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Journal of Natural Medicines Jan 2020Carotenoids are tetraterpene pigments that are distributed in photosynthetic bacteria, some species of archaea and fungi, algae, plants, and animals. About 850 naturally... (Review)
Review
Carotenoids are tetraterpene pigments that are distributed in photosynthetic bacteria, some species of archaea and fungi, algae, plants, and animals. About 850 naturally occurring carotenoids had been reported up until 2018. Photosynthetic bacteria, fungi, algae, and plants can synthesize carotenoids de novo. Carotenoids are essential pigments in photosynthetic organs along with chlorophylls. Carotenoids also act as photo-protectors, antioxidants, color attractants, and precursors of plant hormones in non-photosynthetic organs of plants. Animals cannot synthesize carotenoids de novo, and so those found in animals are either directly accumulated from food or partly modified through metabolic reactions. So, animal carotenoids show structural diversity. Carotenoids in animals play important roles such precursors of vitamin A, photo-protectors, antioxidants, enhancers of immunity, and contributors to reproduction. In the present review, I describe the structural diversity, function, biosyntheses, and metabolism of natural carotenoids.
Topics: Animals; Carotenoids; Fungi; Pigmentation; Plants
PubMed: 31588965
DOI: 10.1007/s11418-019-01364-x -
Head and Neck Pathology Mar 2019Black and brown pigmentation of the oral mucosa can occur due to a multitude of non-neoplastic causes. Endogenous or exogenous pigments may be responsible for oral... (Review)
Review
Black and brown pigmentation of the oral mucosa can occur due to a multitude of non-neoplastic causes. Endogenous or exogenous pigments may be responsible for oral discoloration which can range from innocuous to life-threatening in nature. Physiologic, reactive, and idiopathic melanin production seen in smoker's melanosis, drug-related discolorations, melanotic macule, melanoacanthoma and systemic diseases are presented. Exogenous sources of pigmentation such as amalgam tattoo and black hairy tongue are also discussed. Determining the significance of mucosal pigmented lesions may represent a diagnostic challenge for clinicians. Biopsy is indicated whenever the source of pigmentation cannot be definitively identified based on the clinical presentation.
Topics: Humans; Mouth Diseases; Mouth Mucosa; Pigmentation; Pigmentation Disorders
PubMed: 30671761
DOI: 10.1007/s12105-018-0980-9 -
International Journal of Biological... 2023Hair graying is a common and visible sign of aging resulting from decreased or absence of melanogenesis. Although it has been established that gray hair greatly impacts... (Review)
Review
Hair graying is a common and visible sign of aging resulting from decreased or absence of melanogenesis. Although it has been established that gray hair greatly impacts people's mental health and social life, there is no effective countermeasure other than hair dyes. It has long been thought that reversal of gray hair on a large scale is rare. However, a recent study reported that individual gray hair darkening is a common phenomenon, suggesting the possibility of large-scale reversal of gray hair. In this article, we summarize the regulation mechanism of melanogenesis and review existing cases of hair repigmentation caused by several factors, including monoclonal antibodies drugs, tyrosine kinase inhibitors (TKIs), immunomodulators, other drugs, micro-injury, and tumors, and speculate on the mechanisms behind them. This review offers some insights for further research into the modulation of melanogenesis and presents a novel perspective on the development of clinical therapies, with emphasis on topical treatments.
Topics: Humans; Hair; Hair Color; Hair Follicle; Melanocytes; Pigmentation; Administration, Topical; Mental Health
PubMed: 37781032
DOI: 10.7150/ijbs.86911 -
Trends in Ecology & Evolution Apr 2020Mammalian colors and color patterns are some of the most diverse and conspicuous traits found in nature and have been widely studied from genetic/developmental and... (Review)
Review
Mammalian colors and color patterns are some of the most diverse and conspicuous traits found in nature and have been widely studied from genetic/developmental and evolutionary perspectives. In this review we first discuss the proximate causes underlying variation in pigment type (i.e., color) and pigment distribution (i.e., color pattern) and highlight both processes as having a distinct developmental basis. Then, using multiple examples, we discuss ultimate factors that have driven the evolution of coloration differences in mammals, which include background matching, intra- and interspecific signaling, and physiological influences. Throughout, we outline bridges between developmental and functional investigatory approaches that help broaden knowledge of mammals' memorable external appearances, and we point out areas for future interdisciplinary research.
Topics: Animals; Biological Evolution; Color; Mammals; Phenotype; Pigmentation
PubMed: 31980234
DOI: 10.1016/j.tree.2019.12.008 -
Pigment Cell & Melanoma Research Nov 2023Understanding individuals' skin pigmentation and photosensitivity is important in judging risk of skin cancer and response to certain treatment modalities. However,... (Review)
Review
Understanding individuals' skin pigmentation and photosensitivity is important in judging risk of skin cancer and response to certain treatment modalities. However, individuals with darkly pigmented skin are poorly represented in the widely used Fitzpatrick skin phototype (FST) system. Moreover, the FST system is prone to misuse, as it relies on subjective patient and clinician assessment of skin type, and does not clearly differentiate pigmentation from photosensitivity. By evaluating the key literature surrounding the FST system, its criticisms and proposed alternatives, this review serves to understand how skin phototype classification can be optimised.
Topics: Humans; Skin; Photosensitivity Disorders; Skin Pigmentation; Skin Neoplasms; Pigmentation Disorders
PubMed: 37550876
DOI: 10.1111/pcmr.13110 -
Pigment Cell & Melanoma Research Jul 2021Skin complexion is among the most recognizable phenotypes between individuals and is mainly determined by the amount and type of melanin pigment deposited in the... (Review)
Review
Skin complexion is among the most recognizable phenotypes between individuals and is mainly determined by the amount and type of melanin pigment deposited in the epidermis. Persons with dark skin complexion have more of a brown/black pigment known as eumelanin in their epidermis whereas those with fair skin complexions have less. Epidermal eumelanin acts as a natural sunblock by preventing incoming UV photons from penetrating into the skin and therefore protects against UV mutagenesis. By understanding the signaling pathways and regulation of pigmentation, strategies can be developed to manipulate skin pigmentation to improve UV resistance and to diminish skin cancer risk.
Topics: Animals; Enzyme Inhibitors; Humans; Melanins; Pharmaceutical Preparations; Skin Pigmentation; Translational Research, Biomedical
PubMed: 33666358
DOI: 10.1111/pcmr.12969 -
Science (New York, N.Y.) Aug 2017Coloration mediates the relationship between an organism and its environment in important ways, including social signaling, antipredator defenses, parasitic... (Review)
Review
Coloration mediates the relationship between an organism and its environment in important ways, including social signaling, antipredator defenses, parasitic exploitation, thermoregulation, and protection from ultraviolet light, microbes, and abrasion. Methodological breakthroughs are accelerating knowledge of the processes underlying both the production of animal coloration and its perception, experiments are advancing understanding of mechanism and function, and measurements of color collected noninvasively and at a global scale are opening windows to evolutionary dynamics more generally. Here we provide a roadmap of these advances and identify hitherto unrecognized challenges for this multi- and interdisciplinary field.
Topics: Animals; Biological Evolution; Color Perception; Color Vision; Photoreceptor Cells; Pigmentation; Pigments, Biological; Reproduction
PubMed: 28774901
DOI: 10.1126/science.aan0221 -
Annales de Dermatologie Et de... Oct 2019The key diagnostic tool for hyperpigmentation is histopathology, which may be accompanied by certain laboratory tests. Hyperpigmentation may result from excess melanin... (Review)
Review
The key diagnostic tool for hyperpigmentation is histopathology, which may be accompanied by certain laboratory tests. Hyperpigmentation may result from excess melanin (hypermelanosis), cutaneous iron deposits (hemosiderosis), cutaneous carotene deposits (carotenoderma), or cutaneous deposits of a substance not normally found in the skin (dyschromia). The different types of hypermelanosis may be classified as either localised or generalised. The former generally correspond to skin tumours and may form a cutaneous expression of complex syndromes, which most notably include cardiac abnormalities, or to pigmented forms of inflammatory and/or infectious dermatoses. Diffuse hypermelanosis is frequently a sign of systemic disease, generally metabolic or endocrine disease, or else it may result from pharmaceutical therapy. Herein we review the various causes of hyperpigmentation and the corresponding therapy.
Topics: Diagnosis, Differential; Humans; Hyperpigmentation; Skin Pigmentation
PubMed: 31537319
DOI: 10.1016/j.annder.2019.05.005 -
The Veterinary Clinics of North... Mar 2023The transparency of the cornea is critical to its role in transmitting light. Loss of corneal transparency results in visual impairment. Corneal pigmentation results... (Review)
Review
The transparency of the cornea is critical to its role in transmitting light. Loss of corneal transparency results in visual impairment. Corneal pigmentation results from melanin accumulation in the epithelial cells of the cornea. Differential diagnosis for corneal pigmentation include corneal sequestrum, corneal foreign body, limbal melanocytoma, iris prolapse, and dermoid. These conditions must be excluded to reach a diagnosis of corneal pigmentation. A myriad of ocular surface conditions are associated with corneal pigmentation, including qualitative and quantitative tear film deficiency, adnexal disease, corneal ulceration, and breed-related corneal pigmentation syndromes. Accurate etiologic diagnosis is critical to determining effective treatment.
Topics: Animals; Cornea; Eye Injuries; Pigmentation; Vision Disorders
PubMed: 36813389
DOI: 10.1016/j.cvsm.2022.11.001 -
Biological Reviews of the Cambridge... May 2017The phylum Mollusca is highly speciose, and is the largest phylum in the marine realm. The great majority of molluscs are shelled, including nearly all bivalves, most... (Review)
Review
The phylum Mollusca is highly speciose, and is the largest phylum in the marine realm. The great majority of molluscs are shelled, including nearly all bivalves, most gastropods and some cephalopods. The fabulous and diverse colours and patterns of molluscan shells are widely recognised and have been appreciated for hundreds of years by collectors and scientists alike. They serve taxonomists as characters that can be used to recognise and distinguish species, however their function for the animal is sometimes less clear and has been the focus of many ecological and evolutionary studies. Despite these studies, almost nothing is known about the evolution of colour in molluscan shells. This review summarises for the first time major findings of disparate studies relevant to the evolution of shell colour in Mollusca and discusses the importance of colour, including the effects of visual and non-visual selection, diet and abiotic factors. I also summarise the evidence for the heritability of shell colour in some taxa and recent efforts to understand the molecular mechanisms underpinning synthesis of shell colours. I describe some of the main shell pigments found in Mollusca (carotenoids, melanin and tetrapyrroles, including porphyrins and bile pigments), and their durability in the fossil record. Finally I suggest that pigments appear to be distributed in a phylogenetically relevant manner and that the synthesis of colour is likely to be energetically costly.
Topics: Animal Shells; Animals; Color; Ecology; Fossils; Mollusca; Pigmentation
PubMed: 27005683
DOI: 10.1111/brv.12268