Xanthophylls (originally phylloxanthins) are yellow pigments of oxycarotenoid type, from the carotenoid group. Thier chemical structure is C40H54(OH)2.They are found in the leaves of most plants and are synthesized within the plastids. They are involved in photosynthesis along with green chlorophyll, which typically covers up the yellow except in autumn, when the chlorophyll is denatured by the cold.