Occurrence of alpha-tocopherolquinone and alpha-tocopherolquinol in microorganisms

Both alpha-tocopherolquinol and alpha-tocopherolquinone were found in 56 of 93 strains of microorganisms examined. Organisms that contained these compounds included the single example of a eucaryotic alga, a Euglena, and a cyanobacterium (blue-green alga), 22 of 32 genera of bacteria, and 9 genera of yeasts. In the bacteria and yeasts the levels of quinone and hydroquinone were nearly equal and averaged about 3 nmol of each compound g-1 of packed cells. Included among the bacteria that contained these compounds were three examples from the newly proposed kingdom of Archaebacteriae. Those microorganisms that did not contain alpha-tocopherolquinol or alpha-tocopherolquinone tended to fall into two groups. One group consisted of gram-positive, anaerobic or facultative bacteria with a low content of guanine and cytosine, and the second group encompassed all of the filamentous microorganisms studied. No metabolic function is known for alpha-tocopherolquinol or its quinone other than as a cofactor in the biohydrogenation of unsaturated fatty acids that can be carried out by only a few organisms.