Molecular Structure

Most carotenoids are derived from a 40-carbon basal structure that includes a system of conjugated double bonds [1]. The pattern of conjugated double bonds in the carotenoid backbone determines their light absorbing properties and antioxidant ability of carotenoids. In addition, the number of double bonds enable several cis or trans-configurations of a given carotenoid molecule. While the all-trans forms are predominant in nature generally, carotenoids tend to isomerize and form a mixture of mono- and poly-cis-isomers apart from the all-trans form [2].

Figure 1: The molecular Structure of major carotenoids in human plasma
Figure 1: The molecular Structure of major carotenoids in human plasma [3]

References:

  1. Britton, G. (1995). Structure and Properties of Carotenoids In Relation To Function. The FASEB Journal, 9, 1551-1558.
  2. Stahl, W., Schwarz, W., & Sies, H. (1993). Human Serum Concentrations of All-Trans Beta-And Alpha-Carotene but Not 9-Cis Beta-Carotene Increase upon Ingestion of a Natural Isomer Mixture Obtained from Dunaliella salina (Betatene). The Journal of Nutrition, 123, 847-851.
  3. Fiedor, J., & Burda, K. (2014). Potential Role of Carotenoids as Antioxidants in Human Health and Disease. Nutrients, 6, 466-488.