Stimulation of the Fibrillar Collagen and Heat Shock Proteins by Nicotinamide or Its Derivatives in Non-Irradiated or UVA Radiated Fibroblasts, and Direct Anti-Oxidant Activity of Nicotinamide Derivatives

Mechanistic Insights into the Multiple Functions of Niacinamide: Therapeutic Implications and Cosmeceutical Applications in Functional Skincare Products

Niacinamide (or nicotinamide) is a small-molecule hydrosoluble vitamin with essential metabolic functions in mammalian cells. Niacinamide has become a key functional ingredient in diverse skincare products and cosmetics. This vitamin plays a pivotal role in NAD+ synthesis, notably contributing to redox reactions and energy production in cutaneous cells. Via diversified biochemical mechanisms, niacinamide is also known to influence human DNA repair and cellular stress responses. Based on decades of safe use in cosmetics, niacinamide recently gained widespread popularity as an active ingredient which aligns with the "Kligman standards" in skincare. From a therapeutic standpoint, the intrinsic properties of niacinamide may be applied to managing acne vulgaris, melasma, and psoriasis. From a cosmeceutical standpoint, niacinamide has been widely leveraged as a multipurpose antiaging ingredient. Therein, it was shown to significantly reduce cutaneous oxidative stress, inflammation, and pigmentation. Overall, through multimodal mechanisms, niacinamide may be considered to partially prevent and/or reverse several biophysical changes associated with skin aging. The present narrative review provides multifactorial insights into the mechanisms of niacinamide's therapeutic and cosmeceutical functions. The ingredient's evolving role in skincare was critically appraised, with a strong focus on the biochemical mechanisms at play. Finally, novel indications and potential applications of niacinamide in dermal fillers and alternative injectable formulations were prospectively explored.

Natural Retinol Analogs Potentiate the Effects of Retinal on Aged and Photodamaged Skin: Results from In Vitro to Clinical Studies

INTRODUCTION

Plants are a source of natural ingredients with retinol-like properties that can deliver anti-aging benefits without the side effects typically associated with retinoid use. We hypothesized that by combining two such analogs, bakuchiol (BAK) and Vigna aconitifolia extract (VAE), with the potent retinoid retinal (RAL), the anti-photoaging potential of RAL could be enhanced without compromising its skin irritation profile. The purpose of this study was to demonstrate that BAK and VAE potentiate the anti-photoaging activity of RAL.

METHODS

Gene expression profiling of full-thickness reconstructed skin was first used to examine the impact of BAK or VAE in combination with RAL on skin biology. Next, the irritative potential of this combination, and its capacity to reverse key signs of photoaging in an ex vivo model was assessed. Finally, a proof-of-concept open label clinical study was performed to evaluate the anti-photoaging capacity and skin compatibility of a cosmetic formulation (tri-retinoid complex; 3RC) containing this complex in combination with other well characterized anti-photoaging ingredients.

RESULTS

In vitro profiling suggested that combining 0.1% RAL with BAK or VAE potentiates the effect of RAL on keratinocyte differentiation and skin barrier function without affecting its skin irritation profile. When formulated with other anti-photoaging ingredients, such as niacinamide and melatonin, 3RC reversed ultraviolet radiation-induced deficits in structural components of the dermal extracellular matrix, including hyaluronic acid and collagen. In vivo, it led to a reversal of clinical signs of age and photodamage, with statistically significant improvement to skin firmness (+5.6%), skin elasticity (+13.9%), wrinkle count (-43.2%), and skin tone homogeneity (+7.0%), observed within 28 days of once nightly use. Notably, the number of crow's feet wrinkles was reduced in 100% of subjects. Furthermore, 3RC was very well tolerated.

CONCLUSION

These data suggest that 3RC is a highly effective and well-tolerated treatment for photoaging.

Beneficial Regulation of Cellular Oxidative Stress Effects, and Expression of Inflammatory, Angiogenic, and the Extracellular Matrix Remodeling Proteins by 1α,25-Dihydroxyvitamin D3 in a Melanoma Cell Line

The causes of cancer include the cellular accumulation reactive oxygen species (ROS), which overrides the cellular antioxidants such as superoxide dismutase, from intrinsic aging, genetics, and exposure to environmental pollutants and ultraviolet (UV) radiation. The ROS damage biomolecules such as DNA (including p53 gene), RNA, and lipids, and activate inflammatory, angiogenic, and extracellular matrix (ECM) remodeling proteins; which collectively facilitate carcinogenesis. The 1α,25-dihydroxyvitamin D3 (Vitamin D) has anti-carcinogenic potential from its antioxidant, anti-inflammatory, and endocrine properties. We examined the anti-carcinogenic mechanism of vitamin D through the beneficial regulation of oxidative stress effects (oxidative DNA/RNA damage, superoxide dismutase expression, membrane damage, and p53 promoter activity), and expression (at the protein, mRNA and/or promoter levels) of inflammatory mediators (interleukin-1 (IL-1) and tumor necrosis factor-α (TNF-α)), angiogenic mediators (transforming growth factor-β (TGF-β), and vascular endothelial growth factor (VEGF)), and the ECM remodeling proteins (matrix metalloproteinases (MMP)-1 and MMP-2) by vitamin D in melanoma cells. Vitamin D inhibited oxidative DNA/RNA damage and membrane damage; and stimulated superoxide dismutase expression and p53 promoter activity in melanoma cells. It inhibited the expression of IL-1, TNF-α, TGF-β, VEGF, MMP-1 and MMP-2 by transcriptional or post-transcriptional mechanisms. We conclude that vitamin D is beneficial to melanoma cells through the inhibition of oxidative DNA/RNA damage, membrane damage, and the expression of inflammatory, angiogenic and ECM remodeling proteins; and the stimulation of superoxide dismutase expression and p53 promoter activity.

The Beneficial Regulation of Extracellular Matrix and Heat Shock Proteins, and the Inhibition of Cellular Oxidative Stress Effects and Inflammatory Cytokines by 1α, 25 dihydroxyvitaminD3 in Non-Irradiated and Ultraviolet Radiated Dermal Fibroblasts

Intrinsic skin aging and photoaging, from exposure to ultraviolet (UV) radiation, are associated with altered regulation of genes associated with the extracellular matrix (ECM) and inflammation, as well as cellular damage from oxidative stress. The regulatory properties of 1α, 25dihydroxyvitamin D3 (vitamin D) include endocrine, ECM regulation, cell differentiation, photoprotection, and anti-inflammation. The goal of this research was to identify the beneficial effects of vitamin D in preventing intrinsic skin aging and photoaging, through its direct effects as well as its effects on the ECM, associated heat shock proteins (HSP-47, and -70), cellular oxidative stress effects, and inflammatory cytokines [interleukin (IL)-1 and IL-8] in non-irradiated, UVA-radiated, UVB-radiated dermal fibroblasts. With regard to the ECM, vitamin D stimulated type I collagen and inhibited cellular elastase activity in non-irradiated fibroblasts; and stimulated type I collagen and HSP-47, and inhibited elastin expression and elastase activity in UVA-radiated dermal fibroblasts. With regard to cellular protection, vitamin D inhibited oxidative damage to DNA, RNA, and lipids in non-irradiated, UVA-radiated and UVB-radiated fibroblasts, and, in addition, increased cell viability of UVB-radiated cells. With regard to anti-inflammation, vitamin D inhibited expression of Il-1 and IL-8 in UVA-radiated fibroblasts, and stimulated HSP-70 in UVA-radiated and UVB-radiated fibroblasts. Overall, vitamin D is predominantly beneficial in preventing UVA-radiation induced photoaging through the differential regulation of the ECM, HSPs, and inflammatory cytokines, and protective effects on the cellular biomolecules. It is also beneficial in preventing UVB-radiation associated photoaging through the stimulation of cell viability and HSP-70, and the inhibition of cellular oxidative damage, and in preventing intrinsic aging through the stimulation of type I collagen and inhibition of cellular oxidative damage.