title: Assessment of the potential skin irritation of lysine-derivative anionic surfactants using mouse fibroblasts and human keratinocytes as an alternative to animal testing.
abstract: OBJECTIVE
  The aim of this study was to identify new surfactants with low skin irritant properties for use in pharmaceutical and cosmetic formulations, employing cell culture as an alternative method to in vivo testing. In addition, we sought to establish whether potential cytotoxic properties were related to the size of the counterions bound to the surfactants.
  
  
  METHODS
  Cytotoxicity was assessed in the mouse fibroblast cell line 3T6 and the human keratinocyte cell line NCTC 2544 using the MTT assay and uptake of the vital dye neutral red 24 h after dosing (NRU).
  
  
  RESULTS
  Lysine-derivative surfactants showed higher IC50s than did commercial anionic irritant compounds such as sodium dodecyl sulfate, proving to be no more harmful than amphoteric betaines. The aggressiveness of the surfactants depended on the size of their constituent counterions: surfactants associated with lighter counterions showed a proportionally higher aggressivity than those with heavier ones.
  
  
  CONCLUSIONS
  Synthetic lysine-derivative anionic surfactants are less irritant than commercial surfactants such as sodium dodecyl sulfate and hexadecyltrimethylammonium bromide and are similar to betaines. These surfactants may offer promising applications in pharmaceutical and cosmetic preparations, representing a potential alternative to commercial anionic surfactants as a result of their low irritancy potential.
authors.affiliation: Dept. Fisiologia, Facultat de Farmàcia, Universitat de Barcelona, Spain.
authors.forename: L
authors.initials: L
authors.lastname: Sanchez
authors.forename: M
authors.initials: M
authors.lastname: Mitjans
authors.forename: M R
authors.initials: MR
authors.lastname: Infante
authors.forename: M P
authors.initials: MP
authors.lastname: Vinardell
mesh_terms: D000826:Animal Testing Alternatives / Q000379:methods*; D000818:Animals; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D005347:Fibroblasts / Q000187:drug effects*; D006801:Humans; D015603:Keratinocytes / Q000187:drug effects*; D008239:Lysine / Q000737:chemistry; D051379:Mice; D015394:Molecular Structure; D012867:Skin / Q000187:drug effects*; D013501:Surface-Active Agents / Q000737:chemistry* / Q000633:toxicity*
chemical_list: D013501:Surface-Active Agents; D008239:Lysine