Blue natural pigments are rare, especially among plants. However, flowering species that evolved to attract Hymenoptera pollinators are colored by blue anthocyanin-metal complexes. Plants lacking anthocyanins are pigmented by betalains but are unable to produce blue hues. By extending the π-system of betalains, we designed a photostable and metal-free blue dye named BeetBlue that did not show toxicity to human hepatic and retinal pigment epithelial cells and does not affect zebrafish embryonal development. This chiral dye can be conveniently synthesized from betalamic acid obtained from hydrolyzed red beetroot juice or by enzymatic oxidation of l-dopa. BeetBlue is blue in the solid form and in solution of acidified polar molecular solvents, including water. Its capacity to dye natural matrices makes BeetBlue the prototype of a new class of low-cost bioinspired chromophores suitable for a myriad of applications requiring a blue hue.

蓝色天然色素很少见，尤其是在植物中。然而，进化成吸引膜翅目昆虫传粉者的开花物种被蓝色的花青素-金属配合物着色。缺少花色素苷的植物被甜菜碱着色，但不能产生蓝色。通过扩展betalains的π系统，我们设计了一种名为BeetBlue的光稳定且不含金属的蓝色染料，该染料不显示对人肝和视网膜色素上皮细胞的毒性，并且不影响斑马鱼的胚胎发育。此手性染料可以从水解红甜菜根汁或者通过酶促氧化得到betalamic酸来方便地合成升-多巴 BeetBlue是蓝色，呈固体形式，在酸化的极性分子溶剂（包括水）的溶液中呈蓝色。BeetBlue具有对天然基质染色的能力，因此成为新型低成本生物启发发色团的原型，适用于多种需要蓝色调的应用。