Comparative bioactivity assessment of bixin pigment and associated phytochemicals extracted from annatto seeds using conventional and green solvents

Nutraceuticals, that include food ingredients and bioactives from natural products, confer physiological health benefits and protection against chronic diseases. Annatto is a tropical shrub grown in Central and South America and parts of India. Its seeds are rich in the edible carotenoid-derived apocarotenoid pigment, bixin, which is used as a natural colorant in food, textiles, and cosmetics, and is now gaining attention for its potential health-promoting attributes. Here, we compared a green solvent (ethyl lactate) based extraction of bixin and associated metabolites in annatto seeds (crushed and seed coat) with two other conventional solvents (acetone and acid-base). Bixin was characterized in the extracts using UV-visible- and FTIR-spectroscopy and thin-layer chromatography. The bixin-containing solvent extracts were then profiled for other co-existing metabolites using GC-MS analysis, which were found to be sesquiterpenes, terpenes, terpenoids, phytosterols, and tocotrienols. Their bioactivity was evaluated based on antioxidant and wound-healing efficacies and compared with pure bixin, using NIH-3T3 fibroblast cells in-vitro. Pure bixin, as well as the annatto solvent extracts, showed strong antioxidant and wound healing properties, wherein pure bixin and green solvent extract (ethyl lactate coat) exhibited higher levels of antioxidant activity, achieving 46.00% and 44.60% reduction in MDA levels, respectively, as well as enhanced wound-healing activity, with 54.09% and 53.60% wound closure within 24 h. The green solvent extracts of annatto seeds revealed: (a) differential bioactive profiles in annatto seeds (crushed and seed coat) in comparison with other solvents, and (b) strong antioxidant and wound healing properties. Thus, ethyl lactate extraction shows strong potential for sustainable environmental friendly production of functional foods/nutraceuticals from annatto seeds.