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Natural Polyoses Provide Immediate Tightening Effects



Avena Sativa Extract has a tensor, smoothing and anti-wrinkle effect that is visible



Published March 28, 2008
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Natural Polyoses Provide Immediate Tightening Effects

Natural Polyoses Provide Immediate Tightening Effects



Avena Sativa Extract has a tensor, smoothing and anti-wrinkle effect that is visible 30 minutes after its application and still significant after four hours.



By C. Lenaers, F. Crémilleux, M. Dana, E. Vignau, B. Closs
R&D Department
Silab



Consumers of cosmetic products, especially women, are very attentive to the appearance of their skin. They take good care of it and become increasingly demanding of the products that they use. Indeed, women know that in addition to long-term preventive treatments, it is now possible, thanks to the progress made in the fields of chemistry and biochemistry of the skin, to get instant results. They want natural high-performance products that are effective on sagging skin, that are capable of reducing, immediately and visibly, wrinkles and fines lines, whichever the treated area of the body, without forgetting the pleasure aspect related to application of skin care products.
   
To meet this demand, anti-aging products have, for several years now, incorporated tensor agents capable of instantly and visibly smoothing the skin. They boost the skin’s radiance and lift it.
   
Supported by our know-how and expertise in the field of tensor active ingredient, Silab researchers have turned their attention to new molecular structures—sugars—little used as tensor agents to date, to propose Avena Sativa Extract (ASE), a purified fraction of natural polyoses derived from oats.
   
This innovative, natural active ingredient has a three-dimensional, high molecular weight configuration capable of adjusting perfectly to the skin’s microrelief, of strongly and durably adhering to it and spreading to form a cohesive and continuous biological film with a lifting effect.

Mechanism of Action



ASE is obtained by various gentle and non-denaturing selectivefractioning and purification steps, making it possible to target a fraction of natural oat polyoses with a specific structure and molar mass, naturally presenting a high tensor capacity.
   
The polysaccharide fraction of ASE is composed of a glucose chain linked by α-1,4 bonds, forming a helicoidal structure, ramified by an α-1,6 bond every 12 oses on average (Figure 1).
   
As Figure 2 shows, stabilized by inter- and intra-chain hydrogen bridges, ASE forms a three-dimensional configuration capable of adhering to the surface of the skin and forming a cohesive biological film with sufficient flexibility to stretch and adjust between the polar heads of the lipids without disrupting their organization (Sum et al., 2003).

Its adhesion capacities are the result of the presence of numerous hydroxyl functions along its oside chains, which form multiple hydrogen bonds with the intercellular lipids of the stratum corneum and, in particular, the ceramides, via their amide function and hydroxyl groups (Pascher, 1976).
   
Each glucoside unit of ASE, presenting several hydroxyl functions, can simultaneously form several hydrogen bonds with three adjacent lipid molecules. This means ASE can bind strongly and durably to the surface of the skin and form a cohesive and continuous film, which can even stabilize the adjacent lamellar structures of the lipids, acting as bridges between each of them (Sum et al., 2003).
   
Different approaches enabled us to evaluate the performance of ASE:
    • A sensory approach to assess the sensations perceived on application of the formulated product by trained panelists.
    • A classic instrumental approach to measure and quantify the effectiveness of ASE in the short term.
    • An esthetic approach to check if ASE formulated in a foundation can improve the hold of the make-up over time in comparison with a placebo formula.
    For different in vivo studies, the study information sheet and consent form were read and signed for approval before each study, conditions during the measurements were:
    • Temperature: 20 ± 2°C
    • Relative humidity between 40 and 60%.

Sensorial Evaluation of the Tensor Effect



The aim of this study was to quantify the tensor effect perceived by a trained panel after a single application on the crow’s feet of either ASE formulated at 4% in a gel or bovine serum albumin (BSA) formulated at 10%, both vs. a placebo. The study was conducted on 17 healthy male and female volunteers, between 23 and 51 years of age, mean age 31 ± 6 years.
   
The intensity of the tensor effect was evaluated using a scoring scale from 0 to 10 by this panel previously trained to perceive different albumin concentrations formulated in a gel.
   
Each evaluator noted the intensity of the perceived sensation after applying a similar quantity of product (ASE, BSA or placebo) on crow's feet, using a 0 to 10 scale (0: no tensor effect perceived, 10: substantial tensor effect). Scores were noted 3, 5 and 10 minutes after application of the product.
   
The mean score of each evaluator was calculated from the scores at 3, 5 and 10 minutes after application of the product. The results presented are the mean scores of each evaluator for the three times (Figure 3).
   
After the application of ASE formulated at 4% in a gel on crow’s feet, 86% of the panelists trained to perceive and quantify the tensor effect sensation reported a tensor effect greater than that obtained with the placebo. The tensor effect observed was comparable to that of a formula containing 10% BSA, since 88% of the panelists felt a BSA tensor effect greater than that obtained with the placebo during the evaluation.

Immediate Efficacy of Avena Sativa Extract (4%)


To evaluate the material’s immediate tensor effect,
astudy was conducted on 33 healthy female volunteers, between 24 and 61 years of age (mean age 31 ± 8 years). Measurements were made on the forearm with a SEM 575 Cutometer, before and two hours after a single application of ASE formulated at 4% in an emulsified gel vs. placebo.
   
Following parameters Uf and Ue, characteristic of skin tension were studied. If Uf increases, the skin is less extensible thus tauter and if Ue increases, the skin is less supple thus tauter (Figure 4).

In the conditions of this study, two hours after a single application and compared to the placebo, ASE formulated at 4% in an emulsified gel led to a statistically significant improvement of the parameters characteristic of skin tension:

Uf: +6.3%,  P = 0.0003
 
Ue: +9.3%, P = 0.00005

Evaluation of the Immediate Anti-wrinkles Effect



The study was carried out by profilometry on 19 healthy female volunteers between 41 and 72 years of age, mean age 55 ± 9 years. Photographs and replicas of the two crow’s feet were made before and after treatment with ASE formulated at 4% in an emulsion vs. placebo, two hours after a single application (Figure 5).
   
In the conditions of this study, two hours after a single application and compared to the placebo, ASE formulated at 4% in an emulsion, significantly reduces the number of wrinkles (-11.5%, P = 0.0446), the total wrinkled surface (-17.4%, P = 0.0337) and the total length of wrinkles (-13.9%, P = 0.0346).
   
Then, an immediate smoothing effect on the cutaneous microrelief was underlined by profilometry on the forearms, 2 hours after a single application of ASE at 4% (Ra=-5,7%, P=0,0099; Rz=-3,5%, P=0,0056).

Improved Makeup Wear



The aim of this in vivo study on volunteers was to quantify the influence of ASE formulated at 4% vs. placebo, on the hold of a makeup foundation over time. This study was conducted on 18 healthy female volunteers with mixed skin, between 25 and 65 years of age, mean age 46 ± 14 years.
   
A determined volume of makeup foundation containing ASE formulated at 4% or placebo makeup foundation were applied on one side of the face with a makeup sponge. Skin color was measured with a chromameter immediately after application of the makeup and 2-, 4- and 6 hours after application. Six hours after the makeup foundation application, a matifying paper was applied to each side of the forehead with a standard pressure. The deposit of residual makeup foundation on each paper was evaluated visually.
   
Colorimetric measurements and matifying papers analysis showed that the use of ASE at 4% in a makeup foundation significantly improved its hold during the day (Figure 6).
 
Thanks to multiple interactions between its oside chains and the intercellular lipids of the stratum corneum, ASE is capable of adsorbing on the skin’s surface. Since each glucose in ASE can create several hydrogen bonds with several ceramides, the strongly cohesive biological film formed can nonetheless easily spread over the cutaneous surface and visibly tighten the skin.
   
Panelists trained and conditioned in feeling and quantifying a tensor effect assessed the tensor effect of ASE formulated at concentrations of 2-4% and 10% and applied to crow’s feet area. They reported a significant and dose-dependent sensation for the product’s tensor effect in comparison with placebo and bovine serum albumin (BSA) at a concentration of 10%.
   
A study carried out with untrained volunteers also significantly observed a tightening effect, a smoother, firmer and more toned skin 30 minutes after application of ASE at a concentration of 4% to the face in comparison with placebo (Figure 7).
   
ASE has a tensor, smoothing and anti-wrinkle effect that is visible 30 minutes after its application and still significant after four hours. The tensor effect of ASE is dose-dependent, and measurable on the face, body, bust and thighs, in both gel and emulsion formulas (data not shown).
   
ASE also has anti-wrinkle properties following a month of twice-daily treatment on the crow’s feet area (data not shown). Then, ASE has been tested at 5% in different formulas (aqueous solution, alcoholic solution, clear gel, opaque gel, emulsified gel, nonionic emulsion, anionic emulsion, cationic emulsion) and results have proven than ASE did not modify formulas (absence of precipitation of the active substance, absence of creaming or phase separation of the formula).
   
It has the advantages of non-charged saccharide molecules: solubility in water and ethanol up to 30%, it is not very sensitive to variations in pH, temperature and salinity, and does not have the disadvantages of synthetic polymers: stickiness and shininess on the skin. What’s more, ASE, which has very little color, can be easily adapted for use in the whitest emulsions and the clearest serums.

Conclusion



ASE, a purified fraction of high-molecular weight natural polyoses, has a strong lifting capacity, and a high solubility in aqueous medium, making it easy to formulate. ASE, formulated in a gel or an emulsion, presents a dose-dependent tensor effect, immediately visible and perceptible by the consumer. Its tensor effect works on the face and the body (arm, thighs and bust).
   
ASE tones the skin, makes it firmer, smoothes the skin’s microrelief and reduces wrinkles and lines. From an esthetic point of view, it also improves the hold of makeup over time. ASE can therefore be incorporated in all skin care products for the face or body designed to sculpt, model and smooth the skin.

Bibliography


    1. Pascher I. Molecular arrangements in sphingolopids. Conformation and hydrogen bonding of ceramide and their implication of membrane stability and permeability. Biochimica et biophysica acta, 455 : 433-451 (1976).
    2. Sum AK, Faller R, de Pablo JJ. Molecular simulation study of phospholipid bilayers and insights of the interactions with disaccharides. Biophysical journal, 85(5) : 2830-2844 (2003).

More info:

To learn more about ASE, contact D. Boudier, Silab, BP 213, 19108 Brive Cedex, France.
E-mail: silab@silab.fr


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