title: Boosting antioxidants by lipophilization: a strategy to increase cell uptake and target mitochondria.
abstract: OBJECTIVE
  To explore the possibility to boost phenolic antioxidants through their structural modification by lipophilization and check the influence of such covalent modification on cellular uptake and mitochondria targeting.
  
  
  METHODS
  Rosmarinic acid was lipophilized by various aliphatic chain lengths (butyl, octyl, decyl, dodecyl, hexadecyl, and octadecyl) to give rosmarinate alkyl esters which were then evaluated for their ability (i) to reduce the level of reactive oxygen species (ROS) using 2',7'-dichlorodihydrofluorescein diacetate probe, (ii) to cross fibroblast cell membranes using confocal microscopy, and (iii) to target mitochondria using MitoTracker® Red CMXRos.
  
  
  RESULTS
  Increasing the chain length led to an improvement of the antioxidant activity until a threshold is reached for medium chain (10 carbon atoms) and beyond which lengthening resulted in a decrease of activity. This nonlinear phenomenon-also known as the cut-off effect-is discussed here in connection to the previously similar results observed in emulsified, liposomal, and cellular systems. Moreover, butyl, octyl, and decyl rosmarinates passed through the membranes in less than 15 min, whereas longer esters did not cross membranes and formed extracellular aggregates. Besides cell uptake, alkyl chain length also determined the subcellular localization of esters: mitochondria for medium chains esters, cytosol for short chains and extracellular media for longer chains.
  
  
  CONCLUSIONS
  The localization of antioxidants within mitochondria, the major site and target of ROS, conferred an advantage to medium chain rosmarinates compared to both short and long chains. In conjunction with changes in cellular uptake, this result may explain the observed decrease of antioxidant activity when lengthening the lipid chain of esters. This brings a proof-of-concept that grafting medium chain allows the design of mitochondriotropic antioxidants.
authors.affiliation: CIRAD, UMR Ingénierie des Agropolymères et Technologies Emergentes, Montpellier 34398, France.
authors.forename: Christelle
authors.initials: C
authors.lastname: Bayrasy
authors.forename: Béatrice
authors.initials: B
authors.lastname: Chabi
authors.forename: Mickaël
authors.initials: M
authors.lastname: Laguerre
authors.forename: Jérôme
authors.initials: J
authors.lastname: Lecomte
authors.forename: Elodie
authors.initials: E
authors.lastname: Jublanc
authors.forename: Pierre
authors.initials: P
authors.lastname: Villeneuve
authors.forename: Chantal
authors.initials: C
authors.lastname: Wrutniak-Cabello
authors.forename: Gérard
authors.initials: G
authors.lastname: Cabello
mesh_terms: D000975:Antioxidants / Q000737:chemistry* / Q000493:pharmacokinetics* / Q000494:pharmacology; D002460:Cell Line; D002934:Cinnamates / Q000737:chemistry* / Q000493:pharmacokinetics* / Q000494:pharmacology; D053630:Depsides / Q000737:chemistry* / Q000493:pharmacokinetics* / Q000494:pharmacology; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D008055:Lipids / Q000737:chemistry; D008928:Mitochondria / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000037:antagonists & inhibitors / Q000378:metabolism; D000097123:Rosmarinic Acid
chemical_list: D000975:Antioxidants; D002934:Cinnamates; D053630:Depsides; D008055:Lipids; D017382:Reactive Oxygen Species; D000097123:Rosmarinic Acid