What are the Most Important Components of Vitamin A?

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:
  1. Retinol – Vitamin A alcohol
  2. Retinal – Vitamin A aldehyde and
  3. Retinoic acid – Vitamin A acid.


The term Retinoids,  collectively refers to various forms of Natural & Synthetic Vitamin A.

  1. Retinol is a primary alcohol with a β-ionone ring and Unsaturated fatty acids.
  2. Retinal also called as Retinaldehyde is the aldehyde form of retinol.
  3. Retinoic acid is the oxidized form of retinal.
  4. 11-cis retinal is the isomer of all-trans retinal.
  5. β-carotene is found in plants. It yields 2 molecules of retinal upon oxidation.
All these lectures are organized and listed in detail in their proper sections. To view these lessons please visit the Vitamins Section in Biochemistry I. This can be approached by directly clicking the Biochemistry I button or it can also be approached from the drop down menu in Biochemistry I tab. Once you reach the section click the curriculum tab to view the full list in the section.
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