Class Of Pigments Research Articles

Phenological traits of red amaranth varieties with a high content of amaranthine cultivated in open fields of Moscow region

The article focuses on phenological features of amaranth varieties grown in open fields as a reaction to variability of weather conditions in the Moscow region. Amaranthine is one of the promising compounds found in red-colored amaranths. It refers to a class of betalain pigments. The study revealed growth stages defined by the highest content of amarantine per plant and analyzed accumulation of the pigment in amaranth leaves and inflorescences. Phenological observations of introduced plant species under new conditions are important and determine their resistance to adverse environmental factors, ability to produce high quality fruits and seeds, and potential for cultivation. During the introduction of new amaranth varieties, the most adapted forms were selected for the conditions of the Non-Chernozem zone of the Russian Federation in 2013-2016. The studied Russian and Ecuador varieties were divided into 4 groups depending on the growth period (from germination to seed maturity). Analysis of phenological traits of plants confirmed that period of amaranth development did not depend on the variety, except the fourth stage of late-ripening cultivars - Don Pedro and Eku 17020, dependent on weather conditions. Being dependent on weather conditions, the vegetative growth period turned to be the most stable. Late cv. Eku 17020 did not form mature seeds in open ground conditions, which is explained by its origin (Ecuador). In the present study we identified growth stages when plant raw materials had the highest dye content in red-leaved amaranth varieties (Valentina, Don Pedro and Fakel). We also considered the perspective of cultivation of green-leaved varieties with red inflorescences - Pamyati Kovasa and Eku-17020 - as sources of biologically valuable compounds in the Moscow region.

Natural and Synthetic Flavylium-Based Dyes: The Chemistry Behind the Color

Flavylium compounds are a well-known family of pigments because they are prevalent in the plant kingdom, contributing to colors over a wide range from shades of yellow-red to blue in fruits, flowers, leaves, and other plant parts. Flavylium compounds include a large variety of natural compound classes, namely, anthocyanins, 3-deoxyanthocyanidins, auronidins, and their respective aglycones as well as anthocyanin-derived pigments (e.g., pyranoanthocyanins, anthocyanin-flavan-3-ol dimers). During the past few decades, there has been increasing interest among chemists in synthesizing different flavylium compounds that mimic natural structures but with different substitution patterns that present a variety of spectroscopic characteristics in view of their applications in different industrial fields. This Review provides an overview of the chemistry of flavylium-based compounds, in particular, the synthetic and enzymatic approaches and mechanisms reported in the literature for obtaining different classes of pigments, their physical-chemical properties in relation to their pH-dependent equilibria network, and their chemical and enzymatic degradation. The development of flavylium-based systems is also described throughout this Review for emergent applications to explore some of the physical-chemical properties of the multistate of species generated by these compounds.

Environmentally benign rare earth pigments: effect of calcium dopant and tuning of bandgaps for different color hues

PurposeAs there is a strong inducement to develop new colored inorganic materials to substitute the current industrial pigments that are based on toxic metals hazardous to health and the environment, the purpose of this paper is to invent environmentally benign rare earth-based colorants as viable alternatives to the traditional toxic pigment formulations. Herein, the authors developed a series of rare earth pigments having the general formula Ca0.1 Ln0.9 PO4 ( Ln = Y , Pr , mixed rare earth oxides, RE and Di). After studying all the optical properties, the authors have gone for some coloring application in plastic like PMMA.Design/methodology/approachThe designed pigments were synthesized by traditional solid-state method. Stoichiometric amounts of each reagent were mixed in an agate mortar and the mixtures were calcined at optimized temperature 1000 °C for 4 h in electric furnace followed by auto–cooling. The samples were characterized by X-ray diffraction diffraction, UV–vis spectroscopy, scanning electron microscope (SEM), particle size distribution, color coordinates determination, acid/alkali test, thermo gravimetric (TG) analysis and CIE–1976 L*a*b* color scales. Among the various lanthanide ions and calcium ion as dopant, the pigment composition shows various hues ranges from green to yellow. The designed pigments consist of non–toxic elements and were further found to possess high thermal and chemical stability. The pigments were also found to be appropriate candidates for the coloration of polymer substrates like PMMA.FindingsThe present investigations establish that various color hues can be achieved by the incorporation of suitable chromophore metal ions like calcium in various rare earth host lattice by tuning of the band gaps. The coloring mechanism is based on the strong absorption of the pigments in the blue and red regions due to electronic transitions of the micro states of rare earth ion. The pigment composition shows various hues ranges from green to yellow. The coloring mechanism is based on the tuning of band gap by the dopant like calcium in various rare earth host lattice. In addition, this pigment was chemically and thermally stable. Finally, it has applied in plastics like PMMA.Research limitations/implicationsMechanism of the color appearance using band calculations and on possible applications of rare earth phosphate powders as pigments in plastics and paints have not been explored much. However, the properties of the Ca-doped rare earth phosphate implies that this material has a potential to be applied as a satisfactory pigment for coating or coloring except for glaze, which may cause a side reaction at high temperatures, especially taking into consideration the economics and ecologies. The possibility of Ca2+ incorporation in CePO4 with monazite structure-type has been established.Practical implicationsThe designed pigments consist of non-toxic elements and were further found to possess high thermal and chemical stability. The pigments were also found to be appropriate candidates for the coloration of polymer substrates. Thus, the present environmental friendly pigment powders may find potential alternative to the classical toxic inorganic pigments for various applications.Social implicationsThere is a strong incentive to design new colorants based on inorganic materials to substitute for industrial pigments that are based on heavy elements hazardous to health and the environment. However, several industrial yellow pigments such as cadmium yellow (CdS), chrome yellow (PbCrO4) and nickel titanium yellow (TiO2-NiO-Sb2O3) contain the harmful elements (e.g. Cd, Pb, Cr and Sb) for the human body as well as the environment. The designed pigments consist of non-toxic elements and were further found to possess high thermal and chemical stability. The pigments were also found to be appropriate candidates for the coloration of polymer substrates. Thus, the present environmental friendly pigment powders may find potential alternative to the classical toxic inorganic pigments for various applications.Originality/valueThere is a strong incentive to design new colorants based on inorganic materials to substitute for industrial pigments that are based on heavy elements hazardous to health and the environment. However, several industrial yellow pigments such as cadmium yellow (CdS), chrome yellow (PbCrO4) and nickel titanium yellow (TiO2-NiO-Sb2O3) contain the harmful elements (e.g. Cd, Pb, Cr and Sb) for the human body as well as the environment. So, the authors have developed new class of inorganic pigments that are both non-toxic and environmentally unimpeachable, while preserving or even exceeding the optical, thermal and chemical characteristics of the existing commercial pigments. The developed colorants find practical applications in polymer matrix like PMMA.

Hierarchical regulation of MYBPA1 by anthocyanin- and proanthocyanidin-related MYB proteins is conserved in Vaccinium species.

Members of the Vaccinium genus bear fruits rich in anthocyanins, a class of red-purple flavonoid pigments that provide human health benefits, although the localization and concentrations of anthocyanins differ between species: blueberry (V. corymbosum) has white flesh, while bilberry (V. myrtillus) has red flesh. Comparative transcriptomics between blueberry and bilberry revealed that MYBPA1.1 and MYBA1 strongly correlated with the presence of anthocyanins, but were absent or weakly expressed in blueberry flesh. MYBPA1.1 had a biphasic expression profile, correlating with both proanthocyanidin biosynthesis early during fruit development and anthocyanin biosynthesis during berry ripening. MYBPA1.1 was unable to induce anthocyanin or proanthocyanidin accumulation in Nicotiana benthamiana, but activated promoters of flavonoid biosynthesis genes. The MYBPA1.1 promoter is directly activated by MYBA1 and MYBPA2 proteins, which regulate anthocyanins and proanthocyanidins, respectively. Our findings suggest that the lack of VcMYBA1 expression in blueberry flesh results in an absence of VcMYBPA1.1 expression, which are both required for anthocyanin regulation. In contrast, VmMYBA1 is well expressed in bilberry flesh, up-regulating VmMYBPA1.1, allowing coordinated regulation of flavonoid biosynthesis genes and anthocyanin accumulation. The hierarchal model described here for Vaccinium may also occur in a wider group of plants as a means to co-regulate different branches of the flavonoid pathway.

Induction of the antioxidant defense system using long-chain carotenoids extracted from extreme halophilic archaeon, Halovenus aranensis.

The field of microbial pigments is an emerging area in natural products science. Carotenoids form a major class of such pigments and are found to be diversely synthesized by microorganisms that reside in hypersaline ecosystems to provide resistance against oxidative stress. Human cells can benefit from compounds such as carotenoids as antioxidant agents through either their capability to quench free radicals or their effect on promoting the antioxidant defense pathway. In this study, the antioxidant effectiveness of carotenoid extract from an extremely halophilic archaeon Halovenus aranensis strain EB27T has been evaluated using different approaches. Finally, the ability of the extracted pigment to induce the antioxidant defense pathway of human primary skin fibroblast cells was studied. Hvn. aranensis carotenoid extract exhibited strong effectiveness such that at 2µg/ml, the carotenoid extract fully neutralized the oxidative stress of hydrogen peroxide at its EC50 based on MTT assay. Results from real-time PCR of relevant genes, luciferase bioreporter of oxidative stress, and the western blot analysis further confirmed the antioxidant capability of the carotenoids. It was also shown the carotenoid extract had more antioxidant activity compared to β-carotene the same concentration. Results suggest the carotenoid extract from this archaeon to have high potential for clinical and industrial applications.

English

The pigment content in Blue-green algae is a specific feature of each species. The pigment variation is specific features among microalgae. The paper aim to analyze cyanobacterial extracts of different Usar soil of Azamgarh and Varanasi, Uttar Pradesh. The main object here is the importance of the blue green algae especially because of the pigments present in this class of algae. Pigments from natural sources are gaining more importance mainly due to health and environmental issues. Algae contain a wide range of pigments. Three major classes of pigments are chlorophylls, carotenoids (carotenes and xanthophylls) and phycobilins (Phycocyanin and phycoerythrin). Our present study investigates the efficiency for phycobiliprotein pigment production from four different cyanobacteria Hapalosiphon sp., Phormidium sp., Anabaena sp. and Nostoc sp. The harvested and dried biomass was subjected to extract pigments using different solvents. Thin Layer Chromatography was performed from extracted pigments using Acetone as extraction solvents. And running solvent especially for phycocyanin pigment was optimized and concluded that Petroleum ether and Acetone in the ratio of 7:3. This paper presents the information about the natural pigments of cyanobacteria and how they can be extracted and identified using different procedures and spectrophotometry. It emphasizes that the principal algal pigments are Phycobilins, Chlorophylls and Carotenoids.

Pterin-based pigmentation in animals

Pterins are one of the major sources of bright coloration in animals. They are produced endogenously, participate in vital physiological processes and serve a variety of signalling functions. Despite their ubiquity in nature, pterin-based pigmentation has received little attention when compared to other major pigment classes. Here, we summarize major aspects relating to pterin pigmentation in animals, from its long history of research to recent genomic studies on the molecular mechanisms underlying its evolution. We argue that pterins have intermediate characteristics (endogenously produced, typically bright) between two well-studied pigment types, melanins (endogenously produced, typically cryptic) and carotenoids (dietary uptake, typically bright), providing unique opportunities to address general questions about the biology of coloration, from the mechanisms that determine how different types of pigmentation evolve to discussions on honest signalling hypotheses. Crucial gaps persist in our knowledge on the molecular basis underlying the production and deposition of pterins. We thus highlight the need for functional studies on systems amenable for laboratory manipulation, but also on systems that exhibit natural variation in pterin pigmentation. The wealth of potential model species, coupled with recent technological and analytical advances, make this a promising time to advance research on pterin-based pigmentation in animals.

New red pigments based on Li3AlMnO5 for NIR reflective cool coatings

The exploration of new red pigments based on transition elements is of great practical value in the field of inorganic pigments, since the red coloured pigments have unique applications in paints, ceramic tiles, cosmetics, etc. Here we mainly reported a new class of eco-friendly red pigments based on substituted Li3AlMnO5 (LAMO) and briefly state about the other rock salt layered structure Li3GaMnO5 (LGMO). The solid-state synthesized powders were crystallized to monoclinic structure having MnIV(1)2b and MnIV(2)4g site. The absorption bands in the synthesized samples mainly arises due to the octahedrally coordinated MnIVO6 in the 4g site. Among the synthesized samples, LAMO: 0.10Ti4+ showed exemplary chromatic properties. The doping of tetravalent Ti4+ ions in the Mn4+ sites altered the MnIV(2)O6 bond lengths and increased the crystal field around the absorption band attributed to the 4A2g→4T2g transitions. The ball milled LAMO: 0.10Ti4+shows the a* value of 40.05, which is higher than that of the commercially available red iron oxide pigments (a* = 28.9). Meanwhile, the brighter red powder LAMO: 0.10Ti4+ demonstrated appreciable thermal and chemical stability. From the thermal evaluating study, we observed that, LAMO: 0.10Ti4+ pigment coated roof panels showed a temperature difference of (3.2 °C) compared to the bare roof panel (3.7 °C). We estimated the coating's performance of the LAMO: 0.10Ti4+ in concrete block, metal plate and ceramic tile. In these substrates, the pigment possesses distinctly elevated NIR‐reflectance, which makes these materials worthwhile for cool coating applications.

Identification of Pre-1950 Synthetic Organic Pigments in Artists’ Paints. A Non-Invasive Approach Using Handheld Raman Spectroscopy

There is little information on the actual use of early synthetic organic pigments (SOPs) in art objects, especially those from before 1950. Their presence can, however, pose a challenge to conservation because their chemical composition, as well as their lightfastness and sensitivity to solvents, are often unknown. Here, a study on the non-invasive identification of SOPs in historic pre-1950 varnished paint-outs from artists’ materials manufacturer Royal Talens is presented. The paints were analysed using a handheld Raman device. Spectra were evaluated by recording the spectra of the same samples with a benchtop instrument. This study demonstrated that the identification of SOPs in varnished oil paints with a non-invasive approach is possible and rather straightforward. The handheld Raman device allowed us to identify fourteen SOPs from eight pigment classes. Besides the occurrence of expected and the known SOPs of this time period, there were also some surprising results, like the detection of the triarylcarbonium pigments PG2 and PB8, and the monoazo Mordant Yellow 1.

Integrative analysis of metabolome and transcriptome reveals the mechanism of color formation in white root (Salvia miltiorrhiza)

Tanshinones are a class of bioactive components and pigments found in the traditional Chinese herb Salvia miltiorrhiza (S. miltiorrhiza). To clarify the biosynthesis of tanshinones in S. miltiorrhiza roots, the metabolome and transcriptome were compared among three S. miltiorrhiza lines (two red root lines: HG and CK, one white root line: BG). In this study, 18 tanshinones showed markedly lower abundances in BG lines than in other lines and 15 significant differentially accumulated metabolites (DAMs) were chosen as potential marker compounds. Meanwhile, the expression of 5 tanshinone biosynthesis genes in BG was significantly downregulated, which affected the metabolic flow of tanshinones. We speculated that this was the reason BG exhibited white roots. Moreover, 49 cytochrome P450 genes and 22 transcription factors were identified as candidate genes for tanshinone synthesis and regulation. Our results not only explain the formation of root color in S. miltiorrhiza, but also provide an effective solution to explore the biosynthetic pathway of tanshinones.

Classes of organic pigments meet tentative PSLT criteria and lack toxicity in short-term inhalation studies

Here, we present a non-animal testing battery to identify PSLT (poorly soluble, low toxicity) substances based on their solubility in phagolysosomal lung fluid simulant, surface reactivity and effects on alveolar macrophages in vitro. This is exemplified by eleven organic pigments belonging to five chemical classes that cover a significant share of the European market. Three of the pigments were tested as both, nanoform and non-nanoform. The results obtained in this integrated non-animal testing battery qualified two pigments as non PSLT, one pigment as poorly soluble and eight pigments as poorly soluble and low toxicity in vitro. The low toxic potency of the eight PSLT and the one poorly soluble pigment was corroborated by short-term inhalation studies with rats. These pigments did not elicit apparent toxic effects at 10 mg/m3 (systemic and in the respiratory tract). One of the pigments, Diarylide Pigment Yellow 83 transparent, however, caused minimal infiltration of neutrophils; hence its low toxicity is ambiguous and needs further verification or falsification. The present test battery provides an opportunity to identify PSLT-properties of test substances to prioritise particles for further development. Thus, it can help to reduce animal testing and steer product development towards safe applications.

Carbonyl pigments: General principles

AbstractThis chapter describes the general features of the chemical class of pigments designated as carbonyl pigments. These pigments are characterized by the presence of carbonyl groups linked to one another via an extended conjugated system, often forming polycyclic aromatic structures. Carbonyl pigments have experienced distinct phases in their histories. Certain carbonyl colorants, notably anthraquinonoids, were discovered in the early twentieth century and subsequently used as vat dyes for textiles, but their potential as high-performance pigments was not realized until the mid-twentieth century when demand began to emerge for pigments of the quality that they could provide. After conversion to a suitable physical form, several vat dyes were then introduced as vat pigments. Several other carbonyl pigment types did not originate as vat dyes but were developed specifically for pigment use. Carbonyl pigments provide a wider diversity of structural arrangements. The broad carbonyl chemical class may be categorized into several sub-types, each with its own characteristic structural features. These categories, which are discussed in separate chapters, include anthraquinonoids, quinacridones, diketopyrrolopyrroles, perylenes, perinones, indigoids, isoindolines, isoindolinones, and quinophthalones. These products generally owe their high levels of technical performance to their large molecular size and high molecular planarity, which lead to highly compact crystal structures and, in many cases, to the ability of the carbonyl group to participate in strong intra- and intermolecular hydrogen bonding.

The colour variations of flowers in wild Paeonia delavayi plants are determined by four classes of plant pigments

ABSTRACT Paeonia delavayi is listed as an endangered species in the southwest of China. The flower colours of cultivated examples of this species are most commonly yellow and red, but a much wider range of flower colours can be found in plants growing in the natural habitat. To elucidate the basis of the colour range, pigments were extracted from flower petals of seven selected colours and profiled and quantified using High Performance Liquid Chromatography (HPLC) and Liquid Chromatography–Mass Spectrometry (LC-MS). All the petal colours were found to share the same base pigment types as the yellow flower – a composite colour based on a mix of flavonoids, carotenoids and chlorophyll. Anthocyanin profiling revealed the same anthocyanin compositions in all red coloured flowers, namely, cyanidin-3,5-diglucoside, cyanidin-3-glucoside, cyanidin-3-arabinoside, peonidin-3,5-diglucoside, peonidin-3-glucoside and peonidin 3-arabinoside. Quantitative analysis suggested the yellow colour was principally formed by the flavonoid naringenin chalcone 2'-glucoside (2’,4’,6’,4-tetrahydroxychalcone 2'-glucoside). The various red/orange flower colours were the result of superimposing different amounts of anthocyanins onto the yellow flower background, with carotenoids and chlorophylls having only a minor contribution to the final colour. The results provide useful information for breeding programmes for ornamental varieties of P. delavayi.

Avian Coloration Genetics: Recent Advances and Emerging Questions.

The colorful phenotypes of birds have long provided rich source material for evolutionary biologists. Avian plumage, beaks, skin, and eggs-which exhibit a stunning range of cryptic and conspicuous forms-inspired early work on adaptive coloration. More recently, avian color has fueled discoveries on the physiological, developmental, and-increasingly-genetic mechanisms responsible for phenotypic variation. The relative ease with which avian color traits can be quantified has made birds an attractive system for uncovering links between phenotype and genotype. Accordingly, the field of avian coloration genetics is burgeoning. In this review, we highlight recent advances and emerging questions associated with the genetic underpinnings of bird color. We start by describing breakthroughs related to 2 pigment classes: carotenoids that produce red, yellow, and orange in most birds and psittacofulvins that produce similar colors in parrots. We then discuss structural colors, which are produced by the interaction of light with nanoscale materials and greatly extend the plumage palette. Structural color genetics remain understudied-but this paradigm is changing. We next explore how colors that arise from interactions among pigmentary and structural mechanisms may be controlled by genes that are co-expressed or co-regulated. We also identify opportunities to investigate genes mediating within-feather micropatterning and the coloration of bare parts and eggs. We conclude by spotlighting 2 research areas-mechanistic links between color vision and color production, and speciation-that have been invigorated by genetic insights, a trend likely to continue as new genomic approaches are applied to non-model species.

Mixed metal oxide pigments

Abstract Mixed metal oxide (MMO) pigments, also knowns as complex inorganic color pigments (CICPs), are an important class of inorganic pigments. They are representatives of the blue, green, yellow, brown, and black pigments. These pigments are called mixed complex because they contain two or more different metals in the composition. Their main advantages are high opacity, heat stability, useful infrared properties, light- and weather fastness, and chemical resistance. MMOs are solid solutions of metal oxides, which are homogenously distributed in their crystal lattices. They are based on different types of crystal structures, such as rutile, spinel, inverse spinel, hematite, priderite, and pseudobrookite. Other products belonging to the CICPs besides the rutile and spinel type MMOs are pigments based on zirconium silicate (zircon, ZrSiO4). Such compositions belong to the class of ceramic pigments (color stains for glazes).

Special effect pigments

Abstract Special effect pigments are in the very most cases synthetic pigments, characterized by high luster, brilliance and iridescent colors known from optically thin films. The visual appearance has its origin in reflection and refraction of light at thin single and multiple layers. The pigments are either transparent, semitransparent or light-absorbing platelet-shaped crystals or layer systems. They can consist of single crystals, but also of monolayer or a multilayer structures in which the layers have different refractive indices and light absorption properties. Pigment based on the layer-substrate principle represent the technically most important class of special effect pigments. There are many variation and combination possibilities for the layer and substrate materials used. Special effect pigments based on platelets of natural or synthetic mica, on alumina, silica, or borosilicate flakes are the main representatives of layer-substrate pigments. They are manufactured in most cases by wet chemical processes combined with high-temperature processes. The production of substrate particles includes mechanical processes, but also crystal growth, glass formation, and web coating.

Retrieval of betalain contents based on the coupling of radiative transfer model and SVM model

Betalain (Bt) is as a class of edible natural pigments and important biochemical aparmeter can explain the physiological response and the resistance of plants caused by different environmental stress factors. Hyperspectral spectroscopy has been widely used to estimate plant pigments contents accurately and non-destructively. However, there is very little research about hyperspectral remote sensing estimation and inversion of betalain contents. The algorithm of Bt content inversion with viable universality is the key to improving the practicality of quantitative remote sensing. Therefore, in this study, based on the radioactive transfer mechanism and SVM model, the optical characteristics of Bt and other factors of Suaeda salsa are analyzed, and a coupling model (PROSAIL + SVM) of simulated canopy reflectivity and factor contents is established. The model was then applied to the remote sensing inversion. Results demonstrated that Bt content was sensitive to the spectral range between 460 and 592 nm, particularly between 530 and 550 nm where the sensitivity index reached 0.7. Optimized indices; NDSI473nm,475nm, RSI473nm,475nm and NDPI473nm,475nm, calculated by simulated spectral reflectance had a significant correlation with Bt content (R= ±0.80, p < 0.001). Moreover, simulated Sentinel-2A reflectance of the Blue (B2) and Green (B3) bands showed sensitivity of 66% and 68%, respectively. Spectral indices NDPI b2, b3, NDSI b2, b3, RSIb2, b3 showed correlation of ± 0.71. The PROSAIL + SVM model developed from simulated hyperspectral reflectance, estimated Bt content with high R2 (0.82), indicating that the precision of the model was higher and the universality was stronger. A model composed of optimized indices (NDSI473nm, 475nm, RSI473nm, 475nm and NDPI473nm, 475nm) showed promising estimation ability with low RMSE (0.39 μg·cm−2) with R2 = 0.78 and RPD = 1.99. When the PROSAIL + SVM model was extended to multispectral images (Sentinel-2A), the model estimated the Bt content at moderate to good levels (R2 = 0.68). The results indicated that optimized hyperspectral and multispectral NDPI, NDSI, RSI have significant correlation with betalain content of S. salsa, suggesting these indices might be used to quantify Bt content with high accuracy, thereby alleviating the ill-posed inverse problem and improving sensitivity. Not only would this enhance the application of quantitative remote sensing technology in betalain research, but the results also pose positive application for precision agriculture in detecting Bt pigments in crops, as a surrogate for evaluating the health condition of crops.

Azo (Hydrazone) pigments: general principles

Abstract This paper presents an overview of the general chemical principles underlying the structures, synthesis and technical performance of azo pigments, the dominant chemical class of industrial organic pigments in the yellow, orange, and red shade areas, both numerically and in terms of tonnage manufactured. A description of the most significant historical features in this group of pigments is provided, starting from the discovery of the chemistry on which azo colorants are based by Griess in the mid-nineteenth century, through the commercial introduction of the most important classical azo pigments in the early twentieth century, including products known as the Hansa Yellows, β-naphthol reds, including metal salt pigments, and the diarylide yellows and oranges, to the development in the 1950s and 1960s of two classes of azo pigments that exhibit high performance, disazo condensation pigments and benzimidazolone-based azo pigments. A feature that complicates the description of the chemical structures of azo pigments is that they exist in the solid state as the ketohydrazone rather than the hydroxyazo form, in which they have been traditionally been illustrated. Numerous structural studies conducted over the years on an extensive range of azo pigments have demonstrated this feature. In this text, they are referred to throughout as azo (hydrazone) pigments. Since a common synthetic procedure is used in the manufacture of virtually all azo (hydrazone) pigments, this is discussed in some detail, including practical aspects. The procedure brings together two organic components as the fundamental starting materials, a diazo component and a coupling component. An important reason for the dominance of azo (hydrazone) pigments is that they are highly cost-effective. The syntheses generally involve low cost, commodity organic starting materials and are carried out in water as the reaction solvent, which offers obvious economic and environmental advantages. The versatility of the approach means that an immense number of products may be prepared, so that they have been adapted structurally to meet the requirements of many applications. On an industrial scale, the processes are straightforward, making use of simple, multi-purpose chemical plant. Azo pigments may be produced in virtually quantitative yields and the processes are carried out at or below ambient temperatures, thus presenting low energy requirements. Finally, provided that careful control of the reaction conditions is maintained, azo pigments may be prepared directly by an aqueous precipitation process that can optimise physical form, with control of particle size distribution, crystalline structure, and surface character. The applications of azo pigments are outlined, with more detail reserved for subsequent papers on individual products.

The role of carotenoids in enhancing the health of aquatic organisms

Carotenoids constitute a class of pigments derived from photosynthetic plants, algae, bacteria and some fungi. Carotenoids act as potent antioxidants scavenging reactive oxygen species. They hold a vital role in the antioxidant defense system of humans. Several studies have shown carotenoid can increase the growth overall well being of aquatic animals. This review examined the effect of carotenoid in aquatic organisms on growth, survival, immunity, pigmentation and reproductive performance. The review recommends the use of carotenoid as feed additive for enhance the overall improvement of the aquatic organisms.

Linking phytoplankton absorption to community composition in Chinese marginal seas

Phytoplankton pigments significantly affect photosynthesis and play a crucial role in regulating marine ecological and biogeochemical processes. Assessment of phytoplankton pigments through optical means is desirable as it may be extended to satellite remote sensing. Here, using an extensive data set of high performance liquid chromatography (HPLC) phytoplankton pigment concentrations and phytoplankton absorption spectra (aph(λ)) collected through five cruise surveys of the Chinese marginal seas during 2016 and 2017, we explore the potentials of using aph(λ) to estimate twenty pigments. Specifically, the first and second derivatives of aph(λ) are used to construct an aph(λ) - pigment model. The validation of the aph(λ)-derived pigment classes, specific to individual phytoplankton community and size groups, shows a generally satisfactory model performance. Additionally, hierarchical cluster analysis also exhibits high similarity within the classification results based on the measured and modeled pigments, where only two pigments were decided into different clusters. Although still preliminary in nature, this proof-of-concept study for the Chinese marginal seas shows the potentials of using satellite remote sensing to assess phytoplankton pigment composition once hyperspectral satellite data are available and aph(λ) inversion algorithms are developed and validated.