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Carotenoids are produced by all photosynthetic organisms and are primarily used as accessory pigments to chlorophyll in the light-harvesting part of photosynthesis. They are highly unsaturated with conjugated double bonds , which enables carotenoids to absorb light of various wavelengths .
Carotenes contribute to photosynthesis by transmitting the light energy they absorb to chlorophyll. They also protect plant tissues by helping to absorb the energy from singlet oxygen, an excited form of the oxygen molecule O 2 which is formed during photosynthesis.
In plants, carotenoids can occur in roots, stems, leaves, flowers, and fruits. Carotenoids have two important functions in plants. First, they can contribute to photosynthesis. They do this by transferring some of the light energy they absorb to chlorophylls, which then uses this energy for photosynthesis. Second, they can protect plants which ...
The carotenoids have another role as an antioxidant to prevent photo-oxidative damage of chlorophyll molecules. Each antenna complex has between 250 and 400 pigment molecules and the energy they absorb is shuttled by resonance energy transfer to a specialized chlorophyll-protein complex known as the reaction center of each photosystem . [ 1 ]
In addition, there are many non-chlorophyll accessory pigments, such as carotenoids or phycobiliproteins, which also absorb light and transfer that light energy to photosystem chlorophyll. Some of these accessory pigments, in particular the carotenoids, also serve to absorb and dissipate excess light energy, or work as antioxidants. [1]
Carotenoids with preferential affinity to different organs may serve as a vector for the whole particles and for more targeted delivery of their “cargo” of bioactive molecules. Inclusion of carotenoids into complexes with hydrophobic bioactive molecules, which have metabolic or therapeutic targets in particular organs, can reduce their ...
Like other carotenoids, xanthophylls are found in highest quantity in the leaves of most green plants, where they act to modulate light energy and perhaps serve as a non-photochemical quenching agent to deal with triplet chlorophyll (an excited form of chlorophyll), [citation needed] which is overproduced at high light levels in photosynthesis ...
Lutein (/ ˈ lj uː t i ɪ n,-t iː n /; [2] from Latin luteus meaning "yellow") is a xanthophyll and one of 600 known naturally occurring carotenoids.Lutein is synthesized only by plants, and like other xanthophylls is found in high quantities in green leafy vegetables such as spinach, kale and yellow carrots.