Exploring natural colorants from plants to insects: chemistry, functions, and modern uses

Natural pigments and dyes provide a rich interface between biodiversity and chemistry, offering structurally diverse molecules with distinctive reactivity and bioorganic relevance. These compounds occur in plants, marine organisms, fungi, bacteria, insects, birds, animals, and mineral sources. They encompass major chemical classes such as carotenoids, tetrapyrroles and their degradation products. Owing to their biocompatibility and natural origin, these pigments are increasingly explored as safer alternatives to synthetic dyes and as functional ingredients in food, cosmetic, textile, and pharmaceutical applications. In recent years, these natural pigments have gained significant attention as bioactive molecules with antioxidant, anti-inflammatory, antimicrobial, antiviral, anticancer, neuroprotective, hepatoprotective, and immunomodulatory potential, exhibiting beneficial effects in preventing chronic disorders like diabetes, cardiovascular and degenerative eye diseases. This review provides an integrated examination of biodiversity, chemical classes, biosynthetic logic, structure-activity relationships, and biological properties of these natural pigments and dyes. Key challenges related to chemical stability, bioavailability, and scalable production are discussed, together with emerging biotechnological strategies designed to enhance their stability and sustainable supply.