Carotenoids are essential pigments in photosynthetic organs along with chlorophylls. Carotenoids also act as photo-protectors, antioxidants, color attractants, and precursors of plant hormones in non-photosynthetic organs of plants.
Carotenoids are the precursors for biosynthesis of plant growth regulators and protect photosynthetic apparatus by quenching harmful ROS (reactive oxygen species).
Plants can be selectively bred to contain higher carotenoid content, making them better sources of the carotenoid in question, and can be supplemented in the human diet to influence development, maturation, and nutritional status.
Carotenoids are divided into two groups: carotenes and xanthophylls. Carotenes, such as α-carotene, β-carotene, β,ψ-carotene (γ-carotene), and lycopene, are hydrocarbons. About 50 kinds of carotenes are present in nature.
Xanthophylls, which are essentially oxidation products of the carotenes, include lutein, zeaxanthin, canthaxanthin, and β-cryptoxanthan. α-carotene possesses 50–54% and ϵ -carotene 42–50% of the antioxidant activity as compared to β -carotene.
Carotenoids occur widely in nature and, in general, all fruits and vegetables of color are good sources of these compound. Carotenoids are most concentrated in green leafy vegetables (e.g., kale, spinach, collards, and mustard greens) and colored fruits (e.g., kiwi, tomatoes).
Carotenoids
