Ethyl oleate

Ethyl acetate, ethyl 2-methylpropionate, propyl acetate, ethyl propionate, ethyl butyrate, isobutyl acetate, ethyl 2-methylbutyrate, ethyl 3-methyl butyrate, isoamyl acetate, ethyl valerate, butyl butyrate, ethyl hexanoate, isoamyl butyrate, propyl hexanoate, ethyl heptanoate, ethyl lactate, 3-methylbutyl hexanoate, propyl octanoate, ethyl nonanoate, hexyl hexanoate, ethyl 2-furoate, ethyl caprate, ethyl benzoate, ethyl phenylacetate, ethyl laurate, ethyl 3-phenylpropanoate, ethyl tetradecanoate, ethyl pentadecanoate, ethyl palmitate, ethyl oleate, and linoleic acid ethyl ester were obtained from Sigma-Aldrich (Shanghai, China). The internal standard (IS) was 2-octanol (Sigma-Aldrich, Shanghai, China). The linear retention index (RI) was determined with a C7–C30 n-alkane mixture (Sigma-Aldrich, Shanghai, China). All of the reagents used were of analytical grade with a purity of at least 97%, and most with a purity exceeding 99%. A Milli-Q purification system provided pure water (Millipore, Bedford, MA, USA). Sodium chloride (analytical grade) and absolute ethanol (analytical grade) were obtained from Sino-pharm Chemical Reagent Co., Ltd (Shanghai, China).

Fatty acids composition was determined by gas chromatography–mass spectrometry (GC-MS) as previously reported [64 (link)] with some modifications. Briefly, total lipids were extracted from isolated HDL and the fatty acids were esterified using anhydrous benzene/methanol solution (1:1, v/v) and concentrated sulfuric acid. The esterified fatty acids were extracted with hexane and it was evaporated with a flow of N₂. Five µl of ethyl oleate (1:50 in hexane as internal control, Sigma-Aldrich, St Louis, MO, USA) and 15 µl of hexane were added to the esterified fatty acids samples and 0.8 µl were injected into the chromatograph. Fatty acids were separated and analyzed in a Hewlett Packard 5972 GC-MS system using the following conditions: capillary column coated with polyethylene glycol (30 m length, 0.32 mm diameter, and 0.5 µm film thickness, HP-INNOWAX 19091N-213, Hewlett Packard, Palo Alto, CA, USA), helium as a mobile phase (pressure 244 kPa), split flow at 15 mL/min, temperature of injector at 240 °C, detector at 260 °C, oven initial temperature at 170 °C, and final temperature 260 °C, and a total run time of 21 min. The conditions were standardized with a commercially available mixture of fatty acids methyl esters SUPELCO FAME MIX GLC-10, GLC-20 and GLC-50 (Sigma-Aldrich, St Louis, MO, USA).

A total of 66 commercial standards (analytical reagent grade, ≥97% purity) were used. Ethyl acetate, acetic acid, Ethyl lactate, 1-propanol, acetal, acetaldehyde, 3-methyl butanol, furfural, ethyl palmitate, isobutanol, methanol, 3-methylbutyraldehyde, ethyl butyrate, ethyl propionate, meso-2,3-butanediol, butyrate, 1-butanol, (2R,3R)-(-)-2,3-butanediol, 2-butanol, hexanoic acid, ethyl hexanoate, 3-hydroxy-2-butanone, ethyl isovalerate, furfuryl alcohol, isobutyric acid, hexyl hexanoate, ethyl valerate, 1-hexanol, propionic acid, acetone, ethyl laurate, 2-methylbutyraldehyde, isoamyl acetate, 2-butanone, ethyl isobutyrate, ethyl phenylacetate, nonanoic acid, propyl acetate, isobutyraldehyde, ethyl octanoate, 1,1-diethoxy-2-methylbutane, ethyl linoleate, valeric acid, ethyl oleate, ethyl heptanoate, ethyl formate, phenylethyl alcohol, ethyl hexadecenoate, 1-pentanol, ethyl tetradecanoate, diethyloxymethane, 2-pentanone, 2-methyl butanol, isovaleric acid, ethyl nonanoate, 2-pentanol, 1,1-diethoxy-3-methylbutane, benzaldehyde, ethyl decanoate, heptanoic acid, octanoic acid, 2-ethoxy-5-methylfuran, 1-propanal, butyl hexanoate, ethyl phenylpropionate, and benzyl alcohol were purchased from Sigma-Aldrich (Shanghai, China).

Ethyl palmitate, ethyl palmitoleate, ethyl stearate, ethyl oleate, methyl nonadecanoate, 1-oleoyl-rac-glycerol, trioleoylglycerol, Orlistat (tetrahydrolipstatin), and phenylmethylsulfonyl fluoride (PMSF) were obtained from Sigma. Cholesteryl oleate was obtained from Avanti Polar Lipids (Alabaster, AL). Palmitic acid (9,10-³H(N)) and 1-palmitoyl rac-[1-¹⁴C]glycerol were obtained from American Radiolabeled Chemicals, Inc. (St. Louis, MO). Palmitic acid (1-¹⁴C) and oleic acid (1-¹⁴C) were obtained from Moravek Biochemicals (Brea, CA). Monoacylglycerol (MAG) lipase inhibitor JZL-184 was obtained from Abcam (Cambridge, UK).