Institute for Bioscience and Biotechnology Research, Fischell Department of Bioengineering, University of Maryland , College Park, Maryland 20742, United States.
Biomacromolecules. 2014 May 12;15(5):1653-62. doi: 10.1021/bm500026x. Epub 2014 Apr 8.
Macromolecular phenolics are among the most abundant organic molecules in nature, yet their biological activities are largely unresolved because of their structural complexity and because of an inability to probe their functionality experimentally. We developed thin film and electrochemical methodologies to probe the redox properties of melanin, lignin, and humic acid, three of the most abundant phenolic materials. We observed that all three phenolic matrixes possess redox activity and can be repeatedly switched between oxidized and reduced states. Furthermore, we observed that melanin possesses pro-oxidant activities exemplified by the uncatalyzed generation of reactive oxygen species (ROS) upon exposure to air; however, this pro-oxidant activity is observed only for melanin films that are poised in their reduced state. Conversely, melanin's antioxidant radical-scavenging activities are insensitive to its redox state. These results demonstrate that natural phenolic matrixes are not inert but rather serve as open-source redox media with significant potential for impacting redox signaling and redox biology.
高分子酚类物质是自然界中最丰富的有机分子之一，但由于其结构复杂性以及无法通过实验探测其功能，它们的生物活性在很大程度上仍未得到解决。我们开发了薄膜和电化学方法来探测黑色素、木质素和腐殖酸这三种最丰富的酚类物质的氧化还原性质。我们观察到所有三种酚基质都具有氧化还原活性，并且可以在氧化和还原状态之间反复切换。此外，我们观察到黑色素具有促氧化剂活性，例如在暴露于空气中时会无催化剂地生成活性氧物种 (ROS)；然而，这种促氧化剂活性仅在处于还原状态的黑色素膜中观察到。相反，黑色素的抗氧化自由基清除活性对其氧化还原状态不敏感。这些结果表明，天然酚基质并非惰性物质，而是作为开源氧化还原介质，具有显著影响氧化还原信号和氧化还原生物学的潜力。
