With the collaboration of Toyobo Co., Ltd (Ryuzo Sakamoto, President), Dai Kitamoto, Group Leader of the Biochemical Materials Group of the Research Institute for Innovation in Sustainable Chemistry (Hiromichi Shimada, Director), of the National Institute of Advanced Industrial Science and Technology (AIST; Hiroyuki Yoshikawa, President), has succeeded in developing a highly functional biosurfactants.

The developed biosurfactants present superb skin moisturizing characteristics equivalent to those of natural ceramides, and it can be used in functional cosmetics and for other skin care products. The biosurfactants consist of only sugar and fatty acids, and are thus highly environmentally friendly. They can also be used for high-performance washing detergents and advanced nanomaterials, because they easily form a variety of liquid crystals in aqueous solutions.

The present biosurfactants also exhibit a spontaneous formation of capsules of nanometer size (1 nanometer = 1 x 10^-9 meters), so-called liposomes, which considerably improve the stability of cosmetic ingredients and their permeability to the skin.

Natural ceramides have been praised for its moisturizing properties, and together with hyaluronic acids, they have become a crucial material for skin care applications. However, the use of natural ceramides set its cost in the range from several hundred thousand yen to several million yen per kilogram. It has been therefore strongly desired to develop a safe product with characteristics similar to natural ceramides at a lower cost. The present R&D has enabled us to develop the desired moisturizing materials, using yeast fermentation processes and vegetable oils (Figure 1).

Figure 1

In recent years, increasing interest in skin care awareness, together with advances in the understanding of skin structure, the aging process, roughening of skin, and sunburn, and elucidation of the mechanisms of blotch, has led to new materials and treatments being continuously introduced, with an ever expanding market for highly functional products for skin care and other skin applications.

Skin care products can be classified into products that control the moisture evaporation ("control type") such as hyaluronic acid and products that help to preserve the moisture of the skin ("supplement type") such as amino acids or ceramide. Natural ceramide presents superb moisturizing characteristics, but the use of natural raw materials makes the refining process troublesome to obtain a final product of reasonable purity, and the cost reaches the range from several hundred thousand yen to several million yen per kilogram. In addition, synthesis of natural or pseudo-ceramide requires high-level chemical technologies, but it does not contribute to reduce costs. Not so highly functional but low-cost chemical products are used as alternatives to natural ceramide. The need for a substitute product for ceramide that combines low cost and high functionality is evident.

In addition, from the point of view of safety and environmental concerns, natural products that are not based on petroleum are required.

In the search for materials that have low environmental impact, AIST has tackled the development of a biosurfactant and established that it is possible to produce it efficiently from vegetable oil through a process of yeast fermentation. At the same time, to establish the most advantageous applications for this product, we started to analyze the physical properties and functions of this biosurfactant.

Based on its accumulated experience in the field of biotechnology, Toyobo has been opening new fields of applications for highly functional biomaterials. Toyobo's interest in the biosurfactant developed by AIST brought the start of collaborative research between the two entities.

Biosurfactants are natural lipids produced by microbes such as yeast or the bacillus natto, with diverse properties reflecting their structure. Their main functions are as surface agents (for emulsification, dispersion, moisturizing, etc.), and they have the characteristic of being effective even at extremely low concentrations compared to synthetic reactants. Also, in some cases, biosurfactants have unique characteristics not observed in synthetic surfactants, such as formation of diverse liquid crystals, anti-tumor activity, etc. However, to this date, mass production of biosurfactants has been difficult and their applications and industrial use were limited.

At AIST, the starting point was the search for a mass producible microbe, which led to the discovery of a yeast with a relatively higher productivity than the present biosurfactant. Evaluation of the production conditions was carried out and a mass production method using olive oil or other vegetable oils was established (Figure 1). Joint research with Toyobo led to the development of a method for effective production of the present biosurfactant, followed by an active search for new applications in the field of functional materials.

In the quest to establish new applications, evaluation of the unique structure of the biosurfactant molecular model (simultaneous coexistence of glucose, sugar alcohol, fatty acid, etc.) showed its similarity with the ceramide molecule, which is an intercellular lipid. At the beginning, the lack of a method for accurate assessment of the moisturizing effect on the skin made it difficult to evaluate the effects of the surfactant. However, after the joint research with Toyobo was begun, the use of the three-dimensional cultured skin surface developed by this company became the breakthrough that accelerated the process for confirmation of the moisturizing properties of the biosurfactant, and made possible determination of its suitability for use in skin care products and cosmetics (Figure 2). Regarding the mechanisms for preservation of moisture, we expect 1) the structure resembling ceramide will easily penetrate the intercellular spaces in the stratum corneum, and 2) it will be effective in moisture retention and maintenance at the skin intercellular level, as it easily forms liquid crystals (Figure 3).

Figure 2. Moisturizing effect of biosurfactants on cultured human skin

Figure 3. Effects of biosurfactants on rough skin

Furthermore, as the biosurfactant easily forms capsule of nano-meter size (liposome), it is easy to mix with other cosmetic components, which could contribute to stabilization of these components (capsule protection effect), and improves the permeability to the skin (capsule affinity effect).

From the point of view of the production process, fermentation of yeast can yield a high purity biosurfactant, with a cost reduction in the order of one fifth to one tenth of the current costs of producing natural ceramide from vegetables, or synthesizing pseudo-ceramide through chemical processes (several hundred thousand yen to several million yen per kilogram). The present production method does not use petroleum but biomass resources as a raw material, achieving production in one step by fermentation of vegetable oils. Compared with other chemical processes, high expectations are set on it as a resource saving and low environmental impact process.

Biosurfactants that can be used in skin care products (cosmetics, medicines for external application) are the focus of attention. Through application of microbial biotechnology, AIST is engaged in the search for and development of biosurfactants with new structures and new properties. Toyobo, with vast experience in the field of biotechnology, is making inroads in the field of functional biomaterials. Starting from the autumn of this year, we will provide samples to diverse manufacturers in the field with the aim of achieving industrialization in a two or three year span. Lowering of costs is another topic to be pursued, as is the discovery of new applications aside from cosmetic products that take advantage of the superb characteristics of the surfactant.

A portion of the results from the present research will be made public at the 45th Meeting of the Japan Oil Chemists' Society held at Tokyo University of Science (Noda City in Chiba) on September 8, 2006, and at the 58th Annual Meeting of the Society for Biotechnology of Japan held in Toyonaka City in Osaka on September 11, 2006.