Key Laboratory of Advanced Light Conversion Materials and Biophotonics, Department of Chemistry, Renmin University of China, Beijing 100872, China.
Department of Food Science, University of Copenhagen, Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark.
Biophys Chem. 2022 Jun;285:106807. doi: 10.1016/j.bpc.2022.106807. Epub 2022 Mar 23.
The present work is intended to investigate the morphological instability of lipid membrane induced by peroxyl radical (ROO) and the underlying mechanism. To this end, the giant unilamellar vesicle (GUV) made from phosphatidylcholine was employed as a membrane model, and the azo compounds 2,2'-azobis(2,4-dimethylvaleronitrile) (AMVN) and 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) were used as the precursors of ROO. Upon mild pyrolysis, the GUV immobilized in agarose gel was followed by conventional optical microscopy in real time, and the morphological variation was quantified by the image heterogeneity, perimeter and area all as a function of time for up to an hour. Lipid oxidation initiated from lipid phase with AMVN and from aqueous phase with AAPH led to different types of morphological changes, i.e. membrane coarsening and vesicle deformation/budding, respectively. Based on the compositional analysis of lipid oxidation products, we propose that ROO as the primary radical initiator is responsible for the morphological changes of the GUV-AMVN while both ROO and RO are responsible for the morphological changes of the GUV-AAPH system. Lipophilic β-carotene and amphipathic plant phenols as antioxidants are found to be able to stabilize the membrane integrity effectively, in corroboration with the proposed mechanisms for membrane destruction.
本工作旨在研究过氧自由基（ROO）诱导的脂质膜的形态不稳定性及其潜在机制。为此，采用由磷脂制成的巨大单层囊泡（GUV）作为膜模型，并用偶氮化合物 2,2'-偶氮双（2,4-二甲基戊腈）（AMVN）和 2,2'-偶氮双（2-脒基丙烷）二盐酸盐（AAPH）作为 ROO 的前体。在温和热解后，通过传统的光学显微镜实时跟踪固定在琼脂糖凝胶中的 GUV，并通过图像异质性、周长和面积随时间的变化来定量形态变化，最长可达 1 小时。从 AMVN 的脂质相和从 AAPH 的水相引发的脂质氧化导致不同类型的形态变化，即膜粗化和囊泡变形/出芽。基于脂质氧化产物的组成分析，我们提出 ROO 作为主要自由基引发剂负责 GUV-AMVN 的形态变化，而 ROO 和 RO 都负责 GUV-AAPH 系统的形态变化。亲脂性β-胡萝卜素和两亲性植物酚作为抗氧化剂被发现能够有效地稳定膜完整性，与提出的膜破坏机制相符。
