# SciCombinator

Discover the most talked about and latest scientific content & concepts.

### Concept: Vermilion

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To isolate and characterize indigenous algicidal bacteria and their algae-lysing compounds active against Microcystis aeruginosa, strains TH1, TH2, and FACHB 905.

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Some species of Talaromyces secrete large amounts of red pigments. Literature has linked this character to species such as Talaromyces purpurogenus, T. albobiverticillius, T. marneffei, and T. minioluteus often under earlier Penicillium names. Isolates identified as T. purpurogenus have been reported to be interesting industrially and they can produce extracellular enzymes and red pigments, but they can also produce mycotoxins such as rubratoxin A and B and luteoskyrin. Production of mycotoxins limits the use of isolates of a particular species in biotechnology. Talaromyces atroroseus sp. nov., described in this study, produces the azaphilone biosynthetic families mitorubrins and Monascus pigments without any production of mycotoxins. Within the red pigment producing clade, T. atroroseus resolved in a distinct clade separate from all the other species in multigene phylogenies (ITS, β-tubulin and RPB1), which confirm its unique nature. Talaromyces atroroseus resembles T. purpurogenus and T. albobiverticillius in producing red diffusible pigments, but differs from the latter two species by the production of glauconic acid, purpuride and ZG-1494α and by the dull to dark green, thick walled ellipsoidal conidia produced. The type strain of Talaromyces atroroseus is CBS 133442.

Concepts: Biology, Fungus, Phylogenetics, Green, Purple, White, Vermilion, Carmine

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Grape anthocyanins reacted with diacetyl, a secondary metabolite of microorganisms involved in winemaking, to form 10-acetyl-pyranoanthocyanins, a type of anthocyanin-derived pigments similar to other vitisin-type pyranoanthocyanins found in red wines. The structures of 10-acetyl-pyranomalvidin-3-β-O-glucoside and 10-acetyl-pyranopeonidin-3-β-O-glucoside were confirmed by spectroscopic methods (UV-vis, MS/MS, and NMR) after their synthesis and isolation. In contrast to other vitisin-type pyranoanthocyanins, the newly described 10-acetyl-pyranoanthocyanins exhibited differentiated color-related properties. They showed an important tendency to occur as colorless hemiacetals at C-10 under wine pH conditions, while co-occurrence of flavylium cation and quinoidal base yield a broad visible absorbance band around 510-520 nm. Moreover, they easily reacted with bisulfite in acidic aqueous solution (pH 2.0), but the expected bleaching was not observed. Bisulfite bonded to the carbonyl of 10-acetyl substituent instead the expected C-10 position of the pyranoanthocyanin core, thus giving rise to a red pigment hypsochromically shifted towards orangish nuances (maximum absorbances at 487-491 nm).

Concepts: Spectroscopy, Chemistry, Color, Vermilion, Wine, Oenology, Base, Anthocyanin

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Betalains are bright red and yellow pigments, which are produced in only one order of plants, the Caryophyllales, and replace the more familiar anthocyanin pigments. The evolutionary origin of betalain production is a mystery, but a new study has identified the first regulator of betalain production and discovered a previously unknown link between the two pigment pathways.

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The analysis of paint cross-sections can reveal a remarkable amount of information about the layers and materials in a painting without visibly altering the artwork. Although a variety of analytical approaches are used to detect inorganic pigments as well as organic binders, proteins, and lipids in cross-sections, they do not provide for the unambiguous identification of natural, organic colorants. Here, we develop a novel combined surface-enhanced Raman scattering (SERS), light microscopy, and normal Raman scattering (NRS) approach for the identification of red organic and inorganic pigments in paint cross-sections obtained from historic 18th and 19th century oil paintings. In particular, Ag nanoparticles are directly applied to localized areas of paint cross-sections mounted in polyester resin for SERS analysis of the organic pigments. This combined extractionless non-hydrolysis SERS and NRS approach provides for the definitive identification of carmine lake, madder lake, and vermilion in multiple paint layers. To our knowledge, this study represents the first in situ identification of natural, organic pigments within paint cross-sections from oil paintings. Furthermore, the combination of SERS and normal Raman, with light microscopy provides conservators with a more comprehensive understanding of a painting from a single sample and without the need for sample pretreatment.

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Traditional methods for the production of food grade pigments from fungus Monascus spp. are mostly relying on submerged fermentation. However, cell bound nature and intracellular accumulation of pigments in Monascus spp is the major hurdle in pigment production by submerged fermentation. The present study focused on the investigation of the effect of the antifungal agent, fluconazole on red pigment production from Monascus purpureus (NMCC-PF01). At the optimized concentration of fluconazole (30 μg/ml), pigment production was found to be enhanced by 88% after 96 h and it remained constant even after further incubation up to 168 h. An ergosterol, a sterol specific for fungi was also extracted and estimated as a function of fungal growth. The concentration of ergosterol in fluconazole-treated fermentation broth was reduced by 49% as compared to control broth. Thus it could be responsible for facilitating the release of intracellular and cell bound pigments. Nevertheless, the role of cell transporters in transporting out the red pigments cannot be ignored and deserves further attention. Qualitative analysis of red pigment by TLC, UV spectroscopy and mass spectrometric analysis (ESIMS) has confirmed the presence of well-known pigment, Rubropunctamine. In addition, this fermentation process produces citrinin-free pigments. This novel approach will be useful to facilitate increased pigment production by the release of intracellular or cell bound Monascus pigments.

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Mating behaviour and predation avoidance in Heliconius involve visual colour signals; however, there is considerable inter-individual phenotypic variation in the appearance of colours. In particular, the red pigment varies from bright crimson to faded red. It has been thought that this variation is primarily due to pigment fading with age, although this has not been explicitly tested. Previous studies have shown the importance of red patterns in mate choice and that birds and butterflies might perceive these small colour differences. Using digital photography and calibrated colour images, we investigated whether the hue variation in the forewing dorsal red band of Heliconius melpomene rosina corresponds with age. We found that the red hue and age were highly associated, suggesting that red colour can indeed be used as a proxy for age in the study of wild-caught butterflies.

Concepts: Psychology, Color, Red, White, Vermilion, Hue, Photography, Heliconius

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The red pigment α-HgS tends to blacken in the presence of light and chloride ions. Hypotheses exist for the decomposition and discoloration, including formation of β-HgS (black) or of metallic mercury, but these have not been detected on naturally or synthetically degraded HgS paint. Electrochemical experiments now demonstrate the formation of metallic mercury in the presence of light and chloride ions.

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This research aims to characterize the pigment produced by isolated fungi and to evaluate its anti-cancer activities.

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As the most important component of deep red pigments, alkannin is investigated theoretically in detail based on time-dependent density functional theory (TDDFT) method. Exploring the dual intramolecular hydrogen bonds (O$1$-H$2$$\cdot\cdot\cdotO3 and O4-H5$$\cdot\cdot\cdot$O$6$) of alkannin, we confirm the O$1$-H$2$$\cdot\cdot\cdotO3 plays a more important role in the excited state than O4-H5$$\cdot\cdot\cdot$O$6$ one. Infrared (IR) vibrational analyses and subsequent charge redistribution also support this viewpoint. Via constructing the S$_1$-state potential energy surface (PES) and searching transition state (TS) structures, we illuminate the excited state double proton transfer (ESDPT) mechanism of alkannin is the stepwise process that can be firstly launched by the O$1$-H$2$$\cdot\cdot\cdot$O$3$ hydrogen bond wire in gas state, acetonitrile (CH$3$CN) and cyclohexane (CYH) solvents. We present a novel mechanism that polar aprotic solvents can contribute to the the first-step proton transfer (PT) process in the S$_1$ state, and nonpolar solvents play important roles in lowering the potential energy barrier of the second-step PT reaction.