Digital Database of Absorption Spectra of Carotenoids Found in Food and Photosynthetic Organisms

Carotenoidsubiquitous pigments in the plant and animal kingdomplay roles in coloration, light-harvesting, photoprotection, and nutrition. More than 1200 carotenoids are known. The yellow, orange, or red color of carotenoids stems from absorption of light by the linear polyene chromophore. Here, a digital database of absorption spectra has been assembled for 44 naturally occurring carotenoids, which range from astaxanthin to zeaxanthin and encompass conjugation pathlengths from 7 (ζ-carotene) to 13 (spirilloxanthin) carbon-carbon double bonds. Three spectra are included for carotenoids that contain a central cis-configuration. The spectra encompass the often-neglected ultraviolet region (to 230 nm) and the well-known visible region (to 650 nm). An absorption spectrum of each carotenoid was recorded at room temperature in one or more solvents, and 27 carotenoids were examined at 77 K in frozen media. Altogether, 121 spectra were collected and have been made available in PhotochemCAD. The availability of curated digital spectra of diverse carotenoids enables comparison of structural effects and photophysical features, and should be particularly useful in studies of agriculture, ecology, nutrition, and photosynthesis.