School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA.
Sustainable Aquatics, 110 W. Old Andrew Johnson Highway, Jefferson City, TN 37760, USA.
Nutrients. 2022 Apr 6;14(7):1522. doi: 10.3390/nu14071522.
Astaxanthin (ASX) is a natural product and one of the most powerful antioxidants known. It has significant effects on the metabolism of many animals, increasing fecundity, egg yolk volume, growth rates, immune responses, and disease resistance. A large part of the bioactivity of ASX is due to its targeting of mitochondria, where it inserts itself into cell membranes. Here, ASX stabilizes membranes and acts as a powerful antioxidant, protecting mitochondria from damage by reactive oxygen species (ROS). ROS are ubiquitous by-products of energy metabolism that must be tightly regulated by cells, lest they bind to and inactivate proteins, DNA and RNA, lipids, and signaling molecules. Most animals cannot synthesize ASX, so they need to acquire it in their diet. ASX is easily thermally denatured during extraction, and its high hydrophobicity limits its bioavailability. Our focus in this review is to contrast the bioactivity of different ASX stereoisomers and how extraction methods can denature ASX, compromising its bioavailability and bioactivity. We discuss the commercial sources of astaxanthin, structure of stereoisomers, relative bioavailability and bioactivity of ASX stereoisomers, mechanisms of ASX bioactivity, evolution of carotenoids, and why mitochondrial targeting makes ASX such an effective antioxidant.
虾青素（ASX）是一种天然产物，也是已知的最强大的抗氧化剂之一。它对许多动物的新陈代谢有显著影响，可提高繁殖力、蛋黄体积、生长速度、免疫反应和抗病能力。ASX 的大部分生物活性归因于其对线粒体的靶向作用，它会插入细胞膜。在这里，ASX 稳定膜并作为一种强大的抗氧化剂，保护线粒体免受活性氧（ROS）的损伤。ROS 是能量代谢的普遍副产物，细胞必须对其进行严格调控，以免它们与蛋白质、DNA 和 RNA、脂质和信号分子结合并使其失活。大多数动物不能合成 ASX，因此它们需要从饮食中获取。在提取过程中，ASX 很容易受热变性，其高疏水性限制了其生物利用度。我们在这篇综述中的重点是对比不同 ASX 立体异构体的生物活性，以及提取方法如何使 ASX 变性，从而降低其生物利用度和生物活性。我们讨论了虾青素的商业来源、立体异构体的结构、ASX 立体异构体的相对生物利用度和生物活性、ASX 生物活性的机制、类胡萝卜素的进化，以及为什么线粒体靶向使 ASX 成为如此有效的抗氧化剂。
