Carotenoid metabolic pathways and their functional role in health and diseases

Abstract In nature, carotenoids fulfill vital functions including photosynthesis, photoprotection, precursor for growth hormones, development of aroma, and flavor in certain plant sources. In humans, carotenoids are considered as vital source of provitamin A, macular pigments, and antioxidants offer frontline defense against cardiovascular diseases, age-related neurodegenerative disorders, and certain cancers. Owing to their structural and chemical properties, carotenoids are believed to be involved in oxidative reaction, cell signaling, and modulation of immune system. Carotenoids exhibit pro- and antioxidant actions, with varied selectivity in normal and stress condition or in cancer manifestations. Apart from these, carotenoid organization in membrane, absorption and distribution, biotransformation, and their possible pathways has been described. Further the property of carotenoids on the metabolism with respect to specific biological functions is addressed at physiological level. Also the significance of carotenoids and their derivatives are described vis a vis their role in humans and animals. Overall, this chapter described the metabolic pathways of few major carotenoids (β-carotene, lycopene, lutein, astaxanthin etc.) and their biofunctinality in cell models, animals and humans.