Niacinamide and 12‐hydroxystearic acid prevented benzo(a)pyrene and squalene peroxides induced hyperpigmentation in skin equivalent

Abstract

Skin surface is constantly exposed to environmental and secreted stressors such as UV, air pollution and peroxidized sebum. The current study aims to use reconstructed human skin equivalents to demonstrate topical stressor‐induced hyperpigmentation and evaluate bioactives’ potential protective effect. Given that polycyclic aromatic hydrocarbons are representative airborne particle‐bound organic compounds with known relevance to pigmentation pathways, benzo(a)pyrene was selected as surrogate environmental toxin. On the other hand, squalene monohydroperoxides are well‐characterized sebum peroxidation product under UV and pollutant exposure, thus are used as another representative skin stressor. With 3‐day continuous exposure, 30 pmol/cm2 of benzo(a)pyrene and 3.4 nmol/cm2 of squalene monohydroperoxides induced significant viability loss, inflammatory response, and approximately 10 shades of pigmentation increase in pigmented living skin equivalents. At the same time, pretreatment and co‐treatment with 12‐hydroxystearic acid (12‐HSA, 20 μmol/L) or niacinamide (5 mmol/L) ameliorated such stressor‐induced consequences. Niacinamide was particularly effective against benzo(a)pyrene damage, probably as a substrate for important NAD+ dependent detoxification pathways, while 12‐HSA was potent against squalene monohydroperoxides through barrier enhancing, anti‐inflammatory, and anti‐oxidative mechanisms. In summary, topical stressor‐induced hyperpigmentation was achieved in vitro, with known bioactives showing protective benefits.

Rational Engineering of Hydratase from Lactobacillus acidophilus Reveals Critical Residues Directing Substrate Specificity and Regioselectivity

“…Ricinoleic acid (12‐hydroxy‐9‐ cis ‐octadecenoic acid) is used in several industries for the manufacturing of various products, such as surfactants, plastics (Nylon‐11), plasticizers, polyurethane resins, emulsifiers, and lubricant additives . 12‐Hydroxystearic acid is commonly used in skincare preparations . HFAs can also be used to produce polymers for durable and flexible bioplastics with properties that can be tailored for a specific application .…”

Evolution of the use of antioxidants in anti‐ageing cosmetics

“…More recently, niacinamide has been proposed as an anti‐pollution agent because of its ability to protect cells from common air pollutants. This has been investigated through the exposure of primary keratinocytes and melanocytes to squalene monohydroperoxides and benzo(a)pyrene in similar concentrations to reported real‐life exposure . The topical application of this cosmetic ingredient has shown benefits across a wide range of skin conditions; from pruritic disorders to acne vulgaris and hyperpigmentation , but also for wrinkles reduction .…”

Focus Theme Issue: “Vitiligo and other pigmentary disorders”

“…The authors show evidence of a decreased expression of tyrosinase, Tyrp‐1 and Tyrp‐2, by inhibition of the ERK/CREB/MiTF signalling pathway . Rounding off this issue, Tingyan Mi et al, from Unilever Shanghai, China, present an interesting model of environmental stress–induced hyperpigmentation using epidermal 3D constructs, in which they emphasize the benefit of NAD+ ‐dependent detoxification pathways in this setting …”