Characterisation of Carotenoids Involved in the Xanthophyll Cycle

Carotenoids are known for versatile roles they play in living organisms; however, their most pivotal function is involvement in scavenging reactive oxygen species (ROS) and photoprotection. In plant kingdom, an important photoprotective mechanism, referred to as the xanthophyll cycle, has been developed by photosynthetic organism to avoid excess light that might lead to photoinhibition and inactivation of photosystems and induce the formation of reactive oxygen species (ROS), resulting in photodamage and long-term changes in the cells caused by oxidative stress. Apart from high-light driven enzymatic conversion of violaxanthin (Viola) to zeaxanthin (Zea) that occurs mostly in higher plants, mosses and lichens, other less known types of the xanthophyll cycle have been hitherto described. The work is aimed at summarising the current knowledge on the pigments engaged in the xanthophyll cycles operating in various organisms