Wang Wenxin, Yang Peiqing, Gao Fuqing, Wang Yongtao, Xu Zhenzhen, Liao Xiaojun
College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China; National Engineering Research Center for Fruit & Vegetable Processing, Beijing, China; Key Laboratory of Fruit & Vegetable Processing, Ministry of Agriculture and Rural Affairs, Beijing, China; Beijing Key Laboratory for Food Non-thermal Processing, Beijing, China.
J Adv Res. 2025 Feb;68:17-29. doi: 10.1016/j.jare.2024.02.018. Epub 2024 Feb 24.
The scarcity of naturally available sources for blue colorants has driven reliance on synthetic alternatives. Nevertheless, growing health concerns have prompted the development of naturally derived blue colorants, which remains challenging with limited success thus far. Anthocyanins (ACNs) are known for providing blue colors in plants, and metal complexation with acylated ACNs remains the primary strategy to generate stable blue hues. However, this approach can be costly and raise concerns regarding potential metal consumption risks.
Our study aims to introduce a metal-free approach to achieve blue coloration in commonly distributed non-acylated 3-glucoside ACNs by exploring their interactions with proteins and unveiling the underlying mechanisms.
Using human serum albumin (HSA) as a model protein, we investigated the structural influences of ACNs on their blue color generation using visible absorption spectroscopy, fluorescence quenching, and molecular simulations. Additionally, we examined the bluing effects of six proteins derived from milk and egg and identified the remarkable roles of bovine serum albumin (BSA) and lysozyme (LYS).
Our findings highlighted the importance of two or more hydroxyl or methoxyl substituents in the B-ring of ACNs for generating blue colors. Cyanidin-, delphinidin- and petunidin-3-glucoside, featuring two neighboring hydroxyl groups in the B-ring, exhibited blue coloration when interacting with HSA or LYS, driven primarily by favorable enthalpy changes. In contrast, malvidin-3-glucoside, with two methoxyl substituents, achieved blue coloration through interactions with HSA or BSA, where entropy change played significant roles.
Our work, for the first time, demonstrates the remarkable capability of widely distributed 3-glucoside ACNs to generate diverse blue shades through interactions with certain proteins. This offers a promising and straightforward strategy for the production of ACN-based blue colorants, stimulating further research in this field.
天然蓝色素来源稀缺，这促使人们依赖合成替代品。然而，对健康问题的日益关注推动了天然衍生蓝色素的开发，到目前为止，这一过程仍然具有挑战性，成效有限。花青素（ACNs）在植物中可呈现蓝色，与酰化ACNs形成金属络合物仍是产生稳定蓝色调的主要策略。然而，这种方法成本高昂，且引发了对潜在金属消耗风险的担忧。
我们的研究旨在引入一种无金属方法，通过探索常见的非酰化3 - 葡萄糖苷ACNs与蛋白质的相互作用并揭示其潜在机制，实现蓝色着色。
以人血清白蛋白（HSA）作为模型蛋白，我们使用可见吸收光谱、荧光猝灭和分子模拟研究了ACNs对其蓝色生成的结构影响。此外，我们检测了六种源自牛奶和鸡蛋的蛋白质的呈蓝效果，并确定了牛血清白蛋白（BSA）和溶菌酶（LYS）的显著作用。
我们的研究结果强调了ACNs的B环中两个或更多羟基或甲氧基取代基对于产生蓝色的重要性。花青素 - 3 - 葡萄糖苷、飞燕草素 - 3 - 葡萄糖苷和矮牵牛素 - 3 - 葡萄糖苷在B环中有两个相邻的羟基，与HSA或LYS相互作用时呈现蓝色，主要由有利的焓变驱动。相比之下，具有两个甲氧基取代基的锦葵色素 - 3 - 葡萄糖苷通过与HSA或BSA相互作用实现蓝色着色，其中熵变起着重要作用。
我们的工作首次证明了广泛分布的3 - 葡萄糖苷ACNs通过与某些蛋白质相互作用产生多种蓝色调的显著能力。这为基于ACN的蓝色素生产提供了一种有前景且直接的策略，激发了该领域的进一步研究。
