Graduate School of Informatics, Nagoya University, Chikusa, Nagoya, 464-8601, Japan.
Graduate School of Information Science, Nagoya University, Chikusa, Nagoya, 464-8601, Japan.
Sci Rep. 2020 Oct 14;10(1):17184. doi: 10.1038/s41598-020-74098-6.
The seed coat of mature black soybean, Glycine max, accumulates a high amount of cyanidin 3-O-glucoside (Cy3G), which is the most abundant anthocyanin in nature. In the pod, it takes two months for the seed coat color change from green to black. However, immature green beans rapidly adopt a black color within one day when the shell is removed. We analyzed the components involved in the color change of the seed coat and detected a new precursor of Cy3G, namely 5,7,3',4'-tetrahydroxyflav-2-en-3-ol 3-O-glucoside (2F3G). Through quantitative analysis using purified and synthetic standard compounds, it was clarified that during this rapid color change, an increase in the Cy3G content was observed along with the corresponding decrease in the 2F3G content. Chemical conversion from 2F3G to Cy3G at pH 5 with air and ferrous ion was observed. Our findings allowed us to propose a new biosynthetic pathway of Cy3G via a colorless glucosylated compound, 2F3G, which was oxidized to give Cy3G.
成熟的黑大豆（Glycine max）种皮积累了大量的矢车菊素 3-O-葡萄糖苷（Cy3G），它是自然界中最丰富的类黄酮。在豆荚中，种皮颜色从绿色变为黑色需要两个月的时间。然而，当壳被去除时，未成熟的绿豆在一天内迅速变成黑色。我们分析了种皮颜色变化涉及的成分，并检测到 Cy3G 的一个新前体，即 5,7,3',4'-四羟基黄酮-2-烯-3-醇 3-O-葡萄糖苷（2F3G）。通过使用纯化和合成的标准化合物进行定量分析，结果表明在这种快速的颜色变化过程中，Cy3G 的含量增加，同时 2F3G 的含量相应减少。在 pH 值为 5 的条件下，在空气中和亚铁离子的存在下，观察到 2F3G 向 Cy3G 的化学转化。我们的发现使我们能够提出一种通过无色葡萄糖苷化化合物 2F3G 合成 Cy3G 的新生物合成途径，该化合物被氧化生成 Cy3G。
