Rohto Group Discovers New Potential in Tooth Development and Salivary Gland Activation with Proprietary Ingredients

Rohto Pharmaceutical Co., Ltd. (Headquarters: Osaka, President: Hidetoshi Segi) is advancing research in the oral domain to support food and health in the future, in pursuit of the Rohto Group's comprehensive management vision "Connect for Well-being & Longevity." In joint research with Associate Professor Hiroko Yoda of the Department of Hard Tissue Morphology, Graduate School of Medical and Dental Sciences, Niigata University, and Dr. Yuki Ohno of the Department of Otorhinolaryngology-Head and Neck Surgery, Rohto has identified new potential in its proprietary Group ingredients: globin protein hydrolysate, milk-derived hydrolyzed peptides (hereinafter, milk peptides), and hydrolyzed soy peptides (hereinafter, soy peptides) related to tooth enamel formation/maturation and salivary gland activation.

A portion of these research findings was presented orally at the 131st Annual Meeting of the Japanese Association of Anatomists (to be held from March 24 to 26, 2026, in Tokyo).

1. Key Research Findings

◆ Investigated the effects of Rohto's proprietary ingredients, globin protein hydrolysate, milk peptides, and soy peptides, on cellular functions related to enamel formation and maturation, and on cell proliferation and differentiation related to salivary gland activation.

◆ Confirmed that globin protein hydrolysate, milk peptides, and soy peptides are involved in cellular functions related to tooth enamel formation and maturation.

◆ Observed changes related to cell proliferation and differentiation involved in salivary gland activation with milk peptides and soy peptides.

◆ Suggested the potential application of Rohto Group's proprietary ingredients to the oral functional development of children and future measures against oral frailty.

2. Background of the Research

In recent years, changes in diet and living environments have drawn attention to the societal issue of underdeveloped or insufficient oral functions in children. Functions such as chewing, swallowing, pronunciation, and maintaining the oral environment through saliva are crucial elements deeply connected to future dietary habits and health maintenance. Focusing on the societal issue of children's oral functions, we conducted basic research related to tooth development and salivary gland function as a research theme to protect future food and health.

Enamel is the hard tissue forming the outermost layer of the tooth, supporting masticatory function, protecting teeth from external stimuli and physical damage, and contributing to dental aesthetics. If enamel is not formed normally for any reason, tooth strength and durability decrease, making teeth more susceptible to cavities, chipping, and wear, as well as causing aesthetic problems like tooth discoloration. Various factors can lead to abnormal enamel formation, with dental caries in primary teeth, trauma, and malnutrition being considered factors, particularly for permanent teeth.

Saliva not only prevents oral dryness but also plays a vital role in the remineralization of enamel and dentin, maintaining the balance of oral microflora, and protecting the oral environment. Especially in the oral functional development of children, salivary secretion function is thought to contribute to maintaining a healthy oral environment.

This research was conducted in collaboration with Niigata University with the aim of clarifying the basic mechanisms related to the enamel formation and maturation stages in tooth development and salivary gland development.

3. Results

Result 1: Confirmed the effects of globin protein hydrolysate, milk peptides, and soy peptides on cellular functions related to enamel formation and maturation.

This study focused on the expression patterns and roles of AMP-activated protein kinase (hereinafter, AMPK) in tooth development. AMPK is a factor that regulates cellular energy metabolism and may be involved in tooth morphogenesis and maturation. Therefore, globin protein hydrolysate, milk peptides, and soy peptides were added to a culture system of enamel epithelial stem cells, and their effects on cell proliferation, differentiation, and related gene expression involved in enamel formation and maturation were examined. As a result, in conditions where globin protein hydrolysate, milk peptides, and soy peptides with AMPK expression-promoting activity were added, an acceleration of cell proliferation in enamel epithelial stem cells involved in enamel formation was confirmed. For milk peptides and soy peptides, an increasing trend in gene expression related to the promotion of differentiation and maturation of ameloblasts (amelogenin (ameloblast differentiation marker), KLK4 (ameloblast maturation marker)) was observed.

Figure 1: Enamel Epithelial Stem Cell Proliferation Test Results (Excerpt from research results conducted by Niigata University)

<Test Method>

Globin protein hydrolysate, milk peptides, and soy peptides were added to enamel epithelial stem cells, and a cell proliferation test (CCK-8 assay: n=4, t-test *p<0.05) was performed as an evaluation related to enamel formation and maturation.

◎ Cell Proliferation Test (CCK-8 assay: n=4, t-test *p<0.05)

(Conducted by Niigata University)

Result 2: Confirmed the cell proliferation-promoting effect related to salivary gland activation by milk peptides and soy peptides.

Using epithelial cells derived from salivary glands (submandibular glands), changes related to cell proliferation were evaluated as an indicator of the expression of factors related to salivary gland activation by adding milk peptides and soy peptides. As a result, a significant cell proliferation-promoting effect was confirmed in cells derived from salivary glands (submandibular glands) with the addition of milk peptides and soy peptides.

Figure 2: Salivary Gland Epithelial Cell Proliferation Test

<Test Method>

Changes related to cell proliferation were evaluated (CCK-8 assay) by adding milk peptides and soy peptides to epithelial cells derived from salivary glands (submandibular glands) (n=5, t-test *p<0.05, **p<0.01)

(Conducted by Niigata University)

4. Future Prospects

These research findings indicate the potential of Rohto Group's proprietary ingredients, globin protein hydrolysate, milk peptides, and soy peptides, in tooth formation, and milk peptides and soy peptides in salivary gland activation.

The school age is a particularly important period for the transition from deciduous to permanent teeth and the development of oral functions. Creating an oral environment that supports tooth formation and saliva secretion during this period leads to the foundation for future health. Furthermore, beyond the growth period, expansion to a wide range of life stages is expected, including maintaining oral functions in adulthood, preventing age-related decline in oral functions, and addressing oral frailty in old age.

As the importance of oral care throughout life stages, from children to the elderly, increases, we aim to explore the new value of Rohto Group's proprietary ingredients, accumulate scientific evidence through multifaceted verification, and establish our unique oral theory and apply it to products for a wide range of life stages.

Glossary

・Globin Protein Hydrolysate A material held by Rohto Group company MG Pharma. A peptide material obtained by decomposing globin protein contained in hemoglobin, etc., using enzymes. It is being researched as a functional material in the food and health fields.

・Milk-Derived Hydrolyzed Peptides (Milk Peptides) A material held by Rohto Pharmaceutical. Raw material developed in 2009. It contains numerous peptides (chains of approximately 2 to 50 amino acids), and peptides are thought to have significant potential for health maintenance due to their biological regulatory effects.

・Hydrolyzed Soy Peptides (Soy Peptides) Hydrolyzed soy peptides obtained by enzymatic hydrolysis of "soybeans," a functional ingredient independently developed by our company.

・AMPK Abbreviation for AMP-activated protein kinase. An enzyme that senses the energy status within cells and regulates metabolism. It is known as an important factor involved in energy metabolism and the maintenance of cell function.

・Enamel A hard tissue covering the surface of the tooth. It is said to be the hardest tissue in the body and plays a role in protecting teeth from external stimuli and wear.

・Oral Frailty A condition where oral functions such as chewing, swallowing, and speaking decline due to aging, etc. It is known to be related to overall frailty and health status.

Special Notes

A portion of these research findings was presented orally at the 131st Annual Meeting of the Japanese Association of Anatomists (to be held from March 24 to 26, 2026, in Tokyo).

Title: Expression and Function of AMP-activated Protein Kinase (AMPK) in Tooth Development

○ Hiroko Yoda1, Yuki Ohno1,2, Sachiko Naka3, Kotaro Yamada3, Hayato Oshima1

1Graduate School of Medical and Dental Sciences, Niigata University, Department of Hard Tissue Morphology; 2Graduate School of Medical and Dental Sciences, Niigata University, Department of Otorhinolaryngology-Head and Neck Surgery; 3Rohto Pharmaceutical Co., Ltd.

Title: AMP-activated Protein Kinase (AMPK) Activation Promotes Salivary Gland Development

○ Yuki Ohno1,2, Sachiko Naka3, Kotaro Yamada3, Shusuke Oshima1,2, Yushi Ueki1, Shin Horii1, Hayato Oshima2, Hiroko Yoda2

1Department of Otorhinolaryngology-Head and Neck Surgery, Graduate School of Medical and Dental Sciences, Niigata University; 2Department of Hard Tissue Morphology, Graduate School of Medical and Dental Sciences, Niigata University; 3Rohto Pharmaceutical Co., Ltd.