Neoxanthin

Neoxanthin is a xanthophyll carotenoid found in many photosynthetic organisms, including plants and algae. As a pigment, it contributes to yellow-to-orange coloration and resides in chloroplast thylakoid membranes alongside other carotenoids and chlorophylls. Neoxanthin is formed in the plant carotenoid biosynthetic pathway and is typically produced from violaxanthin through enzyme-catalyzed steps that involve neoxanthin synthase. It can also serve as a substrate in the 9-cis-epoxycarotenoid dioxygenase pathway that generates xanthoxin, a precursor of abscisic acid (ABA), the plant stress hormone.

In plants, neoxanthin participates in light harvesting and photoprotection, helping to dissipate excess energy and mitigate reactive oxygen species. While not the central component of the xanthophyll cycle (which mainly involves violaxanthin, antheraxanthin, and zeaxanthin), neoxanthin contributes to the overall function of carotenoids within the photosystems. It also links to ABA biosynthesis, influencing processes such as seed dormancy and stress responses.

Occurrence and nutrition: Neoxanthin occurs in a wide range of vegetables and fruits, with levels varying by species, developmental stage, and environmental conditions. In foods, it is quantified by chromatographic methods such as high-performance liquid chromatography. Like other carotenoids, its bioavailability in humans depends on dietary fat and the food matrix.

Health relevance: Dietary neoxanthin is part of the broader carotenoid intake associated with antioxidant activity, though specific health effects attributable to neoxanthin alone are not well established, and it is not considered an essential nutrient.