Retinyl acetate: a naturally occurring fatty acid ester form of retinol

Introduction

Retinyl acetate (IUPAC name: all-(E)-3,7-dimethyl-9-(2,6,6-trimethyl-1-cyclohex-1-enyl)nona 2,4,6,8-tetraen-1-yl acetate; synonyms: retinol acetate, vitamin A acetate, all-trans vitamin A acetate, all-(E)-retinol acetate) is identified by Chemical Abstracts Service (CAS) number 127-47-9 and European Inventory of Existing Chemical Substances (EINECS) number 204-884-2.

Chemical property

The molecular formula of retinyl acetate is C22H32O2, and its molecular weight is 328.5. It has a melting point of 53–59 ℃ (pure), a density of 0.91–0.92 g/cm3 (20 °C, stabilised) and an octanol/water partition coefficient of 7.3 (pure). It is insoluble in water and glycerol and soluble in organic solvents such as anhydrous ethanol (25 mg/mL), methanol, chloroform and ethers, fats and oils. Retinyl acetate appears as yellowish crystals or crystalline powder. By specification, the active substance has a minimum vitamin A activity of 2.76 × 106 IU/g.

Biological activity

Retinyl Acetate is a naturally occurring fatty acid ester form of retinol (vitamin A) with potential antineoplastic and chemopreventive activities. Retinyl acetate binds to and activates retinoid receptors, inducing cell differentiation and decreasing cell proliferation. This agent also inhibits carcinogen-induced neoplastic transformation in some cancer cell types and exhibits immunomodulatory properties.

Vitamin A and retinyl acetate

Vitamin A is available in dietary supplements, usually in retinyl acetate or retinyl palmitate (preformed vitamin A), beta-carotene (provitamin A), or a combination of preformed and provitamin A. Most multivitamin/mineral supplements contain vitamin A. Dietary supplements that contain only vitamin A are also available. Human studies often feed vitamin A in retinyl acetate or retinyl palmitate, the two most common forms of vitamin A also used to supplement dairy and fortified cereals.

References

[1] on Additives, EFSA Panel and Products or Substances used in Animal Feed (FEEDAP). “Scientific Opinion on the safety and efficacy of vitamin A (retinyl acetate, retinyl palmitate and retinyl propionate) as a feed additive for all animal species and categories.” EFSA Journal 11 1 (2013).