title: Stearic acid delivery to corneum from a mild and moisturizing cleanser.
abstract: OBJECTIVE
  A mild moisturizing body wash with stearic acid, a key component of corneum lipids, and emollient soybean oil has been introduced in the market place. The objectives of this study are to determine the amount and the location of the stearic acid in the corneum after in vivo cleansing by the formulation.
  
  
  METHODS
  Clinical cleansing studies for one and five consecutive days were carried out with the formulation containing soybean oil or petroleum jelly (PJ). The free stearic acid in it was replaced by the fully deuterated variant. The amounts of stearic acid in 10 consecutive corneum tape strips were measured by liquid chromatograph-mass spectroscopy. Separately, electron paramagnetic resonance (EPR) measurements were taken with a porcine skin after a wash by the soybean oil formulation with its free fatty acid replaced by its spin probe analogue, 5-doxyl stearic acid.
  
  
  RESULTS
  Deuterated stearic acid was detected in all 10 consecutive layers of stratum corneum and the total amount after five washes with the soybean oil formulation was 0.33 μg/cm². The spin probe in cleanser-treated skin was incorporated in a partially ordered hydrophobic region similar to corneum lipids. The probe mobility increased in the temperature region where lipid disorder was expected.
  
  
  CONCLUSIONS
  The estimated total fatty acid delivered to skin from cleansing is comparable to the amount of fatty acid in a corneum layer. The delivered fatty acid is most likely incorporated in the corneum lipid phase.
authors.affiliation: Unilever HPC-NA, Trumbull, CT, USA. surajit.mukherjee@unilever.com
authors.forename: Surajit
authors.initials: S
authors.lastname: Mukherjee
authors.forename: Melody
authors.initials: M
authors.lastname: Edmunds
authors.forename: Xuegong
authors.initials: X
authors.lastname: Lei
authors.forename: Maria Francesca
authors.initials: MF
authors.lastname: Ottaviani
authors.forename: Kavssery P
authors.initials: KP
authors.lastname: Ananthapadmanabhan
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Turro
mesh_terms: D000818:Animals; D001494:Baths; D003497:Cyclic N-Oxides / Q000494:pharmacology; D003902:Detergents / Q000008:administration & dosage / Q000627:therapeutic use*; D016503:Drug Delivery Systems; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D005260:Female; D016037:Single-Blind Method; D012879:Skin Physiological Phenomena / Q000187:drug effects; D013113:Spin Labels; D013229:Stearic Acids / Q000008:administration & dosage / Q000627:therapeutic use*; D013552:Swine
chemical_list: D003497:Cyclic N-Oxides; D003902:Detergents; D013113:Spin Labels; D013229:Stearic Acids; C005072:5-doxylstearic acid; C031183:stearic acid