Sigma-Aldrich Retinyl palmitate. Type IV, ~1,800,000 USP units/g, oil. 1 g

Retinal, retinol and retinoic acid are the aldehyde, alcohol and acid forms of vitamin A, respectively.[1] The retinoids comprise a cyclohexenyl ring with a 20-carbon with double bonds in cis and trans configuration.[1] Retinyl palmitate is a major storage form of vitamin A. Retinyl esters provide pools of vitamin A that are converted into retinol and other retinoids as needed.[2] Retinoids also exist as retinyl esters such as retinyl propionate, retinyl acetate and retinyl palmitate.[1]

Retinyl palmitate has been used as:

• a retinoid derivative to modulate expression of connexin Cx26 and Cx30 in the cochlea[3]
• a standard in high performance liquid chromatography(HPLC)
• as a retinoid substrate in the isomerase assay of eyecup protein homogenates[4]

Retinoids are ligands to nuclear receptors and have antioxidant functionality.[5] Retinyl palmitate is widely used in pharmaceutical and cosmetic applications.[1] In sunscreen, it protects from UVB-induced DNA damage and apoptosis.[6] Retinyl palmitate is used to treat photoaging in skincare cosmetics.[1] Retinyl palmitate is an effective chemopreventive agent to treat lung cancer.[7] It also regulates various biological processes including cell differentiation and proliferation.[1]

Review: Vitamin A metabolism.

Sealed ampule.

Oil at room temperature