Chemistry of Natural Retinoids and Carotenoids: Challenges for the Future

Natural retinoids, especially retinol, are present in all living organisms and are known as fundamental mediators for many biological processes. Recently, protective effects of carotenoids against severe diseases have encouraged exhaustive chemical and biochemical researches. The emphasis for the past twenty years has been the stereoselective syntheses of economically important retinoids and carotenoids, such as retinol, retinal, RAs, β-carotene, astaxanthin, lycopene etc. This review covers the major developments of synthetic chemistry on natural retinoids and carotenoids from 1990 to the present.