title: Distribution of Tocopherols and Tocotrienols in Guinea Pig Tissues Following Parenteral Lipid Emulsion Infusion.
abstract: Tocopherols and tocotrienols possess vitamin E activity and function as the major lipid-soluble antioxidants in the human body. Commercial lipid emulsions are composed of different oils and supply different amounts of vitamin E. The objective of this study was to measure all 8 vitamin E homologs within 4 different commercial lipid emulsions and evaluate their distribution in guinea pig tissues.
  
  
  
  The distribution of vitamin E homologs within plasma and guinea pig tissues was determined using a high-performance liquid chromatography (HPLC) system. Lipid hydroperoxides in lipid emulsions were determined using a commercial kit (Cayman Chemical Company, Ann Arbor, MI), and malondialdehyde tissue levels were determined using an HPLC system.
  
  
  
  The lipid emulsions contained variable amounts of tocopherols, which were significantly different between emulsions. Tocotrienols were present at very low concentrations (≤0.3%). We found no correlation between the amount of vitamin E present in the lipid emulsions and lipid peroxidation. Hydroperoxides were the lowest with an olive oil-based emulsion and highest with a fish oil emulsion. The predominant vitamin E homolog in guinea pig tissues was α-tocopherol. No tissues had detectable levels of tocotrienols. Vitamin E levels (primarily α-tocopherol and γ-tocopherol) were highly variable among organ tissues. Plasma levels were a poor reflection of most tissue levels.
  
  
  
  Vitamin E levels within different lipid emulsions and plasma/tissues are highly variable, and no one tissue or plasma sample serves as a good proxy for levels in other tissues. All study emulsions were well tolerated and did not significantly increase systemic lipid peroxidation.
authors.affiliation: Cellular Biochemistry Laboratory, Methodist Research Institute, Indiana University Health, Indianapolis, Indiana.
authors.forename: Zhidong
authors.initials: Z
authors.lastname: Xu
authors.affiliation: Cellular Biochemistry Laboratory, Methodist Research Institute, Indiana University Health, Indianapolis, Indiana.
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Harvey
authors.affiliation: Baxter Healthcare Corporation, Deerfield, Illinois.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Pavlina
authors.affiliation: Baxter Healthcare Corporation, Deerfield, Illinois.
authors.forename: Gary P
authors.initials: GP
authors.lastname: Zaloga
authors.affiliation: Cellular Biochemistry Laboratory, Methodist Research Institute, Indiana University Health, Indianapolis, Indiana Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana rsiddiqu@iuhealth.org.
authors.forename: Rafat A
authors.initials: RA
authors.lastname: Siddiqui
mesh_terms: D000818:Animals; D000975:Antioxidants; D005217:Fat Emulsions, Intravenous / Q000008:administration & dosage* / Q000032:analysis; D005395:Fish Oils; D006168:Guinea Pigs; D015227:Lipid Peroxidation; D000069463:Olive Oil; D010288:Parenteral Nutrition; D014018:Tissue Distribution; D024505:Tocopherols / Q000032:analysis / Q000097:blood / Q000493:pharmacokinetics*; D024508:Tocotrienols / Q000032:analysis / Q000493:pharmacokinetics*; D024502:alpha-Tocopherol / Q000032:analysis / Q000097:blood
chemical_list: D000975:Antioxidants; D005217:Fat Emulsions, Intravenous; D005395:Fish Oils; D000069463:Olive Oil; D024508:Tocotrienols; D024502:alpha-Tocopherol; D024505:Tocopherols
keywords: lipid emulsions; lipid peroxidation; tissues; tocopherol; tocotrienol; vitamin E