A comprehensive review of eco-friendly extraction and chemistry of anthocyanins with preparation and properties of natural deep eutectic solvents

Natural deep eutectic solvents (NADES) are emerging as eco-friendly, sustainable alternatives to conventional synthetic solvents across various industries. Composed of natural, biodegradable components such as sugars, amino acids, and organic acids, NADES offer a greener approach to extraction and processing. Their unique ability to dissolve both hydrophilic and lipophilic compounds—due to hydrogen bonding and other molecular interactions—makes them highly versatile for applications in pharmaceuticals, food science, cosmetics, and environmental remediation. One of the key advantages of NADES is their tunability. By adjusting the ratios of ingredients or adding water, researchers can tailor their properties to meet specific needs, such as preserving delicate bioactive compounds or enhancing solubility. Numerous studies have demonstrated that NADES-based extractions not only improve yield but also maintain the bioactivity of sensitive plant-derived compounds like antioxidants and flavonoids, while significantly reducing environmental impact. Despite their promise, NADES do present some challenges, particularly their high viscosity, which can hinder extraction efficiency. However, this can often be mitigated by mild heating or dilution. Additionally, variability in performance depending on composition remains a concern, especially for complex environmental tasks like heavy metal removal. Continued research is focused on overcoming these limitations by improving viscosity control and broadening NADES applications in green technologies. As demand grows for cleaner, safer chemical processes, NADES offer a flexible and sustainable solution, representing a key advancement in the movement toward greener, more responsible innovation. In conclusion, the use of NADES for anthocyanin extraction not only enhances recovery yields compared to conventional solvents but also significantly improves the stability and bioavailability of anthocyanins during storage and processing. Comparative studies demonstrate that anthocyanins are more resistant to degradation in NADES than in methanol or ethanol, retaining higher concentrations and bioactivity over time. The review covers NADES chemistry, preparation, properties, customization, applications in green extraction, and challenges with future perspectives.