Blood was obtained from normolipidemic volunteers with approval based on the Recommendations of Blood Donation Program to get a Research of the Korea Red Cross Blood Center. After equilibration of the cholesterol pool, the cells were washed with PBS and incubated in RPMI 1640 medium containing 0. Two weeks BSA with or without OAA. Efflux incubations were performed for up to 24 h in 6 well plates. Quantification of intracellular and secreted cholesterol and biliary cholesterol To measure intracellular storage of cholesterol and non GW0742 cholesterol 3 fi hydroxysteroid, macrophages were collected after incubation for 48 h in RPMI 1640 medium with or without 100 fig/ml of acLDL or oleic acid anilide. For quantification of released sterols, the cells were washed extensively with PBS and incubated for an additional 24 h in RPMI 1640 medium with or without OAA. The medium was gathered and centrifuged at 13,000 g for 30 min at 4oC to remove cell debris and detached cells. Some of the cells was assayed for protein utilising the Bio Rad DC protein assay kit, and the amount of cell suspension containing 1 mg of the corresponding method and protein were analyzed for mass Metastatic carcinoma of steroids. FC and TC were quantified by an enzymatic spectrophotometric method after extraction with hexane/isopropyl alcohol, and CE mass was calculated from the difference between the measurements. The mass of 3 fi hydroxysteroid was quantified also by an enzymatic spectrophotometric method after extraction with hexane/isopropyl alcohol, and the mass of biliary cholesterol was determined by subtraction of the mass of FC in the mass of 3fiHS. Neutral lipids deposited in the cells were visualized by staining with oil red O as described. Actual time quantitative reverse transcriptionpolymerase chain reaction Real time quantitative reverse transcription polymerase chain reaction analysis was done to ascertain the expression of genes involved in cholesterol metabolic rate and mobilization in THP 1 macrophages, encoding for apoE, ABCA1, ABCG1, CYP7A1, CYP7B1, CYP27 having a rotor gene 3000. The cells were contact us incubated for 48 h with or without OAA as indicated, in the existence of 100 fig/ml of acLDL. Statistical evaluation was done using Students t test. A value of G 0. 05 was accepted as statistically significant. Unless noted otherwise the experiments were repeated three times. Results OAA inhibited ACAT action in THP 1 macrophages using an IC50 value of 15. 2 fiM, which is a higher price than that from an in vitro assay. OAA showed a moderate permeability in the parallel artificial membrane permeation assay with a Log Pe value of. As the outcome, only 3 fimol of OAA was shown to be able to cross the natural membrane from 100 fimol of OAA in the donor area. For that reason, the reason why OAA exhibits a somewhat lower ACAT inhibition activity within the cell system could be explained by the poor membrane permeability. But there is no doubt that OAA inhibits CE formation in acLDL loaded macrophages.