Natural Pigments in Phytochemistry: A Review of Extraction Strategies and Functional Potentials of Curcumin, Anthocyanins, and Related Compounds

The resurgence of interest in plant-based compounds has intensified the search for eco-friendly, multifunctional alternatives to synthetic colorants in various industries. Among these, curcumin, the principal curcuminoid derived from Curcuma longa, stands out due to its vivid yellow color and diverse biological activities, including antioxidant, antimicrobial, and anti-inflammatory effects. However, its industrial applicability is constrained by poor aqueous solubility, limited photothermal stability, and low bioavailability. This comprehensive review critically evaluates curcumin alongside other major natural pigments, anthocyanins, betalains, and carotenoids, highlighting their comparative phytochemical profiles, extraction methods, stability parameters, and functional potentials. Both conventional and advanced green extraction techniques, such as ultrasound-assisted, microwave-assisted, and supercritical fluid extraction, are discussed in relation to pigment yield, efficiency, and environmental impact. Furthermore, recent developments in encapsulation strategies and delivery systems aimed at improving pigment stability and bioactivity are explored. The review emphasizes the need for standardized protocols, regulatory harmonization, and interdisciplinary collaboration to facilitate the integration of natural colorants into scalable industrial systems. Future directions for synergistic pigment formulations and smart packaging applications are also outlined.