BETATAB 7.5% SI

Carotenoids(/kəˈrɒtɪnɔɪd/) are yellow, orange, and redorganicpigmentsthat are produced byplantsandalgae, as well as several bacteria, archaea, andfungi.Carotenoids give the characteristic color topumpkins,carrots,parsnips,corn,tomatoes,canaries,flamingos,salmon,lobster,shrimp, anddaffodils.​‍​​​​​‍​‍‍‍‍​‍‍ Over 1,100 identified carotenoids can be further categorized into two classes –xanthophylls(which contain oxygen) andcarotenes(which are purelyhydrocarbonsand contain no oxygen). All arederivativesoftetraterpenes, meaning that they are produced from 8isopreneunits and contain 40 carbon atoms. In general, carotenoids absorb wavelengths ranging from 400 to 550 nanometers (violet to green light). This causes the compounds to be deeply colored yellow, orange, or red. Carotenoids are the dominant pigment inautumn leaf colorationof about 15-30% of tree species,but many plant colors, especially reds and purples, are due topolyphenols. Carotenoids serve two key roles in plants and algae: they absorb light energy for use inphotosynthesis, and they providephotoprotectionvianon-photochemical quenching.Carotenoids that contain unsubstituted beta-ionone rings (includingβ-carotene,α-carotene,β-cryptoxanthin, andγ-carotene) havevitamin Aactivity (meaning that they can be converted toretinol). In the eye,lutein,meso-zeaxanthin, andzeaxanthinare present asmacular pigmentswhose importance in visual function, as of 2016, remains underclinical research.