Lipidomic Analysis of Oxidized Fatty Acids in Plant and Algae Oils

Abstract

Linoleic acid (LA) and alpha-linolenic acid (ALA) in plant or algae oils are precursors to oxidized fatty acid metabolites known as oxylipins. Liquid chromatography tandem mass spectrometry was used to quantify oxylipins in soybean, corn, olive, canola and four high-oleic acid algae oils at room temperature or after heating for 10 minutes at 100°C. Flaxseed oil oxylipin concentrations were determined in a follow-up experiment that compared it to soybean, canola, corn and olive oil. Published economic disappearance data for soybean, canola, corn and olive oil were used to estimate daily oxylipin intake. The LA and ALA fatty acid composition of the oils was generally related to their respective oxylipin metabolites, except for olive and flaxseed oil which had higher LA-derived mono-hydroxy and ketone oxylipins than other oils, despite their low LA content. Algae oils had the least amount of oxylipins. The change in oxylipin concentrations was not significantly different amongst the oils after short-term heating. Estimated oxylipin intake from non-heated soybean, canola, corn and olive oil was 1.1 mg per person per day. These findings suggest that oils represent a dietary source of LA- and ALA- derived oxylipins and that the response of oils to short-term heating does not differ amongst the various oils.

The distribution of 4‐hydroxy‐hexenal and 4‐hydroxy‐nonenal in different vegetable oils and their formation from fatty acid methyl esters

“…HHE and HNE detected in fresh vegetable oils were likely formed by enzymatic or nonenzymatic pathways. Enzymatic oxidation is mediated in part by lipoxygenase, which is activated when the barrier integrity of the seed or fruit is compromised by homogenisation during the extraction process (Richardson et al ., ). Nonenzymatic oxidation is inevitable during the refining process of vegetable oils (Cheng et al ., ).…”

Malondialdehyde, 4‐Hydroxy‐2‐Hexenal, and 4‐Hydroxy‐2‐Nonenal in Vegetable Oils: Formation Kinetics and Application as Oxidation Indicators

“…The presence of MDA, HHE, and HNE in fresh vegetable oils was likely due to their formation by enzymatic or nonenzymatic pathways. Enzymatic oxidation is mediated in part by the lipoxygenase enzyme, which is activated when the barrier integrity of the seed or fruit is compromised by homogenization during the extraction process . Nonenzymatic oxidation is inevitable during the refining process of vegetable oils …”

Effects of industrial heat treatments on bovine milk oxylipins and conventional markers of lipid oxidation

“…A targeted lipidomics platform was used to quantify LA and ALA derived oxylipins listed in Supplementary Table 1 [24]. Six hundred µL of milk were weighed and spiked with 10 µL of an antioxidant solution containing 0.2 mg/mL BHT, EDTA, and triphenylphosphine (TPP) in water:methanol (1:1), and 10 µL of a surrogate standard solution containing 2 µM d11-11(12)-EpETrE, d11-11,14-DiHETrE, d4-6-keto-PGF1α, d4-9-HODE, d4-LTB4, d4-PGE2, d4-TXB2, d6-20-HETE and d8-5-HETE (Cayman Chemical, Ann Arbor, MI, USA).…”

“…The pH was confirmed to be between 4 and 6 in one of the samples using litmus paper. Ultrapure water (4725 µL) was added and the samples were centrifuged for 10 min at 388 × g. The supernatant loaded onto Oasis HLB columns (60 mg, 3 cm cartridges; Waters, Milford, MA, USA), pre-washed with one volume of ethyl acetate and two volumes of methanol and conditioned with two volumes of solid phase extraction (SPE) buffer containing 0.1% (v/v) acetic acid and 5% (v/v) methanol in ultrapure water [24,25]. Upon loading the samples, the columns were washed with two volumes of SPE buffer and dried under vacuum for 20 min.…”