CPIA-cholesterol ester

Similarly, in other mouse tissues and also in rat tissues, the presence of CPIA-cholesterol ester was demonstrated following administration of the Ba isomer or fenvalerate. Thus, CPIA-cholesterol ester proves now to be a novel type of conjugate which is more lipophilic than the parent compound and CPIA. 

Figure 9. Purification and identification of [2R]-CPIA-cholesterol ester.

Similarly, to demonstrate the presence of CPIA-cholesterol ester in the phagocytes, histochemical staining of cholesterol esters was performed on the same liver used for the... 

Finally, the enzymatic nature of CPIA-cholesterol ester formation will be briefly mentioned. None of the enzyme preparations of three known biosynthetic pathways for cholesterol esters, namely, acyl-CoA cholesterol Q-acyltransferase (ACAT), lecithin cholesterol 0-acyltransferase (LCAT), nor cholesterol esterase, was effective in producing CPIA-cholesterol ester from the Ba isomer or CPIA. In contrast, the 9,000 g supernatant or microsomal fractions from liver or kidney homogenate were found to be capable of producing CPIA-cholesterol ester without the addition of any cofactors. As substrate, only the Ba isomer was effective, and none of the 3 other fenvalerate isomers nor free CPIA was effective. The hepatic enzyme preparation also catalyzed hydrolysis of fenvalerate, and in this case all the 4 isomers were utilized as substrates. These facts imply that CPIA-cholesterol ester is formed from the Ba isomer through a transesterification reaction via intermediary acyl-enzyme complex. 

The enzyme activity responsible for CPIA-cholesterol ester formation is distributed in several tissues of animal species including rats, mice, dogs and monkeys, as shown in Table VI. No tissue enzymes were found to react with the Aa, a6 or b6 isomer. 

Figure 11. Microscopic autoradiography of liver of a mouse treated with tritium labelled CPIA-cholesterol (X540) 5 weeks after single intravenous injection of ca. 30 mg/kg of 3-H-[2R]-CPIA-cholesterol ester. 3-H label is localized in Kupffer cells (arrow and giant cells (long arrows).

Table VI. CPIA-Cholesterol Ester Formation from the Btx Isomer...

Tissues of CPIA-cholesterol ester relative to applied 14-C ... 

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