title: Bioavailability of selenium from the selenotrisulphide derivative of lipoic acid.
abstract: OBJECTIVE
  Selenium is a required micronutrient in mammals, needed for the activity of enzymes that contain selenocysteine at their active site. Several isoenzymes of glutathione peroxidase and thioredoxin reductase contain selenocysteine and thus the nutritional status of selenium in tissues can have significant impact on the steady state level of reactive oxygen species. The aims of this study were to evaluate the bioavailability of selenium derived from the selenotrisulfide derivative of lipoic acid (LASe) and determine the ability of this compound to be absorbed into skin.
  
  
  METHODS
  Bioavailability of selenium derived from LASe was determined using a keratinocyte cell model (HaCat). Efficiency of utilization of selenium was assessed by following the decrease in the incorporation of radiolabeled selenite (75Se) in the presence of increasing concentration of selenium compounds. Percutaneous absorption of LASe was measured by determining selenium levels in full thickness biopsy of skin using a Yorkshire pig model.
  
  
  RESULTS
  LASe was efficiently absorbed topically into pig skin, a good model of human skin. In a keratinocyte cell line LASe was an efficient source of selenium for selenoprotein synthesis, demonstrating that LASe is a good candidate as a topical selenium micronutrient. Both L-selenomethionine and selenate were found to be poor sources of selenium for selenoprotein synthesis in the skin cell model and L-selenomethionine was poorly absorbed into pig skin.
  
  
  CONCLUSIONS
  These results indicate that stable selenotrisulfides, such as LASe, are good candidates for testing as topical selenium supplements.
authors.affiliation: Department of Molecular Biology and Microbiology, Burnett College of Biomedical Sciences, University of Central Florida, Orlando, FL, USA.
authors.forename: Melenie
authors.initials: M
authors.lastname: Alonis
authors.forename: Sheldon
authors.initials: S
authors.lastname: Pinnell
authors.forename: William T
authors.initials: WT
authors.lastname: Self
mesh_terms: D000279:Administration, Cutaneous; D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage / Q000493:pharmacokinetics; D001682:Biological Availability; D006801:Humans; D015603:Keratinocytes / Q000187:drug effects / Q000378:metabolism*; D023421:Models, Animal; D011829:Radiation Dosage; D018036:Selenium Compounds / Q000008:administration & dosage / Q000493:pharmacokinetics*; D012644:Selenium Radioisotopes / Q000008:administration & dosage / Q000493:pharmacokinetics*; D012867:Skin / Q000378:metabolism*; D013440:Sulfides / Q000008:administration & dosage / Q000493:pharmacokinetics*; D013552:Swine; D008063:Thioctic Acid / Q000008:administration & dosage / Q000493:pharmacokinetics; D014466:Ultraviolet Rays
chemical_list: D000975:Antioxidants; D018036:Selenium Compounds; D012644:Selenium Radioisotopes; D013440:Sulfides; C059755:selenotrisulfide; D008063:Thioctic Acid