Abstract：
Natural products are a great resource for physiologically active substances. It is widely recognized that a major percentage of current medications are derived from natural compounds or their synthetic analogues. Triterpenoids are widespread in nature and can prevent cancer formation and progression. Despite considerable interest in these triterpenoids, their interactions with lipid bilayers still need to be thoroughly investigated. The aim of this study is to examine the interactions of lupeol, a pentacyclic triterpenoid, with model membranes composed of 1,2‑dipalmitoyl‑sn‑glycerol‑3‑phosphocholine (DPPC) by using non-invasive techniques such as differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. The DSC study demonstrated that the incorporation of lupeol into DPPC membranes shifts the Lβ\'-to-Pβ\' and Pβ\'-to-Lα phase transitions toward lower values, and a loss of main phase transition cooperativity is observed. The FTIR spectra indicated that the increasing concentration (10 mol%) of lupeol causes an increase in the molecular packing and membrane fluidity. In addition, it is found that lupeol\'s OH group preferentially interacts with the head group region of the DPPC lipid bilayer. These findings provide detailed information on the effect of lupeol on the DPPC head group and the conformation and dynamics of the hydrophobic chains. In conclusion, the effect of lupeol on the structural features of the DPPC membrane, specifically phase transition and lipid packing, has implications for understanding its biological function and its applications in biotechnology and medicine.
摘要：
天然产物是生理活性物质的重要资源。广泛认识到,当前药物的大部分衍生自天然化合物或其合成类似物。三萜类化合物在自然界中广泛存在，可以预防癌症的形成和进展。尽管对这些三萜类化合物有相当大的兴趣，它们与脂质双层的相互作用仍需要彻底研究。这项研究的目的是检查羽扇豆醇的相互作用，五环三萜类化合物，通过使用非侵入性技术，例如差示扫描量热法（DSC）和傅立叶变换红外（FTIR）光谱法，使用由1,2-二棕榈酰-sn-甘油-3-磷酸胆碱（DPPC）组成的模型膜。DSC研究表明，在DPPC膜中掺入羽扇豆醇使Lβ'至Pβ'和Pβ'至Lα相变向较低值移动，并观察到主相变协同性的损失。FTIR光谱表明，羽扇豆醇浓度的增加（10mol％）导致分子填充和膜流动性的增加。此外,发现羽扇豆醇的OH基团优先与DPPC脂质双层的头基区域相互作用。这些发现提供了关于羽扇豆醇对DPPC头部基团的影响以及疏水链的构象和动力学的详细信息。总之,羽扇豆醇对DPPC膜的结构特征的影响，特别是相变和脂质包装，对于理解其生物学功能及其在生物技术和医学中的应用具有重要意义。
