title: Oxylipins, endocannabinoids, and related compounds in human milk: Levels and effects of storage conditions.
abstract: The presence of fatty acid derived oxylipins, endocannabinoids and related compounds in human milk may be of importance to the infant. Presently, clinically relevant protocols for storing and handling human milk that minimize error and variability in oxylipin and endocannabinoid concentrations are lacking. In this study, we compared the individual and combined effects of the following storage conditions on the stability of these fatty acid metabolites in human milk: state (fresh or frozen), storage temperature (4 °C, -20 °C or -80 °C), and duration (1 day, 1 week or 3 months). Thirteen endocannabinoids and related compounds, as well as 37 oxylipins were analyzed simultaneously by liquid chromatography coupled to tandem mass spectrometry. Twelve endocannabinoids and related compounds (2-111 nM) and 31 oxylipins (1.2 pM-1242 nM) were detected, with highest levels being found for 2-arachidonoylglycerol and 17(R)hydroxydocosahexaenoic acid, respectively. The concentrations of most endocannabinoid-related compounds and oxylipins were dependent on storage condition, and especially storage at 4 °C introduced significant variability. Our findings suggest that human milk samples should be analyzed immediately after, or within one day of collection (if stored at 4 °C). Storage at -80 °C is required for long-term preservation, and storage at -20 °C is acceptable for no more than one week. These findings provide a protocol for investigating the oxylipin and endocannabinoid metabolome in human milk, useful for future milk-related clinical studies.
authors.affiliation: Department of Chemistry, Umeå University, 901 87 Umeå, Sweden. Electronic address: junfang.wu@umu.se.
authors.forename: Junfang
authors.initials: J
authors.lastname: Wu
authors.affiliation: Department of Chemistry, Umeå University, 901 87 Umeå, Sweden; Department of Pharmacology and Clinical Neuroscience, Umeå University, 901 87 Umeå, Sweden. Electronic address: sandra.gouveia@umu.se.
authors.forename: Sandra
authors.initials: S
authors.lastname: Gouveia-Figueira
authors.affiliation: Department of Clinical Sciences, Umeå University, 901 87 Umeå, Sweden. Electronic address: magnus.domellof@umu.se.
authors.forename: Magnus
authors.initials: M
authors.lastname: Domellöf
authors.affiliation: Department of Nutrition, University of California, Davis, CA 95616, USA; Foods for Health Institute, University of California, Davis, CA 95616, USA. Electronic address: amzivkovic@ucdavis.edu.
authors.forename: Angela M
authors.initials: AM
authors.lastname: Zivkovic
authors.affiliation: Department of Chemistry, Umeå University, 901 87 Umeå, Sweden. Electronic address: malin.nording@umu.se.
authors.forename: Malin L
authors.initials: ML
authors.lastname: Nording
mesh_terms: D002853:Chromatography, Liquid / Q000379:methods; D003080:Cold Temperature; D063388:Endocannabinoids / Q000032:analysis* / Q000378:metabolism; D005227:Fatty Acids / Q000032:analysis* / Q000378:metabolism; D061353:Food Storage / Q000379:methods*; D005615:Freezing; D006801:Humans; D008895:Milk, Human / Q000737:chemistry*; D054883:Oxylipins / Q000032:analysis* / Q000378:metabolism; D053719:Tandem Mass Spectrometry / Q000379:methods; D013997:Time Factors
chemical_list: D063388:Endocannabinoids; D005227:Fatty Acids; D054883:Oxylipins
keywords: Eicosanoids; Endocannabinoids; Human milk; LC–MS/MS; Quantitative