Tocopherol isoforms in parenteral lipid emulsions and neutrophil activation.
OBJECTIVE
Tocopherol is a lipid-soluble anti-oxidant that exists in several isoforms. Patients on total parenteral nutrition depend on lipid emulsions for their tocopherol intake. In the present study, we analysed the content of tocopherol isoforms in various lipid emulsions. We also tested the hypothesis that immune-modulating effects of lipid emulsions could be attributed to different concentrations of alpha-tocopherol (alpha-toc) or peroxidation products.


METHODS
alpha-, beta-, gamma- and delta-toc were measured in emulsions containing long-chain triglycerides (LCT), mixed long- and medium-chain triglycerides (LCT/MCT), structured lipids (SL), olive oil (OO) or fish oil (FO). As a measure for cellular activation, neutrophil membrane adhesion markers were assessed after exposure to two LCT/MCT emulsions that differ only in alpha-toc content.


RESULTS
Various emulsions differed widely in tocopherol contents, especially with respect to the alpha- isoform. The latter isomer also was subject to considerable degradation despite adequate storage conditions. The previously observed activation of neutrophils by LCT/MCT was not influenced by the increased concentration of alpha-toc or the decreased concentration of lipid peroxidation products in a new LCT/MCT emulsion.


CONCLUSIONS
Tocopherol supplementation by parenteral lipid emulsions strongly depends on the lipid source and the storage lifetime of the emulsion. The effects of LCT/MCT on the immune system are not modulated by alpha-toc or by lipid peroxidation products.
Wanten
G
G
Department of Gastroenterology, University Medical Centre Nijmegen, Nijmegen, The Netherlands.
Beunk
J
J
Naber
A
A
Swinkels
D
D
D000328:Adult; D002851:Chromatography, High Pressure Liquid; D005217:Fat Emulsions, Intravenous / Q000378:metabolism*; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D015227:Lipid Peroxidation / Q000502:physiology; D008297:Male; D018375:Neutrophil Activation / Q000502:physiology*; D010288:Parenteral Nutrition; D012016:Reference Values; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism; D024505:Tocopherols / Q000378:metabolism*; D014280:Triglycerides / Q000378:metabolism
D005217:Fat Emulsions, Intravenous; D017392:Thiobarbituric Acid Reactive Substances; D014280:Triglycerides; D024505:Tocopherols