Division of Applied Bioscience, Research Faculty of Agriculture, Hokkaido University, Kita-9 Nishi-9, Kita-ku, Sapporo 0608589, Japan.
Graduate School of Agriculture, Hokkaido University, Kita-9 Nishi-9, Kita-ku, Sapporo 0608589, Japan.
Int J Mol Sci. 2023 Oct 21;24(20):15411. doi: 10.3390/ijms242015411.
Reactive oxygen species and reactive nitrogen species (RNS) are damaging for many biomolecules. Peroxynitrite (ONOO) is the most toxic molecular species among RNS. Betalains are known to possess ONOO scavenging ability. Betanin, a betalain isolated from red beet, possesses antioxidant, anti-inflammatory, and antitumor activities; however, detailed studies of this isolated pigment have not been conducted, owing to its instability under physiological conditions. This study aimed to isolate highly purified betanin from red beetroots using an improved purification method involving deproteinization and citric acid co-precipitation and evaluated its antioxidant activities. The purified betanin thus obtained had a significantly lower isobetanin content than the commercially available betanin dyes. The antioxidant activity of purified betanin examined in the 2,2-diphenyl-1-picrylhydrazyl assay, the direct ONOO reaction, ONOO-dependent DNA damage, and lipid peroxidation reactions revealed that betanin possessed higher antioxidant capacity than general antioxidants such as ascorbic acid and quercetin. Furthermore, betanin showed indirect and direct cytoprotective effects against HO and ONOO cytotoxicity, respectively, in cultured mouse fibroblasts. To the best of our knowledge, this is the first study to demonstrate the cytoprotective effects of betanin against ONOO toxicity. The highly purified betanin obtained in this study will aid in further exploring its physiological functions.
活性氧（ROS）和活性氮（RNS）会对许多生物分子造成损害。过氧亚硝酸盐（ONOO）是 RNS 中最具毒性的分子种类。甜菜红素已知具有清除 ONOO 的能力。甜菜红是从红甜菜中分离出的一种甜菜红素，具有抗氧化、抗炎和抗肿瘤活性；然而，由于其在生理条件下不稳定，对这种分离出的色素尚未进行详细研究。本研究旨在使用改良的蛋白质沉淀和柠檬酸共沉淀法从红甜菜中分离出高度纯化的甜菜红素，并评估其抗氧化活性。与市售的甜菜红素染料相比，由此获得的纯化甜菜红素的异甜菜红素含量显著降低。在 2,2-二苯基-1-苦基肼测定法、直接 ONOO 反应、ONOO 依赖性 DNA 损伤和脂质过氧化反应中，对纯化甜菜红素的抗氧化活性进行了检测，结果表明，甜菜红素的抗氧化能力强于抗坏血酸和槲皮素等一般抗氧化剂。此外，甜菜红素对培养的小鼠成纤维细胞中的 HO 和 ONOO 细胞毒性分别表现出间接和直接的细胞保护作用。据我们所知，这是首次证明甜菜红素具有对抗 ONOO 毒性的细胞保护作用的研究。本研究获得的高度纯化的甜菜红素将有助于进一步探索其生理功能。
