Coenzyme Q. LX. Vitamin-Like Activity of Coenzyme Q. ∗

Summary

Vitamin-like activity for hexahydrocoenzyme Q₄ in the dystrophic rabbit is demonstrated. This activity for a quinone member of the CoQ group is comparable to the activity of α-tocopherol and CoQ₄-chromanol which has previously been demonstrated. By contrast, a sample of 2,3,5-trimethyl-6-phytylbenzoquinone, which was free of contamination with α-tocopherol, exhibited only a low order of activity in the dystrophic rabbit. The dystrophic rabbit failed to recover when coenzyme Q₁₀ was administered orally; it is apparent that the administered CoQ₁₀ failed to reach its mitochondrial and microsomal sites since a lower homolog, hexahydrocoenzyme Q₄, exhibits activity in the dystrophic rabbit. It is considered that CoQ₁₀, which is normally present in rabbit tissue, does inherently have this vitamin-like activity.