Biochemistry and Physiological Role

J L Napoli, University of California, Berkeley, CA, USA

© 2005 Elsevier Ltd. All rights reserved.

In 1913, E.V. McCollum isolated a yellow, fat-soluble substance from egg yolks that was critical for animal growth. He called it fat-soluble A, indicating the first isolated of several dietary microconsti-tuents emerging as obligatory for vertebrate life and health. Later, fat-soluble A was renamed vitamin A, derived from the terminology 'vital amine,' coined by Casmir Funk to describe these obligatory micronutrients.

Currently, the term vitamin A refers to the specific organic compound all-trans-retinol (atROH). atROH, however, does not have biological activity in its own right. Rather, it serves as a circulating substrate for metabolism into the compounds that fulfill the biological functions attributed to vitamin A. These metabolites include, but may not be limited to, 11-ds-retinal (11cROH) and all-trans--retinoic acid (atRA). The term 'retinoids' describes all compounds that support vitamin A activity, both naturally occurring and synthetic, including atROH. Figure 1 illustrates the structures of key carotenoids and retinoids.

Quick Permanent Weight Loss

Quick Permanent Weight Loss

A Step By Step Guide To Fast Fat Loss. Do you ever feel like getting rid of the extra weight of your body? If you do, it‟s quite normal because

Get My Free Ebook


Post a comment