Agati Giovanni, Brunetti Cecilia, Fini Alessio, Gori Antonella, Guidi Lucia, Landi Marco, Sebastiani Federico, Tattini Massimiliano
Institute of Applied Physics 'Carrara', National Research Council of Italy (CNR), Via Madonna del Piano 10, Sesto F.no, I-50019 Florence, Italy.
Institute for Sustainable Plant Protection, National Research Council of Italy (CNR), Via Madonna del Piano 10, I-50019, Sesto F.no, Florence, Italy.
Antioxidants (Basel). 2020 Nov 9;9(11):1098. doi: 10.3390/antiox9111098.
Whether flavonoids play significant antioxidant roles in plants challenged by photooxidative stress of different origin has been largely debated over the last few decades. A critical review of the pertinent literature and our experimentation as well, based on a free-of-scale approach, support an important antioxidant function served by flavonoids in plants exposed to a wide range of environmental stressors, the significance of which increases with the severity of stress. On the other side, some questions need conclusive answers when the putative antioxidant functions of plant flavonoids are examined at the level of both the whole-cell and cellular organelles. This partly depends upon a conclusive, robust, and unbiased definition of "a plant antioxidant", which is still missing, and the need of considering the subcellular re-organization that occurs in plant cells in response to severe stress conditions. This likely makes our deterministic-based approach unsuitable to unveil the relevance of flavonoids as antioxidants in extremely complex biological systems, such as a plant cell exposed to an ever-changing stressful environment. This still poses open questions about how to measure the occurred antioxidant action of flavonoids. Our reasoning also evidences the need of contemporarily evaluating the changes in key primary and secondary components of the antioxidant defense network imposed by stress events of increasing severity to properly estimate the relevance of the antioxidant functions of flavonoids in an in planta situation. In turn, this calls for an in-depth analysis of the sub-cellular distribution of primary and secondary antioxidants to solve this still intricate matter.
在过去几十年里，黄酮类化合物在受到不同来源的光氧化胁迫挑战的植物中是否发挥重要的抗氧化作用一直存在很大争议。基于无标度方法对相关文献及我们的实验进行的批判性综述表明，黄酮类化合物在遭受多种环境胁迫的植物中发挥着重要的抗氧化功能，且这种功能的重要性会随着胁迫的严重程度而增加。另一方面，当在全细胞和细胞器水平上研究植物黄酮类化合物的假定抗氧化功能时，一些问题需要确凿的答案。这部分取决于对“植物抗氧化剂”的明确、可靠且无偏的定义，而目前仍缺乏这样的定义，同时也需要考虑植物细胞在应对严重胁迫条件时发生的亚细胞重组。这可能使我们基于确定性的方法不适用于揭示黄酮类化合物作为抗氧化剂在极其复杂的生物系统（如暴露于不断变化的胁迫环境中的植物细胞）中的相关性。这仍然引发了关于如何测量黄酮类化合物已发生的抗氧化作用的开放性问题。我们的推理还表明，需要同时评估由日益严重的胁迫事件对抗氧化防御网络的关键初级和次级成分造成的变化，以便在植物体内正确估计黄酮类化合物抗氧化功能的相关性。相应地，这就需要深入分析初级和次级抗氧化剂的亚细胞分布来解决这个仍然错综复杂的问题。
