ANTI-AGEING
51
Retinyl esters are not alike: an in vitro study
Caroline Smal, Roland Hubaux, Michel Salmon – StratiCELL, Belgium Stephanie Clendennen, Robin Matton - Eastman Chemical Company, US
The processes underlying changes in the appearance of skin over time, such as the fine lines and wrinkles, are fairly well understood. Natural or intrinsic skin ageing is accompanied by thinning of the epidermis, slower cell turnover and a reduction in the number and thickness of collagen fibres. Aged skin can appear thin, fragile, saggy or wrinkled.1 Extrinsic skin ageing, or photoageing, results from sun exposure and damage can also appear as fine lines and wrinkles along with hyperpigmentation.2 The skin’s extracellular matrix is the primary
location for structural proteins such as collagen and elastin responsible for maintaining skin firmness and elasticity. During both extrinsic and intrinsic skin ageing, reactive intermediates induce the expression of matrix metalloproteinases (MMP). These proteases break down collagen in the skin, and degraded collagen and reduced collagen synthesis are both diagnostic of naturally aged and photoaged skin.3
Skin ageing is also associated
with loss of skin moisture which can contribute to loss of firmness. The key molecule involved in skin moisture is hyaluronic acid (HA), an extracellular matrix component with a very high water-binding capacity.4 Vitamin A and its derivatives, also known as
retinoids, occur naturally in the skin, with retinol and retinyl esters being the most abundant forms.5
Retinoids are proven anti-ageing
ingredients when applied topically on the skin. Retinoids can reduce the appearance of fine lines and wrinkles by acting through well-documented biological pathways in skin.6
Retinoids regulate
epithelial cell growth and differentiation and exert this effect by their ability to diffuse through the extracellular matrix and cellular membranes. Once they are inside cells, retinoids can bind to specific nuclear receptors and modulate expression of genes involved in cellular proliferation and differentiation.6 Retinol and related compounds applied to
the skin can reduce the visible effects of ageing in both lab and clinical studies. Topically applied retinol is recognised as an effective means to address the signs of ageing and sun damage and has been shown to induce proliferation of keratinocytes and lead to a thickening or pluming of the epidermal layer. 1; 7; 8; 9
Lab tests have
shown that retinol can induce HA production and stimulate the expression of genes encoding all three forms of hyaluronic acid synthases (HAS) in cultured normal human epidermal keratinocytes.4
www.personalcaremagazine.com 0.1% Retinyl palmitate 0.1% Retinol 0.1% 0.05% 0.01% 0.005% 0.001%
Figure 1: Representative images of fibroblast cultures after 72h of treatment under control conditions and with test retinoids.
Clinical studies on both naturally and extrinsically aged skin showed that topically applied retinol not only increased fibroblast growth and collagen synthesis, but also reduced the levels of matrix degrading MMP.10 Familiar examples of retinoids are retinoic acid, retinol, and retinol esters like retinyl
palmitate. retinol, the alcohol form of Vitamin A, is commonly used in cosmetic skin care products. While retinol itself is highly effective, it has a reputation as being both unstable in formulation and irritating to skin at cosmetically useful levels. In a summary of published studies, retinol was shown to have adverse local effects
July 2021 PERSONAL CARE 0.05% 0.01% 0.005% 0.001% 0.05% 0.01% 0.005% 0.001% ABSTRACT
Retinol is well-established in cosmetics as an anti-ageing ingredient. It is known to increase cell proliferation and production of extracellular matrix elements such as hyaluronic acid. Anti-ageing products containing retinol may therefore decrease the appearance of wrinkles and improve skin texture. Unfortunately, retinol also suffers from chemical instability and the potential to irritate skin. To circumvent these issues, several derivatives of retinol have been developed with improved stability while still retaining the anti-ageing effects. The derivatives contain unsaturated fatty acids, either purified linoleic acid or a blend derived from sunflower seed oil. A comparative in vitro study was conducted to compare the effect of different test materials on human dermal fibroblast proliferation and production of hyaluronic acid. The test materials included retinol and three different esters of retinol (Retinyl sunflowerseedate, Retinyl linoleate, and Retinyl palmitate).
Controls Untreated control Retinyl linoleate 0.1% Retinyl sunflowerseedate 0.05% 0.01% 0.005% 0.001% Mitomycin C 2 µg/ml FBS 10% DMSO 0.5% Chloroform 1%
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84
