Lutein

Lutein is a yellow-orange xanthophyll carotenoid found in plants and algae. It contributes to light harvesting and protects photosynthetic cells from excess light and oxidative damage.

Xanthophyll cycle: A set of interconversions among xanthophyll pigments that helps plants dissipate excess absorbed light as heat. Lutein works alongside cycle pigments in photoprotection, though it is not itself a cycle intermediate.
Xanthophyll: An oxygen-containing carotenoid pigment found in plants, algae, and some microorganisms. Lutein belongs to this carotenoid subgroup.
Macular pigment: A yellow pigment in the central retina composed mainly of lutein, zeaxanthin, and meso-zeaxanthin. Lutein is one of the principal dietary components of this retinal pigment.
Zeaxanthin: A xanthophyll carotenoid found in plants and concentrated with lutein in the central retina. It resembles lutein chemically but occupies a distinct role in retinal pigment and photoprotection.
Non-photochemical quenching: The dissipation of excess excitation energy as heat rather than its use in photosynthesis. Lutein supports energy dissipation within photosynthetic antenna complexes.
Carotene: A carotenoid composed only of carbon and hydrogen, such as beta-carotene. Unlike carotenes, lutein contains oxygen-bearing groups.
Age-related macular degeneration: A progressive disorder of the central retina that can impair detailed vision in older adults. Lutein supplementation has been studied as a way to support retinal health in people at risk.
Beta-carotene: An orange carotenoid that serves as a provitamin A and occurs in plants and other organisms. It is a carotenoid alternative that lacks lutein's oxygen atoms and retinal distribution.
Photosystem II: A protein-pigment complex that uses light energy to extract electrons from water during photosynthesis. Lutein helps stabilize pigment-protein complexes associated with light capture.
Conjugated system: A sequence of alternating single and multiple bonds that allows electrons to be delocalized across a molecule. Lutein's conjugated bonds absorb visible light and give it its yellow-orange color.

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