Carotenoid

Carotenoids are yellow, orange, and red pigments made by plants, algae, and many microorganisms. They absorb light, protect cells from oxidative damage, and, in some cases, serve as vitamin A precursors.

Terpenes: Terpenes are compounds built from five-carbon isoprene units, common in plants and other organisms. Carotenoids are tetraterpenes assembled from eight isoprene units.
Photoprotection: Photoprotection is the prevention or reduction of damage caused by excessive light exposure. Carotenoids protect photosynthetic machinery from excess absorbed energy.
Beta-carotene: Beta-carotene is an orange carotenoid and a major provitamin A compound in human diets. It is a familiar dietary carotenoid and a precursor of retinal.
Chlorophyll: Chlorophyll is a green magnesium-containing pigment that captures light for photosynthesis. Unlike carotenoids, chlorophyll absorbs strongly in blue and red regions and appears green.
Heinrich Wackenroder: Heinrich Wackenroder was a German pharmacist and chemist who isolated the orange pigment later known as beta-carotene. His nineteenth-century work began the chemical study of carotene pigments.
Conjugated system: A conjugated system is a chain of alternating single and multiple chemical bonds with overlapping p orbitals. Extended conjugation lets carotenoids absorb visible light.
Singlet oxygen: Singlet oxygen is an electronically excited, highly reactive form of molecular oxygen. Carotenoids quench singlet oxygen before it damages cellular components.
Lutein: Lutein is a yellow xanthophyll found in leafy vegetables and concentrated in the human retina. It illustrates carotenoids’ dietary and visual-system roles.
Anthocyanin: Anthocyanins are water-soluble plant pigments that produce red, purple, and blue colors. Their water solubility and pH-sensitive colors differ from carotenoids’ lipid solubility.
Richard Willstätter: Richard Willstätter was a German chemist whose research established the structures of chlorophyll and other plant pigments. His pigment chemistry helped place carotenoids within plant biochemistry.

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