Grupo de Investigación en Productos de Importancia Biológica (GIPIB), Universidad de Nariño, San Juan de Pasto, Nariño 1175, Colombia.
Food Colour and Quality Laboratory, Área de Nutrición y Bromatología, Facultad de Farmacia, Universidad de Sevilla, 41012 Sevilla, Spain.
Molecules. 2024 May 3;29(9):2116. doi: 10.3390/molecules29092116.
The availability of pure individual betalains in sufficient quantities which permit deeper understanding is still a challenge. This study investigates the high-yielding semisynthesis of betaxanthins using betalamic acid from a natural source (), followed by condensation with ʟ-amino acids and further purification. Moreover, the color stability of the four synthesized individual betaxanthins, namely proline (ʟ-ProBX), alanine (ʟ-AlaBX), leucine (ʟ-LeuBX), and phenylalanine (ʟ-PheBX) betaxanthins, was investigated at different pHs. Their relative contribution to free radical scavenging was also scrutinized by TEAC and DPPH. ʟ-AlaBX and ʟ-LeuBx showed a significantly ( < 0.05) higher antioxidant activity, whereas ʟ-ProBX was the most resistant to the hydrolysis of betaxanthin and hence the least susceptible to color change. The color stability was strongly influenced by pH, with the color of ʟ-ProBX, ʟ-LeuBX, and ʟ-AlaBX at pH 6 being more stable, probably due to the easier hydrolysis under acid conditions. The semisynthesis and purification allowed us to have available remarkable quantities of pure individual betaxanthins of for the first time, and to establish their color properties and antioxidant capacity. This study could be a step forward in the development of the best natural food colorant formulation, based on the betalain structure, which is of special interest in food technology.
纯个体甜菜碱在足够数量下的可用性，这使其能够得到更深入的理解，仍然是一个挑战。本研究使用天然来源的甜菜醛氨酸（）进行高产量半合成甜菜黄素，然后与 ʟ-氨基酸缩合，再进一步纯化。此外，还研究了四种合成的个体甜菜黄素，即脯氨酸（ʟ-ProBX）、丙氨酸（ʟ-AlaBX）、亮氨酸（ʟ-LeuBX）和苯丙氨酸（ʟ-PheBX）甜菜黄素，在不同 pH 值下的颜色稳定性。还通过 TEAC 和 DPPH 仔细研究了它们对自由基清除的相对贡献。ʟ-AlaBX 和 ʟ-LeuBx 表现出显著（<0.05）更高的抗氧化活性，而 ʟ-ProBX 对甜菜碱水解的抵抗力最强，因此对颜色变化的敏感性最低。颜色稳定性受 pH 值的强烈影响，在 pH 值为 6 时，ʟ-ProBX、ʟ-LeuBX 和 ʟ-AlaBX 的颜色更稳定，这可能是由于在酸性条件下更容易水解。半合成和纯化使我们能够首次获得大量纯个体甜菜黄素，并确定它们的颜色特性和抗氧化能力。这项研究可能是基于甜菜碱结构开发最佳天然食用色素配方的一个步骤，这在食品技术中具有特殊意义。
