The Biochemistry Online – Free Online Lectures for Medical, Dental and Allied Health Sciences students by the Biochemistry Club.
Vitamin A (Fat Soluble Vitamin)
- Vitamin A is a Fat soluble vitamin.
- Its active form is only present in animals.
- In plants it is present in the form of a pro-vitamin called Beta-carotene.
- All the compounds with Vitamin A activity are referred to as Retinoids (Poly-isoprenoid compounds having a beta-ionone (cyclohexenyl) ring system).
- Three different compounds with Vitamin A activity are:
- Retinol – Vitamin A alcohol
- Retinal – Vitamin A aldehyde and
- Retinoic acid – Vitamin A acid.
The term Retinoids, collectively refers to various forms of Natural & Synthetic Vitamin A.
- Retinol is a primary alcohol with a β-ionone ring and Unsaturated fatty acids.
- Retinal also called as Retinaldehyde is the aldehyde form of retinol.
- Retinoic acid is the oxidized form of retinal.
- 11-cis retinal is the isomer of all-trans retinal.
- β-carotene is found in plants. It yields 2 molecules of retinal upon oxidation.