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Caption : fig. s1 optimization of chromatographic conditions. (a-c) the comparison of separation of long chain phospholipids analyzed by traditional c18, shield rp18 and c8 columns， respectively. (d-e) the comparison of separation of target metabolites between using two different ionic modifiers.
different columns including traditional c18 (acquity c18, 2.1×100 mm, 1.7 μm), shield rp18 (acquity beh shield rp18, 2.1×100 mm, 1.7 μm) and c8 (acquity beh shield c8, 2.1×100 mm, 1.7 μm) were evaluated. the results showed that some long chain phospholipids such as pc 20:0-20:0 and cholesterol compounds were difficult to be eluted from c18 column, and the peak shape of metabolites in rp18 column and c8 column were better than those in c18 column. c8 column tended to provide the best detection effect for most analytes within the shortest analysis time. adding ionic modifier to mobile phase can improve separation effect of oxysterols and bas. 0.02% fa and 20 mmol l-1 nh4cooh were used as ionic modifiers, and the results showed that 20 mmol l-1 nh4cooh (ph =6.4) provided a better separation effect and a higher ionization efficiency of target metabolites. 


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Caption : fig.s2 the extraction efficiency of different extraction methods and solvent systems in plasma (a-c) comparison of lle, lle-lipid and pp extraction methods for target metabolites, (d-f) comparison of 13 extraction solvent system for target metabolites, (g) extraction efficiency of directly injection and sample concentration, (h) extraction efficiency of solvent with or without adding antioxidant bht.

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Caption : fig. s3 extracted ion chromatograms of target metabolites in (a) mouse plasma samples with positive electrospray ionization mode (esi+), (b) mouse plasma samples with negative electrospray ionization mode (esi-), (c) mouse liver tissue with positive electrospray ionization mode (esi+), (d) mouse liver tissue with negative electrospray ionization mode (esi-)
oxysterols and low abundance pls were detected in esi+ mode, and eas, bas, lpls and high abundance pls were detected in esi- mode in this method.


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Caption : fig.s4 expression of lpcat1, cpla2, p-cpla2, spla2-ⅱa in mouse liver tissue. 
mouse liver tissues were fixed in 10% neutralized formalin for 6 h to prepare the paraffin-embedded sections. immunohistochemical staining was performed to locate the expressions of indicated proteins; original magnification: ×100. for each slice, the percentages of positive cells were counted within 5 medium-power magnification fields of view (10×objective lens) under microscope. the results were determined by scoring the stained cell ratio and the staining intensity; *p<0.05 and **p<0.01.