Lithocholic acid methyl ester

Lithocholic acid methyl ester] (triterpene) Human animal origin cf. oleanolic acid PKA (rat) (9)... 

Proteasome regulators Lithocholic acid derivatives 3a-0-Pimeloyl-lithocholic acid methyl ester Isosteric isomer... 

FIGURE 14.4 Lithocholic acid methyl ester TMS ether. (A) EI-MS. The [M] ion is at 462, [M-CHs] at 447, [M-TMSOH] at 372, [M-CH3-TMS0]+ at 357, ABCD+ ion at 257, and the ABC ion at 215. (B) GC-APCI-MS profiie. (C) Upper trace GC-APCI-MS and lower trace GC-APCI-MS . The spectrum in (A) was recorded on a singie quadrupole instrument, while (B) and (C) were recorded on a quadrupole time-of-flight (Q-TOF)-type instrument. The MS spectrum was recorded by raising the coiiision energy across the collision ceii but without mass selection. 

With a purified enzyme preparation from Clostridium perfringens, Roovers et al. (36) cleave conjugated bile acids directly in plasma. Proteins are then precipitated with Ba(OH)2-saturated ethanol (123) and the supernatant is taken to near dryness. The residue is dissolved in a toluene-isopropanol-methanol-30 % aqueous NaOH (10 20 20 6, v/v) mixture, water is added, and neutral lipids removed by light petroleum extraction. Bile acids are then obtained by acidification and diethyl ether extraction. The bile acids are then methylated and analyzed as above except that the bile acid methyl esters are acetylated before chromatography on 1 % XE-60 columns at 250°C. With this column the following retention times relative to that of the diacetoxy derivative of methyl deoxycholate were found for the following acetate methyl ester derivatives lithocholic, 0.60 23-nor-deoxycholic acid (internal standard), 0.77 chenodeoxycholic acid, 1.24 and cholic acid, 1.88. The deoxycholic acid derivative was eluted after 9.0 min and methyl 5 3-cholanoate after 0.32 min. 

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