皮膚角層は皮膚のバリアー機能や水分保持機能において重要な役割を果たしている。角層は角層細胞と細胞間脂質で構成されているが,とくに細胞間脂質はこれらの機能を主として担っている。そのような観点から細胞間脂質集合体がつくる構造を明らかにすることは重要な課題である。われわれは小角広角X線回折像の温度依存性の測定と示差走査熱測定を行い,それら結果を解析することにより,二つのラメラ周期構造と二つの炭化水素鎖の充てんの間の関係を明らかにした。それに基づき,化粧料や経皮吸収剤の開発の応用研究を分子レベルで展開できると考えている。
Stratum corneum which is composed of corneocytes and intercellular lipid matrix plays an important role in barrier function and maintenance of water in skin. The intercellular lipid matrix bears the main part in the function. Therefore, it is important to make clear the structure formed by the intercellular lipids. It is well-known from X-ray diffraction, electron diffraction, neutron scattering, etc. that the structure consists of long and short lamellar structures and in the orthogonal direction hexagonal and orthorhombic hydrocarbon-chain packings. However, until now the relation between each lamellar structure and each hydrocarbon-chain packing has been unresolved. From the thermal analysis and the temperature scanning small- and wide-angle X-ray diffraction analysis in stratum corneum, we revealed that there are two domains: One is the long lamellar structure with the hexagonal hydrocarbon-chain packing and the other the short lamellar structure with the orthorhombic hydrocarbon-chain packing. Based upon the structural evidence we can further study the functional mechanism of cosmetics, the drug penetration mechanism, etc.
Keywords:stratum corneum; thermal analysis; X-ray diffraction; lipid; lamellar