Limonoids, a novel type of inhibitors of sphingomyelin biosynthesis to study the membrane dynamics of sphingolipid domains

鞘脂是形成膜脂双层以及细胞生长、凋亡和炎症的重要细胞组分。使用选择性高通量显微镜为基础的筛选，我们最近分离的天然化合物，Limestone作为新的抑制剂类型的鞘磷脂，在真核细胞膜中的主要鞘脂的生物合成。为了更精确地描述它们的治疗特性，我们建立了实验条件来分析它们对各种鞘脂依赖性事件的影响：1）通过柠檬苦素Gedunin预处理调节鞘脂含量，提高了一些抗癌药物的效率（阿霉素，但不是紫杉醇）在HeLa细胞; 2）鞘脂-Gedunin预处理细胞可抑制疟原虫在红细胞内和弓形虫在HeLa细胞内的依赖性生长但其本身具有毒性作用; 3）由于Limestone有利于在膜中形成富含神经酰胺的结构域，我们试图在体外用神经酰胺的新型巯基类似物分析单层囊泡中的神经酰胺跨双层运动; 4）鞘磷脂的膜分布对于控制如二酰基甘油跨双层运动的各种事件是重要的。

Sphingolipids are important cell components for the formation of membrane lipid bilayers as well as for cell growth, apoptosis and inflammation. Using a selective high-throughput microscopy-based screening, we recently isolated natural compounds, Limonoids as new inhibitor type of the biosynthesis of sphingomyelin, the major sphingolipid in eukaryotic membranes. In order to precise their therapeutic properties, we set up the experimental conditions to analyze their effects on various sphingolipid-dependent events: 1) modulation of sphingolipid content by limonoid Gedunin pretreatment improved the efficiency of some anticancer drugs (doxorubicin but not Paclitaxel) in HeLa cells; 2) sphingolipid-dependent growth of Plasmodium malaria parasite in erythrocytes and Toxoplasma parasite in HeLa cells was decreased by limonoid Gedunin pretreatment of the cells but had a toxic effect by itself; 3) since Limonoids favored the formation of ceramide-rich domains in the membrane, we tried to analyse the ceramide transbilayer movement in vitro in unilamellar vesicles with new type of sulhydryl analogs of ceramides; 4) the membrane distribution of sphingomyelin is important to control various events as diacylglycerol transbilayer movement .