acylated cyanidin glycosides that can bind metal ions and develop intramolecular π-stacking interactions between the cyanidin chromophore and the phenolic acyl residues. In this work, a large set of RC and PSP anthocyanins was investigated for its coloring properties in the presence of iron and aluminum ions. Although relatively modest, the structural differences between RC and PSP anthocyanins, i.e., the acylation site at the external glucose of the sophorosyl moiety (C2-OH for RC vs. C6-OH for PSP) and the presence of coordinating acyl groups (caffeoyl) in PSP anthocyanins only, made a large difference in the color expressed by their metal complexes. For instance, the Al3+-induced bathochromic shifts for RC anthocyanins reached ca. 50 nm at pH 6 and pH 7, vs. at best ca. 20 nm for PSP anthocyanins. With Fe2+ (quickly oxidized to Fe3+ in the complexes), the bathochromic shifts for RC anthocyanins were higher, i.e., up to ca. 90 nm at pH 7 and 110 nm at pH 5.7. A kinetic analysis at different metal/ligand molar ratios combined with an investigation by high-resolution mass spectrometry suggested the formation of metal-anthocyanin complexes of 1:1, 1:2, and 1:3 stoichiometries. Contrary to predictions based on steric hindrance, acylation by noncoordinating acyl residues favored metal binding and resulted in complexes having much higher molar absorption coefficients. Moreover, the competition between metal binding and water addition to the free ligands (leading to colorless forms) was less severe, although very dependent on the acylation site(s). Overall, anthocyanins from purple sweet potato, and even more from red cabbage, have a strong potential for development as food colorants expressing red to blue hues depending on pH and metal ion.

Dry pasteurization of paprika (Capsicum annuum L.) by short time intensive microwave-infrared radiation: Inactivation of Salmonella Typhimurium and Aspergillus flavus considering quality degradation kinetics.

The inactivation of S. Typhimurium and A. flavus along with quality degradation kinetics was studied during combined microwave-infrared (MW-IR) heating of paprika. The spatial changes in the distribution of temperature and variation in water activity (aw) of the paprika samples resulted in a 7.389 log reduction in S. Typhimurium, and 6.182 log reduction in A. flavus. During heating, the deterioration of red pigments was more pronounced compared to that of the yellow pigments. The alteration of color was observed to be due to the increase in a large number of brown pigments. The inhibition of DPPH radicals accelerated with an increase in the power level of MW-IR radiation; the inhibition rate increased from 0.0859 to 0.1485 s-1. Also, the pungency of dried paprika was found to increase due to moisture reduction, inactivation of peroxidase, and the short-duration of heating.

HPLC Detection and Antioxidant Capacity Determination of Brown, Red and Green Algal Pigments in Seaweed Extracts.

This study was carried out to determine the main pigments in some different selected seaweeds and to reveal their antioxidant potential regarding the ever-increasing demand for utilization of marine pigments in human health and nutrition. The individual amounts of algal pigments were found by reverse phase high-performance liquid chromatography (HPLC) and their total antioxidant capacities (TAC) by two spectrophotometric TAC assays, namely: CUPRAC (CUPric ion Reducing Antioxidant Capacity) and ABTS/TEAC (2,2'-azinobis [3-ethyl benzo thiazoline-6-sulfonate])/(trolox equivalent antioxidant capacity). These two tests gave the same rank order for TAC. The TAC of HPLC-quantified compounds accounted for a relatively much lower percentage of the observed CUPRAC capacities of seaweed extracts, namely ranging from 11 to 68% for brown, from 4 to 41% for red and from 3 to 100% for green species, i.e., some TAC originated from chromatographically unidentified compounds. Fucoxanthin, chlorophyll a, and pheophytin a compounds were major pigments in brown algae. The relative carotenoid contents in red marine algae were generally lower than those of chlorophylls. Overall total quantities were quite low compared with those of brown species. In general, chlorophyll a and chlorophyll b were chiefly present in green algae, but ß-carotene, violaxanthin and siphonaxanthin were also detected substantially higher in some species of green algae such as Caulerpa racemosa var. cylindracea and Codium fragile.

Anthocyanin Pigments: Beyond Aesthetics.

Anthocyanins are polyphenol compounds that render various hues of pink, red, purple, and blue in flowers, vegetables, and fruits. Anthocyanins also play significant roles in plant propagation, ecophysiology, and plant defense mechanisms. Structurally, anthocyanins are anthocyanidins modified by sugars and acyl acids. Anthocyanin colors are susceptible to pH, light, temperatures, and metal ions. The stability of anthocyanins is controlled by various factors, including inter and intramolecular complexations. Chromatographic and spectrometric methods have been extensively used for the extraction, isolation, and identification of anthocyanins. Anthocyanins play a major role in the pharmaceutical; nutraceutical; and food coloring, flavoring, and preserving industries. Research in these areas has not satisfied the urge for natural and sustainable colors and supplemental products. The lability of anthocyanins under various formulated conditions is the primary reason for this delay. New gene editing technologies to modify anthocyanin structures in vivo and the structural modification of anthocyanin via semi-synthetic methods offer new opportunities in this area. This review focusses on the biogenetics of anthocyanins; their colors, structural modifications, and stability; their various applications in human health and welfare; and advances in the field.

Response surface optimization of the water immersion extraction and macroporous resin purification processes of anhydrosafflor yellow B from Carthamus tinctorius L.

In this study,based on a developed high performance liquid chromatographic quantitative method, the suitable extraction and purification conditions of anhydrosafflor yellow B (AHSYB) from safflower were determined by response surface methodology. The optimal water immersion extraction parameters were as follows: liquid to solid ratio of 22:1; extraction temperature of 75 °C; extraction time of 35 min. Under these conditions, the maximum extraction yield of AHSYB reached 0.465%. The aqueous extract was further purified by HPD-300 macroporous resin. The optimum adsorption conditions were: pH 2.8; adsorption flow rate of 1.9 mL/min; solution concentration of 0.06 g/mL. The optimum desorption conditions were: ethanol concentrations of 74%; desorption flow rate of 1.6 mL/min; elution volume of 4.4 BV. Under these conditions, the maximum adsorption ratio and desorption ratio reached 1.095 and 0.906 mg/g, respectively. The content of AHSYB reached 6.83%, which was 2.91 times higher than that before purification. PRACTICAL APPLICATION: The suitable conditions for water immersion extraction and macroporous resin purification of AHSYB are first determined, which facilitates the further utilization of AHSYB as a food and drug.

Production and antiproliferative effect of violacein, a purple pigment produced by an Antarctic bacterial isolate.

We studied the production and the potential use of a purple-pigment produced by an Antarctic bacterial isolate. This pigment was identified as violacein, a metabolite produced by many bacterial strains and reported that it has antiproliferative activity in many cell lines. We analyzed the effect of temperature and the composition of the growth medium on pigment production, achieving the highest yield at 20 °C in Tryptic Soy Broth medium supplemented with 3.6 g/L glucose. We doubled the yield of the pigment production when the process was scaled up in a 5 L bioreactor (77 mg/L of crude pigment). The pigment was purified and identified by mass spectrometry (DI-EI-MS) and Nuclear Magnetic Resonance (NMR) spectroscopy as violacein. We performed survival assays that showed that the pure pigment has antiproliferative activity and sensitize HeLa cells (cervix cell carcinoma) to cisplatin. Besides, the pigment did not show genotoxic activity in HeLa cells as found performing micronucleus assays. These results suggest that this pigment may be used as anticancer or sensitizer to cisplatin drug in cervix cancer.

Evolution of Virgin Olive Oil during Long-term Storage.

In this work, the evolution of virgin olive oil from 4 olive varieties when stored at 5°C, 10°C and 20°C for a period of up to 3 years was studied. Free acidity increased progressively for the 4 varieties, staying below the limit for extra virgin olive oil, even at the highest temperature. The peroxide value also increased, reaching its maximum after about 28 months of storage, when some samples stored at 20°C exceeded the limit for extra virgin olive oil. The maximum values for K270 and K232 were reached at the end of the storage period, also exceeding the limit for extra virgin olive oil in the case of some varieties stored at 20°C. Oxidative stability decreased by 38%-50% depending on the storage temperature and the variety. Most of the color indexes increased in value because of the degradation of the oil pigments.

Nanosystems of plant-based pigments and its relationship with oxidative stress.

Plant-based pigments are widely present in nature, they are classified depending on their chemical structure as tetrapyrroles, carotenoids, polyphenolic compounds, and alkaloids and are extensively used in medicine, food industry, clothes, and others. Recently they have been investigated due to their role in the areas of food processing, food safety and quality, packaging, and nutrition. Many studies indicate a relationship between bioactive pigments and Non-Communicable Diseases derived from oxidative stress. Their biological applications can help in preventing oxidative injuries in the cell caused by oxygen and nitrogen reactive species. Those pigments are easily degraded by light, oxygen, temperature, pH conditions, among others. Nanotechnology offers the possibility to protect bioactive ingredients and increase its bioavailability after oral administration. Safety to humans (mainly evaluated from toxicity data) is the first concern for these products. In the present work, we present a comprehensive outlook of the most important plant-based pigments used as food colorants, the principal nanotechnology systems prepared with them, and the relationship of these compounds with the oxidative stress and related Non-Communicable Disease.