Data for “Oxidative stress is inhibited by plant-based supplements: a quantitative lipidomic analysis of antioxidant activity and lipid compositional change”

Raw data obtained by ultra-high pressure liquid chromatography–mass spectrometry, and processed lipid compositional data are presented alongside detailed methodology. Data were obtained as bovine liver lipid extract oxidizes, initiated by 2,2′-Azobis(2-amidinopropane) dihydrochloride, at 0, 6 and 24 h post initiation. Lipid oxidation data in the presence and absence of some supplements with antioxidant properties was obtained. The supplements used were grape seed extract, pine bark extract, milk thistle extract, hawthorn extract and turmeric extract.


Specifications
Omics: Lipidomics Specific subject area Lipidomics data quantifying the oxidation of bovine liver lipids in the presence of supplements with possible antioxidant properties Type of data Raw mzXML files Tables  How the data were acquired Data were acquired using ultra-high performance liquid chromatography (Ultimate 30 0 0, ThermoScientific) coupled with mass spectrometry (hybrid quadrupole Orbitrap mass spectrometer, Q Exactive, ThermoScientific

Value of the Data
• These data record the changing lipid profile of a complex lipid mixture as it undergoes oxidation and the effect of 5 plant extract supplements on lipid oxidation. 15 lipid classes and the absolute amounts of 378 individual lipids were quantified. • Researchers with an interest in oxidative stress and antioxidant plant extracts will benefit from these data. • Analyzed data can be used to parameterize mechanistic models of lipid oxidation and inhibitors of lipid oxidation. • Raw data can be reanalyzed in the future as the field of oxidative lipidomics develops.
• The methodology developed can be used to quantify the antioxidant effects of other compounds.

Objective
This dataset provides raw HPLC-MS/MS data [1] and quantitative lipid amounts of a targeted lipidomic analysis, which revealed 378 individual lipids and 15 lipid classes in a bovine liver lipid mixture undergoing oxidative stress. Numerical values of the PC: PE ratio and double bond index (DBI) are also provided. These data support of our recent publication [2] where the inhibitory effects of five plant-based supplements were investigated. This data-in-brief article adds to the existing publication by providing the scientific community with both the raw HPLC-MS/MS data and the processed numerical lipidomics data, used to generate the plots in our publication. Making this data freely available facilitates subsequent reanalysis.

Data Description
Data presented are the absolute amounts of the individual quantified lipids and their chemical identities obtained as a bovine liver lipid extract is oxidized using the peroxidation agent 2,2 -Azobis(2-amidinopropane) dihydrochloride (AAPH). The antioxidant effect of five different plant extract supplements formed the basis of the experiment, which contrasts lipid oxidation in the presence of these to a control, no supplement, dataset. These data support a recent publication [2] where the possible antioxidant properties of supplements derived from plant extracts were measured using a targeted lipidomics approach. The motivation for the research was to understand how oxidative stress impacts membrane lipid composition [3] , collective membrane physical properties [4] and any ameliorating properties of dietary supplements in this context. Using lipidomics with complex lipid mixtures allows the isolated effects of lipid oxidation to be elucidated away from the lipid homeostatic responses of cells, which is particularly interesting since lipids are associated with many cellular processes and organelles through lipid protein or lipid DNA interactions [3 , 5 , 6] .
Raw mass spectrometry files have been deposited at Mendeley Data [1] . The data presented in tables herein are the analyzed output of a bioinformatic association of chromatographic features obtained using HPLC/MS to a library of lipid molecules and their fragmentation pathways. Proteowizard [7] , Mzmine [8 , 9] and Lipidex [10] software were used process the raw files, identify chromatographic features and make lipid identifications. This process led to the identification of 15 lipid classes. Fig. 1 shows a general scheme for the experimental process, data collection, bioinformatic analysis and data treatment.

Experimental Design, Materials and Methods
The following materials and methods were used throughout the study as described in full in our recent publication [2] , a brief summary of the aspects key to using the data presented follows.

Bioinformatic Association of Chromatographic Features with Lipid Identities
Thermofisher raw format (.raw) file were converted to mzXML files using MSConvert (Proteowizard) [7] , using 64 bit binary encoding precision, write index and TPP compatibility settings. Filtering was performed using the peak picking 'Vendor' algorithm at MS level 1. Lipid identities were assigned using Lipidex software [10] , using the Lipidex_HCD_Formic, Lipidex_HCD_Hydroxy, Lipidex_HCD_Plants, Lipidex_HCD_ULCFA and Lipidex_Splash_ISTD_Formic spectral libraries, using the spectral searching parameters specified previously [2] . HPLC alignment files were generated using MZMine [8] , whereby Thermofisher raw format (.raw) files were imported to MZMine and features were detected using the settings identified in our previous publication [2] .

Experimental Design: Lipid Oxidation Assays
Liposomes were prepared in amber HPLC vials from 40 μL of bovine polar lipid extract and 10 μL of plant extract solution (1 mg/mL in methanol). After drying under nitrogen, water (200 μL) was added, and samples were vortexed to mix and lyophilized overnight. Dry lipid films were hydrated with buffer (169 μL, 0.1 M Trizma, pH 7.2, Sigma Aldrich) and resuspended by vortexing (10 min) and rested (20 min) at room temperature. After sonication (20 min) and resting (20 min) 4 freeze thaw cycles were performed. Before use in the oxidation assay liposomes were equilibrated (60 min) at room temperature. No supplement controls were prepared in the same way, omitting the addition of the plant extract solutions at the first step.
Oxidation assays were initiated by mixing equal volumes (typically 169 μL) of liposome solution and AAPH solution (15 mM, in Trizma buffer, 0.1 M, pH 7.2), incubating for 0, 6 and 24 h in a water bath (37 °C). Reactions were terminated by freezing and after thawing 10 μL of samples were removed and lipids were extracted using the Bligh Dyer protocol [13] as described previously [2] .

Ethical Statements
The authors confirm that this research meets all the ethical criteria for publication in Data in Brief. This research does not involve studies with animals or humans and does not require a detailed ethical statement.

Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Data Availability
Raw HPLC-MS/MS data for ' ' Oxidative stress is inhibited by plant-based supplements: a quantitative lipidomic analysis of antioxidant activity and lipid compositional change'' (Original data) (Mendeley Data).