title: Eucalyptus increases ceramide levels in keratinocytes and improves stratum corneum function.
abstract: The objectives of this study were to identify a plant extract that would improve stratum corneum functions and to elucidate the mechanism(s) involved. Based on the information that stratum corneum functions depend on the level of ceramide in the stratum corneum, we identified a Eucalyptus extract that was able to increase the level of ceramide in human keratinocytes in culture and in human stratum corneum and that improves the stratum corneum water holding and barrier functions. Addition of the Eucalyptus extract to human keratinocytes in culture increased the level of ceramide in a dose-dependent manner and also increased the biosynthesis of ceramide, glucosylceramide and sphingomyelin. Topical application of the Eucalyptus extract on the dry skin of human subjects induced by acetone and diethylether treatment resulted in a significant increase in ceramide level in the stratum corneum, a significant improvement in its water-holding function and an improvement in its barrier function. The addition of macrocarpal A, one of the main components of the Eucalyptus extract, to human keratinocytes in culture increased the level of ceramide and the mRNA expression of serine palmitoyltransferase, acid sphingomyelinase, neutral sphingomyelinase, glucosylceramide synthase and glucocerebrosidase in a dose-dependent manner. Our results indicate that the increased content of ceramides in the stratum corneum may underlie the therapeutic effect of the Eucalyptus extract. Our results also indicate the possibility that macrocarpal A is the key component that stimulates the synthesis of ceramide in the stratum corneum.
authors.affiliation: Biological Science Laboratory, Kao Corporation, 2606 Akabane, Ichikai-machi, Haga, Tochigi 321-3497, Japan. ishikawa.junko1@kao.co.jp
authors.forename: J
authors.initials: J
authors.lastname: Ishikawa
authors.forename: Y
authors.initials: Y
authors.lastname: Shimotoyodome
authors.forename: S
authors.initials: S
authors.lastname: Chen
authors.forename: K
authors.initials: K
authors.lastname: Ohkubo
authors.forename: Y
authors.initials: Y
authors.lastname: Takagi
authors.forename: T
authors.initials: T
authors.lastname: Fujimura
authors.forename: T
authors.initials: T
authors.lastname: Kitahara
authors.forename: Y
authors.initials: Y
authors.lastname: Takema
mesh_terms: D000287:Administration, Topical; D000328:Adult; D002518:Ceramides / Q000096:biosynthesis* / Q000235:genetics; D004311:Double-Blind Method; D005052:Eucalyptus / Q000737:chemistry*; D005260:Female; D006801:Humans; D015603:Keratinocytes / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D010696:Phloroglucinol / Q000008:administration & dosage / Q000031:analogs & derivatives*; D010936:Plant Extracts / Q000008:administration & dosage* / Q000302:isolation & purification; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D012717:Sesquiterpenes / Q000008:administration & dosage*; D012867:Skin / Q000187:drug effects* / Q000378:metabolism; D014870:Water Loss, Insensible / Q000187:drug effects; D055815:Young Adult
chemical_list: D002518:Ceramides; D010936:Plant Extracts; D012333:RNA, Messenger; D012717:Sesquiterpenes; C518771:macrocarpal A; D010696:Phloroglucinol