Church D F, Pryor W A
Environ Health Perspect. 1985 Dec;64:111-26. doi: 10.1289/ehp.8564111.
Cigarette smoke contains two very different populations of free radicals, one in the tar and one in the gas phase. The tar phase contains several relatively stable free radicals; we have identified the principal radical as a quinone/hydroquinone (Q/QH2) complex held in the tarry matrix. We suggest that this Q/QH2 polymer is an active redox system that is capable of reducing molecular oxygen to produce superoxide, eventually leading to hydrogen peroxide and hydroxyl radicals. In addition, we have shown that the principal radical in tar reacts with DNA in vitro, possibly by covalent binding. The gas phase of cigarette smoke contains small oxygen- and carbon-centered radicals that are much more reactive than are the tar-phase radicals. These gas-phase radicals do not arise in the flame, but rather are produced in a steady state by the oxidation of NO to NO2, which then reacts with reactive species in smoke such as isoprene. We suggest that these radicals and the metastable products derived from these radical reactions may be responsible for the inactivation of alpha 1-proteinase inhibitor by fresh smoke. Cigarette smoke oxidizes thiols to disulfides; we suggest the active oxidants are NO and NO2. The effects of smoke on lipid peroxidation are complex, and this is discussed. We also discuss the toxicological implications for the radicals in smoke in terms of a number of radical-mediated disease processes, including emphysema and cancer.
香烟烟雾中含有两类截然不同的自由基，一类存在于焦油中，另一类存在于气相中。焦油相中含有几种相对稳定的自由基；我们已确定主要自由基是一种存在于焦油状基质中的醌/对苯二酚（Q/QH2）复合物。我们认为这种Q/QH2聚合物是一个活性氧化还原系统，能够将分子氧还原以产生超氧化物，最终生成过氧化氢和羟基自由基。此外，我们还表明焦油中的主要自由基在体外会与DNA发生反应，可能是通过共价结合。香烟烟雾的气相中含有以氧和碳为中心的小自由基，它们比焦油相自由基的反应性要强得多。这些气相自由基并非在火焰中产生，而是通过一氧化氮氧化为二氧化氮的稳态过程产生，二氧化氮随后与烟雾中的活性物质如异戊二烯发生反应。我们认为这些自由基以及由这些自由基反应衍生的亚稳态产物可能是导致新鲜烟雾使α1-蛋白酶抑制剂失活的原因。香烟烟雾会将硫醇氧化为二硫化物；我们认为活性氧化剂是一氧化氮和二氧化氮。烟雾对脂质过氧化的影响很复杂，对此将进行讨论。我们还将从包括肺气肿和癌症在内的一些自由基介导的疾病过程方面讨论烟雾中自由基的毒理学意义。
