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"Sericin" had a hair growth effect.

Ask a researcher Seiren "Silk protein, sericin"

Silk protein, sericin, has antioxidant properties for preventing aging as well as moisturizing and beautiful skin effects. The protein is shown to have hair growth effect by activating cells.

Do you know a substance called as “sericin”? Sericin was introduced as one of nature technologies which the Japanese government looked forward to as a growing field in NHK “News: Good Morning, Japan” a few years ago. Silk protein is a component for protecting silkworm cocoon. Skin care products containing sericin was introduced as a popular product “a product which enables moisturizing and whitening at the same time”. In addition, it has been reported at annual meeting of scientific society that the silk protein sericin has skin improvement effects including antioxidant effect. Sericin draws attention as a component of hair care product which promotes hair growth as well.

Seiren with operations in various fields based on its textile technology

At the scene of silk refinement around in 1953

It is Seiren Co., Ltd. comprehensive textile manufacturer based in Fukui Prefecture which advances research and development of silk protein “sericin” and purifies it by increasing its purity to commercialize it into various products. The company started its business as a company to refine silk from silkworm cocoons in 1889. The company has established more than 100 years of history to date. The company name of Seiren was named after “Seiren (refinement)” of silk.
Its textile technology keeps advancing and is integrated with other technologies. Now, the company’s leading products are automotive upholstery materials and airbag materials delivered to Japan’s auto manufacturers. In addition, the company has developed the state-of-the-art production system called “Viscotecs” which enables color representation of 16,770,000 colors with short delivery time under the goal of “From mass production to customized production”. The Viscotecs has revolutionized not only in fashion industry but also various fields like electronics, medical and environment and life materials. Like this, the company’s technology.

Sericin which protects from dryness, sunlight, weather or microbial infection

It is Masahiro Sasaki, Head, Research and Development Group 1 who takes a leadership role in research and development of sericin. “I was born in Fukui Prefecture where Seiren is based and graduated from School of Agricultural Sciences, Nagoya University. To tell you the truth, all I knew about Seiren was that it is a textile manufacturer when I was a college student. I did not know the company well” said Sasaki, laughing. But it is not too much to say that now he is one of the most prominent researchers in the field of extraction technique and functionality of silk protein sericin.

Basement of Sifore, custom-made wig, woven by textiles covered by sericin

How did you discover sericin?

Masahiro Sasaki:Silk fabric is produced by making a thread from a silkworm cocoon and then weaving threads together. By refining silk at this stage, silk fabric becomes shiny and smooth. Silk is composed of two proteins, a filament core protein, silk “fibroin”, and “sericin” surrounding fibroin. It is the process of refinement (Seiren) that leaves core protein, fibroin and removes sericin, a kind of overcoat of fibroin. We had always known that the hands of employees engaging in refinement were white and resilient. Then, I conceived an idea that defense protein, sericin, may make skin revive and shiny and began to collect it. By the way, the amount of sericin disposed had been more than 100,000 ton until recently in the world. Then, we began to tackle with recycling technology of sericin.

Can you extract sericin if only you have silkworm cocoons?

Sasaki:Our extraction technology of sericin is homogeneous. The important thing for manufacturing silk fabric using sericin is that sericin molecules are uniform and the purity of sericin is high by removing impurities. It is only SEIREN that can extract sericin as white powders. Sericin is tarnishable, that is, it may change its color to brownish-red depending on extraction conditions. In addition, if sericin molecules are not homogenized, it may cause irritated skin. Thus, homogenization is important in terms of safety as well.

When did you commercialize sericin extracted by this refinement technology?

Sasaki:It is 1994. The main component of sericin is amino acids. Especially, sericin is rich in hydrophilic amino acids which are similar to a natural moisturizing factor in skin. So, sericin is excellent in moisture retention and gentle on the skin. We developed a processing technology in which the textile surface is coated with sericin. With this technology, sericin can be maintained even if washing the wig 50 times. Then, we commercialized “FRAICHIR” textile coated with sericin. After that, we started a joint research with Osaka Kaisei Hospital and demonstrated that sericin was effective for skin diseases. Then, we developed underwear, bedclothes, children’s clothing, car seat material and “Sifore” with Aderans. We also embarked on a research not only on textile coating but also on cosmetics put on skin directly. Moisturizing consists of immediate moisturizing and continuous moisturizing. Speaking of immediate moisturizing function, sericin penetrates into skin faster than hyaluronic acid which is said to moisturize skin quickly. For continuous moisturizing, it has been demonstrated that sericin keeps moisture in skin as long as 5 hours and that it increases the skin moisture level.

How about its effect on beautiful and glowing skin?

Sasaki:Tyrosinase is one of the enzymes in synthesis of melanin which is a cause of producing dark spots. We conducted a joint research with Hiroshima University and confirmed that sericin inhibited melanin reaction by suppressing tyrosinase activity. Sericin showed a similar whitening effect to that of vitamin C which is known to be a natural whitening agent. Vitamin C is very delicate and is broken by heat. On the other hand, sericin is resistant to heat and a stable protein. Sericin is composed of a variety of amino acids including as serine. This has not been elucidated, but it is thought that sericin existing outside silkworm cocoon protects it from various external damage or stress even at cellular level. I guess one of sericin’s features of being resistant to heat has an ability to protect silkworm cocoon from severe environment.

Its antioxidant effect is meaningful, isn’t it?

Sasaki:When we began to recognize its whitening effect, we also found its antioxidant property in vitro as well. In fact, I studied at Hiroshima University about the antioxidant property of sericin for two years. In the laboratory, they performed screening of antioxidant components. When they noticed sericin by chance and evaluated it, they found that it had an antioxidant property. It is true that there is a Chinese paper showing that people ate sericin for the treatment of diabetes a long time ago. I conducted an experiment in rats which were given diet containing sericin. The result showed that administration of diet containing sericin decreased lipid and cholesterol levels. We see that it is possible to apply sericin’s defensive role of protecting silkworm cocoon to prevention of skin aging and activation of cells.

Sericin’s infinite potential like “activation of cells” and “protection of cells”

Is sericin effective for cultivating scalp where hair barely grows?

Sasaki:As I explained previously, silk is composed of two proteins, a filament core protein, silk fibroin, and “sericin” surrounding fibroin. The structure of hair is very similar, that is, the cuticle of a hair protects the cortex of the hair. When observing enlarged cuticle fragments of damaged hair, the cuticle was open, proteins were lost, and the inside of hair was porous. Then, when applied sericin which is added to mousse-type protein mask to hair, sericin comes in hair to repair. Sericin bonds cuticles fallen off and makes the surface of the hair smooth to prevent proteins from flowing out. We conducted a study in which sericin was applied to the top of the head of a monitor twice a day, morning and evening and we observed the top of the head by microscope every day. As a result, growth phase hair was one before the use of sericin and the number of hairs increased to 6 after 17 days and 7 after 31 days. This study result is still a preliminary one. It seems that sericin plays a role in activating dermal papilla cells which promote hair growth.

Silk is composed of two proteins, a filament core protein, silk “fibroin”, and “sericin” surrounding fibroin. The structure of hair is quite similar to silk. It is highly expected that sericin may have effects of repairing the cuticle of the hair damaged and protecting the cuticle from damage.
Increasing VEGF (vascular endothelial growth factor) secreted by human dermal papilla cells contributes to activation of a large number of capillary vessels. Sericin which promotes hair growth is a protein which is effective for hair regrowth.

Sericin is applied in a variety of fields, isn’t it. It is used as a material comfortable for and gentle on the skin. It is also used in cosmetics and in functional food for improving constipation or promoting mineral absorption. Above all, the potential of sericin attracts attention in medical field.

Sasaki:We are now performing a research focusing on “protecting cells”, one of sericin’s abilities. Then, we have just started a new attempt of using sericin in a solution for storing iPS cells. There are a lot of types of cells. Especially, iPS cells are difficult to store. They have to be put in storage solution and frozen soon after they are extracted. If you do not do so, they will die. The allowable time from putting them in a storage solution to being frozen is around 15 seconds. It is a procedure which only person accustomed to handling of iPS cells can do. If a person who is not accustomed to handling of iPS cells, all of them will die. Under these circumstances, we started to think how to improve a storage solution for iPS cells by utilizing a cellular protective effect of sericin. Then, we discovered a storage solution for iPS cells using sericin which can make iPS cells survive for 60 seconds from extraction to freeze.

You are successful in prolonging the processing time from 15 to 60 seconds. With the conventional storage solution, you had only 15 seconds to freeze the cell but now you have 60 seconds. It results in the improvement of storage of iPS cells.

Sasaki:As a textile manufacturer, we started our research and development in an effort to “aim at differentiating our products from others using sericin” under the slogan of “To create textile products on gentle on the skin” in the first place. Then, we continued research and development aiming at giving additional values to our products and differentiating them from others and finally reached the storage solution for iPS solution.

I was really surprised to learn how high ability sericin created from silkworm cocoon has. Thank you so much for your precious story.

Interviewer/writer: Akiyoshi Sato Photographer: Kuninobu Akutsu Data provided by Seiren Co., Ltd.

History of development, products and services based on research of Aderans
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