The vitamin A metabolite retinol is essential for life, and has been shown to exhibit a diverse range of biological functions. Natural as well as synthetic molecules that are structurally related to vitamin A are referred to as retinoids, and typically consist of a polyene chain linking a cyclic end group to a polar end group (see Figure 1). Within the cell, retinoids function as signaling molecules, and play important roles in vision, embryonic development, cell proliferation, cell differentiation and immune functions.1 Vitamin A is stored intracellularly as retinyl esters, which after conversion to retinol, are oxidized to more bioactive retinaldehydes or retinoic acids. The structural abundance of retinoids (see Figure 2) and subsequent bioactivity allow for a variety of therapeutic applications within the pharmaceutical and cosmetic space.
