Christian A E, Byun H S, Zhong N, Wanunu M, Marti T, Fürer A, Diederich F, Bittman R, Rothblat G H
Department of Biochemistry, MCP Hahnemann University School of Medicine, Philadelphia, PA 19129, USA.
J Lipid Res. 1999 Aug;40(8):1475-82.
Previous studies from this laboratory have demonstrated that low concentrations of cyclodextrins (<1.0 mm), when added to serum, act catalytically as cholesterol shuttles to accelerate the exchange of free cholesterol between cells and serum lipoproteins. As cholesterol shuttles, cyclodextrins have the potential to serve as pharmacological agents for modifying cholesterol metabolism. In the present study, we have quantitated the cholesterol-shuttling capacity of a series of newly synthesized beta-cyclodextrin derivatives (betaCDs), with varying structure, and two double-decker cyclophanes. The general protocol is as follows. [(3)H]cholesterol-labeled CHOK1 cells are incubated for 2 h with the test compounds alone or together with 5% human serum, and efflux of the cellular [(3)H]cholesterol is measured. As methyl beta-cyclodextrin (MbetaCD) served as the basis for comparison, initial experiments were conducted that demonstrated there was a dose-dependent stimulation of cell cholesterol efflux as the concentration of MbetaCD increased, with an EC(50) that was calculated to be 0.05 mm. To determine the cholesterol-shuttling capacity of the newly synthesized compounds, cell cholesterol efflux is measured when the compounds are present alone, at a concentration of 0.05 mm, or together with 5% human serum. Our results demonstrate that the double-decker cyclophanes are the most efficient cholesterol shuttles. Under our experimental conditions, methyl beta-cyclodextrin (MbetaCD) approximately doubles the efflux of cell cholesterol to serum, whereas one of the double-decker cyclophanes produces a 4-fold stimulation in efflux. Four of the beta-cyclodextrin derivatives (betaCDs) display shuttling ability similar to that of MbetaCD. Furthermore, there does not appear to be a structural pattern among the other betaCDs which could explain their shuttling capacity.
本实验室先前的研究表明，低浓度的环糊精（<1.0 mM）添加到血清中时，可作为胆固醇穿梭剂发挥催化作用，加速细胞与血清脂蛋白之间游离胆固醇的交换。作为胆固醇穿梭剂，环糊精有潜力作为调节胆固醇代谢的药物。在本研究中，我们对一系列结构各异的新合成β-环糊精衍生物（βCDs）和两种双环番的胆固醇穿梭能力进行了定量。一般实验方案如下。将[³H]胆固醇标记的CHOK1细胞单独或与5%人血清一起与测试化合物孵育2小时，然后测量细胞内[³H]胆固醇的流出量。以甲基-β-环糊精（MβCD）作为比较基础，初步实验表明，随着MβCD浓度增加，细胞胆固醇流出呈剂量依赖性刺激，计算得出的半数有效浓度（EC₅₀）为0.05 mM。为确定新合成化合物的胆固醇穿梭能力，当化合物单独存在、浓度为0.05 mM或与5%人血清一起存在时，测量细胞胆固醇流出量。我们的结果表明，双环番是最有效的胆固醇穿梭剂。在我们的实验条件下，甲基-β-环糊精（MβCD）使细胞胆固醇向血清的流出量增加约一倍，而其中一种双环番使流出量增加4倍。四种β-环糊精衍生物（βCDs）表现出与MβCD相似的穿梭能力。此外，其他βCDs之间似乎没有能解释其穿梭能力的结构模式。
