On one of the Down Syndrome listservs I am on, someone posted the info from this link ( about Idebenone. Idebenone is a synthetic “analogue” of Coenzyme Q10. Coenzyme Q10 is an anti-oxidant and Idebenone is a synthetic anti-oxidant.

          We do not recommend giving Idebenone, especially to Down Syndrome individuals. In the process of researching out Idebenone, we found that it actually increases superoxide formation (abstract below). It does have a bit of an anti-oxidant effect, but not all that well, since it is “effective” at promoting superoxide production. In Down Syndrome, there is already a lot of oxidative stress and overproduction of super oxide dismutase (SOD) going on (will get more info on the SOD issue soon, Lord willing!), thus they do not need something that will “help” that process out anymore.

Here is the abstract showing that Idebenone does encourage superoxide production:

The site of production of superoxide radical in mitochondrial Complex I is not a bound ubisemiquinone but presumably iron-sulfur cluster N2.

Genova ML, Ventura B, Giuliano G, Bovina C, Formiggini G, Parenti Castelli G, Lenaz G.

Dipartimento di Biochimica 'G. Moruzzi', Universita di Bologna, Via Irnerio 48, 40126, Bologna, Italy.

The mitochondrial respiratory chain is a powerful source of reactive oxygen species, considered as the pathogenic agent of many diseases and of aging. We have investigated the role of Complex I in superoxide radical production in bovine heart submitochondrial particles and found, by combined use of specific inhibitors of Complex I and by Coenzyme Q (CoQ) extraction from the particles, that the one-electron donor in the Complex to oxygen is a redox center located prior to the binding sites of three different types of CoQ antagonists, to be identified with a Fe-S cluster, most probably N2 on the basis of several known properties of this cluster. Short chain CoQ analogs enhance superoxide formation, presumably by mediating electron transfer from N2 to oxygen. The clinically used CoQ analog, idebenone, is particularly effective in promoting superoxide formation. (bold added)