Skin pigmentation and its control: From ultraviolet radiation to stem cells

Abstract

Disorders of skin pigmentation exist across a broad spectrum and include manifestations of hypopigmentation and hyperpigmentation in a variety of benign and malignant contexts. Ultraviolet (UV) radiation is arguably one of the best-understood carcinogens and carries the dubious distinction of being one the most common carcinogenic exposures for man. UV also functions as a significant modulator of

Anti-Pigmentary Natural Compounds and Their Mode of Action

“…There are two kinds of melanin pigment: brownish-black eumelanin and reddishyellow pheomelanin [6]. The synthesis of melanin starts with the oxidation of L-tyrosine to Dopaquinone (DQ) and/or L-dihydroxyphenylalanine (L-DOPA) to DQ by Tyrosinase activation.…”

Neurocosmetics in Skincare—The Fascinating World of Skin–Brain Connection: A Review to Explore Ingredients, Commercial Products for Skin Aging, and Cosmetic Regulation

“…The proopiomelanocortin (POMC)-a protein that contains 267 amino acid residues-is a precursor of these peptide hormones, and β-endorphin is one of them, originating from its cleavage [95][96][97][98]. Among other peptide hormones derived from POMC, it is worth mentioning the adrenocorticotropic hormone (ACTH)-also known as corticotropin, which stimulates the adrenal cortex to secrete the anti-inflammatory and anti-allergic hormone cortisol-and the melanocyte-stimulating hormone (MSH), which is involved in skin pigmentation [99,100]. Generally, the POMC and the related cleavage products are produced mainly in the hypothalamus and the pituitary gland's anterior lobe, but the in situ production of POMC and its products (ACTH, MSH, β-endorphins, and their corresponding receptors) has also been revealed in skin cells [97,99,101].…”

“…Among other peptide hormones derived from POMC, it is worth mentioning the adrenocorticotropic hormone (ACTH)-also known as corticotropin, which stimulates the adrenal cortex to secrete the anti-inflammatory and anti-allergic hormone cortisol-and the melanocyte-stimulating hormone (MSH), which is involved in skin pigmentation [99,100]. Generally, the POMC and the related cleavage products are produced mainly in the hypothalamus and the pituitary gland's anterior lobe, but the in situ production of POMC and its products (ACTH, MSH, β-endorphins, and their corresponding receptors) has also been revealed in skin cells [97,99,101]. Indeed, it has been proposed that the cutaneous POMC system acts in an autocrine manner in response to external or internal stresses, evidencing the effect of opioids on skincare and presenting the necessity of "neuro-relaxing" cosmetic ingredients derived from plant extracts, suitable for the formulation of anti-aging products [102][103][104][105][106].…”

Standardized Edible Bird’s Nest Extract Prevents UVB Irradiation-Mediated Oxidative Stress and Photoaging in the Skin

“…Direct and chronic epidermal exposure to ultraviolet B (UVB) radiation in the epidermis induces overproduction of reactive oxygen species (ROS), including superoxide anions, hydrogen peroxide, singlet oxygen, and hydroxyl radicals, which destroy the antioxidant defense systems and finally cause oxidative stress [6][7][8][9][10][11]. UVB-induced oxidative stress leads to excessive melanin production in melanocytes and a decrease in hyaluronic acid production in keratinocytes, which play an important role in development of pigmentation and moisture loss in the skin [6,7]. In the dermis, UVB-induced oxidative stress stimulates the production of pro-inflammatory cytokines and protein degradation in the extracellular matrix by matrix metalloproteinases (MMPs) that cause skin wrinkle formation [8][9][10][11].…”