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| Newsletter | Energy, structure and hair repair through intelligent proteins | Iris Hütter, Peter Busch, Ute Griesbach, Maya Hohle, Wolf Eisfeld |
Introduction
The image of "A land of with milk and honey" (1) was firmly established in the world of beauty care even before Cleopatra took to bathing in asses's milk, and it still is. One of the most significant components of milk is milk protein (2). For millennia humans have thus put their faith in the remarkable effects of proteins in the care of skin and hair. Modern and traditional formulations have one thing in common - they rely on this genuine classic cosmetic ingredient, which is always relevant and always "in."
In olden days there were only vague suspicions that products containing proteins could have a positive effect on beauty. We now know, however, that the structure of these multifunctional bioactive substances enables them to interact closely with our skin and hair (3). It is therefore no wonder that proteins - and especially milk proteins - have a firmly established place in the world of cosmetics.
Protein active substances for personal care preparations are obtained from a multitude of natural sources of both animal and vegetable origin, such as wheat, almonds and rice, as well as the soybean and milk protein hydrolyzates described here*. The numerous cosmetic benefits of proteins have been intensively studied and are scientifically recognized (3-7). Up-to-the-minute results and insights are now available for newly developed protein hydrolyzates and are described below.
Soybean - a "holy" alternative
Soybean is the nutrient of the new millennium. A versatile ingredient in everyday cooking, it also helps to prevent diseases of civilization, such as cardiovascular illnesses. Scientists are convinced and even speak of a "soybean revolution" (8). In view of this it might be thought that the soybean is a trail-blazing new discovery, but in fact they have a long history, steeped in legend (9).
Soybeans were harvested in China, where they were called "dadou" (big bean), as long as 5000 years ago and there are numerous stories about their discovery. According to one of those tales, these remarkable beans were found by two war-lords in China when they lost their way in the wilderness and they saved them from certain death by starvation (10).
The Chinese therefore consider the soybean - along with rice, wheat, barley and millet - to be one of the 5 holy plants (11). Certainly the nutrient content of this "shooting star" of the plant world gives it a special place among vegetable products in general. Its exceptional mix of amino acids makes it an excellent source of quality protein. Not only do soybeans supply the body with all eight essential amino acids but these amino acids are present in much the same ideal proportions as in meat or poultry protein. Soybean can therefore justifiably be regarded as a perfect substitute for animal protein (12).
"Strength & Energy" for skin and hair
Moreover, the multifunctional soybean protein possesses remarkable cosmetic properties, as explained below. The described soybean protein hydrolyzate (INCI name: Hydrolyzed Soy Protein; trade name: Gluadin® Soy) is characterized by an exceptional amino acid composition (Figure 1). In particular, the high content of arginine, aspartic acid and glutamic acid deserves special mention. The role of arginine in imparting strength and energy is almost proverbial; it strengthens the immune system, stimulates the production of growth hormone and supports skin's healing process (13, 14). This strength aspect was investigated in a study with the soybean active substance. The main objective was first of all to prove whether the hydrolyzed soybean protein can help to strengthen hair, and if so to what extent.
| Figure 1 |
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| Amino acid profile of Gluadin® Soy (relative to amino acid content) |
Intelligent repair process imparts protection and strength to the hair
To demonstrate these properties, Gluadin® Soy was labeled with a fluorescent marker (fluorescein isothiocyanate - FITC) so that its substantivity or its penetration of the hair could be observed by means of fluorescence microscopy. In this way it was possible to trace the following remarkable path of the soybean active substance in the hair (Figure 2).
| Figure 2 | |
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| Fluorescence microscope images of hair after treatment with Gluadin® Soy (1% AS) | |
After just one hair treatment a significant absorption of the labeled soybean hydrolyzate on the hair could be observed from an aqueous solution. Gluadin® Soy forms a protective protein layer around the sensitive hair fiber. A sort of preventive seal can thus be created around the hair, shielding it from environmental influences and harmful substances, and without any undesirable build-up effect. Absorption occurs preferentially in zones where the hair is most "vulnerable", such as sensitive edges of cuticle scales, susceptible hair tips and incipient break sites (Figure 2 and Figure 3).
It follows that a targeted repair effect can be achieved by applying this soybean active substance. Intelligent proteins recognize the exposed weak points of the hair, demonstrating substantivity and strengthening the hair fibers exactly where this is most urgently necessary.
Energizer of the hair's natural protective layer
Gluadin® Soy can also be regarded as an energizer of the cuticle, which is the hair's natural protective layer. Day in, day out the cuticle is exposed to enormous stresses ranging from daily brushing, shampooing and hair styling to ultraviolet radiation and other environmental influences, as well as permanent waving and bleaching (15). The undesirable consequence is lackluster, brittle hair, which is difficult to comb and style (15). This is precisely where the "Strength & Energy" concept of the studied soybean active substance comes in.
Gluadin® Soy protects, strengthens and repairs the hair. It keeps the cuticle smooth and supple and thus has a positive effect on the hair's feel and shine. Sensory assessments attested to a structuring effect and a stronger tactile sensation after the use of Gluadin® Soy.
Penetration as far as the outer cortex
In addition to the formation of an effective protective film on the hair surface, Gluadin® Soy penetrates as far as the outer cortex (Figure 4). In other words, tiny nature-identical building blocks penetrate deep into the hair and strengthen it.
Improvement of hair volume and styling
Another proof of effectiveness, which supports the "Strength & Energy" concept of Gluadin® Soy, is provided by measurements of the bending strength of hair strands. In this test a hair tress is bent to a certain degree and the force that has to be exerted is measured quantitatively. The test can yield information about the strength or stability of the examined hairs and the resulting hair volume, because flexural strength is one of the factors that have a considerable influence on hair volume (16).
Just one treatment with Gluadin® Soy was found to have brought about a significant increase of more than 40% in bending strength (Figure 5). This may be due to an increase in either the flexural strength of the individual hair fibers or the cohesion between the fibers. Both of these effects would improve hair manageability and styling. In addition, the increase in bending stability contributes to an increase in hair volume and body. These results are supported by the above-mentioned penetration measurements and a recent proof of effectiveness concerning hair volume.
| Figure 3 | Figure 4 |
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| Fluorescence microscope image of a hair fracture site after treatment with Gluadin® Soy (1% AS) | Fluorescence microscope image of hair cross sections after treatment with Gluadin® Soy (1% AS) |
| Figure 5 |
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| Bending strength of hair strands - treatment with 0.5% AS Gluadin® Soy |
Modern concepts
All in all, therefore, Gluadin® Soy is especially suitable for concepts focusing on stressed, permanent-wave-damaged, bleached, dyed, brittle, long hair or sensitive hair tips, as the following concept approaches indicate:
ESP-Shampoo - Energy, Strengthening, Protection
ESP-Conditioner - Essential Substances Penetration
MODIC-Repair Balm - Molecular Diagnostic Intelligent Cuticle Repair Balm
Furthermore, Gluadin® Soy can also be used on other types of hair and in all applications to prevent hair damage (Table 1).
Skin care effects
In view of the molecular weight of Gluadin® Soy, the above-mentioned proofs of effectiveness were focused mainly on its effects on the hair. Moreover, it is known from market surveys and product research that hydrolyzed soybean protein is also widely used in the skin care sector, e.g. in skin-structuring, reactivating and anti-wrinkle products.
Milk makes beautiful
Milk is not only one of the most valuable natural nutrients, particularly rich in calcium, vitamins and minerals (2); in addition to this, "milk makes beautiful". Fascinating women from Nefertiti to Cleopatra to Empress Elizabeth of Austria, better known as Sissi, famed for their beauty and their beauty secrets, have known this for thousands of years. Milk had a permanent place in their beauty care.
Nutrilan® Milk - The goodness from milk for the benefit of beauty
The studied milk protein hydrolyzate (INCI name: Hydrolyzed Milk Protein; trade name: Nutrilan® Milk) is obtained from casein, the most important protein fraction of milk (2). Its dominant amino acids are glutamic acid and proline (Figure 6). Two interesting facts are worth mentioning here. Firstly the amino acid profile of casein is very similar to that of the Natural Moisturizing Factor (NMF) of human skin (17). Secondly this special profile is responsible for the much higher thermal stability of these milk proteins in comparison with other proteins. This is why casein does not undergo denaturation like whey proteins during the boiling process of milk (whey proteins form the familiar and widely disliked skin on boiled milk) (17, 18).
The explanation: Proline occupies almost every tenth position in the casein amino acid chain and due to its pyrrole ring it occupies a large amount of space. This frequent occurrence prevents the formation of a higher secondary structure of casein, such as a helix or ß pleated sheet structures. Moreover the proline position acts as a hinge, around which the rest of the protein chain can move relatively freely. This gives the casein molecule an extremely flexible structure, enabling it to cushion very effectively kinetic energy in the form of, for example, heat used for the boiling of milk. Casein can therefore resist denaturing for a long time.
| Figure 6 |
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| Amino acid profile of Nutrilan® Milk (relative to amino acid content) |
| Figure 7 |
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| Skin tonicity by cutometer measurement |
Flexibility and tonicity for the skin
Nutrilan® Milk can transfer natural casein's unique flexibility to human skin. This can be demonstrated by measuring skin tonicity with a cutometer (Figure 7). The parameter "skin tonicity" describes the skin's ability to return to its original state after being extended vertically. It also enables conclusions about specific skin properties such as elasticity and resistance. In comparison with a placebo lotion it was demonstrated that a lotion containing Nutrilan® Milk is able to bring about a significant improvement in skin elasticity and texture after just one application (Figure 7). This active substance derived from milk thus demonstrably displays a positive influence on the mechanical resistance and tonicity of the skin. Nutrilan® Milk is therefore genuinely capable of transferring the flexibility of the casein molecule to human skin.
Revitalization and protection for the hair
| Figure 8 | |
 |
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| Fluorescence microscope images of hair after treatment with Nutrilan® Milk (1% AS) | |
As with Gluadin® Soy, the effect of Nutrilan® Milk on the hair was studied with the help of fluorescence microscopy. In this way it was possible to show the remarkable absorption behavior of Nutrilan® Milk on hair fibers (Figure 8). A significant protective film of milk hydrolyzate was observed on the hair fibers after just one application of Nutrilan® Milk. Nutrilan® Milk thus wraps itself around each single hair fiber, forming a protective protein layer. A striking aspect is that, as well as providing external protection, the active substance penetrates into every layer of the cuticle (Figure 8). In other words, Nutrilan® Milk revitalizes the hair's natural protective layer, the cuticle, through and through by providing it with support just where it is urgently needed. The result is vital, protected and healthy hair.
Soft and supple hair
Alongside this aspect of protection and revitalization, Nutrilan® Milk exhibits a positive effect on the haptic sensation factor of the hair. In sensory assessments - an extremely valuable tool that takes account of the contemporary desire for immediately perceptible cosmetic effects - hair treated with Nutrilan® Milk was assessed as very pleasant (Figure 9). The hair was felt to be less dry and brittle and thus giving an impression of softness, smoothness and suppleness.
All in all, Nutrilan ® Milk, the active agent from the goodness in milk, genuinely pampers skin and hair (Table 2).
| Figure 9 |
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| Sensory assessment
on hair (selected parameters) after conditioner treatment with 3%
AS Nutrilan® Milk (red = negative, green = positive assessment; 0 line = placebo formulation without Nutrilan® Milk) |
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Description of the methods
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Acknowledgements
The authors would like to acknowledge DWI (Deutsches Wollforschungsinstitut) in Aachen, particularly Prof. Franz-Josef Wortmann and Dr. Karola Schäfer for their assistance in carrying out the fluorescence and bending strength measurements.
Author
Dr. Iris Hütter
Dr. Iris Hütter is a State-certified Food Chemist. She completed her doctoral thesis at Henkel, Düsseldorf in cooperation with the University of Hamburg — Institute for Biochemistry and Food Chemistry. In January 2000 she assumed the position of Product Manager at Cognis High Care and was in charge of active ingredients and additives such as proteins, vitamin E and phytosterols for use in cosmetic products. Since January 2002 she has been Global Product Manager HBO for applications in hair, body and oral care, especially for marketing protein products.
References
1. Deuteronomium/5 Mose 26, 5-9
2. H.-D. Belitz, W. Grosch: Lehrbuch der Lebensmittelchemie. Springer-Verlag: Berlin, 4. Auflage (1992), S. 451-464
3. A. Berg: Einsatz von Proteinen in Kosmetika. Parfümerie und Kosmetik, 65, 7 (1984), 391-401
4. U. Griesbach, M. Klingels, V. Hörner: Proteins - Classic Additives and Actives for Skin and Hair Care. Cosmetic & Toiletries 113, 11 (1998)
5. U. Griesbach: Gluadin - Proteinprodukte der Zukunft, Henkel High Care Broschüre (1996)
6. J. Kahre, D. Goebels: Influence of surfactants on the effect of permanent waves on hair. Agro-Food-Industry Hi-Tech, March/April (1995)
7. N.I. Challoner, S.P. Chahal, R.T. Jones. Cosmetic Proteins for Skin Care. Cosmetic & Toiletries 112, 12 (1997)
8. S. Holt: The Soy Revolution. Dell Publishing: New York, 1. Ausgabe (1998)
9. T. Hymowitz: Soybeans - The Success Story in J. Janick, J. Simon: Soybeans - The Success Story, Advances in new crops. Timber Press: Portland, Oregon, USA (1990), 159-163
10. http://www.unclechef.com/funfoodfacts.html, 15.04.2001
11. Soya. IFR Communications, Institute of Food Research, Norwich, UK (2001)
12. Die Sojabohne und ihre Anwendung. ASA (American Soybean Association)-Europa, Hamburg (2001)
13. R.-G. Guilhermet, A. Cochard: Arginine - Healing, immune and endocrine functions. Fr. Cah. Nutr. Diet. 33, 1 (1998), 19-24
14. L. Beaumier, L. Castillo, Y.M. Yu, A.M. Ajami, V.R. Young: Arginine - New and exciting developments for an "old" amino acid. Biomedical and Environmental Sciences, 9, 2-3, (1996), 296-315
15. E. Tolgyesi: Weathering of hair. Cosmetic & Toiletries, 98, 10 (1983), 29-33
16. P. Hough, H. Huey, W. Tolgyesi, J. Soc. Cosmet. Chem. 27, 571 (1976)
17. T. Niederauer: Milchproteine - zukunftsträchtige Rohstoffe für die Kosmetik. Parfümerie & Kosmetik, 75, 10 (1994), 666-670
18. J. Koolman, H. Moeller, K.-H. Röhm (Hrsg.): Kaffee, Käse, Karies ... - Biochemie im Alltag. 1. Aufl., Wiley-VCH-Verlag: Weinheim (1998), 205-208
Gluadin® Soy and Nutrilan® Milk are registered trademarks of Cognis Deutschland GmbH & Co. KG.
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