In Nature

Lutein is a yellow pigment belonging to the chemical family of carotenoids. It is synthesized by certain vegetables, marigold flowers, alfalfa and to a lesser degree in some other plants. Lutein was originally isolated from the corpus luteum, a part of the ovaries, and hence its name. Lutein derives its medical importance due to its presence in the macula of the eye where it is strongly implicated in maintaining eye health. Humans do not synthesize lutein and depend entirely on dietary sources such as vegetables or supplement.
Lutein is a yellow colored oxygenated derivative of a type of carotenoids called xanthophylls. It is chemically represented as dihydroxy carotenoid, ?-?-carotene-3, 3’-diol. Lutein is not produced in human body; hence, the requirements are fulfilled solely from the consumed fruits, leafy vegetables egg yolks and/or supplements.

Sources and Occurrence:

Lutein is widely present in the plant kingdom. Green vegetables, fruits like mango and papaya, red paprika, alfalfa, algae, yellow corn, etc. are fair sources of lutein. However, Marigold flower petals (Tagetes erecta) are among the richest sources of lutein. Marigold flower is commercially grown in Mexico, Peru, Ecuador, Spain and India. The dried flowers are used for obtaining marigold oleoresin, which can be subjected to further purification for enrichment of lutein esters or subjected to saponification process for obtaining lutein free of ester. The extract of marigold flower is mostly lipids and lutein esters. The other di- and mixed esters are distearate, myristate-palmitate, and palmitate-stearate present in small amounts. The dried marigold flower contains approximately 0.1 to 0.16 % carotenoids and the lutein esters account for 90% of the total carotenoids. The approximate carotenoid composition of marigold petals is 50% lutein dipalmitate, 30% lutein dimyristate, 6% lutein monoesters, 5% zeaxanthin esters and 9% unknown.

Lutein occurs naturally and is chemically more stable in the trans conformation. However, heat, light, oxygen, acid, etc. catalyze the isomerization from trans lutein to various mono and di cis- lutein forms.
Lutein was “discovered” in 1869 by Johann Ludwig Wilhelm Thudichum (1829–1901), a chemist at St. Thomas's Hospital in London, as a yellow crystallizable substance found in parts of plants and animals, which he named “luteine”' . In 1929, a new carotenoid was isolated from maize, named zeaxanthin, and characterized by the Swiss biochemist Paul Karrer (1889–1971).
Lutein and zeaxanthin contribute to yellow and orange yellow colour respectively. Lutein and zeaxanthin can be present in plant material in :

	In the free form in green leafy vegetables like spinach, kale and broccoli and
	In ester form(as fatty acid esters) in fruits such as mango, orange and papaya; red paprika, algae, yellow corn. Since preparation of a pure single xanthophylls ester on a large scale is difficult, the characterization of xanthophylls esters has not been studied completely.