Petersen R C, Reddy M S, Liu P-R
Departments of Biomaterials and Restorative Sciences, University of Alabama at Birmingham, USA.
Office of the Dean, School of Dentistry, University of Alabama at Birmingham, USA.
SF J Biotechnol Biomed Eng. 2018;1(1). Epub 2018 Feb 21.
Unsaturated carbon-carbon double bonds particularly at exposed end groups of nonsolid fluids are susceptible to free-radical covalent bonding on one carbon atom creating a new free radical on the opposite carbon atom. Subsequent reactive secondary sequence free-radical polymerization can then continue across extensive carbon-carbon double bonds to form progressively larger molecules with ever-increasing viscosity and eventually produce solids. In a fluid solution when carbon-carbon double bonds are replaced by carbon-carbon single bonds to decrease fluidity, increasing molecular organization can interfere with molecular oxygen (O) diffusion. During normal eukaryote cellular energy synthesis O is required by mitochondria to combine with electrons from the electron transport chain and hydrogen cations from the proton gradient to form water. When O is absent during periods of irregular hypoxia in mitochondrial energy synthesis, the generation of excess electrons can develop free radicals or excess protons can produce acid. Free radicals formed by limited O can damage lipids and proteins and greatly increase molecular sizes in growing vicious cycles to reduce oxygen availability even more for mitochondria during energy synthesis. Further, at adequate free-radical concentrations a reactive crosslinking unsaturated aldehyde lipid breakdown product can significantly support free-radical polymerization of lipid oils into rubbery gel-like solids and eventually even produce a crystalline lipid peroxidation with the double bond of O. Most importantly, free-radical inhibitor hydroquinone intended for medical treatments in much pathology such as cancer, atherosclerosis, diabetes, infection/inflammation and also ageing has proven extremely effective in sequestering free radicals to prevent chain-growth reactive secondary sequence polymerization.
不饱和碳 - 碳双键,特别是在非固体流体的暴露端基处,易受自由基共价键作用,一个碳原子上形成共价键,而在相对的碳原子上产生一个新的自由基。随后,活性二级序列自由基聚合反应可以沿着大量的碳 - 碳双键继续进行,形成分子越来越大、粘度不断增加的物质,最终产生固体。在流体溶液中,当碳 - 碳双键被碳 - 碳单键取代以降低流动性时,分子排列的增加会干扰分子氧(O)的扩散。在正常真核细胞能量合成过程中,线粒体需要O与电子传递链中的电子以及质子梯度中的氢阳离子结合形成水。在线粒体能量合成过程中,当在不规则缺氧期间缺乏O时,过量电子的产生会形成自由基,或者过量质子会产生酸。有限的O形成的自由基会损害脂质和蛋白质,并在不断升级的恶性循环中大幅增加分子大小,从而在能量合成过程中进一步降低线粒体的氧气供应。此外,在足够的自由基浓度下,一种具有反应性的交联不饱和醛脂质分解产物可以显著促进脂质油自由基聚合成橡胶状凝胶状固体,最终甚至产生具有O双键的结晶脂质过氧化产物。最重要的是,用于癌症、动脉粥样硬化、糖尿病、感染/炎症以及衰老等多种病理状况医学治疗的自由基抑制剂对苯二酚,已被证明在螯合自由基以防止链增长反应二级序列聚合方面极为有效。